Sample records for relief valve opening

  1. Adjustable safety relief valve

    Taylor, W.L.


    This patent describes a pressure relief valve having a relief set pressure. It comprises: a valve body having a fluid inlet and outlet, a spherical, metal valve seat associated with the inlet and a valve member comprising at least a portion of a spherical,metal ball attached to a ball holding element, the valve member being biased against the valve seat and thus providing a metal-to-metal seal preventing the passage of fluids past the valve seat when the fluid pressure in the inlet is below the relief pressure setting of the valve.

  2. Vent Relief Valve Test


    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  3. Pressure relief valve/safety relief valve testing

    Murray, W.A.; Hamm, E.R.; Barber, J.R.


    Pressure vessels and piping systems are protected form overpressurization by pressure relief valves. These safety features are required to be tested-inspected on some periodic basis and, in most cases witnessed by a third party inspector. As a result nonconformances found by third parties Westinghouse Hanford Company initiated a task team to develop a pressure safety program. This paper reveals their findings.

  4. Analysis of a loss of feedwater transient with safety/relief valve stuck open in Chin Shan Nuclear Power Station

    Liao, L.Y.; Guey, C.N.; Chen, Y.B.; Lee, C.H.


    An analysis has been made with RELAP 4/MOD5 to simulate the system behavior of loss of feedwater transient with safety/relief valve stuck open in Chin Shan BWR. The initial conditions have been established with 105% rated power and 105% flow rate. System variables such as normalized power, steam dome pressure, core inlet flow rate, fuel cladding temperatures, separator mixture level, downcomer mixture level, and core inlet enthalpy have been calculated. A comparison has also been made between the results obtained and those documented in FSAR. It is observed that the general trends of system parameters in both cases are similar, differing slightly only in the timing of the sequence of events postulated to occur. The possibility of idling of ECCS as a result of pool swelling is ruled out. Core uncovery is not observed. In conclusion, the accident analyzed can be accommodated by the design incorporated in the Chin Shan Plant.

  5. Improved Relief Valve Would Be Less Susceptible to Failure

    Farner, Bruce R.


    The balanced-piston relief valve with side vented reaction cavity has been proposed as an improved alternative to a conventional high-pressure, high-flow relief valve. The proposed valve would be less susceptible to failure. A typical conventional high-pressure, high-flow relief valve contains a piston that is exposed to the upstream pressure across the full valve-seat diameter and is held against the valve seat and the upstream pressure by a large spring. In the event of an increase in upstream pressure to a level above the valve set point (the pressure above which the valve opens), the opening force on the piston can be so large that the piston becomes accelerated to a speed high enough that the ensuing hard impact of the piston within the valve housing results in failure of the valve. For a given flow cross section, the proposal would significantly reduce the force, thereby reducing susceptibility to failure. A basic version of the proposed balanced-piston relief valve with side vented reaction cavity is described.

  6. Inexpensive tamper proof safety relief valve

    Frankewich, P. A.


    Basic relief valve has added safety relief valve capability that relieves overpressure before failure can occur. It may be installed in inaccesible areas with a high degree of reliability, constructed from a variety of materials, and adapted to the user's specific application.

  7. LOFT pressurizer safety: relief valve reliability

    Brown, E.S.


    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice.

  8. Safety/relief-valve test program

    Hunter, J.A.


    In response to the NRC's Task 2.1.2 following the TMI-2 accident, government and industry programs were formulated to address the performance of safety and relief valve systems for pressurized and boiling water reactors. Objective is to demonstrate by testing and analysis that safety and relief valve systems in the reactor coolant system are qualified for the anticipated full range of reactor operating and accident conditions. The EPRI PWR program tested PWR safety valves and power operated relief valves (PORVs) under steam, liquid, and steam/liquid transition conditions. The program also tested PWR PORV block valves under steam conditions. The GE BWR program tested BWR relief and safety/relief valves under high pressure steam and low pressure liquid conditions. EG and G Idaho recent activities have focused on the evaluation of the industry test data, evaluation and modification of analytical codes for safety/relief valve system analysis, and initial evaluation of utility responses to US NRC program requirements.

  9. 46 CFR 154.806 - Capacity of pressure relief valves.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Capacity of pressure relief valves. 154.806 Section 154... Equipment Cargo Vent Systems § 154.806 Capacity of pressure relief valves. Pressure relief valves for each... pressure above the set pressure of the relief valves: (a) The maximum capacity of an installed cargo...

  10. Glovebox pressure relief and check valve

    Blaedel, K.L.


    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

  11. Coincident steam generator tube rupture and stuck-open safety relief valve carryover tests: MB-2 steam generator transient response test program

    Garbett, K; Mendler, O J; Gardner, G C; Garnsey, R; Young, M Y


    In PWR steam generator tube rupture (SGTR) faults, a direct pathway for the release of radioactive fission products can exist if there is a coincident stuck-open safety relief valve (SORV) or if the safety relief valve is cycled. In addition to the release of fission products from the bulk steam generator water by moisture carryover, there exists the possibility that some primary coolant may be released without having first mixed with the bulk water - a process called primary coolant bypassing. The MB-2 Phase II test program was designed specifically to identify the processes for droplet carryover during SGTR faults and to provide data of sufficient accuracy for use in developing physical models and computer codes to describe activity release. The test program consisted of sixteen separate tests designed to cover a range of steady-state and transient fault conditions. These included a full SGTR/SORV transient simulation, two SGTR overfill tests, ten steady-state SGTR tests at water levels ranging from very low levels in the bundle up to those when the dryer was flooded, and three moisture carryover tests without SGTR. In these tests the influence of break location and the effect of bypassing the dryer were also studied. In a final test the behavior with respect to aerosol particles in a dry steam generator, appropriate to a severe accident fault, was investigated.

  12. Refuge alternatives relief valve testing and design.

    Lutz, T J; Bissert, P T; Homce, G T; Yonkey, J A


    The U.S. National Institute for Occupational Safety and Health (NIOSH) has been researching refuge alternatives (RAs) since 2007. RAs typically have built-in pressure relief valves (PRVs) to prevent the unit from reaching unsafe pressures. The U.S. Mine Safety and Health Administration requires that these valves vent the chamber at a maximum pressure of 1.25 kPa (0.18 psi, 5.0 in. H2O), or as specified by the manufacturer, above mine atmospheric pressure in the RA. To facilitate PRV testing, an instrumented benchtop test fixture was developed using an off-the-shelf centrifugal blower and ductwork. Relief pressures and flow characteristics were measured for three units: (1) a modified polyvinyl chloride check valve, (2) an off-the-shelf brass/cast-iron butterfly check valve and (3) a commercially available valve that was designed specifically for one manufacturer's steel prefabricated RAs and had been adapted for use in one mine operator's built-in-place RA. PRVs used in tent-style RAs were not investigated. The units were tested with different modifications and configurations in order to check compliance with Title 30 Code of Federal Regulations, or 30 CFR, regulations. The commercially available relief valve did not meet the 30 CFR relief pressure specification but may meet the manufacturer's specification. Alternative valve designs were modified to meet the 30 CFR relief pressure specification, but all valve designs will need further design research to examine survivability in the event of a 103 kPa (15.0 psi) impulse overpressure during a disaster.

  13. Emergency relief system design: The DIERS users group safety relief valve example problem

    Fisher, H.G. [Union Carbide Corp., South Charleston, WV (United States)


    Emergency relief system design involving two-phase flow is an evolving and complex technology. Aspects of alternative design techniques have been published. Well-documented, comprehensive design methods for safety relief valves, rupture disks and breather vents, however, are not readily available and example problems supported by data do not exist. Design Institute for Emergency Relief Systems (DIERS) Users Group members recently completed an example rating problem consisting of a safety relief valve mounted in a typical industrial configuration. Participants were asked to compute the flow through the device and to calculate the inlet pipe irreversible pressure loss and discharge pipe back pressure. Case studies involving various flows and physical conditions were formulated. A {open_quotes}Modified Delphi{close_quotes} technique was used to encourage participants to work until the {open_quotes}consensus{close_quotes} result was achieved. The exercise served to educate participants in the complexities and subtleties of emergency relief system design involving safety relief installations as compared to ideal nozzle calculations. All learned from the various calculation techniques used by others to solve the problem. Participants corrected parts of their computer codes and/or added procedures to address aspects of the problem. The present example problem is not supported by data. Available safety relief valve two-phase flow data suggest complexity not presently included in problem solutions. Future modification of the results may be required as additional considerations are incorporated into existing analytical methods and computer codes. 20 refs., 21 tabs.

  14. Mechanical Designs for Relief Valves for Cryogenic Apparatuses and Installations

    CERN. Geneva


    There are also pressure relief valves with warm seat available on which the set pressure is based on an adjustment of forces by permanent magnets. Pressure vessel rules allows also the choice for an active triggered pressure relief valve (Cont...

  15. 46 CFR 154.519 - Piping relief valves.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Piping relief valves. 154.519 Section 154.519 Shipping... Process Piping Systems § 154.519 Piping relief valves. (a) The liquid relief valve that protects the cargo piping system from liquid pressure exceeding the design pressure must discharge into: (1) A cargo...

  16. 46 CFR 98.25-60 - Safety relief valves.


    ... 46 Shipping 4 2010-10-01 2010-10-01 false Safety relief valves. 98.25-60 Section 98.25-60 Shipping... § 98.25-60 Safety relief valves. (a) Each tank shall be fitted with two or more approved safety relief valves, designed, constructed, and flow-tested for capacity in conformance with subpart 162.018...

  17. 46 CFR 154.1846 - Relief valves: Changing set pressure.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Relief valves: Changing set pressure. 154.1846 Section... Relief valves: Changing set pressure. The master shall: (a) Supervise the changing of the set pressure of relief valves under § 154.802(b); (b) Enter the change of set pressure in the vessel's log; and...

  18. PWR safety and relief valve test program. Valve selection/juftification report. Final report


    NUREG 0578 required that full-scale testing be performed on pressurizer safety valves and relief valves representative of those in use or planned for use in PWR plants. To obtain valve performance data for the entire population of PWR plant valves, nine safety valves and ten relief valves were selected as a fully representative set of test valves. Justification that the selected valves represent all PWR plant valves was provided by each safety and relief valve manufacturer. Both the valve selection and justification work was performed as part of the PWR Safety and Relief Valve Test Program conducted by EPRI on behalf of the PWR utilities in response to the recommendations of NUREG 0578 and the requirements of the NRC. Results of the Safety and Relief Valve Selection and Justification effort is documented in this report.

  19. 氮气式水击泄压阀初启阶段动态特性研究%Study on dynamic characteristics of nitrogen surge relief valve in opening process

    李树勋; 王虎斌; 范宜霖; 徐晓刚


    For the requirements that nitrogen‐type pressure relief valve for petrol gathering pipeline should open quickly ,close slowly and release largely at a small opening degree ,principle and dynamic characteristic of nitrogen‐type pressure relief valve were analyzed in theory and simulated .After the a‐nalysis of opening and closing process on nitrogen‐type pressure relief valve ,the valve core dynamics equations and spring stiffness expression were established ,and ANSYS CFX software was used to dy‐namically simulate nitrogen‐type surge relief valve′s initial opening process on this basis .The medium velocity and turbulent energy change process in the initial opening process of the relief valve core seal‐ing surface were analyzed ,and the influences of different pressure and the valve core chamber nitrogen pressure of relief valve on dynamic characteristic were discussed .%针对石油集输管网中氮气式水击泄压阀快开慢关、小开度下大泄放量的要求,对氮气式水击泄压阀的工作原理及初启阶段动态特性进行理论分析及仿真研究。通过对氮气式水击泄压阀开启过程的分析,建立阀芯动力学方程及阀芯腔室近似氮气弹簧刚度表达式,在此基础上运用ANSYS CFX软件进行了泄压阀初启阶段动态仿真模拟,研究了在泄压阀初启阶段阀芯密封面处介质流速及湍动能的变化过程,并分析了不同超压比和阀芯腔室氮气压力对泄压阀初启阶段动态特性的影响。

  20. Study of safety relief valve operation under ATWS conditions. [PWR

    Hutmacher, E.S.; Nesmith, B.J.; Brukiewa, J.B.


    A literature survey and analysis project has been performed to determine if recent (since mid-1975) data has been reported which could influence the current approach to predicting PWR relief valve capacity under ATWS conditions. This study was conducted by the Energy Technology Engineering Center for NRC. Results indicate that the current relief valve capacity model tends to predict less capacity than actually obtains; however, no experimental verification at PWR ATWS conditions was found. Other project objectives were to establish the availability of methods for evaluating reaction forces and back pressure effects on relief valve capacity, and to determine if facilities exist which are capable of testing PWR relief valves at ATWS conditions.

  1. The development of safety relief valve for nuclear service

    Kim, Chil Sung; Kim, Kang Tae; Kim, Ji Heon; Jang, Ki Jong [Smart Valve Com., Seoul (Korea, Republic of); Hong, Kee Seong [Korea Hydro and Nuclear Power Co., Ltd., Seoul (Korea, Republic of)


    Safety relief valve is the important equipment used to protect the pressure facility from overpressure. The objective of the study is the development of safety relief valve which protects the boiler and pressure vessel from over pressure by discharging or sucking the operating medium when the pressure of system is reaching the set pressure of the system. It is important to find out the relationship between trim shape and performance, so the characteristics of flow field at the inside of safety relief valve were investigated through computational fluid dynamics analysis. The study shows that safety relief valve is developed though the design using the analysis between flow characteristics and spring force, the experiential verification.

  2. Mitral valve surgery - open

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Mitral Valve Prolapse Browse the Encyclopedia A.D. ...

  3. EPRI PWR Safety and Relief Value Test Program: safety and relief valve test report


    A safety and relief valve test program was conducted by EPRI for a group of participating PWR utilities to respond to the USNRC recommendations documented in NUREG 0578 Section 2.1.2, and as clarified in NUREG 0737 Item II.D.1.A. Seventeen safety and relief valves representative of those utilized in or planned for use in participating domestic PWR's were tested under the full range of selected test conditions. This report contains a listing of the selected test valves and the corresponding as tested test matrices, valve performance data and principal observations for the tested safety and relief valves. The information contained in this report may be used by the participating utilities in developing their response to the above mentioned USNRC recommendations.

  4. Aortic valve surgery - open

    ... Saunders; 2012:chap 61. Otton CM, Bowow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  5. Assessment of SWBR safety-relief valve discharge line dynamic loads due to steam blowdown

    Spoelstra, S.; Stoop, P.M. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Dijk, A.B. van [Stork Nucon BV (Netherlands)


    The Safety/Relief Valve Discharge Lines of the SBWR nuclear power plant are subject to dynamic loads due to steam blowdown after rapid opening of the Safety/Relief Valves. This paper describes the calculation of the thermal-hydraulic loads exerted on the piping system and the calculation of the resulting pipe stresses. These calculations have been performed using the CHARME and PS+CAEPIPE computer programs respectively. The calculated pipe stresses have been combined with the ones resulting from dead weight and thermal expansion and compared with ASME III criteria. (orig.).

  6. Rapidly design safety relief valve inlet piping systems

    Westman, M.A.


    Safety relief valves (SRVs) used to protect against overpressure require well-designed inlet piping for proper operation. The engineer`s job is to produce these designs from a thorough understanding of the inlet piping as a key component in the safety relief system and the correct application of the governing fluid dynamics principles. This article will present a technique for analysis and design using classical ideal-gas adiabatic fluid flow principles. Also, it will discuss the advantages of using the personal computer (PC) to quickly arrive at accurate designs. This work applies to SRVs in which relief flows are limited by sonic conditions at their nozzles.

  7. 49 CFR 230.49 - Setting of safety relief valves.


    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and... safety relief valves, two steam gauges shall be used, one of which must be so located that it will be in... varies more than 3 psi they shall be removed from the boiler, tested, and corrected before the...

  8. Presentation of the development of the SRV valve (safety relief valve); Presentation du developpement de la vanne SRV (Safety Relief Valve)

    Manguette, P. [Adareg, 59 - Haubourdin (France)


    Adareg has 30 years experience in Hydrane and control valves. Its know-how moves towards extreme technologies: control of all types of fluids (hot, cold, aggressive ones, clean ones etc... ). A perfect control is essential for very low temperatures (nuclear submarines, Ariane). Adareg Research and Development activities, certified ISO 9001, have developed valves accepting temperatures reaching 2 degrees above the absolute 0. Increasing requirements concerning low temperatures have encouraged Adareg to develop a research programme in partnership with CEA - French Atomic Energy Commission - for valves type 'SRV' (Safety Relief Valves). This type of valve is designed for a new accelerator of particles, the LHC, at CERN, in Geneva. (author)

  9. 49 CFR 179.220-24 - Tests of pressure relief valves.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Tests of pressure relief valves. 179.220-24 Section 179.220-24 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS...-24 Tests of pressure relief valves. Each safety relief valve must be tested by air or gas...

  10. 46 CFR 38.25-10 - Safety relief valves-TB/ALL.


    ... 46 Shipping 1 2010-10-01 2010-10-01 false Safety relief valves-TB/ALL. 38.25-10 Section 38.25-10... and Inspections § 38.25-10 Safety relief valves—TB/ALL. (a) The cargo tank safety relief valves shall be inspected at least once in every 2 years. (b) The safety relief valve discs must be lifted...

  11. Acoustic Resonance Frequency Elimination Device for Safety Relief Valves

    Redmond, J.


    Industry experience has shown that Safety Relief Valves (SRVs) and Steam Dryers installed in Boiling Water Reactors (BWRs) experience vibration induced degradation and failures caused by acoustic resonance vibration of the main steam lines, resulting in decreased reliability and potential safety issues. The resonance is caused by vortex shedding from the standpipe inlet and acoustic standing waves in the standpipe, occurring when the two frequencies match. (Author)

  12. PWR safety/relief valve blowdown analysis experience

    Lee, M.Z.; Chou, L.Y.; Yang, S.H. (Gilbert/Commonwealth Engineers and Consultants, Reading, PA (USA). Speciality Engineering Dept.)


    The paper describes the difficulties encountered in analyzing a PWR primary loop pressurizer safety relief valve and power operated relief valve discharge system, as well as their resolution. The experience is based on the use of RELAP5/MOD1 and TPIPE computer programs as the tools for fluid transient analysis and piping dynamic analysis, respectively. General approaches for generating forcing functions from thermal fluid analysis solution to be used in the dynamic analysis of piping are reviewed. The paper demonstrates that the 'acceleration or wave force' method may have numerical difficulties leading to unrealistic, large amplitude, highly oscillatory forcing functions in the vicinity of severe flow area discontinuities or choking junctions when low temperature loop seal water is discharged. To avoid this problem, an alternate computational method based on the direct force method may be used. The simplicity and superiority in numerical stability of the forcing function computation method as well as its drawbacks are discussed. Additionally, RELAP modeling for piping, valve, reducer, and sparger is discussed. The effects of loop seal temperature on SRV and PORV discharge line blowdown forces, pressure and temperature distributions are examined. Finally, the effects of including support stiffness and support eccentricity in piping analysis models, method and modeling relief tank connections, minimization of tank nozzle loads, use of damping factors, and selection of solution time steps are discussed.

  13. 49 CFR 179.100-19 - Tests of safety relief valves.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Tests of safety relief valves. 179.100-19 Section 179.100-19 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS...) § 179.100-19 Tests of safety relief valves. (a) Each valve shall be tested by air or gas for...

  14. 49 CFR 179.200-23 - Tests of pressure relief valves.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Tests of pressure relief valves. 179.200-23 Section 179.200-23 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS...-23 Tests of pressure relief valves. (a) Each valve shall be tested by air or gas for compliance...

  15. 49 CFR 179.400-21 - Test of pressure relief valves.


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Test of pressure relief valves. 179.400-21 Section 179.400-21 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS...-113 and 107A) § 179.400-21 Test of pressure relief valves. Each valve must be tested with air or...

  16. The Design of Impact Test-Bed for High-Flow Water Medium Relief Valve

    Junliang Chang


    Full Text Available Water medium hydraulic systems are widely used in coal mining machinery. As the power of hydraulic system becomes higher, the flow and pressure of water medium relief valve are also higher, and the flow may reach 2000 L/min. However, there is no relevant test-bed which could provide instantaneous high-pressure and high-flow to support the experiment for high-flow relief valve; consequently, this impact test-bed for high-flow water medium relief valve is designed to satisfy fast loading demand. Through building model, simulation analysis, and construction of an impact test-bed of high-flow water medium relief valve, the dynamic performance of high-flow water medium relief valve is detected. The setting pressure of relief valve, the accumulator volume and the filling fluid pressure, and the damping of cartridge valve can be changed, and the dynamic performance of high-flow water medium relief valve under different impact loads is detected. The results show that the designed impact test-bed of high-flow water medium relief valve could provide required high-pressure and high-flow emulsion for the tested water medium relief valve, and it could control the strength of impact load, which is an energy saving, high efficiency, and low cost method.

  17. Excessive blowdown: leads to relief valve slowdowns: Difference in force balance between closed and open valve states determines the extent of the blowdown, which necessitates careful adjustment of seat and poppet dimensions

    Archer, Robert


    ... of the valve. [FIGURE 1 OMITTED] For the valve shown in Figure 1, fluid flow occurs across the seat area [A.sub.1] (an orifice) and is driven by the pressure difference between [p.sub.1] and [p.sub.0]. Normally, this backpressure eventually leads to a sump at atmospheric pressure, such as a reservoir. Sometimes, however, the diameter of downstream t...

  18. Study on hydraulic direct-acting relief valve

    Syrkin, V. V.; Balakin, P. D.; Treyer, V. A.


    Valves with elastic shut-off-and-regulating elements are increasingly applied in hydraulic systems, working in conditions of excessive vibrations. The objective of this study is to determine the dynamic characteristics of regulators with shut-off-and- regulating elements. The method of phase trajectories establishes the controller’s parameters and modes, which provide its work stability. The authors receive dynamic characteristics providing the absence of self-oscillations at the expense of additional damping of the shut-off- and-regulating element. They make a test sample of the pressure regulator with an elastic shut-off-and-regulating element. The article defines the characteristics curve of the pressure regulator (direct operated pressure relief valve) from the initial conditions. The obtained results can be used, when designing hydraulic technological machines. Keywords - oscillation damping, an elastic shut-off-and regulating element.

  19. Safety relief valve instabilities; Instabiles Verhalten beim Betrieb von direkt belasteten Sicherheitsventilen

    Neuhaus, Thorsten; Bloemeling, Frank; Jung, Andreas; Schaffrath, Andreas [TUeV NORD SysTec GmbH und Co. KG, Hamburg (Germany)


    The opening and closing of safety relief valves induce pressure vibrations and respective loads on the piping system. The quantification of the internal pressure load and the pipe segment forces for the proof of the structural integrity of the piping system and the supports is performed using the code DYVRO. It is not clear whether the calculated result of high-frequent opening and closing shows a realistic behavior or is caused by a simplified modeling. The contribution offers strategic recommendations to avoid unrealistic calculations.

  20. Summary of safety relief valve position indication systems

    Cybulski, D.S.; Walter, J.F.


    Mainly as a result of the Three Mile Island-2 (TMI-2) incident, the US Nuclear Regulatory Commission's Regulatory Guide 1.97 instituted criteria recommendations for monitoring variables to: 1. provide information required to permit the operator to take preplanned manual actions to accomplish safe plant shutdown; 2. determine important to safety are performing their functions...; and 3. provide information to the operators that will enable them to determine the potential for causing a gross breach of the barriers to radioactivity release.... This report surveys the methodologies employed in nuclear plants to monitor Type D variables as referred to in Regulatory Guide 1.97. Type D are those variables that provide information to indicate the operation of individual safety systems and other systems important to safety. The specific Type D variable addressed is safety relief valve (i.e., spring style safety relief valve) position indication. The application criteria for each of the methodologies surveyed is as described in Regulatory Guide 1.97. That is, minimally to provide light indications of closed/not closed positions.

  1. 46 CFR 58.16-15 - Valves and safety relief devices.


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Valves and safety relief devices. 58.16-15 Section 58.16... AUXILIARY MACHINERY AND RELATED SYSTEMS Liquefied Petroleum Gases for Cooking and Heating § 58.16-15 Valves and safety relief devices. (a) Each cylinder shall have a manually operated screw-down shutoff...

  2. 46 CFR 38.10-15 - Safety relief valves-TB/ALL.


    ... 46 Shipping 1 2010-10-01 2010-10-01 false Safety relief valves-TB/ALL. 38.10-15 Section 38.10-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Piping, Valves, Fittings, and Accessory Equipment § 38.10-15 Safety relief valves—TB/ALL. (a) Each tank shall be...

  3. 77 FR 59408 - Finding of Equivalence; Alternate Pressure Relief Valve Settings on Certain Vessels Carrying...


    ... SECURITY Coast Guard Finding of Equivalence; Alternate Pressure Relief Valve Settings on Certain Vessels... Coast Guard announces the availability of CG-ENG Policy Letter 04-12, ``Alternative Pressure Relief Valve Settings on Vessels Carrying Liquefied Gases in Bulk in Independent Type B and Type C...

  4. 46 CFR 56.50-25 - Safety and relief valve escape piping.


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Safety and relief valve escape piping. 56.50-25 Section 56.50-25 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-25 Safety and relief valve escape piping. (a) Escape piping...

  5. Analytical model for computing transient pressures and forces in the safety/relief valve discharge line. Mark I Containment Program, task number 7. 1. 2

    Wheeler, A.J.


    An analytical model is described that computes the transient pressures, velocities and forces in the safety/relief valve discharge line immediately after safety/relief valve opening. Equations of motion are defined for the gas-flow and water-flow models. Results are not only verified by comparing them with an earlier version of the model, but also with Quad Cities and Monticello plant data. The model shows reasonable agreement with the earlier model and the plant data.

  6. Specifications and Performances of Series Superfluid Helium Safety Relief Valves for the LHC

    Perin, A.; Fontanive, V.


    Protecting the LHC magnets requires safety relief valves operating with 1.9 K pressurized superfluid helium at their inlet. Following the evaluation of prototype valves, a specification for the production of the 360 safety relief valves needed for the LHC was issued. The production of the safety valves was then awarded to an industrial contractor. The performances of pre-series valves were assessed for a variety of aspects including thermal performance, leak tightness in superfluid helium, dynamic behavior and resistance to intensive mechanical cycling. After the initial validation phase the series production was completed within the technical requirements of the specification. This paper describes the characteristics of the safety relief valves and the specifications for their industrial production. The performances of the pre-series valves are presented and an overview of the series production phase is given.

  7. Development of the large main steam safety relief valve

    Takeshima, Kikuo [Hitachi Ltd., Tokyo (Japan); Takasaki, Kiyoshi; Hamada, Nobuyoshi


    In order to control rise of reactor pressure at formation of over-pressure transition accident in a boiling water (BWR) type nuclear power plant, the numbers of the main steam safety relief valve (MSSRV) installed in a storage vessel increases with out-put in the plant, and for 1.35 MkW class improved BWR (ABWR) 18 sets of MSSRV are installed. And, in an ABWR preparing of construction at Ohma-cho, Aomori prefecture by the Electric Power Development Co., Ltd., uranium-plutonium mixed oxides (MOX) fuel is planned to load, to tend to further increase required numbers of MSSRV. In order to control arrangement in a storage vessel and increase of conservative inspection work together with increase the required numbers of MSSRV, it was planned to develop a large volume of MSSRV (16% increase in volume on comparison with that of conventional one), to confirm its function and feature by its testing and to apply to an actual machine. Here was introduced on its developmental contents and testing results. As a result, it could be estimated that required numbers of MSSRV would be sixteen, and was confirmed that features such as correlation on flowing-out pressure between nitrogen and steam, durability, work stability, valve seat leakage resistance, and so forth were similar to those of present MSSRV. (G.K.)

  8. Valve inlet fluid conditions for pressurizer safety and relief valves in combustion engineering-designed plants. Final report. [PWR

    Bahr, J.; Chari, D.; Puchir, M.; Weismantel, S.


    The purpose of this study is to assemble documented information for C-E designed plants concerning pressurizer safety and power operated relief valve (PROV) inlet fluid conditions during actuation as calculated by conventional licensing analyses. This information is to be used to assist in the justification of the valve inlet fluid conditions selected for the testing of safety valves and PORVs in the EPRI/PWR Safety/Relief Valve Test Program. Available FSAR/Reload analyses and certain low temperature overpressurization analyses were reviewed to identify the pressurization transients which would actuate the valves, and the corresponding valve inlet fluid conditions. In addition, consideration was given to the Extended High Pressure Liquid Injection event. A general description of each pressurization transient is provided. The specific fluid conditions identified and tabulated for each C-E designed plant for each transient are peak pressurizer pressure, pressure ramp rate at actuation, temperature and fluid state.

  9. Investigation Of Adhesion Formation In New Stainless Steel Trim Spring Operated Pressure Relief Valves

    Gross, Robert E. [Savannah River Site (SRS), Aiken, SC (United States); Bukowski, Julia V. [Villanova University, Villanova, PA (United States); Goble, William M. [exida, Sellersville, PA (United States)


    Examination of proof test data for new (not previously installed) stainless steel (SS) trim spring operated pressure relief valves (SOPRV) reveals that adhesions form between the seat and disc in about 46% of all such SOPRV. The forces needed to overcome these adhesions can be sufficiently large to cause the SOPRV to fail its proof test (FPT) prior to installation. Furthermore, a significant percentage of SOPRV which are found to FPT are also found to ''fail to open'' (FTO) meaning they would not relief excess pressure in the event of an overpressure event. The cases where adhesions result in FTO or FPT appear to be confined to SOPRV with diameters < 1 in and set pressures < 150 psig and the FTO are estimated to occur in 0.31% to 2.00% of this subpopulation of SS trim SOPRV. The reliability and safety implications of these finding for end-users who do not perform pre-installation testing of SOPRV are discussed.

  10. The optimization of design parameters for surge relief valve for pipeline systems

    Kim, Hyunjun; Hur, Jisung; Kim, Sanghyun


    Surge is an abnormal pressure which induced by rapid changes of flow rate in pipeline systems. In order to protect pipeline system from the surge pressure, various hydraulic devices have been developed. Surge-relief valve(SRV) is one of the widely applied devices to control surge due to its feasibility in application, efficiency and cost-effectiveness. SRV is designed to automatically open under abnormal pressure and discharge the flow and makes pressure of the system drop to the allowable level. The performance of the SRV is influenced by hydraulics. According to previous studies, there are several affecting factors which determine performance of the PRV such as design parameters (e.g. size of the valve), system parameters (e.g. number of the valves and location of the valve), and operation parameters (e.g. set point and operation time). Therefore, the systematic consideration for factors affecting performance of SRV is required for the proper installation of SRV in the system. In this study, methodology for finding optimum parameters of the SRV is explored through the integration of Genetic Algorithm(GA) into surge analysis.

  11. Segmented ball valve is easy to open and close

    Prono, E.; Shinault, L. H.; Speisman, C.


    Segmented ball valve and flowmeter in the same spherical housing provide a valve that will handle large fluid volume without bulkiness and weight of blade valves or conventional ball valves. The valve is easily opened or closed and the flowmeter remains stationary, so errors are eliminated.

  12. Resolving plant operational issues related to pressurizer safety relief valve piping

    Bain, R.A. [Stone and Webster Engineering Corp., Boston, MA (United States). Mechanical Engineering Div.; Testa, M.F. [Duquesne Light Co., Shippingport, PA (United States). Mechanical Engineering Dept.


    Pressurizer safety and relief valve (PSARV) piping has many technical issues related to the qualification and operation of the system that have been addressed at Beaver Valley Unit 2. The PSARV piping is part of a system that must meet Code requirements while being subjected to very significant fluid transient loadings. Valve components include safety valves, power operated relief valves (PORVs), and motor operated block valves. Fluid slugs upstream of these valves can be steam or can be hot or cold water, resulting in a significant variance in possible slug densities. Problems with design options and hardware installed to decrease slug density such as heat tracing, and the susceptibility of the PORVs to leak are issues that affect plant operation, efficiency and cost effectiveness.

  13. EPRI PWR Safety and Relief Valve Test Program: test condition justification report

    Hosler, J.


    In response to NUREG 0737, Item II.D.1.A requirements, several safety and relief valve designs were tested by EPRI under PWR utility sponsorship. Justification that the inlet fluid conditions under which these valve designs were tested are representative of those expected in participating domestic PWR units during FSAR, Extended High Pressure Injection, and Cold Overpressurization events is presented.

  14. 46 CFR 54.15-10 - Safety and relief valves (modifies UG-126).


    ... reference; see 46 CFR 54.01-1). (f) Cast iron may be employed in the construction of relief valves for... with CGA S-1.2 (incorporated by reference; see 46 CFR 54.01-1). (2) 110 percent of the valve...

  15. Valve inlet fluid conditions for pressurizer safety and relief valves in Westinghouse-designed plants. Final report. [PWR

    Meliksetian, A.; Sklencar, A.M.


    The overpressure transients for Westinghouse-designed NSSSs are reviewed to determine the fluid conditions at the inlet to the PORV and safety valves. The transients considered are: licensing (FSAR) transients; extended operation of high pressure safety injection system; and cold overpressurization. The results of this review, presented in the form of tables and graphs, define the range of fluid conditions expected at the inlet to pressurized safety and power-operated relief valves utilized in Westinghouse-designed PWR units. These results will provide input to the PWR utilities in their justification that the fluid conditions under which their valve designs were tested as part of the EPRI/PWR Safety and Relief Valve Test Program indeed envelop those expected in their units.


    Gross, Robert; Harris, Stephen


    Proof test results were analyzed and compared with a proposed life cycle curve or hazard function and the limit of useful life. Relief valve proof testing procedures, statistical modeling, data collection processes, and time-in-service trends are presented. The resulting analysis of test data allows for the estimation of the PFD. Extended maintenance intervals to the limit of useful life as well as methodologies and practices for improving relief valve performance and reliability are discussed. A generic cost-benefit analysis and an expected life cycle cost reduction concludes that $90 million maintenance dollars might be avoided for a population of 3000 valves over 20 years.

  17. Transient analysis of water slug discharge in PWR safety/relief valve piping. [WATSLUG code

    Van Duyne, D.A.; Hsieh, J.S.; Shave, D.F.


    The sudden discharge of the water loop seal, which is often present upsteam of pressurizer safety and relief valves, creates large momentum and inertia forces on the piping segments downstream of the valve. This paper provides a brief discussion of the commonly available control-volume calculation techniques, a description of the governing equations and a recently developed computer routine (WATSLUG) for their solution, and a review of results calculated using this method for a typical pressurizer safety and relief valve system. 8 refs.

  18. Comparison Study on Thermal-Hydraulic Analysis Depending on Liquid Relief Valve Response for an Station Blackout in CANDU-6

    Kim, S. M.; Kho, D. W. [KHNP-CRI, Daejeon (Korea, Republic of); Choi, S. H.; Moon, B. J.; Kim, S. R. [Nuclear Engineering Service and Solution Co., Daejeon (Korea, Republic of)


    The purpose of this analysis is to compare the results of thermal-hydraulic analysis depending on liquid relief valve response during a station black out (SBO) events in CANDU-6. The primary heat transport system (PHTS) behavior following the postulated SBO is analyzed using CATHENA code. In the paper, analysis was performed to evaluate the effect on coolant system where LRVs are assumed to be opened or opened according to normal open characteristics in the condition of SBO. The result showed that the primary pressure boundary is extended from LRV to DCT and the effects on primary system behavior were neglectable.


    Gross, R; Stephen Harris, S


    The Savannah River Site operates a Relief Valve Repair Shop certified by the National Board of Pressure Vessel Inspectors to NB-23, The National Board Inspection Code. Local maintenance forces perform inspection, testing, and repair of approximately 1200 spring-operated relief valves (SORV) each year as the valves are cycled in from the field. The Site now has over 7000 certified test records in the Computerized Maintenance Management System (CMMS); a summary of that data is presented in this paper. In previous papers, several statistical techniques were used to investigate failure on demand and failure rates including a quantal response method for predicting the failure probability as a function of time in service. The non-conservative failure mode for SORV is commonly termed 'stuck shut'; industry defined as the valve opening at greater than or equal to 1.5 times the cold set pressure. Actual time to failure is typically not known, only that failure occurred some time since the last proof test (censored data). This paper attempts to validate the assumptions underlying the statistical lifetime prediction results using Monte Carlo simulation. It employs an aging model for lift pressure as a function of set pressure, valve manufacturer, and a time-related aging effect. This paper attempts to answer two questions: (1) what is the predicted failure rate over the chosen maintenance/ inspection interval; and do we understand aging sufficient enough to estimate risk when basing proof test intervals on proof test results?

  20. Safety/relief valve quencher loads: evaluation for BWR Mark II and III containments

    Su, T.M.


    Boiling water reactor (BWR) plants are equipped with safety/relief valves (SRVs) to protect the reactor from overpressurization. Plant operational transients, such as turbine trips, will actuate the SRV. Once the SRV opens, the air column within the partially submerged discharge line is compressed by the high-pressure steam released from the reactor. The compressed air discharged into the suppression pool produces high-pressure bubbles. Oscillatory expansion and contraction of these bubbles create hydrodynamic loads on the containment structures, piping, and equipment inside containment. This report presents the results of the staff's evaluation of SRV loads. The evaluation, however, is limited to the quencher devices used in Mark II and III containments. With respect to Mark I containments, the SRV acceptance criteria are presented in NUREG-0661 issued July 1980. The staff acceptance criteria for SRV loads for Mark II and III containments are presented in this report.

  1. Study of safety relief valve operation under ATWS conditions. [Supercritical flow

    Hutmacher, E.S.; Whitten, S.D.


    In March 1979, the NRC published a report (NUREG/CR-0687) prepared by the Energy Technology Engineering Center (ETEC-TDR-78-19). That report presented a literature survey which updated earlier NRC studies of saturated or subcooled water flow through relief valves, under ATWS conditions. This supplement expands upon that search to include supercritical steam-water flow. No applicable data for the supercritical conditions were found, nor were any newer data on saturated or subcooled conditions uncovered. This supplement also updates a look for facilities currently capable of simultaneously imposing all ATWS conditions upon test relief valves. Results confirmed the negative findings of NUREG/CR-0687.

  2. Study of safety relief valve operation under ATWS conditions. [Super critical flow

    Hutmacher, E.S.; Whitten, S.D.


    In March 1979, ETEC published as ETEC-TDR-78-19 a search which updated earlier NRC studies of saturated or subcooled water flow through relief valves, under ATWS conditions. This Supplement expands upon that search to include supercritical steam-water flow. No applicable data for the supercritical conditions was found, nor were any newer data on saturated or subcooled conditions uncovered. The Supplement also updated a look for facilities currently capable of simultaneously imposing all ATWS conditions upon test relief valves. Results confirmed the negative findings of ETEC-TDR-78.19.


    Gao Hong; Lin Wanlai; Fu Xin; Yang Huayong; Tsukiji Tetsuhiro


    The aim of this study is to suppress a cavitation near the orifice of a relief valve by changing the shape of a poppet. An experimental flow visualization technique and a numerical cavitating flow simulation, using a RNG k-ε turbulence model and a cavitation model, are employed to achieve the purpose. In the flow visualization, the cavitation phenomenon near the orifice of a relief valve is observed using a transparent test valve body model and a camera. On the other hand, a three dimensional cavitating flow simulation is conducted to predict the cavitation near the orifice of a relief valve.Six types of poppets are designed by changing the shape of a traditional poppet shape, which is expected to influence the cavitating flow in an orifice. In addition, the cavitation noise of a relief valve is measured and the noise spectrum is analyzed. In conclusion, the cavitation intensity and the cavitation noise are reduced for an optimal poppet geometry obtained in the present study.

  4. 46 CFR 53.05-2 - Relief valve requirements for hot water boilers (modifies HG-400.2).


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Relief valve requirements for hot water boilers... requirements for hot water boilers (modifies HG-400.2). (a) The relief valve requirements for hot water boilers... (incorporated by reference; see 46 CFR 53.01-1) except as noted otherwise in this section. (b) Hot water...

  5. Review of the development of safety and relief valve silencers for steam discharge

    Crawford, C.J.


    The progress made by the Central Electricity Generating Board (CEGB) in the development of silencers for the control of boiler safety valve and relief valve noise is reviewed. System noise sources and the formulation of environmental noise criteria are discussed; the silencer design philosophy adopted by the CEGB is described and the progressive improvements are charted to demonstrate the advances made over earlier practices. The results of this work are design concepts which provide silencers which are suitable for application to any of the CEGB's steam valve vent systems and are capable of meeting stringent neighbourhood noise criteria.

  6. Examples, clarifications, and guidance on preparing requests for relief from pump and valve inservice testing requirements

    Ransom, C.B.; Hartley, R.S. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States)


    In this report, the Idaho National Engineering Laboratory reviewers discuss related to requests for relief from the American Society of Mechanical Engineers code requirements for inservice testing (IST) of safety-related pumps and valves at commercial nuclear power plants. This report compiles information and examples that may be useful to licensees in developing relief requests submitted to US Nuclear Regulatory Commission (NRC) for their consideration and provides insights and recommendations on related IST issues. The report also gives specific guidance on relief requests acceptable and not acceptable to the NRC and advises licensees in the use of this information for application at their facilities.

  7. Recent performance experience with US light water reactor self-actuating safety and relief valves

    Hammer, C.G.


    Over the past several years, there have been a number of operating reactor events involving performance of primary and secondary safety and relief valves in U.S. Light Water Reactors. There are several different types of safety and relief valves installed for overpressure protection of various safety systems throughout a typical nuclear power plant. The following discussion is limited to those valves in the reactor coolant systems (RCS) and main steam systems of pressurized water reactors (PWR) and in the RCS of boiling water reactors (BWR), all of which are self-actuating having a setpoint controlled by a spring-loaded disk acting against system fluid pressure. The following discussion relates some of the significant recent experience involving operating reactor events or various testing data. Some of the more unusual and interesting operating events or test data involving some of these designs are included, in addition to some involving a number of similar events and those which have generic applicability.

  8. The optimum design of the pressure control spring of the relief valve based on neural networks

    FU Xiao-jin


    Based on the traditional optimization methods about the pressure control spring of the relief valve and combined with the advantages of neural network, this paper put forward the optimization method with many parameters and a lot of constraints based on neural network. The object function of optimization is transformed into the energy function of the neural network and the mathematical model of neural network optimization about the pressure control spring of the relief valve is set up in this method which also puts forward its own algorithm. An example of application shows that network convergence gets stable state of minimization object function E, and object function converges to the utmost minimum point with steady function, then best solution is gained, which makes the design plan better. The algorithm of solution for the problem is effective about the optimum design of the pressure control spring and improves the performance target.

  9. Water hammer, flow induced vibration and safety/relief valve loads

    Valandani, P.; Uffer, R.; Sexton, D.


    This report presents the results of an evaluation performed to determine current and recommended practices regarding the consideration of water hammer, flow-induced vibration and safety-relief valve loads in the design of nuclear power plant piping systems. Current practices were determined by a survey of industry experts. Recommended practices were determined by evaluating factors such as load magnitude and frequency content, system susceptibility to load occurrence and safety effects of postulated piping damage.

  10. In-plant safety/relief valve discharge load test, Monticello Plant. Final report

    Buzek, E.A. (comp.)


    This document reports the results of the test program of safety/relief valve (SRV) discharge load phenomena through a ramshead discharge device, and the effects upon the Mark I primary containment torus structure of the Monticello Nuclear Power Plant. The objectives were to provide a data base for verifying/improving bubble pressure, water reflood and piping load analytical models, and to measure the structural response of the torus, SRV piping, supports and acceleration of the basement and pedestal.

  11. Experimental Investigation of Cavitation in a Safety Relief Valve using water. Extension to Cryogenic fluids.

    Pinho, Jorge


    This thesis addresses the experimental investigation of the cavitation phenomenon and its main consequences on the normal operation of a safety relief valve (SRV). More particularly, limitation of the mass flux discharged and alteration of the hydraulic fluid forces behavior is of main interest for the proper design and sizing of such devices. In nuclear or thermal engineering systems, the use of SRVs is mandatory since it represents the ultimate protection device before an accident occurs, c...

  12. Standard Practice for Installation, Inspection, and Maintenance of Valve-body Pressure-relief Methods for Geothermal and Other High-Temperature Liquid Applications

    American Society for Testing and Materials. Philadelphia


    1.1 This practice covers installation, inspection, and maintenance of valve body cavity pressure relief methods for valves used in geothermal and other high-temperature liquid service. The valve type covered by this practice is a design with an isolated body cavity such that when the valve is in either the open or closed position pressure is trapped in the isolated cavity, and there is no provision to relieve the excess pressure internally. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  13. Safety relief valves according new requirements of EN (PED) versus AD/TRD or ASME

    Foellmer, B.; Schnettler, A. [Bopp and Reuther, Mannheim (Germany)


    In Europe, only Pressure safety relief valves which conform with the Pressure Equipment Directive (PED) 97/23 EC may be used. They are classified PED Category IV and a Notified Body validates the fulfilment of the PED requirements in accordance with a selected conformity evaluation procedure also drawn from PED. The harmonized standards or other technical reference works are stated in a manufacturer's declaration of conformity, which is supplied with the safety relief valve at delivery. Only this ultimately makes it possible to establish the basis used for CE certification and the certified properties which can be derived there from. The CE symbol in the identification plate alone does not supply sufficient information for this purpose. A comparative assessment of the harmonized EN standards compared against the AD and TRD technical rules in this article discloses differences in the certified properties and the applications for spring-loaded safety relief valves. The ASME code is also included in the assessment, since it plays a significant role at least outside Europe. (orig.)

  14. Valve inlet fluid conditions for pressurizer safety and relief valves for B and W 177-FA and 205-FA plants. Final report. [PWR

    Cartin, L.R.; Winks, R.W.; Merchent, J.W.; Brandt, R.T.


    The overpressurization transients for the Babcock and Wilcox Company's 177- and 205-FA units are reviewed to determine the range of fluid conditions expected at the inlet of pressurizer safety and relief valves. The final Safety Analysis Report, extended high-pressure injection, and cold overpressurization events are considered. The results of this review, presented in the form of tables and graphs, provide input to the PWR utilities in their justification that the fluid conditions under which their valve designs were tested as part of the EPRI PWR Safety and Relief Valve Test Program are representative of those expected in their unit(s).

  15. Assessment study of RELAP5/MOD2 Cycle 36. 04 based on pressurizer safety and relief valve tests

    Stubbe, E.J.; Vanhoenacker, L.


    This report presents a code assessment study based on full size relief and assisted safety valve (called SEBIM) tests performed on the CUMULUS valve test rig operated by Electricite de France (EdF). The increased awareness that the pressuriser safety and relief valves are not reliable under water blowdown conditions, has led to the design, testing and installation of so called assisted safety valves of which the SEBIM (TM) valves are an example. These valves, used in tandem, are gradually replacing the safety and relief valves on pressurisers in some European PWR's. Before installation at the plant, the Belgian safety authorities requested a thorough full scale testing of these valves on a test rig (CUMULUS) equipped with sufficient diagnostics to measure the characteristics of the valve. The Belgian architect-engineering firm TRACTEBEL was called upon the specify, order and test these valves for installation at the DOEL 1 and DOEL 2 power plants. These tests do provide sufficient data of high quality to justify an assessment study of the code RELAP-5 MOD-2 CYCLE 36 in the ICAP framework which is the subject of this report.

  16. Electromagnetically driven, fast opening and closing gas jet valve

    Krishnan, Mahadevan; Elliott, Kristi Wilson; Geddes, C. G. R.; van Mourik, R. A.; Leemans, W. P.; Murphy, H.; Clover, M.


    The design and performance are presented of an electromagnetically driven gas valve [M. Krishnan, J. Wright, and T. Ma, Proceedings of the 13th Advanced Accelerator Concepts Workshop, Santa Cruz, CA, AIP Conf. Proc. No. 1086 (AIP, New York, 2008)] that opens in <100μs, closes in <500μs, and can operate at pressures of ˜1000psia to drive supersonic nozzles. Such a valve has applications to laser-plasma accelerators, where the fast opening and closing would allow sharper edges to the flow and also allow higher rep-rate operation without loading the vacuum chamber. The valve action is effected by a flyer plate accelerated by the electromagnetic impulse of a low inductance, spiral wound, strip-line coil driven by a capacitor. Gas flows out of the valve when the seal between this flyer plate and the valve seat is broken. The electromagnetic force greatly exceeds the restoring forces provided by a spring and the gas pressure against the valve seat. Piezoresistive sensor and laser interferometer measurements of flow show that the valve opens in ˜100μs for all pressures up to 800 psia. The closing time is 500μs, set by the spring constant and mass. The prototype valve has been operated with helium at 0.5 Hz and at 500 psia for ˜1 hour at a time with no cooling.

  17. Long-term outcomes following Medtronic Open Pivot valved conduit.

    Naidoo, Rishendran; Pearse, Bronwyn; Tesar, Peter J; Yap, Su-Ann; Barnett, Adrian G; Fayers, Trevor


    Aortic root replacement is a complex procedure, though subsequent modifications of the original Bentall procedure have made surgery more reproducible. The study aim was to examine the outcomes of a modified Bentall procedure, using the Medtronic Open PivotTM valved conduit. Whilst short-term data on the conduit and long-term data on the valve itself are available, little is known of the long-term results with the valved conduit. Patients undergoing aortic root replacement between February 1999 and February 2010, using the Medtronic Open Pivot valved conduit were identified from the prospectively collected Cardiothoracic Register at The Prince Charles Hospital, Brisbane, Australia. All patients were followed up echocardiographically and clinically. The primary end-point was death, and a Cox proportional model was used to identify factors associated.with survival. Secondary end-points were valve-related morbidity (as defined by STS guidelines) and postoperative morbidity. Predictors of morbidity were identified using logistic regression. A total of 246 patients (mean age 50 years) was included in the study. The overall mortality was 12%, with actuarial 10-year survival 79% and a 10-year estimate of valve-related death of 0.04 (95% CI: 0.004, 0.07). Preoperative myocardial infarction (p = 0.004, HR 4.74), urgency of operation (p = 0.038, HR 2.8) and 10% incremental decreases in ejection fraction (p = 0.046, HR 0.69) were predictive of mortality. Survival was also affected by the valve gradients, with a unit increase in peak gradient reducing mortality (p = 0.021, HR 0.93). Valve-related morbidity occurred in 11 patients. Urgent surgery (p Medtronic Open Pivot valved conduit is a safe and durable option for aortic root replacement, and is associated with low morbidity and 10-year survival of 79%. However, further studies are required to determine the effect of valve gradient on survival.

  18. Guidelines for confirmatory inplant tests of safety-relief valve discharges for BWR plants

    Su, T.M.


    Inplant tests of safety/relief valve (SRV) discharges may be required to confirm generically established specifications for SRV loads and the maximum suppression pool temperature, and to evaluate possible effects of plant-unique parameters. These tests are required in those plants which have features that differ substantially from those previously tested. Guidelines for formulating appropriate test matrices, establishing test procedures, selecting necessary instrumentation, and reporting the test results are provided in this report. Guidelines to determine if inplant tests are required on the basis of the plant unique parameters are also included in the report.

  19. Mark II containment, supporting program report. Ramshead safety/relief valve loads methodology summary. [BWR

    Anderson, G.L.


    An overview of information describing and supporting the analytical methods for determining loads associated with safety/relief valve discharge to the suppression pool of the Mark II containment lead plants is presented. SRV discharge phenomena and associated loads, analytical methods for calculating these loads, supporting experimental information, application of the methods to lead plant assessment, and supporting programs are summarily described. The report demonstrates that, with regard to SRV discharge loads on the containment, an adequate technical basis exists for permitting the licensing assessment of the Mark II lead plants to continue on schedule.

  20. Preliminary planning study for safety relief valve experiments in a Mark III BWR pressure suppression system

    McCauley, E.W.; Holman, G.S.


    In response to a request from the Water Reactor Safety Research Division of the US NRC, a preliminary study is provided which identifies key features and consideration involved in planning a comprehensive in-plant Safety Relief Valve experimental program for a Mark III containment design. The report provides identification of program objectives, measurement system requirements, and some details quantifying expected system response. In addition, a preliminary test matrix is outlined which involves a supporting philosophy intended to enhance the usefulness of the experimental results for all members of the program team: experimentalists, analysts, and plant operator.

  1. Preliminary report: in-plant safety/relief valve discharge load test, Monticello Plant

    Chang, H.C. (comp.)


    This preliminary report covers the results of the test program of safety/relief valve (SRV) discharge load phenomena and the effects upon the Mark I primary containment torus structure of the Monticello Nuclear Power Plant. The objectives of the test were to provide a data base for verifying/improving analytical models and to measure the structural response of the torus to SRV discharges. Objectives, instrumentation, and test plan are described. Results of continuing data evaluation will be included in the final report scheduled for publication later in 1977.

  2. CCF analysis of high redundancy systems safety/relief valve data analysis and reference BWR application. Main report

    Mankamo, T. [Avaplan Oy (Finland); Bjoere, S.; Olsson, Lena [ABB Atom AB, Vaesteraas (Sweden)


    Dependent failure analysis and modeling were developed for high redundancy systems. The study included a comprehensive data analysis of safety and relief valves at the Finnish and Swedish BWR plants, resulting in improved understanding of Common Cause Failure mechanisms in these components. The reference application on the Forsmark 1/2 reactor relief system, constituting of twelve safety/relief lines and two regulating relief lines, covered different safety criteria cases of reactor depressurization and overpressure protection function, and failure to re close sequences. For the quantification of dependencies, the Alpha Factor Model, the Binomial Probability Model and the Common Load Model were compared for applicability in high redundancy systems.

  3. MEPR versus EEPR valves in open supermarket refrigerated display cabinets

    Tahir, A.; Bansal, P.K. [Auckland Univ, (New Zealand). Dept. of Mechanical Engineering


    This paper presents the comparative experimental field performance of mechanical evaporator pressure regulating valves (MEPR) and electronic evaporator pressure regulating valves (EEPR) under the identical operating conditions of supermarket open multi-deck refrigerated display cabinets. The main goal of the supermarket refrigeration system design is to keep the displayed product at the required constant temperature, while minimising the cooling load to increase the overall energy efficiency of the system. Field tests have shown that the electronic evaporator pressure valve has a significant effect on improving the cabinet temperature and reducing the rate of frost formation on the evaporator coils with subsequent improvements in the air curtain strength. (author)

  4. RELAP5/MOD3 assessment for calculation of safety and relief valve discharge piping hydrodynamic loads. International agreement report

    Stubbe, E.J.; VanHoenacker, L.; Otero, R. [TRACTEBEL, Brussels (Belgium)


    This report presents an assessment study for the use of the code RELAP 5/MOD3/5M5 in the calculation of transient hydrodynamic loads on safety and relief discharge pipes. Its predecessor, RELAP 5/MOD1, was found adequate for this kind of calculations by EPRI. The hydrodynamic loads are very important for the discharge piping design because of the fast opening of the valves and the presence of liquid in the upstream loop seals. The code results are compared to experimental load measurements performed at the Combustion Engineering Laboratory in Windsor (US). Those measurements were part of the PWR Valve Test Program undertaken by EPRI after the TMI-2 accident. This particular kind of transients challenges the applicability of the following code models: two-phase choked discharge; interphase drag in conditions with large density gradients; heat transfer to metallic structures in fast changing conditions; two-phase flow at abrupt expansions. The code applicability to this kind of transients is investigated. Some sensitivity analyses to different code and model options are performed. Finally, the suitability of the code and some modeling guidelines are discussed.

  5. Transient flow analysis of integrated valve opening process

    Sun, Xinming; Qin, Benke; Bo, Hanliang, E-mail:; Xu, Xingxing


    Highlights: • The control rod hydraulic driving system (CRHDS) is a new type of built-in control rod drive technology and the integrated valve (IV) is the key control component. • The transient flow experiment induced by IV is conducted and the test results are analyzed to get its working mechanism. • The theoretical model of IV opening process is established and applied to get the changing rule of the transient flow characteristic parameters. - Abstract: The control rod hydraulic driving system (CRHDS) is a new type of built-in control rod drive technology and the IV is the key control component. The working principle of integrated valve (IV) is analyzed and the IV hydraulic experiment is conducted. There is transient flow phenomenon in the valve opening process. The theoretical model of IV opening process is established by the loop system control equations and boundary conditions. The valve opening boundary condition equation is established based on the IV three dimensional flow field analysis results and the dynamic analysis of the valve core movement. The model calculation results are in good agreement with the experimental results. On this basis, the model is used to analyze the transient flow under high temperature condition. The peak pressure head is consistent with the one under room temperature and the pressure fluctuation period is longer than the one under room temperature. Furthermore, the changing rule of pressure transients with the fluid and loop structure parameters is analyzed. The peak pressure increases with the flow rate and the peak pressure decreases with the increase of the valve opening time. The pressure fluctuation period increases with the loop pipe length and the fluctuation amplitude remains largely unchanged under different equilibrium pressure conditions. The research results lay the base for the vibration reduction analysis of the CRHDS.

  6. Processing techniques for data from the Kuosheng Unit 1 shakedown safety-relief-valve tests

    McCauley, E.W.; Rompel, S.L.; Weaver, H.J.; Altenbach, T.J.


    This report describes techniques developed at the Lawrence Livermore National Laobratory, Livermore, CA for processing original data from the Taiwan Power Company's Kuosheng MKIII Unit 1 Safety Relief Valve Shakedown Tests conducted in April/May 1981. The computer codes used, TPSORT, TPPLOT, and TPPSD, form a special evaluation system for treating the data from its original packed binary form to ordered, calibrated ASCII transducer files and then to production of time-history plots, numerical output files, and spectral analyses. Using the data processing techniques described, a convenient means of independently examining and analyzing a unique data base for steam condensation phenomena in the MARKIII wetwell is described. The techniques developed for handling these data are applicable to the treatment of similar, but perhaps differently structured, experiment data sets.


    Harris, S.; Gross, R.


    The safety integrity level (SIL) of equipment used in safety instrumented functions is determined by the average probability of failure on demand (PFDavg) computed at the time of periodic inspection and maintenance, i.e., the time of proof testing. The computation of PFDavg is generally based solely on predictions or estimates of the assumed constant failure rate of the equipment. However, PFDavg is also affected by maintenance actions (or lack thereof) taken by the end user. This paper shows how maintenance actions can affect the PFDavg of spring operated pressure relief valves (SOPRV) and how these maintenance actions may be accounted for in the computation of the PFDavg metric. The method provides a means for quantifying the effects of changes in maintenance practices and shows how these changes impact plant safety.

  8. State-of-the-Art Report on Pilot Operated Safety Relief Valve

    Lee, Jun; Yoon, Ju Hyeon


    The pilot operated safety relief valve(POSRV) is a overpressure protection device. But the POSRV is additionally designed to be functioned as a fast depressurization device differently from the pressurizer safety valve(PSV). So, the POSRV assembly takes on the complicated configuration differently from the PSV, and also its configuration and component parts are much different according to its manufacturers. The objective of the study is to investigate the state of the art for POSRV. We want that the findings of the study are put to practical use as a selection guide to the utilities or system designers which want to purchase the POSRV. In this study, we selected the SEBIM and CCI made goods as the subject of investigation, and have investigated the technical characteristics and operating principles of the goods. However, in this report, the comparative contents with other company which were issued by one company were not handled. Also the advantages or disadvantages between two companies were not handled. Only the technical characteristics and operating principles with each company were described. For reference, the main considerations to select the POSRV' type are follows. - the characteristics of the system that the POSRV is to be installed - the fitness of the POSRV for the system - the requirements related to the function and operation of the POSRV - the vender's opinion.

  9. Development of large capacity main steam safety relief valve in BWR

    Hama, Teruo; Takasaki, Kiyoshi [Electric Power Development Co. Ltd., Tokyo (Japan); Takeshima, Kikuo; Hamada, Nobuyoshi


    As a change of reactor performance on design of an improved type boiling water reactor aiming at loading of uranium-plutonium mixed oxides fuel (MOX fuel) at Oma town in Aomori prefecture, negative absolute value in void coefficient has an increasing trend due to loading of the MOX fuel. As a result, pressure increase in reactor pressure vessel has increasing trend at forming of pressurized transient phenomenon such as negative loading loss, and then it was attempted to increase total flushing amount of a main stream safety relief valve (MSSRV) for its relaxation. Then, in order to control increase of setting numbers of the valve, relax limitation of arrangement of its storing vessel, and control increase of maintenance and inspection works, a large capacity MSSRV of 460 t/h with about 16% larger flushing amount than that of present MSSRV was planned to an actual reactor. As a result, it could be confirmed by its functional tests and so forth that it had nearly equal correlation of flushing pressure on nitrogen and steam to that of the present MSSRV, nearly same reliability on enough durability, good working stability, and so forth as that of the present MSSRV, and no obstacle on its application to an actual reactor. (G.K.)

  10. Navier-Stokes flow field analysis of compressible flow in a high pressure safety relief valve

    Vu, Bruce; Wang, Ten-See; Shih, Ming-Hsin; Soni, Bharat


    The objective of this study is to investigate the complex three-dimensional flowfield of an oxygen safety pressure relieve valve during an incident, with a computational fluid dynamic (CFD) analysis. Specifically, the analysis will provide a flow pattern that would lead to the expansion of the eventual erosion pattern of the hardware, so as to combine it with other findings to piece together a most likely scenario for the investigation. The CFD model is a pressure based solver. An adaptive upwind difference scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the velocity-pressure coupling. The computational result indicated vortices formation near the opening of the valve which matched the erosion pattern of the damaged hardware.

  11. Analysis of pressure oscillations and safety relief valve vibrations in the main steam system of a Boiling Water Reactor

    Galbally, David, E-mail: [Innomerics, Calle San Juan de la Cruz 2, 28223 Madrid (Spain); García, Gonzalo [Alava Ingenieros, Calle Albasanz 16, 28037 Madrid (Spain); Hernando, Jesús; Sánchez, Juan de Dios [Iberdrola, Calle Tomás Redondo 1, 28033 Madrid (Spain); Barral, Marcos [Alava Ingenieros, Calle Albasanz 16, 28037 Madrid (Spain)


    Highlights: • We analyze the vibratory response of safety relief valves in the main steam system of a Boiling Water Reactor. • We show that valve internals experience acceleration spikes of more than 20 g. • Spikes are caused by impacts between the valve disc and the seating surface of the valve nozzle. • Resonances occur at higher Strouhal numbers than those reported in the literature for tandem side branches. • Valves experience high vibration levels even for resonances caused by second order hydrodynamic modes. - Abstract: Steam flow inside the main steam lines of a Boiling Water Reactor can generate high-amplitude pressure oscillations due to coupling between the separated shear layer at the mouth of the safety relief valves (SRVs) and the acoustic modes of the side branches where the SRVs are mounted. It is known that certain combinations of flow velocities and main steam line geometries are capable of generating self-excited pressure oscillations with very high amplitudes, which can endanger the structural integrity of main steam system components, such as safety valves, or reactor internals such as steam dryers. However, main steam systems may also experience lower amplitude pressure oscillations due, for example, to coupling of higher order hydrodynamic modes with acoustic cavity modes, or to incipient resonances where the free stream velocity is slightly lower than the critical flow velocity required to develop a stable locked-on acoustic resonance. The amplitude of these pressure oscillations is typically insufficient to cause readily observable structural damage to main steam system components, but may still have subtle effects on safety relief valves. The investigation presented in this article focuses on the characterization of the response of SRVs under the effects of pressure oscillations associated with acoustic excitations that are insufficient to cause structural damage to the valves or associated equipment. It is shown that valve

  12. The performance evaluation for passive type's pressurizer and pilot operated safety relief valve of SMART

    Lee, Jun; Yoon, Ju Hyeon


    In this report, the performance for PZR of SMART has been evaluated in which the passive cold PZR and PRHRS had been installed and the FW control system that reactor power is controlled by FW flow rate had been adopted. After the present analysis of the coolant volume of PZR end cavity, it was evaluated that the results could be satisfied if the coolant volume and pressure are controlled in order to be maintained within their set points. Also after the analysis of the gas volume, it was evaluated that the results is much satisfied. Especially, it was analyzed that the peak pressure of end cavity is raised only about 50%(0.6 MPa) as contrasted with the commercial plants. Also, the relieving capacity for pilot operated safety relief valve(POSRV) of SMART was analyzed. The related requirements of 10 CFR 50.55a (c) (1), ASME Code, Sec. III, NB-7000, NUREG-0800 were applied to the analysis. After the present analysis, it was evaluated that the RCS peaking pressure is about 18.2 MPa, 107% of system design pressure, and that it has 3% margin against the design requirement. Also, after the additional analysis, it was evaluated that the open dead/stroke time of POSRV has just a little effect on the peak pressure of PZR EC and MCP discharge.

  13. The performance evaluation for passive type's pressurizer and pilot operated safety relief valve of SMART

    Lee, Jun; Yoon, Ju Hyeon


    In this report, the performance for PZR of SMART has been evaluated in which the passive cold PZR and PRHRS had been installed and the FW control system that reactor power is controlled by FW flow rate had been adopted. After the present analysis of the coolant volume of PZR end cavity, it was evaluated that the results could be satisfied if the coolant volume and pressure are controlled in order to be maintained within their set points. Also after the analysis of the gas volume, it was evaluated that the results is much satisfied. Especially, it was analyzed that the peak pressure of end cavity is raised only about 50%(0.6 MPa) as contrasted with the commercial plants. Also, the relieving capacity for pilot operated safety relief valve(POSRV) of SMART was analyzed. The related requirements of 10 CFR 50.55a (c) (1), ASME Code, Sec. III, NB-7000, NUREG-0800 were applied to the analysis. After the present analysis, it was evaluated that the RCS peaking pressure is about 18.2 MPa, 107% of system design pressure, and that it has 3% margin against the design requirement. Also, after the additional analysis, it was evaluated that the open dead/stroke time of POSRV has just a little effect on the peak pressure of PZR EC and MCP discharge.

  14. The safety relief valve handbook design and use of process safety valves to ASME and International codes and standards

    Hellemans, Marc


    The Safety Valve Handbook is a professional reference for design, process, instrumentation, plant and maintenance engineers who work with fluid flow and transportation systems in the process industries, which covers the chemical, oil and gas, water, paper and pulp, food and bio products and energy sectors. It meets the need of engineers who have responsibilities for specifying, installing, inspecting or maintaining safety valves and flow control systems. It will also be an important reference for process safety and loss prevention engineers, environmental engineers, and plant and process designers who need to understand the operation of safety valves in a wider equipment or plant design context. . No other publication is dedicated to safety valves or to the extensive codes and standards that govern their installation and use. A single source means users save time in searching for specific information about safety valves. . The Safety Valve Handbook contains all of the vital technical and standards informat...

  15. Design of Pressure Relief Valves for Protection of Steel-Lined Pressure Shafts and Tunnels Against Buckling During Emptying

    Schleiss, Anton; Manso, Pedro


    Using high-strength steels for pressure shafts and tunnel liners and taking into account significant rock mass participation allows the design of comparatively thin steel liners in hydropower projects. Nevertheless, during emptying of waterways, these steel linings may be endangered by buckling. Compared with traditional measures such as increased steel liner thickness and stiffeners, pressure relief valves are a very economical solution for protection of steel liners against critical extern...

  16. Analysis of operational methane emissions from pressure relief valves from biogas storages of biogas plants.

    Reinelt, Torsten; Liebetrau, Jan; Nelles, Michael


    The study presents the development of a method for the long term monitoring of methane emissions from pressure relief valves (PRV(1)) of biogas storages, which has been verified during test series at two PRVs of two agricultural biogas plants located in Germany. The determined methane emission factors are 0.12gCH4kWhel(-1) (0.06% CH4-loss, within 106days, 161 triggering events, winter season) from biogas plant A and 6.80/7.44gCH4kWhel(-1) (3.60/3.88% CH4-loss, within 66days, 452 triggering events, summer season) from biogas plant B. Besides the operational state of the biogas plant (e.g. malfunction of the combined heat and power unit), the mode of operation of the biogas flare, which can be manually or automatically operated as well as the atmospheric conditions (e.g. drop of the atmospheric pressure) can also affect the biogas emission from PRVs.

  17. A conceptual study on large-capacity safety relief valve (SRV) for future BWR plants

    Yamada, Katsumi; Tokunaga, Takashi; Iwanaga, Masakazu; Kurosaki, Toshikazu [Toshiba Corporation, Isogo Nuclear Engineering Center, Yokohama (Japan)


    This paper presents a conceptual study of Safety Relief Valve (SRV) which has larger flow capacity than that of the conventional one and a new structure. Maintenance work of SRVs is one of the main concerns for next-generation Boiling Water Reactor (BWR) plants whose thermal power is planned to be increased. Because the number of SRVs increases with the thermal power, their maintenance would become critical during periodic inspections. To decrease the maintenance work, reduction of the number by increasing the nominal flow rate per SRV and a new structure suitable for easier treatment have been investigated. From a parameter survey of the initial and maintenance cost, the optimum capacity has been estimated to be between 180 and 200 kg/s. Primarily because the number of SRVs decreases in inversely proportional to the capacity, the total maintenance work decreases. The new structure of SRV, with an internally mounted actuator, decreases the number of the connecting parts and will make the maintenance work easier. A 1/4-scale model of the new SRV has been manufactured and performance tests have been conducted. The test results satisfied the design target, which shows the feasibility of the new structure. (author)

  18. BWR suppression pool pressures during safety relief valve discharge. Final report

    Hwang, G.; Gay, R.R.


    An analytical understanding of the pool pressures measured during safety relief valve (SRV) discharge in BWRs equipped with x-quenchers has been developed and compared to experimental data. The local conditions inside the SRV discharge lines and inside of the x-quencher were modeled successfully with RELAP5. The measured pressure surges inside the quencher are successfully predicted by the code. In addition, the analytical predictions allow one to associate the peak pressure inside the quencher arm with the onset of air discharge into the suppression pool. A Rayleigh model of bubble dynamics successfully explained both the higher-frequency and the ensuing lower-frequency pressure oscillations that have been measured in suppression pools during SRV discharge tests. The higher-frequency oscillations are characteristic of an air bubble emanating from a single row of quencher holes. The lower-frequency pressure oscillations are characteristic of a large air bubble containing all the air expelled from one side of an x-quencher arm.

  19. Application of RELAP5/MOD1 for calculation of safety and relief valve discharge piping hydrodynamic loads. Final report. [PWR


    A series of operability tests of spring-loaded safety valves was performed at Combustion Engineering in Windsor, CT as part of the PWR Safety and Relief Valve Test Program conducted by EPRI on behalf of PWR Utilities in response to the recommendations of NUREG-0578 and the requirements of the NRC. Experimental data from five of the safety valve tests are compared with RELAP5/MOD1 calculations to evaluate the capability of the code to determine the fluid-induced transient loads on downstream piping. Comparisons between data and calculations are given for transients with discharge of steam, water, and water loop seal followed by steam. RELAP5/MOD1 provides useful engineering estimates of the fluid-induced piping loads for all cases.

  20. Research on the Digital Water Hydraulic Relief Valve Based on Fluent%基于Fluent的数字式水压溢流阀研究

    贾伟亮; 吴张永; 王娴; 王娟; 莫子勇


    The key technology of water hydraulic transmission was introduced. The structure of the digital water hydraulic relief valve was designed according to the characteristics of the digital valve. The model of flow field cavitation inside the digital water hydraulic relief valve was built and analyzed by Fluent software. The simulation results provide theory basis for the design of the relief valve.%介绍水液压传动的关键技术,根据数字阀的特点设计数字式水压溢流阀.建立其阀口气穴流场的数学模型,并用Fluent软件进行仿真分析,仿真结果为溢流阀的结构改进提供理论依据.

  1. Research on the water hammer protection of the long distance water supply project with the combined action of the air vessel and over-pressure relief valve

    Li, D. D.; Jiang, J.; Zhao, Z.; Yi, W. S.; Lan, G.


    We take a concrete pumping station as an example in this paper. Through the calculation of water hammer protection with a specific pumping station water supply project, and the analysis of the principle, mathematical models and boundary conditions of air vessel and over-pressure relief valve we show that the air vessel can protect the water conveyance system and reduce the transient pressure damage due to various causes. Over-pressure relief valve can effectively reduce the water hammer because the water column re-bridge suddenly stops the pump and prevents pipeline burst. The paper indicates that the combination set of air vessel and over-pressure relief valve can greatly reduce the quantity of the air valve and can eliminate the water hammer phenomenon in the pipeline system due to the vaporization and water column separation and re-bridge. The conclusion could provide a reference for the water hammer protection of long-distance water supply system.

  2. CFD analysis with fluid-structure interaction of opening high-pressure safety valves

    Beune, A.; Kuerten, J.G.M.; Heumen, van M.P.C.


    A multi-mesh numerical valve model has been developed to analyze the opening characteristic of highpressure safety valves. Newton’s law and the CFD result for the flow force are used to model the movement of the valve. In incompressible transient flow simulations a large force rise and collapse is c


    Harris, S.


    Risk-based inspection methods enable estimation of the probability of spring-operated relief valves failing on demand at the United States Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. The paper illustrates an approach based on application of the Frechet and Weibull distributions to SRS and Center for Chemical Process Safety (CCPS) Process Equipment Reliability Database (PERD) proof test results. The methodology enables the estimation of ANSI/ISA-84.00.01 Safety Integrity Levels (SILs) as well as the potential change in SIL level due to modification of the maintenance schedule. Current SRS practices are reviewed and recommendations are made for extending inspection intervals. The paper compares risk-based inspection with specific SILs as maintenance intervals are adjusted. Groups of valves are identified in which maintenance times can be extended as well as different groups in which an increased safety margin may be needed.

  4. The safety relief valve retrofit begins with a slow motion; Le lent demarrage des mises a niveau



    Through two decrees (September, 7 and October, 31), the fitting of a safety pressure relief valve was enforced by French Authorities on every LPG vehicle registered in France and circulating prior to January, 1, 2000. This decision is implemented for vehicles without this SPRV or fitted with a 'low flow' valve, i.e. with a flow under 17.7 m{sup 3}/mn. The fitting must be completed for December, 31, 2001 at the latest. The cost of the retrofit is covered up to 50% by LPG marketers and the Government. Today, the targeted LPG car owners, even these who were informed of this regulation, answer very slowly. Some 100,000 to 120,000 LPG vehicles must be re-equipped and, since the launching of Operation Reflexe GPL last September, only 1% of these vehicles were retro-fitted. Thus, new communication campaigns are prepared to speed up the scheme. (authors)

  5. Shape Memory Actuated Normally Open Permanent Isolation Valve

    Ramspacher, Daniel J. (Inventor); Bacha, Caitlin E. (Inventor)


    A valve assembly for an in-space propulsion system includes an inlet tube, an outlet tube, a valve body coupling the inlet tube to the outlet tube and defining a propellant flow path, a valve stem assembly disposed within the valve body, an actuator body coupled to the valve body, the valve stem assembly extending from an interior of the valve body to an interior of the actuator body, and an actuator assembly disposed within the actuator body and coupled to the valve stem assembly, the actuator assembly including a shape memory actuator member that when heated to a transition temperature is configured to enable the valve stem assembly to engage the outlet tube and seal the propellant flow path.

  6. The effect of maximum open height on operating characteristics of polymer injected pump poppet valve

    Zhang, S. C.; Chen, X. D.; Deng, H. Y.


    Reciprocating polymer injected pump is the key injection equipment of tertiary oil recovery, the poppet valve in it exists the problem of large vibration noise, low efficiency and short life when transportation high viscosity medium. So the CFD technique is adopted to simulate and analyze the inner flow fields of fluid end poppet valve. According to the practical structure of the poppet valve, a simplified 2D axis-symmetry geometry model of the flow field is established. Combined with pump speed, plunger stroke and plunger diameter, given the boundary condition of the inlet valve, then the numerical simulation of flow field under six different maximum open heights is done depending on software Fluent. The relationship between open height to valve gap flow velocity, hydraulic loss and lag angle is obtained. The results indicate that, with the increase of open height, the valve gap flow velocity decreases, inlet outlet pressure differential decreases and hydraulic loss decreases. But the lag angle is continuously increasing with the increase of maximum open height, the valve has a good work performance when the open height is 1, 1.5, 2, 2.5, 3mm, but when it reaches 3.5mm, the valve performance becomes poor. The study can offer certain reference to understand operating characteristics of poppet valve, help to reduce the hydraulic losses and raise volume efficiency of the pump.

  7. 基于CFD加油泵溢流阀的噪声分析%Analysis of the Noise of Oil Pump Relief Valves based on CFD

    马景勇; 谢松林; 童珍容; 苏华山


    为了减小在加油过程中ZCB90型加油泵溢流阀产生的噪声,按照溢流阀的实际结构和参数,建立了溢流阀内部流场的三维模型,应用计算流体动力学软件Fluent,对溢流阀的内部流场进行研究,给出了溢流阀内的压力场、流线分布图.对容易产生漩涡和负压的结构处进行了改进.结果表明,结构改进后的流场中漩涡区分布减小,最低压力得到提高,降低了气蚀和噪声发生的可能性.此研究工作为溢流阀的优化设计提供了理论依据,为降低在实际工作中溢流阀的噪声提供了思路.%In order to reduce the pressure relief valves noise of ZCB90 type pumps during refueling, relief valve three-di-mensional model of the internal flow field was established in accordance with the structure and parameters of the actual relief valves, the flow field of the relief valve with the application of computational fluid dynamics software Fluent was studied, the pressure field within the relief valve and the flow line maps was gotten. It improved the structure there prone to swirl and negative pressure. The results showed that the improved structure made the swirl distribution in the flow field was de-creased and the minimum pressure was improved, which reduced the likelihood of cavitation and noise. This research for the optimized design of the valves provides a theoretical basis and a guideline to reduce the noise of relief valve in the actual work. Though experiment of relief valve noise decreased significantly, it validated the theory mentioned in the paper.

  8. Detecting Aortic Valve Opening and Closing from Distal Body Vibrations

    Wiens, Andrew D; Inan, Omer T


    Objective: Proximal and whole-body vibrations are well studied in seismocardiography and ballistocardiography, yet distal vibrations are still poorly understood. In this paper we develop two methods to measure aortic valve opening (AVO) and closing (AVC) from distal vibrations. Methods: AVO and AVC were detected for each heartbeat with accelerometers on the upper arm (A), wrist (W), and knee (K) of 22 consenting adults following isometric exercise. Exercise-induced changes were recorded with impedance cardiography, and nine-beat ensemble averaging was applied. Our first method, FilterBCG, detects peaks in distal vibrations after filtering with individually-tuned bandpass filters while RidgeBCG uses ridge regression to estimate AVO and AVC without peaks. Pseudocode is provided. Results: In agreement with recent studies, we did not find peaks at AVO and AVC in distal vibrations, and the conventional R-J interval method from the literature also correlated poorly with AVO (r2 = 0.22 A, 0.14 W, 0.12 K). Interestin...

  9. Analytical model for estimating drag forces on rigid submerged structures caused by LOCA and safety relief valve ramshead air discharges. [BWR


    Basic information is presented for estimating drag forces on rigid structural members submerged in a pressure suppression pool, caused by either the air discharge from a loss-of-coolant accident (LOCA), or the air bubble oscillation following safey relief valve ramshead discharge. Methods are described for estimating acceleration (unsteady) and standard (velocity-squared) drag force components for a variety of structural geometries.

  10. 溢流阀先导阀芯的振动特性仿真研究%The Vibration Characteristics Simulation Research of the Relief Valve' s Pilot Valve

    王国志; 李光飞; 刘桓龙; 邓斌; 吕少恒


    The main vibration resource of the pilot operated computed relief valve is the vibration of pilot valve, the vibration of the pilot valve in the engineering is studed on. The vibration system dynamic model of the pilot valve is built, some parameters'effect on the vibration of the pilot valve is simulated and analyzed. The result shows, the steady flow force which make the valve closed , increase the length or decrease the diameter of the flow channel which combined the main valve with the pilot valve, lessen the air content in oil or decrease the oil working temperature which can reduce the vibration of pilot valve and have contribute to the stability of the relief valve.%先导式溢流阀振动的主要来源为先导阀的振动.针对先导阀在工程中出现的振动问题进行研究.建立先导阀芯振动的系统动力学模型,分析相关参数对先导阀振动特性的影响.结果表明,增大连接主阀上腔和先导阀前端孔道的长度、减小孔道直径、减少油液的含气量和减少油液工作温度等有助于减少先导阀的振动,提高溢流阀工作稳定性.

  11. Mixed refrigerant composition shift due to throttle valves opening in auto cascade refrigeration system

    Xiongwen Xu; Jinping Liu; Le Cao


    Auto cascade refrigeration (ACR) cycle with phase separators is widely used in the cryogenic system. The compo-sition of mixed refrigerant has a great effect on the performance of the system. Based on the assumption of infinite volume of phase separator, ACR system with one phase separator is simulated in this paper. The variation of refrigerant composition under different valves opening is obtained. A related experimental system is set up to verify the variation. The result shows that when the valve opening connected to the evaporator increases or the valve opening under the phase separator decreases, the low-boiling component concentration of the working mixture passing through the compressor and condenser increases, while the high-boiling component concentra-tion decreases. Furthermore, the variations of condensation pressure and evaporation pressure under different valves opening are also observed. This paper is helpful to deepen the understanding of ACR system.

  12. Analysis of valve port leakage on direct operated relief valve under foundation vibration%基础振动下直动式溢流阀的阀口泄漏分析

    王蔚坪; 张怀亮; 章国亮


    Aiming at the problem that vibration caused by tunnel boring machine (TBM ) during the process of tunneling has effect on leakage in hydraulic components , the relief valve leakage rate caused by foundation vibration and structure parameters was analyzed . Taking the direct operated relief valve installed on TBM as the example , a mathematical model of valve port leakage of relief valve under foundation vibration was established .Critical inlet pressure was determined by calculating the leakage caused by foundation vibrations . Results showed that the amount of valve port leakage increased approximately linearly as the amplitude and frequency of vibration increased . When the spring stiffness was smaller than 1 .3 × 105 N/m ,the valve leakage increased as the spring stiffness increased ;while when the spring stifness equaled to 1 .3 × 105 N/m ,the valve leakage reached the maximum .Reducing spring stiffness and spool mass can decrease the valve port leakage fault caused by foundation vibration significantly ,and improve the working stability of relief valve .%针对硬岩掘进机(TBM )在掘进过程中产生的振动影响液压元件内泄漏的问题,分析基础振动及结构参数对溢流阀阀口泄漏量的影响规律.以安装在TBM基础上的直动式溢流阀为研究对象,建立基础振动下溢流阀的阀口泄漏量数学模型.通过计算基础振动引起的溢流阀阀口泄漏量,确定溢流阀发生阀口泄漏时的临界入口压力.结果表明:阀口泄漏量随着基础振动振幅及频率的增大而近似线性增大;当弹簧刚度小于1.3×105 N/m时,阀口泄漏量随着弹簧刚度的增大而增大;当弹簧刚度为1.3×105 N/m时,阀口泄漏量达到最大值;减小弹簧刚度和阀芯质量可以显著减少因基础振动引起的阀口泄漏故障,从而提高溢流阀的工作稳定性.

  13. Aging and service wear of spring-loaded pressure relief valves used in safety-related systems at nuclear power plants

    Staunton, R.H.; Cox, D.F. [Oak Ridge National Lab., TN (United States)


    Spring-loaded pressure relief valves (PRVS) are used in some safety-related applications at nuclear power plants. In general, they are used in systems where, during accidents, pressures may rise to levels where pressure safety relief is required for protection of personnel, system piping, and components. This report documents a study of PRV aging and considers the severity and causes of service wear and how it is discovered and corrected in various systems, valve sizes, etc. Provided in this report are results of the examination of the recorded failures and identification of trends and relationships/correlations in the failures when all failure-related parameters are considered. Components that comprise a typical PRV, how those components fail, when they fail, and the current testing frequencies and methods are also presented in detail.

  14. 46 CFR 52.20-17 - Opening between boiler and safety valve (modifies PFT-44).


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Opening between boiler and safety valve (modifies PFT-44). 52.20-17 Section 52.20-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS Requirements for Firetube Boilers § 52.20-17 Opening between boiler and safety...

  15. Technical evaluation report, TMI action NUREG-0737 (II.D.1), relief and safety valve testing, Comanche Peak, Unit 2, Docket No. 50-446

    Fineman, C.P.


    In the past, safety and relief valves installed in the primary coolant system of light water reactors have performed improperly. As a result, the authors of NUREG-0578 (TMI-2 Lessons Learned Task Force Status Report and Short-Term Recommendations) and, subsequently, NUREG-0737 (Clarification of TMI Action Plan Requirements) recommended development and completion of programs to do two things. First, the programs should reevaluate the functional performance capabilities of pressurized water reactor safety, relief, and block valves. Second, they should verify the integrity of the pressurizer safety and relief valve piping systems for normal, transient, and accident conditions. This report documents the review of those programs by EG&G Idaho, Inc. Specifically, this report documents the review of the Comanche Peak, Unit 2, Applicant response to the requirements of NUREG-0578 and NUREG-0737. This review found the Applicant provided an acceptable response reconfirming they met General Design Criteria 14, 15, and 30 of Appendix A to 10 CFR 50 for the subject equipment.

  16. 水击泄压阀在成品油管道的应用%Application of Water Hammer Pressure Relief Valve in the Product Pipeline

    刘洋; 刘威


    The water hammer pressure relief valve is one of the protective equipments of product pipeline. It prevents the piping system through venting the excess pressure. According to 10 years of practical experience of applying the water hammer pressure relief valve in the Lanzhou-Chengdu-Chongqing pipeline, this paper introduces the water hammer pressure relief valve from the structure and principle, routine operations, maintenance and failure analysis and its improvements in the application process.%水击泄压阀是成品油管道的保护设备之一,通过泄放多余的压力防止管道系统受到破坏.本文根据水击泄压阀在兰成渝输油管道应用10年来的实际经验,从水击泄压阀的结构及原理、常规操作、维护保养及故障分析等方面介绍了水击泄压阀以及其在应用过程中的改进.

  17. Gas flow across a wet screen - Analogy to a relief valve with hysteresis

    Nachman, A.; Dodge, F. T.


    The flow of gas through a wet fine-mesh screen is analyzed in terms of the capillary forces of the liquid wetting the screen and the pressure difference across the screen thickness driving the gas flow. Several different types of time-dependent flow are shown to be possible. The most interesting type is one in which the pressure difference opens small channels in the liquid, which are then closed rapidly by the wetting action of the liquid. The opening and closing exhibit hysteresis, and the flow is highly oscillatory.

  18. Numerical Research on Flow Characteristics around a Hydraulic Turbine Runner at Small Opening of Cylindrical Valve

    Zhenwei Mo


    Full Text Available We use the continuity equation and the Reynolds averaged Navier-Stokes equations to study the flow-pattern characteristics around a turbine runner for the small-opening cylindrical valve of a hydraulic turbine. For closure, we adopt the renormalization-group k-ε two-equation turbulence model and use the computational fluid dynamics (CFD software FLUENT to numerically simulate the three-dimensional unsteady turbulent flow through the entire passage of the hydraulic turbine. The results show that a low-pressure zone develops around the runner blades when the cylindrical valve is closed in a small opening; cavitation occurs at the blades, and a vortex appears at the outlet of the runner. As the cylindrical valve is gradually closed, the flow velocity over the runner area increases, and the pressure gradient becomes more significant as the discharge decreases. In addition, the fluid flow velocity is relatively high between the lower end of the cylindrical valve and the base, so that a high-velocity jet is easily induced. The calculation and analysis provide a theoretical basis for improving the performance of cylindrical-valve operating systems.

  19. Taps/valves in extreme conditions. Choice for tap-actuator sets for refining and petrochemical operations in severe conditions. Main steam isolation valves in extremely severe conditions. Presentation of the SRV (Safety Relief Valve) development; Robinets vannes en conditions extremes. Choix d`ensembles robinets-operateurs pour des operations en conditions severes dans le raffinage et la petrochimie. Vannes d`isolement vapeur principales en conditions tres severes. Presentation du developpement de la vanne SRV (safety relief valve)

    Brunet, X.F.; Aubry, F. [Institut Francais du Petrole, 92 - Rueil-Malmaison (France); Guesnon, D. [Technicatome Cadarache, 13 - Saint-Paul-Lez-Durance (France); Martin, R. [Vanatome, 07 - Annonay (France); Mainguette, Ph. [Adareg (France)


    This series of 3 papers was presented during a workshop organized by the French Society of mechanical engineers in 1997. The aim of the workshop was to take stock of the most recent developments in the domain of taps and valves devoted to extreme condition uses (very high or very low temperatures or pressures and corrosive ambiences). The first paper deals with selection criteria for the choice of valve-actuator sets devoted to high temperature liquid aromatic fluids in the refining and petrochemical industries (technical specifications, selection, qualification tests, quality control and tests feedback). The second paper presents the global conceiving process which led to adapt a general concept of valve to a specific application to propulsion reactors of nuclear ships: the steam isolation valves (technical specifications, particular constraints, prototype and serial product, maintenance and experience feedback). The third paper concerns the development of a safety relief valve for the superfluid helium cooling system of the superconducting magnets of the future LHC (Large Hadron Collider) of the CERN (technical specifications, general characteristics, functioning principle, technology and conceiving, test of prototypes and results). (J.S.)

  20. Calculation of Relief Capacity of Process Safety Valve under Control Valve Failure%控制阀故障工况下安全阀泄放量的计算

    曹虎; 周琛; 黄世勇; 王富丽


    It was one of the key factors for the selection of process safety valve (PSV), that was to accurately determine PSV discharge. In the standards,《HG/T20570.2-1995 Setting and Selection of PSV》, the formula to calculate the liquid relief capacity of PSV under control valve failure was not introduced. Basing on some engineering experiences, this paper provided a kind of calculation method to quantify the liquid relief capacity of PSV under control valve failure. Moreover, a example was illustrated to explain how to use this calculation method.%准确确定安全阀的泄放量是安全阀选型的关键之一。标准《HG/T 20570.2-1995安全阀的设置和选用》中针对控制阀故障工况下液体泄放量的计算未提供有效的计算公式。本文通过工程经验总结,提供一种控制阀故障工况下安全阀液体泄放量的计算方式,并举例说明了其使用方法。

  1. The measurement of opening angle and orifice area of a bileaflet mechanical valve using multidetector computed tomography.

    Lee, Dong-Hyeon; Youn, Ho-Joong; Shim, Sung-Bo; Lee, Sun-Hee; Jung, Jung-Im; Jung, Seung-Eun; Choi, Yun-Seok; Park, Chul-Soo; Oh, Yong-Seog; Chung, Wook-Sung; Kim, Jae-Hyung


    The aim of this study was to assess mechanical valve function using 64-slice multidetector computed tomography (MDCT). In 20 patients (mean age, 50+/-12 years; male-to-female ratio, 10:10), 30 St. Jude bileaflet mechanical valves (15 aortic and 15 mitral valves) were evaluated using MDCT. We selected images vertical and parallel to the mechanical valve. The valve orifice area (OA) and valve length were determined by manual tracing and the opening and closing angles were measured using a protractor. The OA and length of the mechanical valves were compared with the manufacturer's values. The geometric orifice areas (GOAs) based on the manufacturer's values and the OAs determined by MDCT were 3.4+/-0.2 cm(2) and 3.4+/-0.3 cm(2) for the mitral valves and 2.1+/-0.3 cm(2) and 2.1+/-0.4 cm(2) for the aortic valves, respectively. The correlation coefficients between the OA measures were 0.433 for the mitral valves and 0.874 for the aortic valves (both pvalves and 21.5+/-2.1 mm and 20.7+/-2.3 mm for the aortic valves, respectively. The correlation coefficients between the measures were 0.651 for the mitral valve and 0.846 for the aortic valve (both pvalves and 11.1+/-0.9 degrees and 120.6+/-1.7 degrees for the aortic valves, respectively. MDCT is an accurate modality with which to assess the function and morphology of bileaflet mechanical valves.

  2. Design of Full-open Cryogenic Safety Valve of Big Size%大口径低温全启式安全阀的设计

    刘屹; 郑鑫


    针对低温贮箱大排放安全的需要,介绍了采用新型密封结构——泛塞封的大口径低温全启式安全阀的设计及研制,并按相关规范要求对其进行了强度、性能等试验,为今后全启式安全阀的丰富和完善取得了一定的经验.%Considering the requirements from safe and large discharge of cryogenic propellant tank, both development and design of big size and full-opening cryogenic safety valve with pan-plug seal structure were introduced and its strength and performance were tested according to relevant specifications. The results show that this newly-developed relief valve conforms to the requirements, and the experience obtained in this design can benefit later improvement of the full-opening valves.

  3. Optimization of valve opening process for the suppression of impulse exhaust noise

    Li, Jingxiang; Zhao, Shengdun


    Impulse exhaust noise generated by the sudden impact of discharging flow of pneumatic systems has significant temporal characteristics including high sound pressure and rapid sound transient. The impulse noise exposures are more hazardous to hearing than the energy equivalent uniform noise exposures. This paper presents a novel approach to suppress the peak sound pressure as a major indicator of impulsiveness of the impulse exhaust noise by an optimization of the opening process of valve. Relationships between exhaust flow and impulse noise are described by thermodynamics and noise generating mechanism. Then an optimized approach by controlling the valve opening process is derived under a constraint of pre-setting exhaust time. A modified servo-direct-driven valve was designed and assembled in a typical pneumatic system for the verification experiments comparing with an original solenoid valve. Experimental results with groups of initial cylinder pressures and pre-setting exhaust times are shown to verify the effects of the proposed optimization. Some indicators of energy-equivalent and impulsiveness are introduced to discuss the effects of the noise suppressions. Relationship between noise reduction and exhaust time delay is also discussed.

  4. Design of pilot-assisted load control valve with load velocity control ability and fast opening feature

    Haibo Xie


    Full Text Available This article presents a design of pilot-assisted load control valve with load velocity control ability and fast opening feature based on static and dynamic modeling. Traditional load control valves do not have the load velocity control ability and its opening feature is very poor because the high spring stiffness comes along with the pressure–spring balance–based principle. Some improvement has been done by employing a two-stage pressure–pressure balance principle to make a load control valve to achieve load velocity control ability while the opening feature was not improved much. In this design, another pressure–pressure balance principle is proposed to make the load control valve achieve load velocity control ability and fast opening closing feature at the same time. Static modeling method based on force balance and Bernoulli orifice pressure-flow equation is used to design the load velocity control ability of the valve. Dynamic modeling method based on Newton’s second law and fluid continuity equation is used to optimize the parameters to give the proposed load control valve a fast opening feature. An actual load control valve was developed according to the above methods and the test results show both good load velocity control ability and fast opening feature of the design, which validates the potentiality of the proposed design in many applications.

  5. 先导腔动压反馈比例溢流阀的动态特性分析%Dynamic Characteristic Analysis of Proportional Relief Valve with Pilot Chamber Dynamic Pressure Feedback

    孙文毅; 陈淑梅; 颜滨曲; 黄彬


    比例溢流阀是保证工程机械运动稳定性的重要元件,针对普通比例先导溢流阀工作过程中响应速度慢和压力超调大的缺陷,该文设计了一款先导腔动压反馈式比例溢流阀.通过数学建模分析了溢流阀的静态和动态特性,并运用AMESim软件对所设计的比例溢流阀进行仿真分析,研究了影响溢流阀性能的结构参数,并验证了数学模型的正确性;用液压刚度替代了弹簧刚度,在结构上克服了弹簧工作过程中响应速度迟缓的缺点,有效改善了溢流阀的寿命.仿真结果表明,改进后的溢流阀较普通比例先导溢流阀的调压精度好、调压范围大,其性能上有明显的提高,对溢流阀的研究设计有一定的参考价值.%Proportional relief valves are the important components to ensure the stability of mechanical engineering movement . This paper designs a novel pilot cavity dynamic pressure feedback proportional relief valve for ordinary proportional pilot-operated relief lacking of slow response and large pressure overshoot in the working process. Theoretically the paper builds mathematical model for analyzing the static and dynamic characteristics of this relief valve, and simulates the model of the designed proportional relief valve by AMESim, which analyzes the structural parameters affecting the relief valve performance and verifies the correctness of the mathematical model. The valve uses hydraulic rigidity to replace spring stiffness, structurally overcoming the disadvantage of low response in the working process, and ef-fectively improving the life of the relief. Simulation results show that the improved relief has good precision regulator, large pressure regula-tion, and its performance has been significantly improved comparing with ordinary proportional pilot-operated relief, which has some refer-ence value for the study and design of the relief valve.

  6. Twenty-year single-center experience with the medtronic open pivot mechanical heart valve.

    Van Nooten, Guido J; Bové, Thierry; Van Belleghem, Yves; François, Katrien; Caes, Frank; Vandenplas, Guy; De Pauw, Michel; Taeymans, Yves


    Since May 1992 the Medtronic Open Pivot mechanical heart valve has been implanted routinely at the authors' institution. The study aim was to analyze, retrospectively, the 20-year clinical results of the valve. Between May 1992 and December 2011 a total of 1,520 valves was inserted into 1,382 consecutive patients (1,012 aortic, 473 mitral, 26 tricuspid, 9 pulmonary). The mean age of the patients was 61±13.2 years. Preoperatively, 65% of the patients were in New York Heart Association (NYHA) class III or greater. Frequent comorbidities included atrial fibrillation (n=419), coronary disease (n=357), and diabetes (n=255). The 99% complete follow-up totaled 10,527 patient-years (range 12 to 244 months). Ninety-day mortality was 5.2% (n=73, 8 valve related). Of the 550 total deaths, 240 were cardiac and 56 valve related. Multivariate analysis selected age, NYHA III or greater, concomitant coronary revascularization, and respiratory insufficiency as risk factors for death. Renal failure was considered a risk factor in the aortic and atrial fibrillation in the mitral subgroup. Erratic international normalized ratio (INR), NYHA class III or greater, and non-sinus rhythm were risk factors for thromboembolism; likewise redo operations in the aortic subgroup. Erratic INR and age were risk factors for bleeding as were over-coagulation and coronary revascularization in the aortic subgroup and redo operations and renal failure in mitral patients. This 20-year experience demonstrated excellent clinical outcomes with no structural valve failure. Odds ratio defined aortic patients as the lowest risk for adverse events. By contrast atrial fibrillation and elderly age, in combination with instable anticoagulation, yielded the worst long-term results. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  7. Analytically predicted versus measured response of a free-standing steel containment vessel subjected to safety-relief valve discharge loads

    Good, H.; Lewis, M.; Fitch, J.; Mattson, R.


    Following the actuation of safety-relief valves in BWR nuclear power plants, first water then air and steam are cleared from the discharge lines through quencher devices into a suppression pool. This clearing results in water spike, air bubble, and condensation pressure loads applied to structures in the pool, and the surrounding containment vessel. The Leibstadt Nuclear Power Plant has the only fre-standing steel Mark III containment vessel in the world. All other steel Mark III containment vessels have concrete backing in the suppression pool region, which dampens clearing load responses. As such, it is of interest to note how this steel vessel responds to discharge pressures, and compare these responses to analytically predicted results. The purpose of this paper is to compare the analytical results used to design the steel containment vessel with the responses measured during in-plant testing. The analytical methods considered the effects of fluid-structure interaction. The test program included initial and consecutive actuations of a single valve, and initial actuation of multiple (four) valves. The conclusion of the comparison is that, in general there are large conservatisms in the analytical predictions versus measured responses.

  8. Structural Design and Performance Simulation of Digital Water Hydraulic Relief Valve%数字式纯水溢流阀的结构设计与性能仿真分析

    颜凌云; 武鹏飞; 包宗贤; 李红星


    This article describes the digital water hydraulic relief valve by self-designed, And through the Matlab/Simulink software simulation the static and dynamic performance of the relief valve, Then the simulation results verify the correctness of the design theory.%该文介绍了自行设计的数字式纯水液压溢流阀,并通过Matlab/Simulink软件对溢流阀的静动态性能进行了仿真分析,由仿真结果验证了设计理论的正确性.

  9. Design and Simulation for Tandem Type Ultra High Pressure Relief Valve%串联式超高压溢流阀设计与仿真研究

    周晓君; 余敏超


    A tandem type ultra high pressure relief value was presented. The relief value could be used in hydraulic system with high pressure and small stream. It is characterized as simple structure, low noise, long life. Its mathematic model was built based on classical control theory. Then it was simulated by MATLAB/Simulink. The results are helpful for the optimization design of tandem type ultra high pressure relief valve.%提出一种串联式超高压溢流阀,适合应用在压力高、流量小的液压系统中,具有结构简单、噪声低、寿命长等优点.根据经典控制理论建立超高压溢流阀的动态特性方程,并应用MATLAB/Simulink软件对其进行动态特性仿真.仿真结果对串联式超高压溢流阀的优化设计有一定的指导意义.

  10. Design guidelines for PWR pressurizer safety and relief valve discharge piping to minimize potential operating and piping qualification problems

    Adams, T.M.; Chang, K.C.; Campbell, T.E.


    General system design considerations such as functional requirements, valve types and operation, and various loading conditions are discussed. General guidelines for the piping layout, support design, and embedment selection are presented and discussed. Also presented and discussed are potential system operating problems which can arise from an improper design. 3 refs.

  11. Evaluation of the simultaneous action of earthquake, LOCA and SRV on Mark-III containment and drywell structures. [Safety Relief Valve

    Philippacopoulos, A.J.; Reich, M.


    The containment and drywell structures of a generic Mark-III nuclear power facility are investigated with respect to their structural response when subjected to various load combinations that may occur during their operational lifetime. Both structures are idealized with three-dimensional finite element models. In addition a lumped-mass cantilever beam representation of the containment and drywell structures is developed and used for the soil-structure interaction analysis. The types of dynamic events considered include earthquakes, loss-of-coolant-accidents (LOCA) and those generated by safety/relief valve actuations. The evaluation of the combined actions of these dynamic events is first performed by using combination methods such as Absolute Sum (ABS) and Square-Root-of-the-Sum-of-the-Squares (SRSS). A Monte Carlo simulation procedure is subsequently used for probabilistic evaluation of the combinations.

  12. The analysis of pressurizer safety valve stuck open accident for low power and shutdown PSA

    Lim, Ho Gon; Park, Jin Hee; Jang, Seong Chul; Kim, Tae Woon


    The PSV (Pressurizer Safety Valve) popping test carried out practically in the early phase of a refueling outage has a little possibility of triggering a test-induced LOCA due to a PSV not fully closed or stuck open. According to a KSNP (Korea Standard Nuclear Power Plant) low power and shutdown PSA (Probabilistic Safety Assessment), the failure of a HPSI (High Pressure Safety Injection) following a PSV stuck open was identified as a dominant accident sequence with a significant contribution to low power and shutdown risks. In this study, we aim to investigate the consequences of the NPP for the various accident sequences following the PSV stuck open as an initiating event through the thermal-hydraulic system code calculations. Also, we search the accident mitigation method for the sequence of HPSI failure, then, the applicability of the method is verified by the simulations using T/H system code.

  13. Safety Analyses on a Safety Valve Stuck-Open for the HANARO fuel test loop

    Park, S. K.; Sim, B. S.; Chi, D. Y.; Lee, J. M.; Lee, C. Y.; Ahn, S. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    A fuel test loop (FTL) for irradiation tests is under development at the HANARO. The construction of the FTL was completed at the beginning of 2007 and integral performance tests have been carried out. The safety of the FTL including the PWR test fuels which will be installed should be verified for design basis accidents and anticipated operational occurrences (AOOs). This paper deals with the thermal-hydraulic transient analyses and the prediction for a departure from a nucleate boiling ratio (DNBR) during a safety valve stuck-open for the HANARO fuel test loop, which is one of the AOOs.

  14. Vascular Complications and Bleeding After Transfemoral Transcatheter Aortic Valve Implantation Performed Through Open Surgical Access.

    Leclercq, Florence; Akodad, Mariama; Macia, Jean-Christophe; Gandet, Thomas; Lattuca, Benoit; Schmutz, Laurent; Gervasoni, Richard; Nogue, Erika; Nagot, Nicolas; Levy, Gilles; Maupas, Eric; Robert, Gabriel; Targosz, Frederic; Vernhet, Hélène; Cayla, Guillaume; Albat, Bernard


    Major vascular complications (VC) remain frequent after transcatheter aortic valve implantation (TAVI) and may be associated with unfavorable clinical outcomes. The objective of this study was to evaluate the rate of VC after transfemoral TAVI performed using an exclusive open surgical access strategy. From 2010 to 2014, we included in a monocentric registry all consecutive patients who underwent transfemoral TAVI. The procedures were performed with 16Fr to 20Fr sheath systems. VC were evaluated within 30 days and classified as major or minor according to the Valve Academic Research Consortium 2 definition. The study included 396 patients, 218 were women (55%), median age was 85 years (81 to 88), and the median logistic Euroscore was 15.2% (11 to 23). The balloon-expandable SAPIEN XT and the self-expandable Medtronic Core Valve prosthesis were used in 288 (72.7%) and 108 patients (27.3%), respectively. The total length of the procedure was 68 ± 15 minutes including 13 ± 5 minutes for the open surgical access. Major and minor VC were observed in 9 (2.3%) and 16 patients (4%), respectively, whereas life-threatening and major bleeding concerned 18 patients (4.6%). The median duration of hospitalization was 5 days (interquartile range 2 to 7), significantly higher in patients with VC (7 days [5 to 15], p strategy, with a particular advantage observed in high-risk bleeding patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. KR500X泄压阀在长输管道中的应用%Application of KR500X Pressure Relief Valve in Long-distance Water Conveyance Pipeline

    姜海萍; 郑全兴


    泄压阀是水力控制阀的一种,能有效防止水击.详细介绍了泄压阀的结构、工作原理、特点、安装和日常维护注意事项.泄压阀通径的选用还没有成熟的理论依据,扬州第五水厂选用泄压阀的方法是一次探索.水厂投产两年来,输水管道运行平稳,确保了城市供水安全.%The pressure relief valve is one of the hydraulic control valves, which can effectively prevent water hammer. The structure of the pressure relief valve, its working principle, characteristics, installation and daily maintenance are introduced. Up to now, no mature theory has been found about the selection of the diameter of the pressure relief valves. Hence the approach adopted by Yangzhou Fifth Water Plant is a successful practice. The water conveyance pipeline has been running smoothly since the water plant was put into operation two years ago, which greatly ensures the safety of the city water supply.

  16. Automatic shutoff valve

    Hawkins, S. F.; Overbey, C. W.


    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  17. Technical evaluation report TMI action -- NUREG-0737 (II.D.1). Relief and safety valve testing, Watts Bar Nuclear Plant, Units 1 and 2 (Dockets 50-390 and 50-391)

    Fineman, C.P.


    In the past, safety and relief valves installed in the primary coolant system of light water reactors have performed improperly. As a result, the authors of NUREG-0578 (TMI-2 Lessons Learned Task Force Status Report and Short-Term Recommendations) and, subsequently, NUREG-0737 (Clarification of TMI Action Plan Requirements) recommended development and completion of programs to do two things. First, they should reevaluate the functional performance capabilities of pressurized water reactor safety, relief, and block valves. Second, they should verify the integrity of the pressurizer safety and relief valve piping systems for normal, transient, and accident conditions. This report documents the review of those programs by Lockheed Idaho Technologies Company. Specifically, this report documents the review of the Watts Bar Nuclear Plant, Units 1 and 2, Applicant response to the requirements of NUREG-0578 and NUREG-0737. This review found the Applicant provided an acceptable response reconfirming they met General Design Criteria 14, 15, and 30 of Appendix A to 10 CFR 50 for the subject equipment. It should also be noted Lockheed Idaho performed this review for both Units 1 and 2. However, the applicability of this review to Unit 2 depends on verifying that the Unit 2 as-built system conforms to the Unit 1 design reviewed in this report.

  18. Simulation and Optimal Design of High-Pressure-Differential and High-Solid-Phase Relief Valves%高压差高固含量减压阀的仿真优化设计

    王新昶; 孙方宏; 孙乐申; 丁庆华; 彭东辉


    Relief valves used in the coal liquefaction equipment are running in an extremely harsh environment with extraordinarily high pressure differential and intensely slurry flow erosion.Based on the finite volume method(FVM),the pressure and flow distributions of relief valves were analyzed,with K-ε turbulence and Mixture multiphase model.Moreover,for the new-style relief valves,variations of pressure drops with valve apertures and turbulence intensities with depths of valve seat hole were studied.Considering the fluid-erosion theory,optimal design was accomplished and the easy-wearing positions of the relief valves were accurately predicted to provide theoretical basis for the choice of wear resistant materials.The application results show that the easy-wearing positions are coincide with the predictions.Moreover,the working lifetime is largely elongated up to 1 200 hours and suitable for the practical application.%基于有限容积法,采用K-ε双方程湍流模型和Mixture多相流模型,对高压差高固态浓度流体冲蚀极端工况条件下工作的煤液化减压阀阀体内的压力分布和流场状态进行了计算流体动力学分析,研究了新型结构减压阀在不同开度下压降的变化情况,以及不同阀座孔深度下湍流强度的变化情况.结合流体冲蚀理论,完成了对其结构的优化改进,并对易磨损部位做出了精确预测,为关键部位耐磨材料的筛选提供了理论依据.实际应用实验结果表明,该新型减压阀使用过程中易磨损部位与仿真预测一致,使用寿命超过了1 200 h,满足实际应用需求.

  19. 安全阀超压泄放过程动力学参数分析与测试%Analysis & testing on dynamic parameters of safety valve during the overpressure relief process

    郭崇志; 姚远


    对3D模型安全阀的超压泄放机理及气体动力学过程进行了模拟分析和试验验证。利用区域分组法和路径分析法,对开启部件在超压泄放过程中的稳态流场参数进行了详细整理,研究了速度、压力参数在内外流场选定路径上的分布以及开启部件的动态力平衡情况。对竖直(Y)方向各种力平衡问题的研究和比较,证明了升力测试值为总力,包括静态力和动态力两部分,其中,静态力占绝对优势;反冲(升)力中,动态力起很大作用,间隙力属于自平衡力系。动态力主要来源于密封面和反冲盘折边出口附近的高速气体流动。阀芯反冲(升)力也主要来源于静态力,动态力影响较小。水平(X)方向力平衡参数研究结果表明,对于反冲盘与阀芯分离结构,阀芯处于严格的动态平衡中,而反冲盘则可能存在水平方向的不平衡力,可能导致阀芯开启和回座过程偏载。无论阀芯与反冲盘是整体还是分离式设计,此偏载均可能导致开启回座偏差,甚至引发颤振、频跳或密封面损坏。利用试验装置和新研制的传感器,获取了试验开启过程中阀芯压力、升力、开启高度和反冲盘测点压力,进一步计算了反冲盘和阀芯反冲(升)力的数值。试验和模拟结果对比表明,数值模拟结果与传感器测试数据吻合,为进一步研究内外流场及其动作机理奠定了基础。%With the numerical simulation and the experiment methods,the safety valve overpressure relief process and the gas dynamic problem are studied. The relief valve interior steady flow field of moving parts was analyzed by using the domain decomposition and paths analysis methods,the dynamic force balance,the distribution of velocity and the stress characteristics of the paths in the interior and external flow field were studied as well. The results showed that according to the

  20. Evaluation of SPACE code for simulation of inadvertent opening of spray valve in Shin Kori unit 1

    Kim, Seyun; Youn, Bumsoo [KHNP Central Research Institute, Daejeon (Korea, Republic of)


    SPACE code is expected to be applied to the safety analysis for LOCA (Loss of Coolant Accident) and Non-LOCA scenarios. SPACE code solves two-fluid, three-field governing equations and programmed with C++ computer language using object-oriented concepts. To evaluate the analysis capability for the transient phenomena in the actual nuclear power plant, an inadvertent opening of spray valve in startup test phase of Shin Kori unit 1 was simulated with SPACE code. To evaluate the analysis capability for the transient phenomena in the actual nuclear power plant, an inadvertent opening of spray valve in startup test phase of Shin Kori unit 1 was simulated with SPACE code.

  1. Sensitivity study on critical flow models of SPACE for inadvertent opening of containment spray valve in Shin Kori unit 1

    Kim, Seyun; Kim, Minhee [KHNP Central Research Institute, Daejeon (Korea, Republic of)


    SPACE (Safety and Performance Analysis Code for Nuclear Power Plants) has been developed by KHNP with the cooperation with KEPCO E and C and KAERI. SPACE code is expected to be applied to the safety analysis for LOCA (Loss of Coolant Accident) and Non-LOCA scenarios. SPACE code solves two-fluid, three-field governing equations and programmed with C++ computer language using object-oriented concepts. To evaluate the analysis capability for the transient phenomena in the actual nuclear power plant, an inadvertent opening of spray valve in startup test phase of Shin Kori unit 1 was simulated with SPACE. To assess the critical flow models of SPACE, the calculation with several critical flow models were carried out. The simulations of an inadvertent opening of spray valve of Shin Kori unit 1 with several critical flow models were carried out. The calculated transient behaviors of major reactor parameters with four critical flow models generally show good agreement with the measured.

  2. Lexical Link Analysis for the Haiti Earthquake Relief Operation Using Open Data Sources


    Information Systems Experimentation ( DISE ) Group Naval Postgraduate School, Monterey, CA 93943,, Open Data Sources Dr. Ying Zhao, Dr. Shelley P. Gallup, and Dr. Douglas J. MacKinnon Distributed Information Systems Experimentation ( DISE ...Proceedings of the Seventh Annual Acquisition Research Program. Monterey, CA: Naval Postgraduate School. DISE Distributed Information Systems


    Hu Yanping; Huang Zhichu; Liu Deshun; Mao Zhengyu


    A new construction of the relief valve is presented with pilot G-( bridg hydraulic resistances network. The design theory of G-( bridge relief valve is studied and the formulas for designing the relief valve with zero static pressure override are obtained. The static performances of the relief valve are experimentally investigated. The theoretical and experimental results show that the static pressure override of the developed relief valve can be zero, i.e. when the overflow increases the control pressure is kept constant.

  4. Some questions about the set pressure and relief area of safety valves in GB 150-1998%GB 150—1998中安全阀开启压力和排放面积疑义

    李志义; 王淑兰; 丁信伟


    The irrationality is analyzed of the design press ure of pressurevessels protected with safety valves, which is regulated in GB 1 50-1998 Steel Pressure Vessels. The error is pointed out relating to the calcul ation of the relief area of safety valves under subcritical flowing in GB 150-19 98. The importance correctly dealing with these two questions is stressed.%分析了GB150—1998《钢制压力容器》对装有安全阀的压力容器设计压力确定方法的不合理性,指出了其附录B中规定的亚临界条件下,安全阀排放面积计算式的错误,强调了正确处理这两个问题的重要性。

  5. 一种高压大流量气动定差压力控制阀的研究%Development of A Novel Pneumatic Relief Valve with High Pressure and Large Flow Capacity

    杨曙东; 李壮云


    In this paper, a novel pneumatic relief valve with high pressure and large flow capacity is presented, its structure characteristics are also presented. And then the valve's performances are investigated by theory analysis and experiments. Because the valve uses a single stage poppet and a rubber membrane with corrugations and air cushion bearing, it shows rapid response, higher pressure control precision and good adaptability to a large range of working pressure. This valve has been used in a projecting system.%介绍一种高压、大流量气动定差压力控制阀及其结构特点,对其性能进行了理论分析和实验研究。由于采用了直动膜片式放大结构和气体静压支承原理,该阀具有响应灵敏、控制精度高、自适应能力强等优点。目前,该阀已用于某发射装置。

  6. Measurement of opening and closing angles of aortic valve prostheses in vivo using dual-source computed tomography: Comparison with those of manufacturers' in 10 different types

    Suh, Young Joo; Kim, Young Jin; Hong, Yoo Jin; Lee, Hye Jeong; Hur, Jin; Im, Dong Jin; Kim, Yun Jung; Choi, Byoung Wook [Dept. of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)


    The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers' values and to compare CT-measured opening angles according to valve function. A total of 140 patients with 10 different types of mechanical aortic valves, who underwent dual-source cardiac CT, were included. Opening and closing angles were measured on CT images. Agreement between angles in normally functioning valves and the manufacturer values was assessed using the interclass coefficient and the Bland-Altman method. CT-measured opening angles were compared between normal functioning valves and suspected dysfunctioning valves. The CT-measured opening angles of normally functioning valves and manufacturers' values showed excellent agreement for seven valve types (intraclass coefficient [ICC], 0.977; 95% confidence interval [CI], 0.962-0.987). The mean differences in opening angles between the CT measurements and the manufacturers' values were 1.2° in seven types of valves, 11.0° in On-X valves, and 15.5° in ATS valves. The manufacturers' closing angles and those measured by CT showed excellent agreement for all valve types (ICC, 0.953; 95% CI, 0.920-0.972). Among valves with suspected dysfunction, those with limitation of motion (LOM) and an increased pressure gradient (PG) had smaller opening angles than those with LOM only (p < 0.05). Dual-source cardiac CT accurately measures opening and closing angles in most types of mechanical aortic valves, compared with the manufacturers' values. Opening angles on CT differ according to the type of valve dysfunction and a decreased opening angle may suggest an elevated PG.

  7. Effect of heart rate on the hemodynamics of bileaflet mechanical heart valves' prostheses (St. Jude Medical) in the aortic position and in the opening phase: A computational study.

    Jahandardoost, Mehdi; Fradet, Guy; Mohammadi, Hadi


    To date, to the best of the authors' knowledge, in almost all of the studies performed around the hemodynamics of bileaflet mechanical heart valves, a heart rate of 70-72 beats/min has been considered. In fact, the heart rate of ~72 beats/min does not represent the entire normal physiological conditions under which the aortic or prosthetic valves function. The heart rates of 120 or 50 beats/min may lead to hemodynamic complications, such as plaque formation and/or thromboembolism in patients. In this study, the hemodynamic performance of the bileaflet mechanical heart valves in a wide range of normal and physiological heart rates, that is, 60-150 beats/min, was studied in the opening phase. The model considered in this study was a St. Jude Medical bileaflet mechanical heart valve with the inner diameter of 27 mm in the aortic position. The hemodynamics of the native valve and the St. Jude Medical valve were studied in a variety of heart rates in the opening phase and the results were carefully compared. The results indicate that peak values of the velocity profile downstream of the valve increase as heart rate increases, as well as the location of the maximum velocity changes with heart rate in the St. Jude Medical valve model. Also, the maximum values of shear stress and wall shear stresses downstream of the valve are proportional to heart rate in both models. Interestingly, the maximum shear stress and wall shear stress values in both models are in the same range when heart rate is valve model when heart rate is >90 beats/min (up to ~40% growth compared to that of the native valve). The findings of this study may be of importance in the hemodynamic performance of bileaflet mechanical heart valves. They may also play an important role in design improvement of conventional prosthetic heart valves and the design of the next generation of prosthetic valves, such as percutaneous valves.

  8. A piezoelectrically actuated ball valve

    Erwin, L. R.; Schwartz, H. W.; Teitelbaum, B. R.


    Bimorph strip composed of two layers of poled piezoelectric ceramic material closes and opens valve. Strip performs like capacitator, allowing initial inrush of current when valve is energized and then only small leakage current flows as valve remains energized.

  9. 46 CFR 153.368 - Pressure-vacuum valves.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve... relief valve must meet the requirements of Subpart 162.017 of this chapter....

  10. Increasing the safety valve relief section of safety valves for discharge of a viscous liquid phase; Zur Vergroesserung des Entlastungsquerschnitts von Sicherheitsventilen bei der Bemessung im Fall des Austrags einer viskosen Fluessigphase

    Wieczorek, M.; Friedel, L. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Arbeitsbereich Stroemungsmechanik


    The cross section of safety valves is widened on the basis of a viscosity-dependend correction factor for higher-viscosity liquids. This method is presumably based on the results of investigations in control valves, and the viscosity correction factors used are therefore compared with those of safety valves. The corrections for safety valves according to API RP 520 for safety valves and draft DIN EN 60534-2-1 for control valves are in the same order of magnitude, while the correction according to Baumann is quite different. In principle, it can be seen that measurements will be required for validating the corrections for safety valves. [German] Der Stroemungsquerschnitt von Sicherheitsventilen in dem Fall einer Durchstroemung mit hoeher viskosen Fluessigkeiten wird mit Hilfe eines viskositaetsabhaengigen Korrekturfaktors vergroessert. Diese Vorgehensweise beruht vermutlich auf den Ergebnissen von Untersuchungen in Regelventilen, daher wurden die in diesem Bereich verwendeten Viskositaet-Korrekturen mit denen fuer Sicherheitsventile verglichen. Die Groessenordnung der Korrekturen gemaess API RP 520 fuer Sicherheitsventile und DIN (Entwurf) EN 60534-2-1 fuer Regelventile unterscheiden sich wenig voneinander. Die notwendige Vergroesserung entsprechend Baumann unterscheidet sich dagegen teilweise deutlich. Im Prinzip ist erkennbar, dass Messungen zur Validierung der Korrekturen fuer Sicherheitsventile erforderlich sind. (orig.)

  11. Face-Sealing Butterfly Valve

    Tervo, John N.


    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  12. The Effects of Wet Compression by the Electronic Expansion Valve Opening on the Performance of a Heat Pump System

    Kyoungjin Seong


    Full Text Available In this study, by controlling the Electronic Expansion Valve opening, the influence of wet compression on a heat pump system was experimentally investigated in different heating conditions. The results demonstrate that the discharge temperature decreased and the mass flow rate increased, due to quality of the rising liquid droplets. It was also found that the heating capacity and power input of wet compression increased more than that of dry compression, with a superheat of 10 °C. The maximum COP (Coefficient of Performance exists at a specific quality of ca. 0.94 to 0.90, as the power input in the region of wet compression is proportionally larger than the increase in the heating capacity, according to the decreasing quality. When the Entering Water Temperature of the Outdoor Heat Exchanger was 10 °C, 5 °C, and 0 °C, the COP increased by a maximum of ca. 12.4%, 10.6%, and 10.2%, respectively, in comparison to the superheat of 10 °C. In addition, the superheat at the discharge line is proposed as a proper controlling parameter to adjust the quality at the suction line, by varying the opening of the expansion valve during wet compression.

  13. EC Hidraulic Drive Cylinder Relief Vlave Test

    Wu, J.; /Fermilab


    This engineering note documents the testing of the set pressure of the EC hydraulic drive cylinder relief valve. The purpose of the relief valve is to provide a safety measure in the event that oil becomes trapped in the rod side of the cylinder and pressure is applied to the cap side. The note includes an explanation of the procedure used and a summary of the result of the testing done on February 14, 1991 by Gary Trotter. The result was that the cylinder relief valve relieved at the correct set pressure of 10,500 psig. The basic concern is for the protection of the cylinder. The pump is capable of providing up to 10,500 psi of pressure to either side of the cylinder. The cylinder is rated for 10,500 psi. Under normal operating conditions, the valves would be open, and the pumping pressure would automatically flow oil into one side, and remove oil from the other side. If, however, the valve for the other side was closed, so that oil could not be removed, then the pressure would build in that side. If the rod side is pressurized to the maximum pump pressure of 10,500 psi, the cross sectional area ratio of 2.29 results in a pressure of approximately 4600 psi in the cap side, which is well under the rated pressure. If, however, the cap side is pressurized to 10,500 psi, the cross sectional area would produce a pressure of approximately 24,000 psi in the rod side, which could damage the cylinder. Therefore, the pressure on the rod side must be limited to the rated pressure of 10,500 psi. In reality, the maximum operating force on the piston would be under 11,000 Ibs., which would result in the maximum cylinder pressure being under 8000 psi to the rod side, and under 3500 psi to the cap side. Therefore, the relief is only needed as a safety precaution in the case that oil becomes trapped.

  14. Heart Valve Diseases

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  15. Dump valve assembly

    Owen, T.J.


    A dump valve assembly comprising a body having a bore defined by a tapered wall and a truncated spherical valve member adapted to seat along a spherical surface portion thereof against said tapered wall. Means are provided for pivoting said valve member between a closed position engagable with said tapered wall and an open position disengaged therefrom.

  16. Torque Production Using Hand Cranks in a Simulated Gear-Operated Valve Opening Task.

    Schulze, Lawrence J H; Stanton, Edward; Patel, Anupam; Cheli, Maurizio


    Hand cranks are used in a variety of industries to actuate valves and in other gear-operated applications. In order to evaluate these types of operations and their compatibility with operator strength capabilities, a rotational dynamometer was used to measure torque production capability of operators using a hand crank at different heights and angles (with respect to the coronal plane). The tests were conducted for both clockwise and counterclockwise rotations using the dominant arm of each test participant. A total of 18 tests were completed by each of five male right-handed test participants. A 0° declination angle, counterclockwise operation, and both 40.65 cm and 60.96 cm heights were found to be associated with the greatest torque production capabilities.

  17. Aerodynamic Shutoff Valve

    Horstman, Raymond H.


    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  18. 46 CFR 64.67 - Shutoff valve.


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Shutoff valve. 64.67 Section 64.67 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.67 Shutoff valve. A shutoff...

  19. Simulation and experiment on static characteristic of water hydraulic proportional pressure relief valve%纯水比例溢流阀静态特性的仿真与试验

    张增猛; 周华; 高院安; 陈英龙


    A three-stage water hydraulic proportional pressure relief valve, with ball seat valve as the throttle control pilot stage, was investigated on the static characteristic. An AMESim model was built based on structure and mathematic analysis. The friction at spool, proportional electromagnetic actuator and steady flow force, which cause the valve hysteresis, were analyzed through simulation. The experiment results were also analyzed and compared to simulation results. The investigation shows that the large hysteresis mainly comes from flow force, hysteresis of electromagnetic actuator, and friction. Due to the static and coulomb friction and the structure of lever, the range of the input signal responding to pressure increasing section is narrower than pressure decreasing. The width of hysteresis is larger at low pressure than high pressure. For the reason of nonlinearity and large hysteresis of the valve, closed-loop control will be unstable and large oscillation may be induced. It should be improved through structure optimization or control compensation.%以带球阀比例节流先导级的三级座式纯水比例溢流阀为对象,在结构分析和数学建模的基础上,建立了阀的AMESim模型,仿真分析了稳态液动力、比例电磁铁、阀芯摩擦力等对阀静态特性的影响,并与试验对比. 结果表明:阀芯摩擦力及力放大杠杆结构降低了阀的静态性能,阀的滞环大,且随控制信号增大的可控线性段窄,阀在低压段的滞环大于高压工况. 阀的大滞环和严重的非线性降低了闭环系统稳定性,应通过改进结构和控制补偿等措施改善静态特性.

  20. Valve Disease

    ... heart valves, valve insufficiency, valve regurgitation, valve stenosis, valvular heart disease Every time your heart beats, blood flows into, ... removed from the market after being linked to heart valve disease. An infection in the lining of the heart's ...

  1. Implementation of an enlarged model of the safety valves and relief in the plant integral model for the code RELAP/SCDAPSIM; Implementacion de un modelo ampliado de las valvulas de seguridad y alivio en el modelo integral de planta para el codigo RELAP/SCDAPSIM

    Amador G, R.; Ortiz V, J.; Castillo D, R. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Hernandez L, E. J. [Instituto Tecnologico de Toluca, Av. Tecnologico s/n, Fracc. La Virgen, 52149 Metepec, Estado de Mexico (Mexico); Galeana R, J. C. [Universidad del Valle de Mexico, Campus Toluca, Av. de Las Palmas 136, 52140 Metepec, Estado de Mexico (Mexico); Gutierrez, V. H., E-mail: [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, 02200 Mexico D. F. (Mexico)


    The present work refers to the implementation of a new model on the logic of the safety valves and relief in the integral model of the Nuclear Power Plant of Laguna Verde of the thermal-hydraulic compute code RELAP/SCDAPSIM Mod. 3.4. The new model was developed with the compute package SIMULINK-MATLAB and contemplates all the operation options of the safety valves and relief, besides including the availability options of the valves in all the operation ways and of blockage in the ways of relief and low-low. The implementation means the elimination of the old model of the safety valves and to analyze the group of logical variables, of discharge and available control systems to associate them to the model of package SIMULINK-MATLAB. The implementation has been practically transparent and 27 cases corresponding to a turbine discharge were analyzed with the code RELAP/SCDAPSIM Mod. 3.4. The results were satisfactory. (Author)

  2. Handwheel valve operation: assessment of four opening methods in terms of muscle loading, perceived comfort, and efficiency.

    Aghazadeh, Fereydoun; Al Qaisi, Saif; Hutchinson, Francis; Ikuma, Laura


    Injuries due to manual valve handwheel operations are a major concern in the chemical process industry. Manual valves are used to start, stop, and control flow in process lines. The torque required to operate handwheels after the initial "breaking" can vary due to the size, design, and condition of the valve. This study tested four methods of turning the handwheel on a medium-sized gate valve at two different torque requirements (25 Nm and 50 Nm). The methods were compared to each other, in terms of efficiency, subjective ratings of perceived exertion, and electromyography activity of the upper extremity and trunk muscles. The results indicate that different methods and torque requirements are compensated for by the use of different muscles. Also, this use of different muscles, along with the increased mechanical advantage of the wrench, can affect the operator's actual and perceived comfort and efficiency while operating a valve handwheel.

  3. 46 CFR 154.912 - Inerted spaces: Relief devices.


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Inerted spaces: Relief devices. 154.912 Section 154.912... Atmospheric Control in Cargo Containment Systems § 154.912 Inerted spaces: Relief devices. Inerted spaces must be fitted with relief valves, rupture discs, or other devices specially approved by the...

  4. Analysis and Comparison of Rated Capacity Calculation of Safety Relief Valves for AP1000 Nuclear Project%AP1000核电项目安全释放阀额定排量计算的分析与比较

    陈中一; 徐陈凯


    安全释放阀[1]是一种通过排出一定量的介质来防止管道或设备内介质压力超过规定数值从而起到保护压力容器、管道和其它受压设备上的重要安全附件。正确的额定排量计算是安全阀的选用及系统保护设计的关键步骤。针对AP1000(第三代压水堆核电站的一种堆型)核电项目安全释放阀的多种排量计算标准进行了经验分析及比较。%The safety relief valve is a significant safety accessory for releasing a certain account of medium to protect pressure vessels, piping and other pressure containment equipment. Correct rated capacity calculation is the important step of safety re-lief valves selection and system protection design. Kinds of rated capacity calculation standards for the AP1000 nuclear project safety relief valves are analyzed and compared for the subsequent tests.

  5. Cryogenic Cam Butterfly Valve

    McCormack, Kenneth J. (Inventor)


    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  6. An open-label pilot study to assess the effectiveness of krill oil with added vitamins and phytonutrients in the relief of symptoms of PMS

    Wakeman MP


    Full Text Available Michael P Wakeman School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, West Midlands, UK Abstract: An open-label pilot study over 4 months to evaluate the effectiveness of a compound formulation of ingredients, which individually have been demonstrated to be implicated in the pathogenesis of premenstrual syndrome to ameliorate the most troublesome symptoms of the condition. The supplement provided thiamine, riboflavin, pyridoxine, vitamin D, soy isoflavones, rosemary extract, and krill oil and was taken each day for the 3 months of the trial. Statistically significant effect was reported by the 29 women who completed the study in relief of anxiety, bloating, mood swings, breast tenderness, skin outbreaks, food cravings, fatigue, forgetfulness, insomnia, and headache after 3 months of treatment compared with baseline. This pilot study indicates the formulation to be effective, and a larger placebo-controlled trial is now planned. Keywords: thiamine, riboflavin, pyridoxine, vitamin D, soy isoflavones, rosemary extract, premenstrual syndrome

  7. Opening Angle and Impact Force Analysis of Different Types Flap Valve in Pumping Stations%泵站不同类型拍门的开启角和撞击力分析

    王志祥; 李端明; 李娜; 陈坚


    Deriving motion equation of flap valve with the energy method,calculating and analyzing the opening angle and impact force of different forms of installation(free rollover,free suspended,covers),different valve pages(single-leaf and double-leaf) and different materials(steel and composite materials) with the example of Bailizhou Pumping Station.Under the same conditions,the results show that:for single-block flap valve of different installations,opening angle of free rollover flap valve is bigger than free suspended flap valve at 22°,and bigger than cover flap valve at 12°,impact force of three installation forms flap valve is close.For different valve pages,opening angle of double-leaf flap valve is slightly larger than the single-leaf,impact force of free rollover double-leaf flap valve is 42% of the single-leaf,and cover double-leaf flap valve is 49% of the single-leaf.Comparing different materials,opening angle of free rollover composite flap valve is 4% bigger than the steel flap valve,its impact force is 9.6% smaller than steel flap valve,and opening angle of free suspended composite flap valve and cover composite flap valve is 10%~15% bigger than their steel flap valve,impact force of free suspended composite flap valve is 39.5% smaller than the steel flap valve,and cover composite flap valve is 28.5% smaller than the steel flap valve.This shows that,for the hydraulic performance,free rollover and composite material flap valve is worthy of popularization.%基于能量法推导了拍门的运动方程,结合百里洲泵站实例,分析计算了不同安装形式(自由侧翻式、自由起落式和井盖式)、不同门页数(单扇、双扇)和不同材质(钢质、复合材料)拍门的开启角和撞击力。同等条件下,计算结果表明:对不同安装形式的单块拍门,自由侧翻式拍门的开启角比自由起落式大22°,比井盖式大12°,撞击力三者相差不多;对不同的

  8. Acoustic Performance Analysis of the Varying Valve Opening Angle for the Muffler with Valve and Its Application%带阀消声器阀体开度变化的声学特性分析及应用

    刘海涛; 郑四发; 但佳壁; 连小珉


    The order noise in low-frequency band has great impact on the sound quality of exhaust noise. The muffler with valve becomes one of the means to eliminate low-frequency noise. The actual muffler with valve is analyzed by experiment and three-dimensional numerical simulation methods. It is found that the resonance frequency shift towards high frequency as the valve’s opening degrees increase. Further, a sub structural unit, named adjustable lumped inertance resonator(ALIR), is extracted from the actual muffler with valve. Three-dimensional numerical simulation and an in-line lumped element model are used to calculate the lumped inertance of the valve structure with different opening angles. The lumped model of ALIR is established. The results show that the lumped inertance, which changes with the valve’s opening degrees, is the key factor on the shifting of resonance frequency. Therefore the low frequency silencer mechanism of the muffler with valve is successfully revealed. At last, actual vehicle test is implemented with the muffler with valve and a contrast muffler. It is found that the muffler with valve can effectively eliminate the order noise tracing the engine speed times.%低频阶次噪声对排气噪声声品质有着重要的影响,带阀消声器成为消除排气低频噪声的手段之一。对带阀消声器进行试验分析和三维数值仿真,发现随着阀体开度的增加,共振器的共振频率向高频移动。进一步从实际带阀消声器结构中提取出一种可调声质量抗共振器子结构单元,采用三维数值方法和集总阻抗传递矩阵模型计算出不同开度下的阀体结构的声质量抗,建立共振器的集总阻抗模型。结果显示,阀体开度变化改变了共振器的声质量抗,而声质量抗是影响共振频率的关键因素,揭示出带阀消声器消除低频阶次噪声的机理。将带阀消声器和对比消声器进行实车测试。结果表明,带阀消声器起

  9. Increasing the Useful Life of Quench Reliefs with Inconel Bellows

    Soyars, W. M. [Fermilab


    Reliable quench relief valves are an important part of superconducting magnet systems. Fermilab developed bellows-actuated cryogenic quench reliefs which have been in use since the early l 980's. The original design uses a stainless steel bellows. A high frequency, low amplitude vibration during relieving events has resulted in fatigue failures in the original design. To take advantage of the improved resistance to fatigue of Inconel, a nickel-chromium alloy, reliefs using Inconel 625 bellows were made. Design, development, and testing of the new version reliefs will be discussed. Tests show that relief valve lifetimes using Inconel bellows are more than five times greater than when using the original stainless steel bellows. Inconel bellows show great promise in increasing the lifetime of quench relief valves, and thus the reliability of accelerator cryogenic systems.

  10. Assessment of a pressurizer spray valve faulty opening transient at Asco Nuclear Power Plant with RELAP5/MOD2. International Agreement Report

    Reventos, F.; Baptista, J.S.; Navas, A.P.; Moreno, P. [Asociacion Nuclear Asco, Barcelona (Spain)


    The Asociacion Nuclear Asco has prepared a model of Asco NPP using RELAP5/MOD2. This model, which include thermalhydraulics, kinetics and protection and controls, has been qualified in previous calculations of several actual plant transients. One of the transients of the qualification process is a ``Pressurizer spray valve faulty opening`` presented in this report. It consists in a primary coolant depressurization that causes the reactor trip by overtemperature and later on the actuation of the safety injection. The results are in close agreement with plant data.


    Shanthi C


    Full Text Available Background: Post surgical mitral valve disease individual focus their cardiac rehabilitation training on two major goal that is to improve cardiac output response exercises and place an important role in determining exercise tolerance and to improve quality of life. Cardiac rehabilitation programs involve prescribed exercise and education however various other method are being used to improve quality of life. But our study to find out the effectiveness of graded aerobic exercise protocol on ejection fraction and quality of life in post surgical mitral valve disease individuals. Methods: The study design was open label studies total of 100 post surgical mitral valve disease individuals patients from the age group of 20-60 years were recruited from SVIMS hospital. They were randomly divided into two groups. Group I underwent a twelve week structured graded individually tailored exercises. The group II received only none graded (not individualized exercise training. The ejection fraction and quality of life was measured before and after 12 weeks of exercise training for two groups. Results: Repeated measures ANOVA was used to compare mean values of continuous variables between baseline and at the time of discharge and three months after surgery for each parameter. Comparison of means between groups was done by the unpaired student t test. Mean age of the subjects was 40.18±10.29. There was a significant increase in the ejection fraction in the group I(61.34±2.49 to 64.4±3.31 compared to with the group II (61.06±2.51. to 61.62 ±2.37. QOL had improved in group I than group II at p<0.05. Conclusion: A 12 week structured graded aerobic exercise training significantly improved ejection fraction and quality of life in post surgical mitral valve disease individuals.

  12. Depth relief

    Kappers, A.M.L.; Koenderink, J.J.; Doorn, A.J. van


    A study is reported of the depth relief in a simple three-dimensional scene consisting of a white, rough sphere on a planar support, illuminated in a natural manner. Viewing conditions included monocular and binocular as well as 'synoptical' viewing. In the synoptical condition the eyes are

  13. Modeling the Mitral Valve

    Kaiser, Alexander


    The mitral valve is one of four valves in the human heart. The valve opens to allow oxygenated blood from the lungs to fill the left ventricle, and closes when the ventricle contracts to prevent backflow. The valve is composed of two fibrous leaflets which hang from a ring. These leaflets are supported like a parachute by a system of strings called chordae tendineae. In this talk, I will describe a new computational model of the mitral valve. To generate geometry, general information comes from classical anatomy texts and the author's dissection of porcine hearts. An MRI image of a human heart is used to locate the tips of the papillary muscles, which anchor the chordae tendineae, in relation to the mitral ring. The initial configurations of the valve leaflets and chordae tendineae are found by solving solving an equilibrium elasticity problem. The valve is then simulated in fluid (blood) using the immersed boundary method over multiple heart cycles in a model valve tester. We aim to identify features and mechanisms that influence or control valve function. Support from National Science Foundation, Graduate Research Fellowship Program, Grant DGE 1342536.

  14. Influence of surgical implantation angle of left ventricular assist device outflow graft and management of aortic valve opening on the risk of stroke in heart failure patients

    Chivukula, V. Keshav; McGah, Patrick; Prisco, Anthony; Beckman, Jennifer; Mokadam, Nanush; Mahr, Claudius; Aliseda, Alberto


    Flow in the aortic vasculature may impact stroke risk in patients with left ventricular assist devices (LVAD) due to severely altered hemodynamics. Patient-specific 3D models of the aortic arch and great vessels were created with an LVAD outflow graft at 45, 60 and 90° from centerline of the ascending aorta, in order to understand the effect of surgical placement on hemodynamics and thrombotic risk. Intermittent aortic valve opening (once every five cardiac cycles) was simulated and the impact of this residual native output investigated for the potential to wash out stagnant flow in the aortic root region. Unsteady CFD simulations with patient-specific boundary conditions were performed. Particle tracking for 10 cardiac cycles was used to determine platelet residence times and shear stress histories. Thrombosis risk was assessed by a combination of Eulerian and Lagrangian metrics and a newly developed thrombogenic potential metric. Results show a strong influence of LVAD outflow graft angle on hemodynamics in the ascending aorta and consequently on stroke risk, with a highly positive impact of aortic valve opening, even at low frequencies. Optimization of LVAD implantation and management strategies based on patient-specific simulations to minimize stroke risk will be presented

  15. Fault diagnosis of reciprocating compressor valve with the method integrating acoustic emission signal and simulated valve motion

    Wang, Yuefei; Xue, Chuang; Jia, Xiaohan; Peng, Xueyuan


    This paper proposes a method of diagnosing faults in reciprocating compressor valves using the acoustic emission signal coupled with the simulated valve motion. The actual working condition of a valve can be obtained by analyzing the acoustic emission signal in the crank angle domain and the valve movement can be predicted by simulating the valve motion. The exact opening and closing locations of a normal valve, provided by the simulated valve motion, can be used as references for the valve fault diagnosis. The typical valve faults are diagnosed to validate the feasibility and accuracy of the proposed method. The experimental results indicate that this method can easily distinguish the normal valve, valve flutter and valve delayed closing conditions. The characteristic locations of the opening and closing of the suction and discharge valves can be clearly identified in the waveform of the acoustic emission signal and the simulated valve motion.

  16. Efficacy of single-injection unilateral thoracic paravertebral block for post open cholecystectomy pain relief: a prospective randomized study at Gondar University Hospital

    Fentie, Demeke Yilkal; Gebremedhn, Endale Gebreegziabher; Denu, Zewditu Abdissa; Gebreegzi, Amare Hailekiros


    Background Cholecystectomy can be associated with considerable postoperative pain. While the benefits of paravertebral block (PVB) on pain after thoracotomy and mastectomy have been demonstrated, not enough investigations on the effects of PVB on pain after open cholecystectomy have been conducted. We tested the hypothesis that a single-injection thoracic PVB reduces pain scores, decreases opioid consumption, and prolongs analgesic request time after cholecystectomy. Methods Of 52 patients recruited, 50 completed the study. They were randomly allocated into two groups: the paravertebral group and the control group. The outcome measures were the severity of pain measured on numeric pain rating scale, total opioid consumption, and first analgesic request time during the first postoperative 24 hours. Result The main outcomes recorded during 24 hours after surgery were Numerical Rating Scale (NRS) pain scores (NRS, 0–10), cumulative opioid consumption, and the first analgesic request time. Twenty four hours after surgery, NRS at rest was 4 (3–6) vs 5 (5–7) and at movement 4 (4–7) vs 6 (5–7.5) for the PVB and control groups, respectively. The difference between the groups over the whole observation period was statistically significant (Ptramadol consumption was 200 (150–250) mg vs 300 (200–350) mg in the paravertebral and in the control group, respectively (P=0.003). After surgery, the median (25th–75th percentile) first analgesic requirement time was prolonged in the PVB group in statistically significant fashion (P<0.0001). Conclusion and recommendations Single-shot thoracic PVB as a component of multi-modal analgesic regimen provided superior analgesia when compared with the control group up to 24 postoperative hours after cholecystectomy, and we recommend this block for post cholecystectomy pain relief. PMID:28744155

  17. A valve disk

    Khayrullin, N.A.; Isayev, B.N.; Kruglov, S.A.; Molokanov, Yu.K.; Shchelkunov, V.A.; Shegay, V.R.; Vizhgorodskiy, B.N.


    A valve disk is proposed which includes a horizontal bed, on which there are laminar valves arranged in staggered order. To ensure the stable and effective operation of the disk in a broad range of loads by compensating for the direct flow and the partial sectioning of the disk bed, it is equipped with compensating elements installed in openings in the bed and hinged with it. They are made in the form of straight, triangular prisms with ports in the bases. The prisms are installed with the capability of movement relative to the disk bed. The valves are positioned on the upper lateral facets of the compensating elements.

  18. Valve stem and packing assembly

    Wordin, J.J.


    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele`s pivot. The Schiele`s pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele`s pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele`s pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  19. Measurement of reed valve kinematics

    Fenkl Michael


    Full Text Available The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed.

  20. Measurement of reed valve kinematics

    Fenkl, Michael; Dvořák, Václav; Vít, Tomáš


    The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed.

  1. Hydraulic engine valve actuation system including independent feedback control

    Marriott, Craig D


    A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

  2. Transapical Mitral Valve-in-Valve Replacement in Patient With Previous Complex Sternal Reconstruction.

    Hynes, Conor F; Fatemi, Omid; Sharma, Aditya C; Nagy, Christian D; Trachiotis, Gregory D


    We present a complex case of a transapical redo mitral valve-in-valve replacement. Repeat mitral valve replacement was indicated for severe symptomatic bioprosthetic stenosis. In addition to the patient's numerous comorbidities that included diabetes, hepatic cirrhosis, ischemic cardiomyopathy, and atrial flutter, he had undergone a previous open mitral valve replacement that was complicated by sternal dehiscence requiring extensive chest wall reconstruction. Transapical approach was performed through left minithoracotomy incision with balloon-expandable valve. Transapical valve-in-valve replacement of a stenotic mitral bioprosthesis is a viable solution in a patient with previous complex chest wall reconstruction and multiple comorbidities.

  3. Variable gas leak rate valve

    Eernisse, Errol P. (Albuquerque, NM); Peterson, Gary D. (Albuquerque, NM)


    A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

  4. Coordinating Robot Teams for Disaster Relief


    Coordinating Robot Teams for Disaster Relief Mark Roberts1, Thomas Apker2, Benjamin Johnson1, Bryan Auslander3, Briana Wellman4 & David W...for Humanitarian Assistance / Disaster Relief operations. We demonstrate that the SDP responds to a dynamic, open world while ensuring that vehicles...facilitate such information gathering tasks, freeing humans to perform more critical tasks in Humanitarian Assistance / Disaster Relief (HA/DR

  5. Method and system for measuring gate valve clearances and seating force

    Casada, Donald A.; Haynes, Howard D.; Moyers, John C.; Stewart, Brian K.


    Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner.

  6. Method and system for measuring gate valve clearances and seating force

    Casada, D.A.; Haynes, H.D.; Moyers, J.C.; Stewart, B.K.


    Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner. 8 figs.

  7. Computational Fluid Dynamics Analysis of Butterfly Valve Performance Factors

    Del Toro, Adam


    Butterfly valves are commonly used in industrial applications to control the internal flow of both compressible and incompressible fluids. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As the valve's opening angle is increased from 0 degrees (fully closed) to 90 degrees (fully open), fluid is able to more readily flow past the valve. Characterizing a valve's performance factors, such as pressure drop, hydrodynamic torqu...

  8. Design of the Opening and Closing Device of the High Pressure Valve Based on Differential Differential Planet Gear Mechanism%基于差速行星轮机构的阀门顺序启闭装置的设计

    邓英剑; 刘忠伟; 翟启; 陈臻阳


    The valves are important components of the pressure piping systems .The leakage ,internal leakage are common phe-nomenon of valves .In order to solve this problem ,a opening and closing device of the valve is designed based on the differential planetary gear ,by adopting double sealing which including cone valve and ball valve ,at the same time taking advantage of the on both sides of the output transform characteristics use of differential planetary gear combined with arc locking device ,in order to a-chieve the relevant sequence of actions with ball and cone valve ,on the structure to ensure that “when opened ,first the cone valve is opened ,then the ball valve is opened;when closed ,first the ball valve is closed ,then the cone valve is closed”.So as to avoid the erosion of high pressure for cone valve ,and improve the service life of the valve ,reliability and accuracy of control .%设计了一种基于差速行星轮机构的阀门顺序启闭装置的阀门,通过采用锥阀和球阀双重密封,同时利用差速行星轮机构两边输出能够转换的特点与圆弧锁止器相结合,从而实现球阀和锥阀的相关顺序动作,在结构上保证了“开启时,锥阀先开启球阀后开启;关闭时,球阀先关闭锥阀后关闭”的顺序动作,从而保证锥阀避免高压的冲蚀,提高了阀门的使用寿命、可靠性以及控制的精确性。

  9. 33 CFR 157.122 - Piping, valves, and fittings.


    ...) Each overpressure relief valve must discharge into the suction side of a pump that meets § 157.126(b... system for oil washing and water washing, that piping system must be designed to drain the crude oil...

  10. Significant issues and changes for ANSI/ASME OM-1 1981, part 1, ASME OMc code-1994, and ASME OM Code-1995, Appendix I, inservice testing of pressure relief devices in light water reactor power plants

    Seniuk, P.J.


    This paper identifies significant changes to the ANSI/ASME OM-1 1981, Part 1, and ASME Omc Code-1994 and ASME OM Code-1995, Appendix I, {open_quotes}Inservice Testing of Pressure Relief Devices in Light-Water Reactor Power Plants{close_quotes}. The paper describes changes to different Code editions and presents insights into the direction of the code committee and selected topics to be considered by the ASME O&M Working Group on pressure relief devices. These topics include scope issues, thermal relief valve issues, as-found and as-left set-pressure determinations, exclusions from testing, and cold setpoint bench testing. The purpose of this paper is to describe some significant issues being addressed by the O&M Working Group on Pressure Relief Devices (OM-1). The writer is currently the chair of OM-1 and the statements expressed herein represents his personal opinion.

  11. Assessment of RELAP5/MOD2 against a pressurizer spray valve inadverted fully opening transient and recovery by natural circulation in Jose Cabrera Nuclear Station

    Arroyo, R.; Rebollo, L. [Union Electrica, SA, Madrid (Spain)


    This document presents the comparison between the simulation results and the plant measurements of a real event that took place in JOSE CABRERA nuclear power plant in August 30th, 1984. The event was originated by the total, continuous and inadverted opening of the pressurizer spray valve PCV-400A. JOSE CABRERA power plant is a single loop Westinghouse PWR belonging to UNION ELECTRICA FENOSA, S.A. (UNION FENOSA), an Spanish utility which participates in the International Code Assessment and Applications Program (ICAP) as a member of UNIDAD ELECTRICA, S.A. (UNESA). This is the second of its two contributions to the Program: the first one was an application case and this is an assessment one. The simulation has been performed using the RELAP5/MOD2 cycle 36.04 code, running on a CDC CYBER 180/830 computer under NOS 2.5 operating system. The main phenomena have been calculated correctly and some conclusions about the 3D characteristics of the condensation due to the spray and its simulation with a 1D tool have been got.

  12. 基于阀门开度的水下闸阀摩擦力负载模型研究%Study on f rictional load model based on subsea gate valve opening

    潘灵永; 王向旗; 李宝仁; 高文金


    In order to study the effects of valve opening ,pressure loss coefficient and operating depth on the frictional load ,the dynamic frictional load model was investigated using both theoretical and empirical method .In this paper ,a subsea gate valve w as tested .Results have show n that the valve o-pening is the key control parameter for minor loss coefficient and frictional load .At low valve open-ing ,increasing valve opening will decrease the frictional load .With further increase ,the frictional load tends to zero .The methodology performs better than the traditional method .It can be used to model the dynamic frictional load based on the complex valve movements and can be potentially applied in practice .%在分析现有水下闸阀设计方法存在不足的基础上 ,综合考虑水下闸阀运动特性以及实际生产工况对摩擦力负载的影响 ,以某水下闸阀为例 ,提出一种基于阀门开度的水下闸阀摩擦力负载建模方法 .采用包括阀门局部阻力和沿程阻力损失、工作水深等数据 ,辨识出阀板上下游之间的压差 ,从而达到模型修正的目的 .与试验数据相比 ,基于阀门开度的摩擦力负载模型能更准确地反映阀门运动对负载的影响以及预测水下闸阀的动态特性 ,从而为高可靠性的水下闸阀及执行机构优化设计和制造提供理论依据 .

  13. [Long-term results of closed mitral commissurotomy--comparative study of closed mitral commissurotomy (CMC), open mitral commissurotomy (OMC) and mitral valve replacement (MVR)].

    Suzuki, S; Kondo, J; Imoto, K; Kajiwara, H; Tobe, M; Sakamoto, A; Isoda, S; Yamazaki, I; Noishiki, Y; Matsumoto, A


    As the technique of open heart surgery has improved, CMC has been abandoned in favor of OMC and MVR. We evaluated and compared the results of CMC, OMC and MVR. METHOD. Between 1965 and 1978, 141 patients with mitral stenosis (MS) underwent CMC, and late follow-up obtained in 117 (83%) of them (CMC group). Between 1980 and 1989, 72 patients and 37 patients underwent OMC (OMC group) and MVR (MVR group), respectively. Cumulative follow-up periods were 1982, 632 and 200 patient-years in the CMC, OMC and MVR groups, respectively. RESULTS. (1) Survival rate; In the CMC group there were 2 operative deaths due to severe mitral regurgitation (MR). There were 17 late deaths, due to reoperations in 4 patients, cerebral infarction in 4 patients, congestive heart failure in 3 patients, myocardial infarction in 2 patients and unknown causes in 4 patients. The survival rate was 95%, 91% and 86% at 5, 10 and 15 years, respectively, in the CMC group. In the OMC and MVR groups there was no death. (2) The event free rate was 89%, 79% and 58% at 5, 10 and 15 years, respectively, in the CMC group, 97% and 97% at 5 and 10 years in the OMC group, and 95% and 90% at 4 and 5 years in the MVR group. (3) Reoperations; In the CMC group of 40 patients (34%) required reoperations in an average of 10.4 years after the initial operation, due to re-MS in 22 patients, MR in 10 patients and MRS in the 8 patients. Reoperative findings consisted of clefts in the mitral leaflets in 7 patients. There were pulmonary hypertension in 15 patients and tricuspid regurgitation in 22 patients. Fourteen patients underwent tricuspid anuloplasty and one patient underwent a tricuspid valve replacement. In the OMC group one patient required a reoperation due to MR; in the MVR group one patient required a reoperation due to a thrombosed valve. CONCLUSION. In the CMC group the survival rate and the event free rate were lower, and the rate of reoperation was higher than in the other two groups.

  14. Latest design of gate valves

    Kurzhofer, U.; Stolte, J.; Weyand, M.


    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  15. Valve stem and packing assembly

    Wordin, J.J.


    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents over tightening of the retaining nut and the resulting excessive friction between stem and stem packing. 2 figures.

  16. Valve stem and packing assembly

    Wordin, John J. (Bingham County, ID)


    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  17. Valve stem and packing assembly

    Wordin, J.J.


    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  18. Itching for Allergy Relief?

    ... Home For Consumers Consumer Updates Itching for Allergy Relief? Share Tweet Linkedin Pin it More sharing options ... your ability to function, you don't find relief from OTC drugs, or you experience allergy symptoms ...

  19. Valve's Way

    Phanish Puranam


    Full Text Available What can we learn from outliers? While statisticians rightly warn us against their non-representativeness, we believe it is also true that thinking carefully about what makes them atypical may improve our understanding of the typical case. This is the premise behind the Organization Zoo series. Valve Corporation (Valve is an unusual firm. It is a rare example of a firm that appears to operate without any formal hierarchy in its organization. What can we learn about the viability of authority hierarchies from Valve’s way of organizing? We wrote a brief account of Valve based on public information sources and asked several renowned organizational experts to comment on this unusual firm. We asked them to write a short commentary on what the Valve example means for organizational theorists and practitioners. Thankfully, they all accepted, and we are excited to present the results of their thinking in this first “exhibit” in the Organization Zoo.

  20. Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

    Abulon DJ


    Full Text Available Dina Joy Abulon,1 Martin Charles,2 Daniel E Charles21Global Medical Affairs, Alcon Laboratories, Inc., Lake Forest, CA, USA; 2Centro Oftalmológico Dr Charles, Buenos Aires, ArgentinaPurpose: To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP, fluid leakage, and vitreous incarceration during simulated vitrectomy.Methods: Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar cannulas. The models were filled with air and IOP was measured. Similar procedures were followed for 36 acrylic eyes filled with saline solution. Vitreous incarceration was analyzed in eleven rabbit and twelve porcine cadaver eyes.Results: In the air-filled model, IOP loss was 89%–94% when two non-valved cannulas were unoccupied versus 1%–5% when two valved cannulas were unoccupied. In the fluid-filled model, with non-valved cannulas, IOP dropped while fluid leaked from the open ports. With two open ports, the IOP dropped to 20%–30% of set infusion pressure, regardless of infusion pressure and IOP compensation. The IOP was maintained in valved cannulas when one or two ports were left open, regardless of IOP compensation settings. There was no or minimal fluid leakage through open ports at any infusion pressure. Direct microscopic analysis of rabbit eyes showed that vitreous incarceration was significantly greater with 23-gauge non-valved than valved cannulas (P<0.005, and endoscopy of porcine eyes showed that vitreous incarceration was significantly greater with 23-gauge (P<0.05 and 27-gauge (P<0.05 non-valved cannulas. External observation of rabbit eyes showed vitreous prolapse through non-valved, but not valved, cannulas.Conclusion: Valved cannulas surpassed non-valved cannulas in maintaining IOP, preventing fluid leakage, and reducing vitreous incarceration during simulated vitrectomy.Keywords: IOP, fluid leakage, vitreous incarceration

  1. 49 CFR 236.383 - Valve locks, valves, and valve magnets.


    ... 49 Transportation 4 2010-10-01 2010-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  2. Low-Pressure-Drop Shutoff Valve

    Thornborrow, John


    Flapper valve remains open under normal flow conditions but closes upon sudden increases to high rate of flow and remains closed until reset. Valve is fluid/mechanical analog of electrical fuse or circuit breaker. Low-pressure-drop shutoff valve contains flapper machined from cylindrical surface. During normal flow conditions, flapper presents small cross section to flow. (Useful in stopping loss of fluid through leaks in cooling systems.)

  3. Gasoline New Timing and Flux Adjustable Rotary Valve Design (Hereinafter: Rotary Valve

    Du huiqi


    Full Text Available Conventional gasoline engine with an umbrella valve control cylinder intake and exhaust, in order to achieve sealing effect, the valve is driven by the spring force; at the same time, when the cam opens the valve to overcome the spring force acting. Sealing the better, the more power consumed in the engine mechanical losses, the valve mechanism consumes about 30%, which is not a small loss! This article describes a new type of rotary valve is to significantly reduce mechanical losses, so as to achieve energy saving purposes.

  4. Piezoelectric valve

    Petrenko, Serhiy Fedorovich


    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  5. A mechanism for the auto-inhibition of hyperpolarization-activated cyclic nucleotide-gated (HCN) channel opening and its relief by cAMP.

    Akimoto, Madoka; Zhang, Zaiyong; Boulton, Stephen; Selvaratnam, Rajeevan; VanSchouwen, Bryan; Gloyd, Melanie; Accili, Eric A; Lange, Oliver F; Melacini, Giuseppe


    Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels control neuronal and cardiac electrical rhythmicity. There are four homologous isoforms (HCN1-4) sharing a common multidomain architecture that includes an N-terminal transmembrane tetrameric ion channel followed by a cytoplasmic "C-linker," which connects a more distal cAMP-binding domain (CBD) to the inner pore. Channel opening is primarily stimulated by transmembrane elements that sense membrane hyperpolarization, although cAMP reduces the voltage required for HCN activation by promoting tetramerization of the intracellular C-linker, which in turn relieves auto-inhibition of the inner pore gate. Although binding of cAMP has been proposed to relieve auto-inhibition by affecting the structure of the C-linker and CBD, the nature and extent of these cAMP-dependent changes remain limitedly explored. Here, we used NMR to probe the changes caused by the binding of cAMP and of cCMP, a partial agonist, to the apo-CBD of HCN4. Our data indicate that the CBD exists in a dynamic two-state equilibrium, whose position as gauged by NMR chemical shifts correlates with the V½ voltage measured through electrophysiology. In the absence of cAMP, the most populated CBD state leads to steric clashes with the activated or "tetrameric" C-linker, which becomes energetically unfavored. The steric clashes of the apo tetramer are eliminated either by cAMP binding, which selects for a CBD state devoid of steric clashes with the tetrameric C-linker and facilitates channel opening, or by a transition of apo-HCN to monomers or dimer of dimers, in which the C-linker becomes less structured, and channel opening is not facilitated.

  6. Transient stress analysis of the main steam isolation valve during the load case ''fast opening of the main steam isolation valve''; Transiente Spannungsanalyse des Gehaeuses eines aeusseren Frischdampfisolierventils beim Lastfall ''Schnelles Oeffnen des Frischdampfisolierventils''

    Pacharzina, B.; Uptmoor, H. [Westinghouse Electric Germany GmbH, Mannheim (Germany)


    The structural integrity was demonstrated for a German NPP including the load case ''fast opening of the main steam isolation valve''. Since the verification of the armature housing integrity was not possible using the component specific method according KTA 3201.2 a detailed finite element analysis using the ANSYS-FE code and elastic material characteristics was performed. The considered loads include operating weight, internal pressure, restrained thermal expansion, and fluid dynamical loads. For the damping behavior according KTA 2201.4 (earth quakes) a damping factor of 4% of the critical damping was assumed. The stress analysis was performed and evaluated.

  7. Excess flow shutoff valve

    Kiffer, Micah S.; Tentarelli, Stephen Clyde


    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  8. Self-Rupturing Hermetic Valve

    Tucker, Curtis E., Jr.; Sherrit, Stewart


    -energizing and requires low force compared to current pyrotechnic-based burst disk hermetic valves. This is a novel design for producing a single-use, self-rupturing, hermetically sealed valve for isolation of pressurized gas and/or liquids. This design can also be applied for single-use disposable valves for chemical instruments. A welded foil diaphragm is fully supported by two mated surfaces that are machined to micron accuracies using EDM. To open the valve, one of the surfaces is moved relative to the other to (a) remove the support creating an unsupported diaphragm that ruptures due to over pressure, and/or (b) produce tension in the diaphragm and rupture it.

  9. Vacuum Valve


    This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.

  10. Valve's Way

    Foss, Nicolai Juul; Dobrajska, Magdalena


    to what extent it represents a new blueprint for organization design, despite it being consistent with an “egalitarian Zeitgeist” (Puranam, 2014). In fact, managerial authority may be of increasing importance rather than the opposite (Guadalupe, Li, & Wulf, 2015). Thus, Valve is, and will remain...

  11. Valve's Way

    Foss, Nicolai Juul; Dobrajska, Magdalena


    Puranam and Håkonsson (2015) challenge us to ponder what we as organization design theorists make of Valve’s way (see also Jeppesen, 2008). We believe that Valve, in spite of its radical vision, does not represent a challenge to fundamental organization design theory and that it is questionable...

  12. 46 CFR 53.05-1 - Safety valve requirements for steam boilers (modifies HG-400 and HG-401).


    ... 46 Shipping 2 2010-10-01 2010-10-01 false Safety valve requirements for steam boilers (modifies HG... requirements for steam boilers (modifies HG-400 and HG-401). (a) The pressure relief valve requirements and the safety valve requirements for steam boilers must be as indicated in HG-400 and HG-401 of section IV...

  13. System and method for controlling engine knock using electro-hydraulic valve actuation

    Brennan, Daniel G


    A control system for an engine includes a knock control module and a valve control module. The knock control module adjusts a period that one or more of an intake valve and an exhaust valve of a cylinder are open based on engine knock corresponding to the cylinder. The valve control module, based on the adjusted period, controls the one or more of the intake valve and the exhaust valve using one or more hydraulic actuators.

  14. Artificial SMA valve for treatment of urinary incontinence: upgrading of valve and introduction of transcutaneous transformer.

    Tanaka, M; Hirano, K; Goto, H; Namima, T; Uchi, K; Jiang, Z W; Matsuki, H; Tanahashi, Y; Orikasa, S; Chonan, S


    This paper is concerned with the development of an artificial urethral valve driven by shape memory alloy actuators, which is attached onto the urethra of a urinary incontinence sufferer for treating the involuntary micturition. Three types of compact cylindrical valves are assembled and their opening and closing functions are examined experimentally. The updated valve is heated and opened by using the transcutaneous energy transformer consisting of a pair of flexible spiral-formed copper wire coils. The experiment using the canine urinary canal verifies that the total system of the valve and the transformer works well as an artificial sphictor muscle and controls the urinary flow through the canal appropriately.

  15. The efficacy of preventive parasternal single injection of bupivacaine on intubation time, blood gas parameters, narcotic requirement, and pain relief after open heart surgery: A randomized clinical trial study

    Mahmoud Saeidi


    Full Text Available Background: Postsurgical pain usually results in some complications in the patients. This study has tried to investigate the effects of parasternal single injection of bupivacaine on postoperative pulmonary and pain consequences in patients after open heart surgery. Methods: : In a prospective double blind clinical study, 100 consenting patients undergoing elective open heart surgery were randomized into two groups. In case group, bupivacaine was injected at both sides of sternum, immediately before sternal closure. In the control group, no intervention was performed. Then, the patients were investigated regarding intubation period, length of ICU stay, arterial blood gas (ABG parameters, morphine requirement, and their severity of postoperative pain using a visual analogue scale (VAS device. Results: No differences were found between the two groups regarding to age, sex, pump time, operation time, and body mass index and preoperative cardiac ejection fraction. Mean intubation length in case group was much shorter than that in control group. Mean PaO 2 in case group was lower in different checking times in postoperative period. The patients in the case group needed less morphine compared to those in the control group during the 24-hour observation period in the ICU. Finally, mean VAS scores of pain in case group were significantly lower than those in control group at 6, 12, and 24 hours postoperatively. Conclusions: Patients′ pain relief by parasternal single injection of bupivacaine in early postoperative period can facilitate earlier ventilator weaning and tracheal extubation after open heart surgery as well as achieving lower pain scores and narcotic requirements.

  16. 46 CFR 109.333 - Fire main cutoff valves.


    ... 46 Shipping 4 2010-10-01 2010-10-01 false Fire main cutoff valves. 109.333 Section 109.333... OPERATIONS Operation and Stowage of Safety Equipment § 109.333 Fire main cutoff valves. The master or person in charge shall insure that each fire main cutoff valve is open and sealed to prevent closing,...

  17. The kinetic characteristic and opening condition of fixed valve for sucker rod pump in CBM wells%煤层气井有杆泵设备泵阀运动规律和开启条件

    刘新福; 綦耀光; 吴建军; 郭本广; 孟尚志


    在分析固定阀开启压差的基础上,建立了泵阀运动规律的数学模型和开启条件的计算模型,并利用仿真分析,获得泵阀在不同工况下的运动规律、水力损失和临界沉没度。结果表明:临界沉没度的存在可很好地解释低沉没度下泵阀不能顺利开启和井口间歇式出水现象;冲程和冲次的增大,使阀球升程增加,利于井液入泵;同时使速度变化加快,提高井液流速和携煤粉能力,但容易造成阀球"抖动"现象,降低泵效;固定阀阀球在开启瞬间的加速度和水力损失较大,二者幅值波动的频率较快并在短时间内迅速变小,最后趋向稳定;临界沉没度和水力损失随泵型和冲次的增加而增大,依据水力损失最大值可得到38 mm和44 mm泵的临界沉没度通常在3~5 m。%The mathematic models of kinematic law and opening condition were developed based on the opening pressure drop of fixed valve.The kinematic relation,hydraulic loss and critical submergence depth of fixed valve under different working condition were obtained with the realistic model.The results show that the critical submergence depth in the wellbore can reveal the phenomenon of the valve shutting down and intermittent water flow at the wellhead.An increased stroke and pumping speed results to an increased displacement of the valve ball and variation of initial velocity.And it is beneficial for the well liquid to go into the valve,enhances the ability to carrying coal dust,and makes the valve tremble and decline the pump efficiency.The instantaneous acceleration and hydraulic loss of the fixed valve are large,the frequencies of oscillation are high,and become low during the stroke.The critical submergence depth and hydraulic loss increase due to the size of pump and pumping speed.And based on the maximum hydraulic loss,the critical submergence depth can be obtained within 3~5 m for the pump of 38 mm and 44 mm.

  18. Dynamic characterization of a new accelerated heart valve tester.

    Menzler, F; Haubold, A D; Hwang, N H


    This paper presents a new accelerated prosthetic heart valve tester prototype that incorporates a camshaft and poppet valves. A three element Windkessel system is used to mimic the afterload of the human systemic circulation. The device is capable of testing eight valves simultaneously at a rate up to 1,250 cycles/min, while the flow rate, the pressure, and the valve loading can be monitored and adjusted individually. The tester was characterized and calibrated using a set of eight Carpentier-Edwards bioprostheses at a flow rate varying between 3 and 5 L/min. The experiment was carried out with the pressure difference across the closed heart valve maintained between 140 and 190 mmHg. Smooth and complete opening and closing of the valve leaflets was achieved at all cycling rates. This confirms that the velocity profiles approaching the test valves were uniform, an important factor that allows the test valves to open and close synchronously each time.

  19. Traumatic Mitral Valve and Pericardial Injury

    Nissar Shaikh


    Full Text Available Cardiac injury after blunt trauma is common but underreported. Common cardiac trauma after the blunt chest injury (BCI is cardiac contusion; it is very rare to have cardiac valve injury. The mitral valve injury during chest trauma occurs when extreme pressure is applied at early systole during the isovolumic contraction between the closure of the mitral valve and the opening of the aortic valve. Traumatic mitral valve injury can involve valve leaflet, chordae tendineae, or papillary muscles. For the diagnosis of mitral valve injury, a high index of suspicion is required, as in polytrauma patients, other obvious severe injuries will divert the attention of the treating physician. Clinical picture of patients with mitral valve injury may vary from none to cardiogenic shock. The echocardiogram is the main diagnostic modality of mitral valve injuries. Patient’s clinical condition will dictate the timing and type of surgery or medical therapy. We report a case of mitral valve and pericardial injury in a polytrauma patient, successfully treated in our intensive care unit.

  20. Aortic valve bypass

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik


    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI...

  1. Robotic mitral valve replacement.

    Senay, Sahin; Gullu, Ahmet Umit; Kocyigit, Muharrem; Degirmencioglu, Aleks; Karabulut, Hasan; Alhan, Cem


    Robotic surgical techniques allow surgeons to perform mitral valve surgery. This procedure has gained acceptance, particularly for mitral valve repair in degenerative mitral disease. However, mitral repair may not always be possible, especially in severely calcified mitral valve of rheumatic origin. This study demonstrates the basic concepts and technique of robotic mitral valve replacement for valve pathologies that are not suitable for repair.

  2. Menopause: Symptom Relief and Treatments

    ... Submit Home > Menopause > Menopause symptom relief and treatments Menopause Menopause symptom relief and treatments Working with your doctor ... on menopause symptom relief and treatments Learning about menopause treatment options Most women do not need treatment ...

  3. Method and apparatus for monitoring motor operated valve motor output torque and power at valve seating

    Casada, Donald A.


    A method and apparatus are provided for monitoring a motor operated valve during the brief period when the valve seats and the torque switch trips to deenergize the valve motor. The method uses voltage measurements on the load side of a deenergizing switch that opens to deenergize the motor to determine, among other things, final motor rotational speed and the decelerating torque at motor deenergization.

  4. Anterior Urethral Valves

    Vidyadhar P. Mali


    Full Text Available We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU (in 2 or on cystoscopy (in 2. All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

  5. Supramolecular spin valves

    Urdampilleta, M.; Klyatskaya, S.; Cleuziou, J.-P.; Ruben, M.; Wernsdorfer, W.


    Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc2 single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties.

  6. Numerical calculation and experimental validation of safety valve flows at pressures up to 600 bar

    Beune, A.; Kuerten, J.G.M.; Schmidt, J.


    A numerical valve model has been validated to predict the discharge capacity in accordance to the requirements of valve sizing method EN ISO 4126-1 and the opening characteristic of high-pressure safety valves. The valve is modeled with computational fluid dynamics software ANSYS CFX, and the model

  7. Study on high reliability safety valve for railway vehicle

    Zhang, Xuan; Chen, Ruikun; Zhang, Shixi; Xu, BuDu


    Now, the realization of most of the functions of the railway vehicles rely on compressed air, so the demand for compressed air is growing higher and higher. This safety valve is a protection device for pressure limitation and pressure relief in an air supply system of railway vehicles. I am going to introduce the structure, operating principle, research and development process of the safety valve designed by our company in this document.

  8. In Vitro Evaluation of the iValve : A Novel Hands-Free Speech Valve

    van der Houwen, E.B.; van Kalkeren, T.A.; Burgerhof, J.G.; van der Laan, B.F.; Verkerke, G.J.


    Objectives: We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure

  9. In Vitro Evaluation of the iValve : A Novel Hands-Free Speech Valve

    van der Houwen, E.B.; van Kalkeren, T.A.; Burgerhof, J.G.; van der Laan, B.F.; Verkerke, G.J.


    Objectives: We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure drops

  10. A low power, on demand electrothermal valve for wireless drug delivery applications.

    Li, Po-Ying; Givrad, Tina K; Sheybani, Roya; Holschneider, Daniel P; Maarek, Jean-Michel I; Meng, Ellis


    We present a low power, on demand Parylene MEMS electrothermal valve. A novel Omega-shaped thermal resistive element requires low power (approximately mW) and enables rapid valve opening (approximately ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, as an inrush current limiter, was added into the valve circuit to provide variable current ramping. Wireless activation of the valve using RF inductive power transfer was demonstrated.

  11. Fast-acting valve actuator

    Cho, Nakwon


    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  12. Low target-INR anticoagulation is safe in selected aortic valve patients with the Medtronic Open Pivot mechanical prosthesis: long-term results of a propensity-matched comparison with standard anticoagulation.

    Bové, Thierry; Van Belleghem, Yves; François, Katrien; Caes, Frank; De Pauw, Michel; Taeymans, Yves; Van Nooten, Guido J


    To investigate the long-term results of a low international normalized ratio (INR)-anticoagulation program in selected patients after aortic valve replacement (AVR) with the Medtronic Open Pivot mechanical heart valve (OPMHV). From January 1993 to December 2012, 909 OPMHV valves were used for single AVR. Patients with preserved sinus rhythm and left ventricular function (Low-INR, n  = 552), were managed to an INR of 1.5-2.5 and compared to patients (Standard-INR, n  = 357) treated with standard anticoagulation (INR 2.5-3.5). Long-term outcome was analysed for survival and valve-related events, on propensity score matched pairs of 169 patients/group. Within a follow-up cumulating 3096 patient-years, 10- and 15-year survival was significantly better for Low-INR patients: 79% and 63% vs 63% and 34% ( P  < 0.001). Multivariate analysis of late mortality identified older age [odds ratio (OR) = 1.05], chronic pulmonary disease (OR = 1.90) and coronary artery disease (OR = 1.57) as patient-related risk factors, and erratic INR (OR = 2.57) as anticoagulation-related factor. The linearized thromboembolic rate was 0.72%/patient-year in Low-INR patients, vs 0.87%/patient-year in Standard-INR patients ( P  = 0.59), revealing INR variability as sole predictor (OR 3.54, 95% confidence interval (CI) 1.20-10.51, P  = 0.022). The linearized bleeding incidence was respectively 0.61%/patient-year and 1.21%/patient-year for Low-INR and Standard-INR patients ( P  = 0.04), retaining older age (OR 1.06, 95% CI 1.02-1.12, P  = 0.009), hypertension (OR 2.06, 95% CI 1.00-4.25, P  = 0.05) and erratic INR (OR 9.83, 95% CI 5.21-18.56, P  < 0.001) as independent risk factors. This study demonstrated that application of an anticoagulation regimen, aiming a low INR, individualized to selected aortic OPMHV patients, is safe and effective over more than 20 years, without increasing the thromboembolic complication rate while lowering the

  13. Non intrusive check valve diagnostics at Bruce A

    Marsch, S.P. [Ontario Hydro, Bruce Nuclear Generating Station A, Tiverton, ON (Canada)


    Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

  14. Non intrusive check valve diagnostics at Bruce A

    Marsch, S.P. [Ontario Hydro, Bruce Nuclear Generating Station A, Tiverton, ON (Canada)


    Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

  15. Apparatus comprising magnetically actuated valves and uses thereof

    Edwards, Thayne L.; Harper, Jason C.


    The present invention, in part, relates to an apparatus having a single-use, normally-closed fluidic valve that is initially maintained in the closed position by a valve element bonded to an adhesive coating. The valve is opened using a magnetic force. The valve element includes a magnetic material or metal. In some examples, the valve is opened by bringing a magnet in proximity to the valve element to provide a magnetic force that delaminates the valve element from the adhesive coating. In particular, the apparatus can be useful for on-chip amplification and/or detection of various targets, including biological targets and any amplifiable targets. Such apparatuses and methods are useful for in-field or real-time detection of targets, especially in limited resource settings.

  16. Mitral valve repair versus replacement: is it a different story for percutaneous compared to surgical valve therapy?

    Inderbitzin, Devdas T; Taramasso, Maurizio; Nietlispach, Fabian; Maisano, Francesco


    The complementary role of mitral valve repair versus replacement is based on evidence of long-term results in open surgery. Transcatheter mitral valve repair and replacement are both under rapid development but subject to clinical feasibility and first in-human short- and midterm outcome studies. The present article aims to review mitral valve repair and replacement by both techniques and to elucidate similar and potentially different aspects among the open and interventional approach.



    A novel pilot stage valve called simplified 2D valve, which utilizes both rotary and linear motions of a single spool, is presented.The rotary motion of the spool incorporating hydraulic resistance bridge, formed by a damper groove and a crescent overlap opening, is utilized as pilot to actuate linear motion of the spool.A criterion for stability is derived from the linear analysis of the valve.Special experiments are designed to acquire the mechanical stiffness, the pilot leakage and the step response.It is shown that the sectional size of the spiral groove affects the dynamic response and the stiffness contradictorily and is also very sensitive to the pilot leakage.Therefore, it is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless, it is possible to sustain the dynamic response at a fairly high level, while keeping the leakage of the pilot stage at an acceptable level.

  18. In vitro evaluation of the iValve: a novel hands-free speech valve.

    van der Houwen, Eduard B; van Kalkeren, Tjouwke A; Burgerhof, Johannes G M; van der Laan, Bernard F A M; Verkerke, Gijsbertus J


    We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure drops. This method makes long sentences or pauses difficult. The novel iValve is designed to allow almost natural speech, with mid-sentence pausing and whispering. The inhalation closing flows and exhalation opening pressures of 6 iValve prototype versions at different settings were compared with physiological values. The airflow resistance at inhalation was compared to physiological values and to commercial valve values. The iValve prototypes showed flow and pressure ranges in concordance with the physiological values in the literature. The airflow resistance in the breathing mode was within the physiological airflow resistance range, yet above the values from the two commercial valves. The resistance in the speaking mode was above the physiological airflow resistance range. In vitro tests show that the iValve versions can be selected and adjusted to operate within the physiological range. The airflow resistance in the breathing mode is good. In speaking mode, inhalation should, and can, be decreased. The iValve should offer the patient a more intuitively useable alternative with more dynamic speech. Its low cost allows disposability and wider use.

  19. 40 CFR 63.169 - Standards: Pumps, valves, connectors, and agitators in heavy liquid service; instrumentation...


    ..., and agitators in heavy liquid service; instrumentation systems; and pressure relief devices in liquid...: Pumps, valves, connectors, and agitators in heavy liquid service; instrumentation systems; and pressure..., pressure relief devices in light liquid or heavy liquid service, and instrumentation systems shall...

  20. Valve-in-valve-in-valve: Treating endocarditis of a transcatheter heart valve.

    Nguyen, Caroline; Cheong, Adrian P; Himbert, Dominique


    Transcatheter heart valve endocarditis is a rare, but life threatening complication. We describe the case of a patient who was successfully treated by transcatheter aortic valve-in-valve-in-valve replacement with a favorable 1-year outcome, despite severe early complications.

  1. Microfluidic sieve valves

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L


    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  2. Remote actuated valve implant

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.; Ericson, Milton Nance; Baba, Justin S.; Wilgen, John B.; Evans, Boyd Mccutchen


    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.


    LIM CC


    Full Text Available Nasal foreign body in children is not an uncommon presentation to the Emergency Department. Removal is essential. Many methods of removal exist. Nasal wash technique is advocated mainly in friable foreign bodies. We report the successful use of the oral bag-valve-mask insufflation technique to remove friable facial tissue in the left nose of a 2 year-old girl. We used a pediatric bag-valve-mask with a pop-off pressure relief valve to avoid barotrauma. Pop-off pressure relief valve limits the pressure beyond 30mmHg. Conscious sedation was not required. There were no complications.

  4. Transcatheter aortic valve replacement in elderly patients

    Dimytri Siqueira; Alexandre Abizaid; Magaly Arrais J.; Eduardo Sousa


    Aortic stenosis is the most common native valve disease, affecting up to 5% of the elderly population. Surgical aortic valve replacement reduces symptoms and improves survival, and is the definitive therapy in patients with symptomatic severe aortic stenosis. However, despite the good results of classic surgery, risk is markedly increased in elderly patients with co-morbidities. Transcatheter aortic valve replacement (TAVR) allows implantation of a prosthetic heart valve within the diseased native aortic valve without the need for open heart surgery and cardiopulmonary bypass, offering a new therapeutic option to elderly patients considered at high surgical risk or with contraindications to surgery. To date, several multicenter registries and a randomized trial have confirmed the safety and efficacy of TAVR in those patients. In this chapter, we review the background and clinical applications of TAVR in elderly patients.

  5. Scissor thrust valve actuator

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.


    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  6. Valve-in-Valve Replacement Using a Sutureless Aortic Valve

    Dohmen, Pascal M.; Lehmkuhl, Lukas; Borger, Michael A.; Misfeld, Martin; Mohr, Friedrich W.


    Patient: Female, 61 Final Diagnosis: Tissue degeneration Symptoms: Dyspnea Medication: — Clinical Procedure: Redo valve replacement Specialty: Surgery Objective: Rare disease Background: We present a unique case of a 61-year-old female patient with homograft deterioration after redo surgery for prosthetic valve endocarditis with root abscess. Case Report: The first operation was performed for type A dissection with root, arch, and elephant trunk replacement of the thoracic aorta. The present re-redo surgery was performed as valve-in-valve with a sutureless aortic biopros-thesis. The postoperative course was uneventful and the patient was discharged on day 6. Conclusions: The current case report demonstrates that sutureless bioprostheses are an attractive option for surgical valve-in-valve procedures, which can reduce morbidity and mortality. PMID:27694795

  7. Cellular regulation of the structure and function of aortic valves

    Ismail El-Hamamsy


    Full Text Available The aortic valve was long considered a passive structure that opens and closes in response to changes in transvalvular pressure. Recent evidence suggests that the aortic valve performs highly sophisticated functions as a result of its unique microscopic structure. These functions allow it to adapt to its hemodynamic and mechanical environment. Understanding the cellular and molecular mechanisms involved in normal valve physiology is essential to elucidate the mechanisms behind valve disease. We here review the structure and developmental biology of aortic valves; we examine the role of its cellular parts in regulating its function and describe potential pathophysiological and clinical implications.

  8. [Fluid solid interaction analysis of bioprosthetic heart valve].

    Ma, Xuejie; Du, Yawei; Zhang, Linan; Hou, Zengtao; Ye, Xin


    This paper constructs numerical models of bioprosthetic heart valve and blood. The fluid solid interaction is carried out using penalty function method. The mechanical property of the bioprosthetic heart valve during cardiac cycle is simulated with ANSYS software. Results show that the Von Mises stress concentrates at the junction of attachment edge and coaptation edge. The open time of bioprosthetic heart valve is consistent with that of actural measurement. The peak velocity of blood is in the range of physiology. This model provides more realistic mechanical property of bioprosthetic heart valve during cardiac cycle compared to pure solid model, and facilitates design and optimization of bioprosthetic heart valve.

  9. Study of relief systems behavior in shipping terminals; Estudo do comportamento de sistemas de alivio em dutos de terminais maritimos

    Pires, Luis F.G.; Ladeia, Renata C. da Cunha; Ortega Malca, Arturo J. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica. Nucleo de Simulacao Termohidraulica de Dutos (SIMDUT); Kossatz, Helmut [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)


    In order to reduce operational costs, maritime terminals work with high flows transferring product between ships and in shore tanks. To protect the pipeline from any hydraulic transient, relief systems are commonly installed in strategic positions. During the project stage, computational simulation is widely used as auxiliary tool to determine the kind of valve and the place where the relief system must be installed. The present work points out the importance of the kind of valve chosen and its location along the pipeline, and shows that these factors affect directly the surge pressure produced by the valve closure. Besides, it compares a conventional spring-loaded relief valve behavior to a rupture disc one, making use of commercial program tools and employing a model based on the method of the characteristics. (author)

  10. Automatic device for maintenance on safety relief valve

    Fujio, M. [Okano Valve Mfg. Co. Ltd., Kitakyushu, Fukuoka (Japan)


    This system offers shorter, labor-saving periodic inspection of nuclear power plants particularly for maintenance of in the BWR plant. This automatic device has the following performance features. (author).

  11. A novel implantable glaucoma valve using ferrofluid.

    Eleftherios I Paschalis

    Full Text Available PURPOSE: To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING: Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. RESULTS: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg. X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. CONCLUSIONS: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway.

  12. Whole Teflon valves for handling droplets.

    Cybulski, Olgierd; Jakiela, Slawomir; Garstecki, Piotr


    We propose and test a new whole-Teflon gate valve for handling droplets. The valve allows droplet plugs to pass through without disturbing them. This is possible due to the geometric design, the choice of material and lack of any pulses of flow generated by closing or opening the valve. The duct through the valve resembles a simple segment of tubing, without constrictions, change in lumen or side pockets. There are no extra sealing materials with different wettability or chemical resistance. The only material exposed to liquids is FEP Teflon, which is resistant to aggressive chemicals and fully biocompatible. The valve can be integrated into microfluidic systems: we demonstrate a complex system for culturing bacteria in hundreds of microliter droplet chemostats. The valve effectively isolates modules of the system to increase precision of operations on droplets. We verified that the valve allowed millions of droplet plugs to safely pass through, without any cross-contamination with bacteria between the droplets. The valve can be used in automating complex microfluidic systems for experiments in biochemistry, biology and organic chemistry.

  13. Relief Aid Carefully Audited


    In a recent interview with the national TV broadcaster CCTV,Wang Zhongxin,Director of the Social Security Audit Department at the National Audit Office,talks about the procedures that are in effect to ensure relief supplies for the Wenchuan earthquake victims reach the end users. Excerpts of

  14. Paper relief architecture

    Latka, J.F.


    The article presents two contemporary projects of paper structures relief architecture designed and built by Shigeru Ban Architects and Voluntary Architect Network. Author of the article took part in design and construction process of one of the projects. The project of Yaan Nursery School, which wa

  15. Note: An improved solenoid driver valve for miniature shock tubes.

    Lynch, P T


    A solenoid driver valve has been built to improve the operating performance of diaphragmless shock tubes, which are used for high pressure, high temperature chemical kinetics, and fluid mechanics studies. For shock tube driver application, the most important characteristics are those of sealing, strength, and quality of the generated shock waves and repeatability of opening characteristics and therefore subsequent post-shock conditions. The main features of the new driver valve are a face o-ring sealing design of the valve, the large internal volume, and through inserts near the solenoid core: adjustable opening characteristics of the valve.

  16. Which valve is which?

    Pravin Saxena


    Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

  17. Allergy Relief for Your Child

    ... For Consumers Home For Consumers Consumer Updates Allergy Relief for Your Child Share Tweet Linkedin Pin it ... counter (OTC) and prescription medicines that offer allergy relief as well as allergen extracts used to diagnose ...

  18. Finding Relief from Allergy's Grip

    ... Navigation Bar Home Current Issue Past Issues Finding Relief from Allergy's Grip Past Issues / Summer 2006 Table ... action for patients who have had inadequate symptom relief with antihistamines and topical nasal steroids. Through injection ...

  19. Aortic Valve Regurgitation

    ... inside your heart that involves heart valves. Rheumatic fever. Rheumatic fever — a complication of strep throat and once a ... the United States — can damage the aortic valve. Rheumatic fever is still prevalent in developing countries but rare ...

  20. Pulmonary Valve Stenosis

    ... growths called carcinoid tumors in the digestive system. Rheumatic fever. This complication of an infection caused by streptococcus ... valve stenosis later in life, including: Carcinoid syndrome Rheumatic fever Noonan's syndrome Mild to moderate pulmonary valve stenosis ...

  1. Aortic Valve Disease

    ... Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Pediatric and Congenital Heart Disease Heart abnormalities that are ... Transplantation End-stage Lung Disease Adult Lung Transplantation Pediatric Lung ... Aortic Aneurysm Aortic Valve Disease Overview The human heart has ...

  2. Mitral Valve Stenosis

    ... up around the ring around the mitral valve (annulus), which can occasionally cause mitral valve stenosis. Other ... the condition of your lungs. Transesophageal echocardiogram. A small transducer attached to the end of a tube ...

  3. Heart valve surgery

    ... Tricuspid valve stenosis Risks The risks of having cardiac surgery include: Death Heart attack Heart failure Bleeding requiring ... and the A.D.A.M. Editorial team. Heart Surgery Read more Heart Valve Diseases Read more Latest ...

  4. Automatic Mesh Generation of Hybrid Mesh on Valves in Multiple Positions in Feedline Systems

    Ross, Douglass H.; Ito, Yasushi; Dorothy, Fredric W.; Shih, Alan M.; Peugeot, John


    Fluid flow simulations through a valve often require evaluation of the valve in multiple opening positions. A mesh has to be generated for the valve for each position and compounding. The problem is the fact that the valve is typically part of a larger feedline system. In this paper, we propose to develop a system to create meshes for feedline systems with parametrically controlled valve openings. Herein we outline two approaches to generate the meshes for a valve in a feedline system at multiple positions. There are two issues that must be addressed. The first is the creation of the mesh on the valve for multiple positions. The second is the generation of the mesh for the total feedline system including the valve. For generation of the mesh on the valve, we will describe the use of topology matching and mesh generation parameter transfer. For generation of the total feedline system, we will describe two solutions that we have implemented. In both cases the valve is treated as a component in the feedline system. In the first method the geometry of the valve in the feedline system is replaced with a valve at a different opening position. Geometry is created to connect the valve to the feedline system. Then topology for the valve is created and the portion of the topology for the valve is topology matched to the standard valve in a different position. The mesh generation parameters are transferred and then the volume mesh for the whole feedline system is generated. The second method enables the user to generate the volume mesh on the valve in multiple open positions external to the feedline system, to insert it into the volume mesh of the feedline system, and to reduce the amount of computer time required for mesh generation because only two small volume meshes connecting the valve to the feedline mesh need to be updated.

  5. Simulant Development for Hanford Tank Farms Double Valve Isolation (DVI) Valves Testing

    Wells, Beric E.


    Leakage testing of a representative sample of the safety-significant isolation valves for Double Valve Isolation (DVI) in an environment that simulates the abrasive characteristics of the Hanford Tank Farms Waste Transfer System during waste feed delivery to the Waste Treatment and Immobilization Plant (WTP) is to be conducted. The testing will consist of periodic leak performed on the DVI valves after prescribed numbers of valve cycles (open and close) in a simulated environment representative of the abrasive properties of the waste and the Waste Transfer System. The valve operations include exposure to cycling conditions that include gravity drain and flush operation following slurry transfer. The simulant test will establish the performance characteristics and verify compliance with the Documented Safety Analysis. Proper simulant development is essential to ensure that the critical process streams characteristics are represented, National Research Council report “Advice on the Department of Energy's Cleanup Technology Roadmap: Gaps and Bridges”

  6. Isolated Pulmonary Valve Endocarditis

    Mohammad Ali Hatamizadeh


    Full Text Available Infective endocarditis is one of the most severe complications of parenteral drug abuse. The outstanding clinical feature of infective endocarditis in intravenous drug abusers is the high incidence of right-sided valve infection, and the tricuspid valve is involved in 60% to 70% of the cases. We herein report a case of isolated pulmonic valve infective endocarditis with a native pulmonary valve.

  7. Quadricuspid Aortic Valve

    Mehmet Taşar


    Full Text Available Quadricuspid aortic valve is an extremely rare congenital defect. Isolated form appears frequently. It is seen with aortic valve regurgitation in adulthood. This case report presents a rare clinical finding of an isolated quadricuspid aortic valve with aortic regurgitation in an 64-year-old female who was referred for cardiac evaluation due to newly identified murmur.

  8. Motor operated valves problems tests and simulations

    Pinier, D.; Haas, J.L.


    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

  9. A multicentre comparative evaluation of catheter valves.

    Fader, M; Pettersson, L; Brooks, R; Dean, G; Wells, M; Cottenden, A; Malone-Lee, J

    Catheter valves are an alternative to leg bags for urine drainage, but no studies have yet been published which have compared the performance of different valves. This study was undertaken to evaluate the performance of the seven catheter valves available on the UK market in April 1996. The study was carried out by the Continence Products Evaluation (CPE) Network funded by the Medical Devices Agency (Department of Health). Each valve type was tested for 1 week by 19-36 cognitively unimpaired and manually dextrous subjects recruited from 11 test centres. At the end of each week, subjects completed an evaluation form (based on a three-point rating scale) to record product performance. The same catheter valves were also tested for ease of opening/closing by 33 subjects (mostly catheter users) who had some manual impairment. Performance scores varied widely between products. It was found that, to be successful, a valve needs to be easy to manipulate, leak-free, comfortable and inconspicuous. Prescribers need to be aware of the strengths and limitations of different valves for appropriate product selection.

  10. Torque characteristics of a 122-centimeter butterfly valve with a hydro/pneumatic actuator

    Lin, F. N.; Moore, W. I.; Lundy, F. E.


    Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.

  11. Electromechanically Actuated Valve for Controlling Flow Rate

    Patterson, Paul


    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  12. 电站锅炉安全阀校验新技术应用%New Calibration Technology for Safety Valves of Utility Boiler

    张传虎; 刘琨


    蝶形弹簧安全阀是锅炉压力容器的重要安全附件,用于防止系统压力超过允许的极限值.安全阀校验的安全、快捷、准确直接关系着机组的安全经济效益.NSH安全阀在线校验仪可在机组运行的情况下,仅需2~5秒时间即可完成对安全阀的在线性能检测和工作参数检测,也可对经检测不合格的安全阀进行在线整定,可以测量和记录安全阀的开启压力和安全阀所在位置系统介质压力等参数.使用NSH定压仪校验安全阀能减少能源消耗,降低噪音污染,提高安全阀校验整定的精确度和工作效率.%Butterfly spring-relief valve, a crucial safety attachment of pressure vessel, is used to prevent pressure system from exceeding allowable limit value. Safe, expeditious and accurate calibration of safety valves is consequently of vital importance to safe and economic operation of generating units. NSH CALIBRATOR could complete, not only the on-line performance and parameter tests of safety valves within two to five seconds with opening pressure of safety valves and steam medium pressure automatically recorded, but also could complete the on-line adjustment of safety valves verified unqualified. It saves energy consumption, decreases noise pollution and improves accuracy and efficiency of safety valve calibration.

  13. Modification and performance evaluation of a mono-valve engine

    Behrens, Justin W.

    A four-stroke engine utilizing one tappet valve for both the intake and exhaust gas exchange processes has been built and evaluated. The engine operates under its own power, but has a reduced power capacity than the conventional 2-valve engine. The reduction in power is traced to higher than expected amounts of exhaust gases flowing back into the intake system. Design changes to the cylinder head will fix the back flow problems, but the future capacity of mono-valve engine technology cannot be estimated. The back flow of exhaust gases increases the exhaust gas recirculation (EGR) rate and deteriorates combustion. Intake pressure data shows the mono-valve engine requires an advanced intake valve closing (IVC) time to prevent back flow of charge air. A single actuation camshaft with advanced IVC was tested in the mono-valve engine, and was found to improve exhaust scavenging at TDC and nearly eliminated all charge air back flow at IVC. The optimum IVC timing is shown to be approximately 30 crank angle degrees after BDC. The mono-valve cylinder head utilizes a rotary valve positioned above the tappet valve. The open spaces inside the rotary valveand between the rotary valve and tappet valve represent a common volume that needs to be reduced in order to reduce the base EGR rate. Multiple rotary valve configurations were tested, and the size of the common volume was found to have no effect on back flow but a direct effect on the EGR rate and engine performance. The position of the rotary valve with respect to crank angle has a direct effect on the scavenging process. Optimum scavenging occurs when the intake port is opened just after TDC.

  14. Leaky valves: new operation improves the heart's pumping action

    Van Kasteren, J.


    The action of any pump will start to decline when the valves no longer close properly. The same goes for the heart, the pump that maintains the circulation in our vascular system. Consequently, a major field of focus of open heart surgery is the repair or replacement of heart valves. Petr Havl a Ph.

  15. Direct aortic transcatheter valve implantation via mini-thoracotomy using the Medtronic CoreValve.

    Bruschi, Giuseppe; Botta, Luca; De Marco, Federico; Colombo, Paola; Nonini, Sandra; Klugmann, Silvio; Martinelli, Luigi


    Transcatheter aortic valve implantation using the Medtronic CoreValve is a well-established procedure. Although previously carried out only through the common femoral artery, today it is possible to perform the procedure through different arterial alternative access sites. A direct aortic approach through the ascending aorta could be carried out via a right anterior mini-thoracotomy in the second intercostal space. The pericardium is opened to expose the aorta. Two purse-string sutures are then placed on the ascending aorta and a standard retrograde CoreValve implantation is performed with the standard delivery system. Advantages, contraindications, surgical technique and results are discussed.

  16. Main Oxidizer Valve Design

    Addona, Brad; Eddleman, David


    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  17. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  18. Case study of relevant pressures for an implanted hydrocephalus valve in everyday life.

    Elixmann, Inga Margrit; Goffin, Christine; Krueger, Rolf; Meier, Ullrich; Lemcke, Johannes; Kiefer, Michael; Antes, Sebastian; Leonhardt, Steffen


    Hydrocephalus patients with increased intracranial pressure are generally treated by draining cerebrospinal fluid (CSF) into the abdomen through an implanted shunt with a passive differential pressure valve. To perfectly adapt the valve's opening pressure to the patient's need, more information on the acutal pressure across the valve in everyday life actions like walking, eating, sleeping etc. is necessary.

  19. Adjustable valves in normal-pressure hydrocephalus: a retrospective study of 218 patients

    Zemack, G.; Rommer, Bertil Roland


    OBJECTIVE: We sought to assess the value of adjusting shunt valve opening pressure, complications, and outcomes with the use of an adjustable shunt valve in the treatment of patients with normal-pressure hydrocephalus (NPH). METHODS: In a single-center retrospective study, 231 adjustable valves (...


    Quan Long; Ma Jian; Wang Yongjin


    A new closed loop flow controlling principle through correcting the valve's opening area while load pressure is changing is carried out. Further more a principle using only one proportional valve to compound control pressure and flow is suggested. By using very simple proportional throttle valve in structure, the functions that five kinds of proportional valves or any two of them combined possess can be complimented. After analyzing, comparing, and testing the dynamic and static characteristics of valve with different controlling principles and main valve structure styles, the optimized structure styles and control methods are achieved.

  1. Human Internal Jugular Valve M-mode Ultrasound Characterization

    Menegatti, Erica; Tessari, Mirko; Gianesini, Sergio; Vannini, Maria Elena; Sisini, Francesco; Zamboni, Paolo


    In humans the mechanism governing the internal jugular vein (IJV) valve opening and closure is still unclear. M-mode is used in echo-cardiology for the heart valves assessment. Sometimes it was performed also in deep peripheral veins and in vena cava assessment, but never in the IJV valve. Aim of the present study is to investigate the IJV valves physiology in healthy volunteers, by means of both B and M-mode ultrasound. Eighty-three (83) healthy volunteers (35 Male, 48 Female, 25.7±6.7 y.o.)...

  2. The Design Improvement and Technical Analysis of the Normally Open Solenoid Valve with a New Control Mode%一种新型控制模式的常开电磁阀的设计改进及技术分析



    该厂为某型机研制的一种新型常开电磁阀在试验过程中出现不能正常打开、关闭现象.该文从理论分析、建模计算及工程经验三个方面,分析了故障现象产生的原因,提出了一种新的随动控制模式并进行了设计改进.改进后的电磁阀按流量大小自动选择介质通道,打破了传统常开电磁阀的控制模式.新设计已通过试验,验证了其可行性.%The normally open solenoid valve developed for some certain type by AVIC No.116 Factory experienced failures of abnormal opening and closing in tests.This paper analyzed the causes of the failures by three approaches including theoretical analysis,model calculation and engineering experience,and provides a new follow-up control mode along with the design improvement.The improved solenoid valve selects media channel according to the mass flow,breaking the traditional control mode of normally open solenoid valve.The new design has been tested to validate its feasibility.

  3. Sapien XT Transcatheter Mitral Valve Replacement Under Direct Vision in the Setting of Significant Mitral Annular Calcification.

    Murashita, Takashi; Suri, Rakesh M; Daly, Richard C


    Mitral valve replacement carries a high risk in patients with extensive mitral annular calcification. We report the case of a 71-year-old woman with severely calcified mitral valve stenosis and extensive annular calcification. We approached the mitral valve through a left atriotomy using cardiopulmonary bypass and cardiac arrest. We successfully deployed a 29-mm Sapien XT valve under direct visualization with satisfactory positioning. We further balloon-expanded the device to diminish the likelihood of periprosthetic regurgitation. Open mitral valve replacement with a transcatheter valve can be performed without the need for decalcification of the mitral annulus and is a good alternative to conventional mitral valve replacement.

  4. Valve selection in aortic valve endocarditis

    Zubrytska, Yana


    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis.

  5. Libraries and information provision for African relief

    Elsemieke Wishart


    Full Text Available This research article explores the concept that libraries as communication centres in sub-Saharan Africa can play a vital role in bringing poverty relief by providing greater access to information through modern technology. It discusses the patrons who can benefit from community information centres and explores their particular needs. I have researched how modern tools like the Internet, computers, e-readers and cell phones can bring valuable information to impoverished citizens. My research was conducted through reading research papers using article databases, books and Internet websites. The future for libraries in sub-Saharan Africa is bright, as new technology opens up vast opportunities to share information in a way that is accessible, affordable and adaptable to the needs of the African people. I recommend that librarians and relief organisations in Southern Africa seriously consider using modern technology to provide information that will empower its citizens.

  6. Prosthetic Aortic Valve Fixation Study: 48 Replacement Valves Analyzed Using Digital Pressure Mapping.

    Lee, Candice Y; Wong, Joshua K; Ross, Ronald E; Liu, David C; Khabbaz, Kamal R; Martellaro, Angelo J; Gorea, Heather R; Sauer, Jude S; Knight, Peter A

    Prostheses attachment is critical in aortic valve replacement surgery, yet reliable prosthetic security remains a challenge. Accurate techniques to analyze prosthetic fixation pressures may enable the use of fewer sutures while reducing the risk of paravalvular leaks (PVL). Customized digital thin film pressure transducers were sutured between aortic annulus models and 21-mm bioprosthetic valves with 15 × 4-mm, 12 × 4-mm, or 9 × 6-mm-wide pledgeted mattress sutures. Simulating open and minimally invasive access, 4 surgeons, blinded to data acquisition, each secured 12 valves using manual knot-tying (hand-tied [HT] or knot-pusher [KP]) or automated titanium fasteners (TFs). Real-time pressure measurements and times were recorded. Two-dimensional (2D) and 3D pressure maps were generated for all valves. Pressures less than 80 mm Hg were considered at risk for PVL. Pressures under each knot (intrasuture) fell less than 80 mm Hg for 12 of 144 manual knots (5/144 HT, 7/144 KP) versus 0 of 288 TF (P valves; 17 of 48 HT, 25 of 48 KP, and 12 of 96 TF for 12 × 4-mm valves; and 15 of 36 HT, 17 of 36 KP, and 9 and 72 TF for 9 × 6-mm valves; P manual versus TF. Annular areas with pressures less than 80 mm Hg ranged from 0% of the sewing-ring area (all open TF) to 31% (12 × 4 mm, KP). The average time per manual knot, 46 seconds (HT, 31 seconds; KP, 61 seconds), was greater than TF, 14 seconds (P valve replacement. This research encourages continued exploration of technical factors in optimizing prosthetic valve security.

  7. Design of damping valve for vehicle hydro pneumatic suspension

    Mingming DONG; Hua HUANG; Lian GU


    According to the design features of a hydro pneumatic spring, the necessity of a separate damping valve is proposed. Based on a 1/4 vehicle linear suspension model, the optimum damping coefficient is worked out and the parameters of the damping valve are determined with the equivalent linearization method. A practical structure of the damping valve is proposed having a small size, high flowrate when the valve opens, and the ability of enduring high back pressure. Based on bench tests, the damping valve has been found to properly work and be suitable. The design method and damping valve structure are useful guides for hydro pneumatic suspension, especially for the design of heavy-duty vehicles.

  8. Development of Overflow-Prevention Valve with Trigger Mechanism.

    Ishino, Yuji; Mizuno, Takeshi; Takasaki, Masaya


    A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore, the valve must be constructed only by mechanical parts. The conventional overflow-prevention valve uses fluid and pneumatic forces. It consists of a sensor probe, a cylinder, a main valve for shutting off the fluid and a locking mechanism for holding an open state of the main valve. The proposed overflow-prevention valve uses the pressure due to the height difference between the fluid level of the tank and the sensor probe. However, the force of the cylinder produced by the pressure is too small to release the locking mechanism. Therefore, a trigger mechanism is introduced between the cylinder and the locking mechanism. The trigger mechanism produces sufficient force to release the locking mechanism and close the main valve when the height of fluid exceeds a threshold value. A trigger mechanism is designed and fabricated. The operation necessary for closing the main valve is conformed experimentally.

  9. Exuberant accessory mitral valve tissue with possible true parachute mitral valve: a case report

    Nikolic Aleksandra


    Full Text Available Abstract Introduction A parachute mitral valve is defined as a unifocal attachment of mitral valve chordae tendineae independent of the number of papillary muscles. Data from the literature suggests that the valve can be distinguished on the basis of morphological features as either a parachute-like asymmetrical mitral valve or a true parachute mitral valve. A parachute-like asymmetrical mitral valve has two papillary muscles; one is elongated and located higher in the left ventricle. A true parachute mitral valve has a single papillary muscle that receives all chordae, as was present in our patient. Patients with parachute mitral valves during childhood have multilevel left-side heart obstructions, with poor outcomes without operative treatment. The finding of a parachute mitral valve in an adult patient is extremely rare, especially as an isolated lesion. In adults, the unifocal attachment of the chordae results in a slightly restricted valve opening and, more frequently, valvular regurgitation. Case presentation A 40-year-old Caucasian female patient was admitted to a primary care physician due to her recent symptoms of heart palpitation and chest discomfort on effort. Transthoracic echocardiography showed chordae tendineae which were elongated and formed an unusual net shape penetrating into left ventricle cavity. The parasternal short axis view of her left ventricle showed a single papillary muscle positioned on one side in the posteromedial commissure receiving all chordae. Her mitral valve orifice was slightly eccentric and the chordae were converting into a single papillary muscle. Mitral regurgitation was present and it was graded as moderate to severe. Her left atrium was enlarged. There were no signs of mitral stenosis or a subvalvular ring. She did not have a bicuspid aortic valve or coarctation of the ascending aorta. The dimensions and systolic function of her left ventricle were normal. Our patient had a normal body habitus

  10. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra


    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  11. JenaValve.

    Treede, Hendrik; Rastan, Ardawan; Ferrari, Markus; Ensminger, Stephan; Figulla, Hans-Reiner; Mohr, Friedrich-Wilhelm


    The JenaValve is a next-generation TAVI device which consists of a well-proven porcine root valve mounted on a low-profile nitinol stent. Feeler guided positioning and clip fixation on the diseased leaflets allow for anatomically correct implantation of the device without rapid pacing. Safety and efficacy of transapical aortic valve implantation using the JenaValve were evaluated in a multicentre prospective study that showed good short and midterm results. The valve was CE-mark released in Europe in September 2011. A post-market registry ensures on-going and prospective data collection in "real-world" patients. The transfemoral JenaValve delivery system will be evaluated in a first-in-man study in the near future.

  12. Effect of Cone Angle on the Hydraulic Characteristics of Globe Control Valve

    LIN Zhe; WANG Huijie; SHANG Zhaohui; CUI Baoling; ZHU Chongxi; ZHU Zuchao


    Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is avallable in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtalned from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle (β). However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient (Cv) when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a stralght line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase ofβ, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.

  13. Phytotherapy for pain relief.

    Zareba, Grazyna


    Pain is considered the third most common healthcare problem disabling more individuals than heart disease and cancer together. Although pharmacological pain management offers a significant relief in several pain-related diseases, many patients turn to its supplementation with complementary and alternative medicine. Botanicals used in pain therapy can contribute to restoring the quality of life to a patient and may effect and enhance conventional pain management. Herbal analgesic use in several pain-related diseases such as rheumatologic diseases, back pain, cancer, diabetic peripheral neuropathy and migraine will be discussed. In addition, this review describes botanicals with known analgesic activity for which randomized, placebo-controlled, double-blind trials assessing their efficacy in different pain-related diseases have been published and which have been recently evaluated in many systematic reviews with well-described methodology.

  14. Reduction of the suction losses through reed valves in hermetic reciprocating compressors using a magnet coil

    Hopfgartner, J.; Posch, S.; Zuber, B.; Almbauer, R.; Krischan, K.; Stangl, S.


    Reed valves are widely used in hermetic reciprocating compressors and are responsible for a large part of the thermodynamic losses. Especially, the suction valve, which is opened nearly during the whole suction stroke, has a big potential for improvement. Usually, suction valves are opened only by vacuum created by the moving piston and should be closed before the compression stroke starts to avoid a reversed mass-flow through the valve. Therefore, the valves are prestressed, which results on the other hand in a higher flow resistance. In this work, a suction valve is investigated, which is not closed by the preload of the valve but by an electromagnetic coil located in the suction muffler neck. Shortly before the piston reaches its bottom dead centre, voltage is applied to the coil and a magnetic force is generated which pulls the valve shut. Thereby, the flow resistance through the valve can be reduced by changing the preload on the reed valve because it is no longer needed to close the valve. The investigation of this adapted valve and the electromagnetic coil is firstly done by numerical simulations including fluid structure interactions of the reed valves of a reciprocating compressor and secondly by experiments made on a calorimeter test bench.

  15. Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves

    Johansen, Peter; Engholt, Henrik; Tang, Mariann


    AIMS: Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, at smaller sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be frac...

  16. Mitral valve prolapse.

    Gould, L; Gopalaswamy, C


    Mitral valve prolapse is a very common condition. It occurs in 4-5% of the population. It may be idiopathic or associated with a number of other conditions. Myxomatous degeneration is the underlying mechanism of mitral valve prolapse. Most patients with mitral valve prolapse have no symptoms. When symptoms do occur, palpitations, chest pain and dyspnea are the major complaints. The midsystolic click occasionally followed by the late systolic murmur are the typical physical findings. The echocardiogram plays a big role in the diagnosis of mitral valve prolapse. The beta blockers are used in the treatment of the symptomatic patient.

  17. Biological heart valves.

    Ciubotaru, Anatol; Cebotari, Serghei; Tudorache, Igor; Beckmann, Erik; Hilfiker, Andres; Haverich, Axel


    Cardiac valvular pathologies are often caused by rheumatic fever in young adults, atherosclerosis in elderly patients, or by congenital malformation of the heart in children, in effect affecting almost all population ages. Almost 300,000 heart valve operations are performed worldwide annually. Tissue valve prostheses have certain advantages over mechanical valves such as biocompatibility, more physiological hemodynamics, and no need for life-long systemic anticoagulation. However, the major disadvantage of biological valves is related to their durability. Nevertheless, during the last decade, the number of patients undergoing biological, rather than mechanical, valve replacement has increased from half to more than three-quarters for biological implants. Continuous improvement in valve fabrication includes development of new models and shapes, novel methods of tissue treatment, and preservation and implantation techniques. These efforts are focused not only on the improvement of morbidity and mortality of the patients but also on the improvement of their quality of life. Heart valve tissue engineering aims to provide durable, "autologous" valve prostheses. These valves demonstrate adaptive growth, which may avoid the need of repeated operations in growing patients.

  18. Waiver Plan Generates Relief, Fret

    Klein, Alyson; McNeil, Michele


    While the Obama administration's plan to offer states relief from parts of the No Child Left Behind (NCLB) Act--if they agree to embrace unspecified education redesign priorities--has drawn kudos from some quarters, it isn't sitting well in others. Officials in a number of states have praised the idea as an opportunity for badly needed relief from…

  19. 24 CFR 965.508 - Individual relief.


    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Individual relief. 965.508 Section... relief. Requests for relief from surcharges for excess consumption of PHA-purchased utilities, or from... appropriate. The PHA's criteria for granting such relief, and procedures for requesting such relief, shall be...

  20. 液压冲击下五星式径向柱塞马达配流轴疲劳分析%Fatigue analysis of pintle valve of motor with five-star radial piston under effect of hydraulic shock

    王建利; 刘晋浩


    Hydraulic shock often happens when valves are opened or closed suddenly, and it may cause a series of trouble for the hydraulic system. If the motor in the hydraulic system has a huge initial load, hydraulic shocks might be larger when the valve is closed. When a hydraulic motor drives a plate whose rotary inertia is as large as 17 kg·m2 running at a highest rotating speed of 400 r/min, if the control valve is suddenly closed, the hydraulic shock is not ignorable. In order to determine the fatigue damage mechanism for a specific five-star radial piston motor under the hydraulic shock, the AMESim software was employed to study hydraulic shock waves and its highest pressure value. The simulation model was built under the guide of the hydraulic schematic of the hydraulic system. In the model, relief valve 1’s opening pressure was set to be 35 MPa, while relief valve 2 and relief valve 3 were both set to be 31 MPa, relief valve 4 was 21 MPa. An IR-C-IR submodel was employed in hose 7 and 8 to simulate hydraulic waves in hoses, while the other pipes were considered as rigid pipe. The control valve was open at the very beginning of the simulation, and closed 4 seconds later, until 16 seconds later the simulation terminated. Simulation results showed that a hydraulic shock whose pressure as high as 36 MPa occurred just after the control valve was shut down, and the amplitude of the wave decreased step by step. After that, the highest pressure value was considered as the pressure boundary on the simulation of ANSYS CFX to simulate impact pressure acting against on valve plate, and the results showed that the impact pressure could be up to 34.9 MPa. This high hydraulic pressure shock pushed the valve plate to knock the upper shell hardly, and the frictional moment between valve plate and upper shell could reach 60.02 Nm. This moment was taken as the load into pintle valve to calculate the fatigue life of the pintle valve, and the results showed that the fatigue life only

  1. Quick-Relief Medications for Lung Diseases

    ... relief medications are used to treat asthma, other lung disease symptoms or an acute episode (such as an ... about the following quick-relief asthma and other lung disease medications: Anticholinergics Anticholinergics are quick-relief asthma and ...

  2. Cooper pairs spintronics in triplet spin valves.

    Romeo, F; Citro, R


    We study a spin valve with a triplet superconductor spacer intercalated between two ferromagnets with noncollinear magnetizations. We show that the magnetoresistance of the triplet spin valve depends on the relative orientations of the d vector, characterizing the superconducting order parameter, and the magnetization directions of the ferromagnetic layers. For devices characterized by a long superconductor, the effects of a polarized current sustained by Cooper pairs only are observed. In this regime, a supermagnetoresistance effect emerges, and the chiral symmetry of the order parameter of the superconducting spacer is easily recognized. Our findings open new perspectives in designing spintronics devices based on the cooperation of ferromagnetic and triplet correlations.

  3. Blocked Urethral Valves

    ... Blocked Urethral Valves Health Issues Listen Español Text Size Email Print Share Blocked Urethral Valves Page Content Article Body Urine leaves the bladder through a tube called the urethra, which in boys passes through the penis. Rarely, small membranes form across the urethra in ...

  4. Shutoff and throttling valve

    Hays, L. G.


    Leaktight shutoff, precise flow control, and very low pressure drop are incorporated in all-metal valve designed for operation under extreme temperatures. Valve constructed with refractory metal is intended for control of high-temperature liquid cesium, but has applications related to control of high- and low-temperature liquids and gases.

  5. Classification of heart valve condition using acoustic measurements

    Clark, G. [Lawrence Livermore National Lab., CA (United States)


    Prosthetic heart valves and the many great strides in valve design have been responsible for extending the life spans of many people with serious heart conditions. Even though the prosthetic valves are extremely reliable, they are eventually susceptible to long-term fatigue and structural failure effects expected from mechanical devices operating over long periods of time. The purpose of our work is to classify the condition of in vivo Bjork-Shiley Convexo-Concave (BSCC) heart valves by processing acoustic measurements of heart valve sounds. The structural failures of interest for Bscc valves is called single leg separation (SLS). SLS can occur if the outlet strut cracks and separates from the main structure of the valve. We measure acoustic opening and closing sounds (waveforms) using high sensitivity contact microphones on the patient`s thorax. For our analysis, we focus our processing and classification efforts on the opening sounds because they yield direct information about outlet strut condition with minimal distortion caused by energy radiated from the valve disc.

  6. In-vitro calcification study of polyurethane heart valves.

    Boloori Zadeh, Parnian; Corbett, Scott C; Nayeb-Hashemi, Hamid


    Tri-leaflet polyurethane heart valves have been considered as a potential candidate in heart valve replacement surgeries. In this study, polyurethane (Angioflex(®)) heart valve prostheses were fabricated using a solvent-casting method to evaluate their calcification resistance. These valves were subjected to accelerated life testing (continuous opening and closing of the leaflets) in a synthetic calcification solution. Results showed that Angioflex(®) could be considered as a potential material for fabricating prosthetic heart valves with possibly a higher calcification resistance compared to tissue valves. In addition, calcification resistance of bisphosphonate-modified Angioflex(®) valves was also evaluated. Bisphosphonates are considered to enhance the calcification resistance of polymers once covalently bonded to the bulk of the material. However, our in-vitro results showed that bisphosphonate-modified Angioflex(®) valves did not improve the calcification resistance of Angioflex(®) compared to its untreated counterparts. The results also showed that cyclic loading of the valves' leaflets resulted in formation of numerous cracks on the calcified surface, which were not present when calcification study did not involve mechanical loading. Further study of these cracks did not result in enough evidence to conclude whether these cracks have penetrated to the polymeric surface.

  7. Bioprinting a cardiac valve.

    Jana, Soumen; Lerman, Amir


    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering.

  8. Anticoagulation for Prosthetic Valves

    Tsuyoshi Kaneko


    Full Text Available Implantation of prosthetic valve requires consideration for anticoagulation. The current guideline recommends warfarin on all mechanical valves. Dabigatran is the new generation anticoagulation medication which is taken orally and does not require frequent monitoring. This drug is approved for treatment for atrial fibrillation and venous thromboembolism, but the latest large trial showed that this drug increases adverse events when used for mechanical valve anticoagulation. On-X valve is the new generation mechanical valve which is considered to require less anticoagulation due to its flow dynamics. The latest study showed that lower anticoagulation level lowers the incidence of bleeding, while the risk of thromboembolism and thrombosis remained the same. Anticoagulation poses dilemma in cases such as pregnancy and major bleeding event. During pregnancy, warfarin can be continued throughout pregnancy and switched to heparin derivative during 6–12 weeks and >36 weeks of gestation. Warfarin can be safely started after 1-2 weeks of discontinuation following major bleeding episode.

  9. Experimental study for flow characteristics and performance evaluation of butterfly valves

    Kim, C. K.; Yoon, J. Y.; Shin, M. S.


    The industrial butterfly valves have been applied to transport a large of fluid with various fields of industry. Also, these are mainly used a control of fluid flux to the water and waste-water pipeline. Present, butterfly valves are manufacturing for multiplicity shape of bodies and discs with many producers. However, appropriate performance evaluation was not yet accomplished to compare about these valves through experiments. This study is performed the experiment of flow characteristics and performance of manufactured 400A butterfly valves for the water and waste pipeline, and compared experimental results. We performed experiments that were controlled fixed a differential pressure condition (1 psi) and the range of the flow rate conditions (500 m3/hr ~ 2500 m3/hr), and also opened the disc of valves to a range of angle from 9 degree to 90 degree. We investigated and compared the valve flow coefficient and the valve loss coefficient of results through experiments with each butterfly valve.

  10. A capillary valve for microfluidic systems.

    Cummings, Eric B.; Kanouff, Michael P.; Rush, Brian M.


    Microfluidic systems are becoming increasingly complicated as the number of applications grows. The use of microfluidic systems for chemical and biological agent detection, for example, requires that a given sample be subjected to many process steps, which requires microvalves to control the position and transport of the sample. Each microfluidic application has its own specific valve requirements and this has precipitated the wide variety of valve designs reported in the literature. Each of these valve designs has its strengths and weaknesses. The strength of the valve design proposed here is its simplicity, which makes it easy to fabricate, easy to actuate, and easy to integrate with a microfluidic system. It can be applied to either gas phase or liquid phase systems. This novel design uses a secondary fluid to stop the flow of the primary fluid in the system. The secondary fluid must be chosen based on the type of flow that it must stop. A dielectric fluid must be used for a liquid phase flow driven by electroosmosis, and a liquid with a large surface tension should be used to stop a gas phase flow driven by a weak pressure differential. Experiments were carried out investigating certain critical functions of the design. These experiments verified that the secondary fluid can be reversibly moved between its 'valve opened' and 'valve closed' positions, where the secondary fluid remained as one contiguous piece during this transport process. The experiments also verified that when Fluorinert is used as the secondary fluid, the valve can break an electric circuit. It was found necessary to apply a hydrophobic coating to the microchannels to stop the primary fluid, an aqueous electrolyte, from wicking past the Fluorinert and short-circuiting the valve. A simple model was used to develop valve designs that could be closed using an electrokinetic pump, and re-opened by simply turning the pump off and allowing capillary forces to push the secondary

  11. Methods for determining atypical gate valve thrust requirements

    Steele, R. Jr.; Watkins, J.C.; DeWall, K.G. [Idaho National Engineering Lab., Idaho Falls, ID (United States)] [and others


    Evaluating the performance of rising stem, wedge type, gate valves used in nuclear power plant is not a problem when the valves can be design-basis tested and their operability margins determined diagnostically. The problem occurs when they cannot be tested because of plant system limitations or when they can be tested only at some less-than-design-basis condition. To evaluate the performance of these valves requires various analytical and/or extrapolation methods by which the design-basis stem thrust requirement can be determined. This has been typically accomplished with valve stem thrust models used to calculate the requirements or by extrapolating the results from a less-than-design-basis test. The stem thrust models used by the nuclear industry to determine the opening or closing stem thrust requirements for these gate valves have generally assumed that the highest load the valve experiences during closure (but before seating) is at flow isolation and during unwedging or before flow initiation in the opening direction. However, during full-scale valve testing conducted for the USNRC, several of the valves produced stem thrust histories that showed peak closing stem forces occurring before flow isolation in the closing direction and after flow initiation in the opening direction. All of the valves that exhibited this behavior in the closing direction also showed signs of internal damage. Initially, we dismissed the early peak in the closing stem thrust requirement as damage-induced and labeled it nonpredictable behavior. Opening responses were not a priority in our early research, so that phenomenon was set aside for later evaluation.

  12. Curved butterfly bileaflet prosthetic cardiac valve

    McQueen, David M.; Peskin, Charles S.


    An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.

  13. Southern Alaska Coastal Relief Model

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building coastal-relief models (CRM) for select U.S. coastal regions. Bathymetric, topographic, and shoreline data...

  14. Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve

    Bazeed, Mohamed Fayez (Dept. of Diagnostic Radiology, Faculty of Medicine, Mansoura Univ. (Egypt)), email:; Moselhy, Mohamed Saleh (Cardiology Dept. Faculty of Medicine, Suez Canal Univ. (Egypt)); Rezk, Ahmad Ibrahim (Dept. of Cardiac Surgery, Faculty of Medicine, Aim Shams Univ. (Egypt)); Al-Murayeh, Mushabab Ayedh (Dept. of Cardiac Services, Armed Forces Hospitals Southern Region (Saudi Arabia))


    Background: Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation. Purpose: To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range. Material and Methods: Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale. Results: The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 +- 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves. Conclusion: MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation

  15. Prosthetic Valve Thrombosis: Diagnosis and Management.

    Garg, Jalaj; Palaniswamy, Chandrasekar; Pinnamaneni, Sowmya; Sarungbam, Judy; Jain, Diwakar


    St. Jude mechanical prosthesis is the most commonly used prosthetic device with least valvular complications with excellent hemodynamics. However, prosthetic valve thrombosis is one of the serious complications, with rates between 0.03% and 0.13% per patient-year depending on the type of anticoagulation used and compliance to the therapy. Transthoracic echocardiography (TTE) is the initial screening tool (class I) that would provide clues for the assessment of valvular hemodynamics. Fluoroscopy is an alternate imaging modality for the assessment of mechanical leaflet motion, especially in patients when prosthetic valves are difficult to image on TTE or transesophageal echocardiography. A complete fluoroscopic evaluation of a prosthetic valve includes assessment of valvular motion and structural integrity. Opening and closing angles can be measured fluoroscopically to determine whether a specific valve is functioning properly. We discuss a case of a 91-year-old man with thrombosis of bileaflet mechanical mitral prosthesis that was demonstrated on real-time fluoroscopy (not evident on TTE). An algorithmic approach to diagnosis and management of prosthetic heart valve thrombosis is outlined.

  16. Mesofluidic two stage digital valve

    Jansen, John F; Love, Lonnie J; Lind, Randall F; Richardson, Bradley S


    A mesofluidic scale digital valve system includes a first mesofluidic scale valve having a valve body including a bore, wherein the valve body is configured to cooperate with a solenoid disposed substantially adjacent to the valve body to translate a poppet carried within the bore. The mesofluidic scale digital valve system also includes a second mesofluidic scale valve disposed substantially perpendicular to the first mesofluidic scale valve. The mesofluidic scale digital valve system further includes a control element in communication with the solenoid, wherein the control element is configured to maintain the solenoid in an energized state for a fixed period of time to provide a desired flow rate through an orifice of the second mesofluidic valve.

  17. Dynamic characteristics research of the pressure reducing valve based on AMESim

    Wang, Weihui; Zhang, Peiyi


    Through the analysis of the structure and working principle of pressure reducing valve, using AMESim software to model, simulate and analyze its working conditions On the basis of the analysis of the structural parameters of the valve: damping hole diameter D, analog load damping hole diameter D1, spring stiffness K and initial opening S 0f analog load, such as which has the impact of hydraulic pressure reducing valve Finally, the influence of the above parameters on the accuracy of the valve is analyzed, which provides a reference for the design of the valve.

  18. Aortic valve replacement

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A


    BACKGROUND AND AIMS OF THE STUDY: Prompted by anecdotal evidence and observations by surgeons, an investigation was undertaken into the potential differences in implanted aortic valve prosthesis sizes, during aortic valve replacement (AVR) procedures, between northern and southern European...... countries. METHODS: A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early...


    Prashanth Kumar


    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  20. Danfos: Thermostatic Radiator Valves

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.


    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...... similar to the one achieved by the expensive and time-consuming CFD calculations. So CFD is only used in case of entirely new designs or where a very detailed knowledge of the flow is required. Even though rules of thumb are useful for those, who have developed them, Danfoss needs an objective and general...... method that can be used to predict the performance of valves....

  1. Design factors for “linear” ball valve: theoretical and experimental studies

    Thananchai Leephakpreeda


    Full Text Available Generic non-linear flow characteristics of the conventional ball valve limit the applications of flow modulation in fluid processes. This work presents the flow characteristics of fluid flowing through the conventional and modified ball valves for feasibility of a “linear” ball valve. Theoretical studies are discussed for determining explicit and implicit factors on the valve coefficient, which modulates the flow rate of fluid when the ball valve is operated in flow control processes. In experiment, the cross- sectional opening area at various opening degrees, the shape, and the location of the hole passage in valve ball are examined for complicated relations dependent to the flow rate of fluid. It can be concluded that those factors cause the modulation of flow rate when the ball is turned at different opening degree. In extended design of flow characteristics for linearity, they are to be taken into account.

  2. Pectus excavatum in relief from Ancient Egypt (dating back to circa 2400 BC).

    Bialas, Adam J; Kaczmarski, Jacek; Kozak, Jozef; Kempinska-Miroslawska, Bogumila


    Pectus excavatum is one of the most common congenital deformities of the chest wall. The aim of the study was to analyse 621 artefacts (reliefs, sculptures, paintings) from Ancient Egypt in terms of anatomical defects of the chest. The team which analysed artefacts consisted of historians of medicine and thoracic surgeons. The researchers found a relief, depicting a man with an abnormal shape of the chest. The relief was from Niankhkhnum and Khnumhotep mastaba and dates back to circa 2400 BC. The authors think it is possible that the relief may represent a pectus excavatum deformity and believe the image will open up debate on the occurrence of this deformity in ancient times.

  3. 7 CFR 760.106 - Equitable relief.


    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Equitable relief. 760.106 Section 760.106 Agriculture... Assistance Programs § 760.106 Equitable relief. (a) The Secretary may provide equitable relief on a case-by... accordance with the FCIA (7 U.S.C. 1501-1524) or (ii) Application closing date for NAP. (b) Equitable relief...

  4. Effects of pressure and temperature on gate valve unwedging

    Damerell, P.S.; Harrison, D.H.; Hayes, P.W.; Simons, J.W.; Walker, T.A.


    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. {open_quotes}Pressure locking{close_quotes} and {open_quotes}thermal binding{close_quotes} refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an {open_quotes}interference{close_quotes} between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat {open_quotes}interference{close_quotes}. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat {open_quotes}interference{close_quotes} or disk-to-seat friction.

  5. Surgical double valve replacement after transcatheter aortic valve implantation and interventional mitral valve repair.

    Wendeborn, Jens; Donndorf, Peter; Westphal, Bernd; Steinhoff, Gustav


    Transcatheter aortic valve implantation, as well as interventional mitral valve repair, offer reasonable therapeutic options for high-risk surgical patients. We report a rare case of early post-interventional aortic valve prosthesis migration to the left ventricular outflow tract, with paravalvular leakage and causing severe mitral valve regurgitation. Initial successful interventional mitral valve repair using a clipped edge-to-edge technique revealed, in a subsequent procedure, the recurrence of mitral valve regurgitation leading to progressive heart failure and necessitating subsequent surgical aortic and mitral valve replacement.

  6. Steam and fuel oil supply and purge valve with cooling steam feature

    Buchanan, B.F.; Buchanan, J.R.


    This patent describes a steam and fuel oil supply and purge valve. It comprises a valve body defining steam and oil inlet ports, at least one discharge port, a steam purge passageway interconnecting the steam inlet and discharge ports, an oil supply passageway interconnecting the oil inlet and discharge ports, a cooling steam passageway interconnecting the steam inlet and discharge ports, a steam valve and actuator member movable between first, second, third, and fourth positions in the valve body and operable to open and close the steam purge and cooling steam passageways, a small metering passageway in the steam valve and actuator member which is so dimensioned and located as to open prior to full opening movement of the valve member and actuator relative to its seat, an oil valve member movable between first and second positions to open and close the oil supply passageway, biasing means urging the oil valve member toward its second and closed positions, the steam valve and actuator member in its first and second positions respectively closing and opening the steam purge passageway.

  7. Mitral Valve Disease

    ... for more information on procedures, news, and pre- & post-operative care. Section Navigation Select Topic Aortic Valve Disease ... is most commonly caused by inflammation from rheumatic fever, a disease that is related to strep infections; ...

  8. Valve Repair or Replacement

    ... valve surgery can be done using a robot. Robotic surgery does not require a large incision in the ... The Texas Heart Institute has a robot. With robotic surgery, the surgeon has a control console, a side ...

  9. Pulmonary valve stenosis

    ... valvuloplasty - pulmonary Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  10. Mitral valve regurgitation

    ... and dentist if you have a history of heart valve disease or congenital heart disease before treatment. Some people ... the middle Heart, front view References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ...

  11. Mitral Valve Prolapse

    ... Kawasaki Disease Long Q-T Syndrome Marfan Syndrome Metabolic Syndrome Mitral Valve Prolapse Myocardial Bridge Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden ...

  12. Compressed gas domestic aerosol valve design using high viscous product

    A Nourian


    Full Text Available Most of the current universal consumer aerosol products using high viscous product such as cooking oil, antiperspirants, hair removal cream are primarily used LPG (Liquefied Petroleum Gas propellant which is unfriendly environmental. The advantages of the new innovative technology described in this paper are: i. No butane or other liquefied hydrocarbon gas is used as a propellant and it replaced with Compressed air, nitrogen or other safe gas propellant. ii. Customer acceptable spray quality and consistency during can lifetime iii. Conventional cans and filling technology There is only a feasible energy source which is inert gas (i.e. compressed air to replace VOCs (Volatile Organic Compounds and greenhouse gases, which must be avoided, to improve atomisation by generating gas bubbles and turbulence inside the atomiser insert and the actuator. This research concentrates on using "bubbly flow" in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. The new valve designed in this investigation using inert gases has advantageous over conventional valve with butane propellant using high viscous product (> 400 Cp because, when the valving arrangement is fully open, there are negligible energy losses as fluid passes through the valve from the interior of the container to the actuator insert. The use of valving arrangement thus permits all pressure drops to be controlled, resulting in improved control of atomising efficiency and flow rate, whereas in conventional valves a significant pressure drops occurs through the valve which has a complex effect on the corresponding spray.

  13. Micro system comprising 96 micro valves on a titer plate

    Krabbe, S.; Flitsch, D.; Büchs, J.; Schomburg, W. K.


    A system of 96 micro valves has been developed and mounted on top of a 48-well micro titer plate providing two valves for each well controlling its air inlet and outlet. Testing of the valve system showed that all valves are working and are opened and closed reliably. A pneumatic system is switching inlet and outlet valves independently of each other. The geometry of the feed channels ensures an equal air flow through all wells, when the valves are open. Between the micro valves, one optical fibre was inserted through the lid of each well allowing measuring the oxygen partial pressure in the enclosed air volume by fluorescence sensor spots. Escherichia coli bacteria were grown inside the wells and their metabolism was observed by the oxygen partial pressure change due to respiration. In all 48 wells, the same oxygen transfer rate was observed within an averaged standard deviation of 1 mmol/L/h. The oxygen transfer rate differences compared to a macroscopic standard shake flask system were overall compatible within their uncertainties.

  14. Signal processing of Shiley heart valve data for fracture detection

    Mullenhoff, C.


    Given digital acoustic data emanating from the heart sounds of the beating heart measured from laboratory sheep with implanted Bjoerk-Shiley Convexo-Concave heart valves, it is possible to detect and extract the opening and closing heart beats from the data. Once extracted, spectral or other information can then obtained from the heartbeats and passed on to feature extraction algorithms, neutral networks, or pattern recognizers so that the valve condition, either fractured or intact, may be determined.

  15. Posterior urethral valves: relationship between vesicoureteral reflux and renal function.

    Cozzi, Denis A; Morgante, Debora; Frediani, Simone; Iaconelli, Romina; Ceccanti, Silvia; Mele, Ermelinda; Cozzi, Francesco


    To investigate the relationship between renal function and vesicoureteral reflux before and after valve ablation in patients with posterior urethral valves. In these patients, back pressure may not be the only cause of renal damage. We conducted a retrospective review of 37 patients with valves consecutively treated between 1970 and 2002. Data were available for 31 patients, 19 of whom presented reflux at presentation. Grade of reflux was ascertained by voiding cystourethrography. Overall renal function was measured by serum creatinine, and split renal function was estimated by dimercaptosuccinic acid scan available for all patients but two. Before relief of obstruction, there was no correlation between split renal function and grade of reflux into 25 kidneys of the 17 patients (r = -.13; 95% CI, -.50 to .27; P = .51). High-grade reflux (grade IV-V) affected 6 of the 11 renal units, with split renal function >40% vs 11 of the 14 units with split renal function 40% vs 4 of the 14 units with split renal function <40% (P = .0005). The good renal function of more than half of the renal units with high-grade reflux at presentation, and the persistence of reflux mainly in nonfunctioning or poorly functioning kidneys after valve ablation, support the concept that in some patients with valves, reflux and renal damage are associated anomalies. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Controlling the cavitation phenomenon of evolution on a butterfly valve

    Baran, G.; Catana, I.; Magheti, I.; Safta, C. A.; Savu, M.


    Development of the phenomenon of cavitation in cavitation behavior requires knowledge of both plant and equipment working in the facility. This paper presents a diagram of cavitational behavior for a butterfly valve with a diameter of 100 mm at various openings, which was experimentally built. We proposed seven stages of evolution of the phenomenon of cavitation in the case of a butterfly valve. All these phases are characterized by pressure drop, noise and vibration at various flow rates and flow sections through the valve. The level of noise and vibration for the seven stages of development of the phenomenon of cavitation were measured simultaneously. The experimental measurements were comprised in a knowledge database used in training of a neural network of a neural flow controller that maintains flow rate constantly in the facility by changing the opening butterfly valve. A fuzzy position controller is used to access the valve open. This is the method proposed to provide operational supervision outside the cavitation for a butterfly valve.

  17. The iValve Hands-Free Speech Valve for Laryngectomized Patients. In Vitro Test of a Novel Device of Revolutionary Design

    van der Houwen, E. B.; van Kalkeren, T. A.; Burgerhof, J. G. M.; van der Laan, B. F. A. M.; Verkerke, G. J.; Jobbagy, A


    Background. Speech valves help restore speech after surgical removal of the larynx (laryngectomy). Laryngectomized Patients breathe through an artificial opening (tracheostoma) in the neck. A shunt valve is routinely inserted between oesophagus and trachea to restore speech. At closure of the stoma

  18. The iValve Hands-Free Speech Valve for Laryngectomized Patients. In Vitro Test of a Novel Device of Revolutionary Design

    van der Houwen, E. B.; van Kalkeren, T. A.; Burgerhof, J. G. M.; van der Laan, B. F. A. M.; Verkerke, G. J.; Jobbagy, A


    Background. Speech valves help restore speech after surgical removal of the larynx (laryngectomy). Laryngectomized Patients breathe through an artificial opening (tracheostoma) in the neck. A shunt valve is routinely inserted between oesophagus and trachea to restore speech. At closure of the stoma

  19. Flow characteristics and performance evaluation of butterfly valves using numerical analysis

    Jeon, S. Y.; Yoon, J. Y.; Shin, M. S.


    The industrial butterfly valves have been applied to various fields that transport fluid in volume, especially water supply and drainage pipeline for flow control. The butterfly valves in various shapes are manufactured, but a fitting performance comparison is not made up. For this reason, we carried out numerical analysis of some kind of butterfly valves for water supply and drainage pipeline using commercial CFD code FLUENT, and made a comparative study of these results. Also, the flow coefficient, the loss coefficient, and pressure distribution of valves according to valve opening rate were compared each other and the influence of these design variables on valve performance were checked over. Through flow around the valve disk, such as pressure distribution, flow pattern, velocity vectors, and form of vortex, we grasped flow characteristics.

  20. A normally-closed piezoelectric micro-valve with flexible stopper

    Chen, Song; Lu, Song; Liu, Yong; Wang, Jiantao; Tian, Xiaochao; Liu, Guojun; Yang, Zhigang


    In the field of controlled drug delivery system, there are still many problems on those reported micro-valves, such as the small opening height, unsatisfactory particle tolerance and high cost. To solve the above problems, a novel normally-closed piezoelectric micro-valve is presented in this paper. The micro-valve was driven by circular unimorph piezoelectric vibrator and natural rubber membrane with high elasticity was used as the valve stopper. The small axial displacement of piezoelectric vibrator can be converted into a large stroke of valve stopper based on hydraulic amplification mechanism. The experiment indicates that maximum hydraulic amplification ratio is up to 14, and the cut-off pressure of the micro-valve is 39kPa in the case of no working voltage. The presented micro valve has a large flow control range (ranging from 0 to 8.75mL/min).

  1. Oil Stiction in Fast Switching Annular Seat Valves for Digital Displacement Fluid Power Machines

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.


    valves suitable for DD applications based on the Reynolds equation and considers contact surface curvature and attack angle. A dynamic cavitation zone is included in the stiction model, and cavitation is found to be present even for seat valves surrounded by high pressure levels....... to the dynamic behaviour of the seat valves must be considered to optimize the machine efficiency. A significant effect influencing the valves switching performance is the presence of oil stiction when separating the contact surfaces in valve opening movement. This oil stiction force is limited by cavitation...... for low pressure levels, e.g. valves connected to the low pressure manifold, however for valves operated at higher pressure levels, the oil stiction force is dominating when the separating surfaces are close to contact. This paper presents an analytic solution to the oil stiction force for annular seat...

  2. Video-based measuring of quality parameters for tricuspid xenograft heart valve implants.

    Condurache, Alexandru Paul; Hahn, Tobias; Scharfschwerdt, Michael; Mertins, Alfred; Aach, Til


    Defective heart valves are often replaced by implants in open-heart surgery. Both mechanical and biological implants are available. Among biological implants, xenograft ones-i.e., valves grafted from animals such as pigs, are widely used. Good implants should exhibit certain typical anatomical and functional characteristics to successfully replace the native tissue. Here, we describe a video-based system for measuring quality parameters of xenograft heart valve implants, including the area of the orifice and the fluttering of the valves' leaflets, i.e., their flaps (or cusps). Our system employs automatic methods that provide a precise and reproducible way to infer the quality of an implant. The automatic analysis of both a valve's orifice and the fluttering of its leaflets offers a more comprehensive quality assessment than current, mostly manual methods. We focus on valves with three leaflets, i.e., aortic, pulmonary, and tricuspid valves.

  3. Design of a New Type of Distribution Valve for Hydraulic Breaker and Analysis of Energy Consumption


    Energy consumed by distribution valves causes an energy loss for the output energy of hydraulic breakers, which has a significant influence on its efficiency. A new type of distribution valve used for hydraulic breakers, designed to reduce energy consumption, is analyzed on the basis of the operating principle and energy loss of the current distribution valve. The new distribution valve adopts a cone valve and the optimization technique of unequal open degree for the valve port. Theoretical calculations and analyses have proven that the new distribution valve can reduce energy loss by 9.0127J, or energy consumption by 31%, during an impact cycle and the efficiency of the hydraulic breaker can be raised by 4.5%. It has the following characteristics: little leakage, little pressure loss and low energy consumption.

  4. Nursing of 13 patients with Mitral Valve Repair received totally robotic surgery without opening chest%13例全机器人不开胸二尖瓣成形术患者的护理

    刘喜梅; 于亚群; 魏新


    Objective To study the characteristics of perioperative care for patients with Mitral Valve Repair (MVP) received totally robotic surgery without opening chest and provide scientific data for the clinic work. Methods The first 13 cases who received MVP with totally robotic was collected on their individual information and nursing data from their admission to discharge. Results All cases were accomplished successfully without complications. After operation 1 patient occurred Cerbral Infarction and recovery activity of extremity prior to discharge. One patient occurred thrombus of right femoral artery and take the right femoral arteriotomy embolectomy. Conclusions Totally robotic surgery with MVP is a new minimally-invasive procedure. Preoperative education is important to alleviate the patient's misgivings care. In early postoperative course, the amount of drainage should be observed and the pulmonary nursing should be carried out, especially the right lung must be stressed. The early postoperative exercise can reduce the recovery time.%目的 总结13例全机器人不开胸二尖瓣成形术的护理特点,为今后的护理提供依据.方法 采用便利抽样前瞻性研究的方法,设计好所要收集资料的项目,从患者入院到出院做全程的护理,入院主要进行相关知识的宣教和心理辅导,术后按体外循环心脏直视手术护理常规进行外,重点做好患者的肺部护理和肢体血液循环的观察,早期进行康复训练.结果 13例患者顺利接受手术.术后1例术后出现脑梗,出院前肢体活动恢复;1例发生右股动脉血栓,术后3 d行右股动脉切开取栓术;其余患者经过康复训练痊愈出院.结论 全机器人不开胸二尖瓣成形术是一项新的微创手术,其护理需注重知识的宣教,消除患者的疑虑,做好充分的术前准备工作,确保患者的安全.术后早期注意观察引流有无出血的发生,做好肺部护理,尤其是右肺的护理,尽早让患者下

  5. Implantation of the CoreValve percutaneous aortic valve.

    Lamarche, Yoan; Cartier, Raymond; Denault, André Y; Basmadjian, Arsène; Berry, Colin; Laborde, Jean-Claude; Bonan, Raoul


    Surgical aortic valve replacement is the only recommended treatment for significant aortic valve stenosis. Percutaneous aortic valve replacement appears to be a novel option for high-risk patients. We report the implantation of the ReValving system (CoreValve, Paris, France) in a 64-year-old woman who was refused aortic valve replacement surgery for critical aortic stenosis and left ventricular dysfunction because of severe pulmonary fibrosis. After anesthesia, the patient was put on femorofemoral cardiopulmonary bypass, and underwent a balloon valvuloplasty with subsequent retrograde aortic valve replacement by the ReValving system. Transesophageal echocardiographic monitoring of the patient's hemodynamics showed immediate improvements of the valvular area and left ventricular ejection fraction and only traces of paravalvular leaks. The patient was easily weaned from ventilation and resumed activity soon after the surgery. A multidisciplinary approach is presently necessary to offer a reliable and safe procedure.

  6. [Technologies for cardiac valve prostheses].

    Nakano, Kiyoharu


    To show the technological development of cardiac valve prostheses, a historical review of both mechanical and biological valve prostheses and a current overview of modern cardiac valve devices are provided. Scince the 1st implantation of Starr-Edwards ball valve in 1960, both mechanical and biological valve prostheses have advanced. The valve design, the material of the leaflet and the hausing of mechanical prostheses have improved. Currently, the majority of the mechanical prostheses are bileaflet tilting disc valves made of pyrolytic carbon, which is antithromboembolic. However, anticoagulation therapy with warfarin is still required. As for the bioprostheses, although the fixation and anti-mineralization methods of the tissues improved, the durability of these valves is still limited. For the material of the current biological valves, the porcine aortic valve or bovine pericardium are used. The tissues are fixed by non-pressure or low-pressure method in glutaraldehyde solution. A stented and non-stented valves are available. Epoch-making events in this field are the implantation of new bioprosthetic valves using tissue engineering methods and the development of the transcatheter valve replacement therapies.

  7. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    Dvir, Danny; Webb, John; Brecker, Stephen;


    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry.......Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....


    Wang Qingfeng; Li Yanmin; Zhong Tianyu; Xu Guohua


    Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems (UHSs), a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.

  9. [Risk of barotrauma when using non-reinhalation Waters valves: a comparative study on bench test].

    Coisel, Y; Galia, F; Conseil, M; Jung, B; Chanques, G; Jaber, S


    Manual ventilation is delivered in the operating room or the intensive care unit to intubated or non-intubated patients, using non-rebreathing systems such as the Waters valve. New generation Waters valves are progressively replacing the historic Waters valve. The aim of this study was to evaluate maximal pressure delivered by these 2 valves. Bench test. Thirty-two different conditions were tested, according to 2 oxygen flow rates (10 and 20L/min), without (static condition) or with manual insufflations (dynamic condition) and 4 valve expiratory opening pressures. The primary endpoint was maximal pressure measured at the exit of the valve, connected to a model lung and a bench test. Measured pressures were different for most evaluated conditions. Increasing oxygen flow from 10 to 20L/min increased maximal pressure for both valves. Increasing valve expiratory opening pressure induced a significant increase in maximal pressure for the new generation valve (from 4 to 61cmH2O in static conditions and from 18 to 68cmH2O in dynamic conditions). For the historic valve, maximal pressure increased significantly but remained below 15cmH2O in both static and dynamic conditions. Use of new generation Waters valves should be different from historic Waters valves. Indeed, barotrauma could be caused by badly adapted valve expiratory opening pressure settings. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

  10. Mitral Valve Aneurysm: A Rare Complication of Aortic Valve Endocarditis

    A Moaref


    Full Text Available A 20-year-old intravenous drug abuser man, refered to our hospital with dyspnea and orthopnea. Tranesophagealechocardiography revealed severe aortic regurgitation, healed vegetation of aortic valve and an aneurysm of theanterior leaflet of the mitral valve. The patient was discharged after aortic valve replacement and mitral valverepair.

  11. Research on Valve Body Design of Large Bore Sodium Valve


    Large bore sodium valve is one kind of key equipments of China Demonstration Fast Reactor (CDFR). It is installed in the pipeline before and behind SG units as a locking mechanism. Valve body which is used to bear pressure is the core of sodium valve design.

  12. Fraktalnist deformational relief polycrystalline aluminum

    М.В. Карускевич


    Full Text Available  The possibility of the fractal geometry method application for the analisys of surface deformation structures under cyclic loading is presented.It is shown, that deformation relief of the alclad aluminium alloyes meets the criteria of the fractality. For the fractal demention estimation the method of  “box-counting”can be applied.

  13. Stress relief of transition zones

    Woodward, J.; van Rooyen, D.


    This paper considers the problem of intergranular stress corrosion cracking, initiated on the primary side, in the expansion transition region of roller expanded Alloy 600 tubing. In general it is believed that residual stresses, arising from the expansion process, are the cause of the problem. The work reported here concentrated on the identification of an optimal, in-situ stress relief treatment.

  14. Transcatheter Aortic Heart Valve Thrombosis

    Hansson, Nicolaj C; Grove, Erik L; Andersen, Henning R;


    BACKGROUND: There is increasing focus on transcatheter heart valve (THV) thrombosis. However, there are limited data on incidence, clinical implications and predisposing factors of THV thrombosis following transcatheter aortic valve replacement (TAVR). OBJECTIVES: We assessed the incidence...

  15. Safety valve for offshore borehole

    McGill, H.L.; Randermann, E. Jr.; Musik, O.J.


    The invention concerns a new and improved submarine safety valve with a valve element which rotate, which can be used, in emergencies, to separate the wound-up piping which extends into the borehole and to close the production line.

  16. Prosthetic valve endocarditis with valvular obstruction after transcatheter aortic valve replacement.

    Pabilona, Christine; Gitler, Bernard; Lederman, Jeffrey A; Miller, Donald; Keltz, Theodore N


    Patients with severe aortic stenosis who are at high risk for open-heart surgery might be candidates for transcatheter aortic valve replacement (TAVR). To our knowledge, this is the first report of Streptococcus viridans endocarditis that caused prosthetic valve obstruction after TAVR. A 77-year-old man who had undergone TAVR 17 months earlier was admitted because of evidence of prosthetic valve endocarditis. A transthoracic echocardiogram revealed a substantial increase in the transvalvular peak gradient and mean gradient in comparison with an echocardiogram of 7 months earlier. A transesophageal echocardiogram showed a 1.5-cm vegetation obstructing the valve. Blood cultures yielded penicillin-sensitive S. viridans. The patient was hemodynamically stable and was initially treated with vancomycin because of his previous penicillin allergy. Subsequent therapy with levofloxacin, oral penicillin (after a negative penicillin skin test), and intravenous penicillin eliminated the symptoms of the infection. Transcatheter aortic valve replacement is a relatively new procedure, and sequelae are still being discovered. We recommend that physicians consider obstructive endocarditis as one of these.

  17. Nasal valve surgery.

    Apaydin, Fazil


    Nasal obstruction can be due to internal and external valve problems that can be seen before and after rhinoplasty. The main scope of this article is to concentrate on surgical solutions to these problems. To overcome nasal obstruction at the internal valve, spreader grafts, spreader flaps, upper lateral splay graft, butterfly graft, flaring suture, M-plasty, Z-plasty, and suspension sutures have been described. The management of the external valve problems is possible by using lateral crural dissection and repositioning, lateral crural strut grafts, alar battens, lateral crural turn-in flap, alar rim grafts, and various other methods. It is not easy to decide which techniques would work best in every case. After a thorough examination and analysis, the underlying cause of the nasal obstruction can be understood, and one or multiple procedures can be chosen according to each individual problem.

  18. Percutaneous mitral valve repair.

    Gillinov, A Marc; Liddicoat, John R


    Surgical mitral valve repair is the procedure of choice to treat mitral regurgitation of all etiologies. Whereas annuloplasty is the cornerstone of mitral valve repair, a variety of other surgical techniques are utilized to correct dysfunction of the leaflets and subvalvular apparatus; in most cases, surgical repair entails application of multiple repair techniques in each patient. Preclinical studies and early human experience have demonstrated that some of these surgical repair techniques can be performed using percutaneous approaches. Specifically, there has been great progress in the development of novel technology to facilitate percutaneous annuloplasty and percutaneous edge-to-edge repair. The objectives of this report were to (1) discuss the surgical foundations for these percutaneous approaches; (2) review device design and experimental and clinical results of percutaneous valve repair; and (3) address future directions, including the key challenges of patient selection and clinical trial design.

  19. Valve Concepts for Microfluidic Cell Handling

    M. Grabowski


    Full Text Available In this paper we present various pneumatically actuated microfluidic valves to enable user-defined fluid management within a microfluidic chip. To identify a feasible valve design, certain valve concepts are simulated in ANSYS to investigate the pressure dependent opening and closing characteristics of each design. The results are verified in a series of tests. Both the microfluidic layer and the pneumatic layer are realized by means of soft-lithographic techniques. In this way, a network of channels is fabricated in photoresist as a molding master. By casting these masters with PDMS (polydimethylsiloxane we get polymeric replicas containing the channel network. After a plasma-enhanced bonding process, the two layers are irreversibly bonded to each other. The bonding is tight for pressures up to 2 bar. The valves are integrated into a microfluidic cell handling system that is designed to manipulate cells in the presence of a liquid reagent (e.g. PEG – polyethylene glycol, for cell fusion. For this purpose a user-defined fluid management system is developed. The first test series with human cell lines show that the microfluidic chip is suitable for accumulating cells within a reaction chamber, where they can be flushed by a liquid medium.

  20. Aortic valve surgery: what is the future?

    Hudorović, Narcis


    Modern surgical treatment for aortic valve disease has undergone significant improvements in all areas of this procedure. Successful treatment strategies for cardiovascular diseases have often been initiated and driven by surgeons. Radical excision of diseased tissue, repair and replacement strategies lead to long-term successful treatment of the underlying diseases and clearly improved patient outcome. In highly developed nations, valve surgery will be increasing applied in older people, with more co-morbidities and a higher incidence of concomitant coronary artery disease. Cardiovascular surgeons will be facing increased competition from the catheter-based procedures; these are already applied clinically, and their numbers will rise in near future. Right now interventional cardiologists supported by some cardiac surgeons are on their way to transform some conventional open surgical procedures into catheter-based less invasive interventions, such as valve repair and replacement. Cardiovascular surgery is undergoing a rapid transformation; socio-economic factors and recent advances in medical technology contribute to these changes. Further developments will come, and surgeons with all their expertise in the treatment of valvular heart disease need to be part of it. Cardiovascular surgeons have to adapt the exciting new approaches of transapical and transfemoral transcatheter valve implantation techniques.

  1. Digital relief generation from 3D models

    Wang, Meili; Sun, Yu; Zhang, Hongming; Qian, Kun; Chang, Jian; He, Dongjian


    It is difficult to extend image-based relief generation to high-relief generation, as the images contain insufficient height information. To generate reliefs from three-dimensional (3D) models, it is necessary to extract the height fields from the model, but this can only generate bas-reliefs. To overcome this problem, an efficient method is proposed to generate bas-reliefs and high-reliefs directly from 3D meshes. To produce relief features that are visually appropriate, the 3D meshes are first scaled. 3D unsharp masking is used to enhance the visual features in the 3D mesh, and average smoothing and Laplacian smoothing are implemented to achieve better smoothing results. A nonlinear variable scaling scheme is then employed to generate the final bas-reliefs and high-reliefs. Using the proposed method, relief models can be generated from arbitrary viewing positions with different gestures and combinations of multiple 3D models. The generated relief models can be printed by 3D printers. The proposed method provides a means of generating both high-reliefs and bas-reliefs in an efficient and effective way under the appropriate scaling factors.

  2. Development of myoelectric control type speaking valve with low flow resistance

    Ooe, Katsutoshi; Sakurai, Kohei; Mimaki, Shinya


    We aimed to develop welfare devices for patients with phonation disorder. One of these devices is the electrical controltype speaking valve system. The conventional speaking valves have one-way valve architecture, they open when the user breathes in, and they close when user breathes out and produce voices. This type is very simple and tough, but some users feel closeness in case of exhalation without phonation. This problem is caused by its mechanism what can not be controlled by user's will. Therefore, we proposed an electrical control-type speaking valve system to resolve this problem. This valve is controlled by neck myoelectric signal of sternohyoid muscle. From our previous report, it was clarified that this valve had better performance about easy-to-breath. Furthermore, we proposed the compact myoelectric control-type speaking valve system. The new-type speaking valve was enough small to attach the human body, and its opening area is larger than that of conventional one. Additionally, we described the improvement of flow channel shape by using of FEM analysis. According to the result of the analysis, it was clarified that the shape-improved speaking valve gets the low flow resistance channel in case of inspiration. In this report, we tried to make the flow resistance lower by the shape of current plates, in case of both inspiration and exhalation. From the result of FEM analysis, our speaking valve could get better flow channel than older one.

  3. Modeling and performance evaluation of an electromechanical valve actuator for a camless IC engine

    Eid Mohamed


    Full Text Available Valve train control is one of the best strategies for optimizing efficiency and emissions of Internal Combustion (IC engines. Applications of solenoid valve actuators in (IC engines can facilitate operations such as variable valve timing and variable valve lifting for improved the engine performance, fuel economy and reduce emission, the electromechanical valve actuator (EMVA uses solenoid to actuate valve movement independently for the application of (IC engine. In this work presents the effects of design and operating parameters on the system dynamic performances of the actuator and the proposed an (EMVA structure by incorporating the hybrid magneto-motive force (MMF implementation in which the magnetic flux is combined by the coil excitation and permanent magnets. A two-degree-of-freedom lumped parameter model is used to simulate the response of valve actuator system in the opening and closing. The model and control of an electromagnetic valve (EMV are described. This is done using electromagnetic force to open and close the valve and a controller regulates the motion specifications required. The developments controller is based on a state-space description of the actuator that is derived based on physical principles and parameter identification. Linear-quadratic regulator design (LQR optimal control is designed with the evaluation reasonable the performance and energy of (EMV valve are obtained with the design.

  4. Modeling and performance evaluation of an electromechanical valve actuator for a camless IC engine

    Mohamed, Eid [Automotive and Tractors Engineering, Faculty of Engineering, Helwan University, Cairo (Egypt)


    Valve train control is one of the best strategies for optimizing efficiency and emissions of Internal Combustion (IC) engines. Applications of solenoid valve actuators in (IC) engines can facilitate operations such as variable valve timing and variable valve lifting for improved the engine performance, fuel economy and reduce emission, the electromechanical valve actuator (EMVA) uses solenoid to actuate valve movement independently for the application of (IC) engine. In this work presents the effects of design and operating parameters on the system dynamic performances of the actuator and the proposed an (EMVA) structure by incorporating the hybrid magneto-motive force (MMF) implementation in which the magnetic flux is combined by the coil excitation and permanent magnets. A two-degree-of-freedom lumped parameter model is used to simulate the response of valve actuator system in the opening and closing. The model and control of an electromagnetic valve (EMV) are described. This is done using electromagnetic force to open and close the valve and a controller regulates the motion specifications required. The developments controller is based on a state-space description of the actuator that is derived based on physical principles and parameter identification. Linear-quadratic regulator design (LQR) optimal control is designed with the evaluation reasonable the performance and energy of (EMV) valve are obtained with the design.

  5. Building valve amplifiers

    Jones, Morgan


    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or



    It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly...... resulted from collision or effusion. A static tower has been applied for the main core of this part of the valve which loses balance state under the effect of collision and bounces to the neighboring part, which results in release of the catch and blockage of the gas passing channel....

  7. Pulsatile prosthetic valve flows.

    Phillips, W M; Snyder, A; Alchas, P; Rosenberg, G; Pierce, W S


    The laser Doppler system has been established as a useful tool for eliciting the properties of simulated cardiovascular flows, and thus for comparative studies of flow properties of prosthetic valves. Significant differences among valve types and between models of one type have been documented. The complex variations of velocity profiles with time show that comparisons must be made for unsteady pulsatile rather than steady flow, despite the volume and complexity of the data required. Future studies will include methods of compacting the data presentation and improving the details of the experimental stimulation.

  8. Proportional directional valve based automatic steering system for tractors

    Jin-yi LIU; Jing-quan TAN; En-rong MAO; Zheng-he SONG; Zhong-xiang ZHU‡


    Most automatic steering systems for large tractors are designed with hydraulic systems that run on either constant flow or constant pressure. Such designs are limited in adaptability and applicability. Moreover, their control valves can unload in the neutral position and eventually lead to serious hydraulic leakage over long operation periods. In response to the problems noted above, a multifunctional automatic hydraulic steering circuit is presented. The system design is composed of a 5-way-3-position proportional directional valve, two pilot-controlled check valves, a pressure-compensated directional valve, a pressure-compensated flow regulator valve, a load shuttle valve, and a check valve, among other components. It is adaptable to most open-center systems with constant flow supply and closed-center systems with load feedback. The design maintains the lowest pressure under load feedback and stays at the neutral position during unloading, thus meeting the requirements for steering. The steering controller is based on proportional-integral-derivative (PID) running on a 51-microcontroller-unit master control chip. An experimental platform is developed to establish the basic characteristics of the system subject to stepwise inputs and sinusoi-dal tracking. Test results show that the system design demonstrates excellent control accuracy, fast response, and negligible leak during long operation periods.

  9. Piezoelectric valve for massive gas injection in ASDEX upgrade

    Dibon, Mathias; Neu, Rudolf [Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching (Germany); Technical University Munich, Boltzmannstr. 15, 85748 Garching (Germany); Herrmann, Albrecht; Mank, Klaus; Mertens, Vitus; Pautasso, Gabriella; Ploeckl, Bernhard [Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching (Germany)


    A sudden loss of plasma temperature can cause a disruption, which poses a significant problem for current Tokamaks and future fusion devices. Hence, mitigating forces and thermal loads during disruptions is important for the integrity of the vessel and first wall components. Therefore, high speed gas valves are used to deliver a pulse of noble gas onto the plasma, which irradiates the thermal energy quickly, avoiding localized heat loads and mechanical stress due to induced currents. A new design for such a valve is currently under development. The valve plate is driven by two piezoelectric stack actuators. The stroke of the actuators (0.07 mm) is amplified by a monolithic titanium frame and reaches 2 mm. The frame also serves as spring to pre-load the actuators. In the idle state, it also presses the conical valve plate into the seal, closing the gas chamber (42 cm{sup 3}). The actuators accelerate the stem and the valve plate until it is fully opened after 2 ms. The orifice of the valve has a diameter of 14 mm. This allows a peak mass flow rate of the gas up to 8 . 10{sup 4} (Pa.m)/(s) after 1.8 ms and an average mass flow rate of 2 . 10{sup 4} (Pa.m)/(s) over the evacuation time of 10 ms. Therefore, one valve would be sufficient to deliver the required amount of gas to mitigate disruptions at ASDEX Upgrade.

  10. Fluid and Structural Analysis of Large Butterfly Valve

    Song, Xueguan; Wang, Lin; Park, Youngchul


    A butterfly valve of large diameter is commonly used as control equipments in applications where the inlet velocity is fast and the pressure is relatively high. Because of the size of the valve is too large, therefore it's too difficult to conduct the experiment in a laboratory. In this paper, the numerical simulation using commercial package-CFX and ANSYS was conducted. In order to do fluid analysis and structural analysis perfectly, large valve models are generated in three dimensions without much simplification, the result of fluid analysis is also fully coupled to the structural domain by the fluid-structural interface to provide an exacter initial condition. In addition to describe the flow patterns and to measure the performance coefficients when the valves with various open angles were used, the verification of the safety performance whether the valve could work normally at those conditions or not was conducted. Fortunately, the result shows this type valve is safe in a given inlet velocity of 3m/s, and it's not necessary to be strengthened anywhere, and if need be, the shape of valve disc can be optimized to reduce the weight of disc, and also to make the flow coefficient be closer to the suggested level.

  11. Effects of bileaflet mechanical heart valve orientation on coronary flow

    Haya, Laura; Tavoularis, Stavros


    The aortic sinus is approximately tri-radially symmetric, but bileaflet mechanical heart valves (BMHVs), which are commonly used to replace diseased aortic valves, are bilaterally symmetric. This mismatch in symmetry suggests that the orientation in which a BMHV is implanted within the aortic sinus affects the flow characteristics downstream of it. This study examines the effect of BMHV orientation on the flow in the coronary arteries, which originate in the aortic sinus and supply the heart tissue with blood. Planar particle image velocimetry measurements were made past a BMHV mounted at the inlet of an anatomical aorta model under physiological flow conditions. The complex interactions between the valve jets, the sinus vortex and the flow in the right coronary artery were elucidated for three valve orientations. The coronary flow rate was directly affected by the size, orientation, and time evolution of the vortex in the sinus, all of which were sensitive to the valve's orientation. The total flow through the artery was highest when the valve was oriented with its axis of symmetry intersecting the artery's opening. The findings of this research may assist surgeons in choosing the best orientation for BMHV implantation. The bileaflet valve was donated by St. Jude Medical. Financial support was provided by the Natural Sciences and Engineering Research Council of Canada.

  12. Transcatheter Valve-in-Valve: A Cautionary Tale.

    Luc, Jessica G Y; Shanks, Miriam; Tyrrell, Benjamin D; Welsh, Robert C; Butler, Craig R; Meyer, Steven R


    Transcatheter aortic valve replacement (TAVR) by valve-in-valve (VIV) implantation is an alternative treatment for high-risk patients with a degenerating aortic bioprosthesis. We present a case of transapical TAVR VIV with a 29-mm Edwards SAPIEN XT (ESV) (Edwards Lifesciences, Irvine, CA) into a 29-mm Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) in which unanticipated dilatation of the Freestyle bioprosthesis resulted in intraprocedural embolization of the TAVR valve, necessitating urgent conversion to a conventional surgical aortic valve replacement (AVR). Our experience suggests that TAVR VIV with the 29-mm ESV in the setting of a degenerated 29-mm Freestyle stentless bioprosthesis must be undertaken with caution.

  13. Slide Valves for Single-Screw Expanders Working Under Varied Operating Conditions

    Yuting Wu


    Full Text Available This paper fully describes the working principle of slide valves in single-screw expanders (SSEs. A geometric analysis of suction and volume ratio slide valves is presented to determine the relations between volume ratio, suction closure volume, discharge opening volume and slide valves displacement. An organic Rankine cycle (ORC thermodynamic model with SSE integrated with slide valves is developed to analyze the power output of SSE and the net power output of ORC system and variation law of slide valves displacement. Analysis of a typical ORC system under changing operating conditions shows that the power output of the expander and the net output power of the ORC system with slide valves are much better than those without slide valves. When the condensing temperature is 40 °C and the waste availability is 80 kW, the increase in output power and net output power are approximately 3.4 kW and 5 kW, respectively. The presented geometric analysis of slide valves and the thermodynamic model integrated with slide valves can be used to provide a theoretical and technical basis for designing the slide valves of SSEs and the control strategies of slide valves under varied operating conditions.

  14. The Team Approach to Pain Relief

    ... Issue Past Issues The Team Approach to Pain Relief Past Issues / Fall 2007 Table of Contents For ... with her quality of life, and acupuncture brought relief from severe shoulder pain. "I'm functional again. ...

  15. Novel Use of an Apical-Femoral Wire Rail to Assist With Transfemoral Transcatheter Aortic Valve Replacement

    Don, Creighton W.; Kim, Michael S.; Verrier, Edward D.; Aldea, Gabriel S.; Dean, Larry S.; Reisman, Mark; Mokadam, Nahush A.


    The inability to reposition or retrieve balloon-expandable transcatheter aortic valves once they have been deployed requires implantation of the valve in the descending aorta or open surgical procedures to extract the valve. We describe the challenging transfemoral delivery of an Edwards Lifesciences Sapien valve wherein we had difficulty crossing the aortic valve and the guidewire position was compromised. We performed a transapical puncture to snare the guidewire and create a left ventricular to femoral wire rail, allowing us to deliver the transfemoral transcatheter valve, salvaging a situation where we would have been required to implant the valve in the descending aorta. We believe this is the first time this technique has been reported and represents an important method to facilitate delivery of transcatheter valves where guidewire support is insufficient or lost. PMID:24907088

  16. Pressure locking and thermal binding of gate valves

    Kelly, E.M.


    Pressure locking and thermal binding represent potential common mode failure mechanisms that can cause safety-related power-operated gate valves to fail in the closed position, thus rendering redundant safety-related systems incapable of performing their safety functions. Supplement 6 to Generic Letter 89-10, {open_quotes}Safety-Related Motor-Operated Gate Valve Testing and Surveillance,{close_quotes} provided an acceptable approach to addressing pressure locking and thermal binding of gate valves. More recently, the NRC has issued Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,{close_quotes} to request that licensees take certain actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the current licensing bases. Over the past two years, several plants in Region I determined that valves in certain systems were potentially susceptible to pressure locking and thermal binding, and have taken various corrective actions. The NRC Region I Systems Engineering Branch has been actively involved in the inspection of licensee actions in response to the pressure locking and thermal binding issue. Region I continues to maintain an active involvement in this area, including participation with the Office of Nuclear Reactor Regulation in reviewing licensee responses to Generic Letter 95-07.

  17. Prosthetic valve thrombosis in a patient with mitral valve replacement.

    Bilal, Muhammad; Khan, Muhammad Shahzeb; Haseeb, Abdul; Khan, Abdul Bari


    Prosthetic valve thrombosis within one year after mitral valve replacement is rarely seen in patients on warfarin therapy and without any risk factor. Here, we describe a case of a 39-year- old female, who presented with dyspnoea and shortness of breath 11 months after mitral valve replacement. The echocardiogram revealed severe valvular stenosis due to presence of clots on the mitral valve and restricted motion of the mitral leaflets. As a result of deterioration of general condition and haemodynamic un-stability, plan was made to re-operate for her valve replacement surgery. This case report highlights the diagnosis, prevention and management of patients with prosthetic valve thrombosis following mitral valve replacement.

  18. Valve Replacement with a Sutureless Aortic Prosthesis in a Patient with Concomitant Mitral Valve Disease and Severe Aortic Root Calcification.

    Lio, Antonio; Scafuri, Antonio; Nicolò, Francesca; Chiariello, Luigi


    Aortic valve replacement with concomitant mitral valve surgery in the presence of severe aortic root calcification is technically difficult, with long cardiopulmonary bypass and aortic cross-clamp times. We performed sutureless aortic valve replacement and mitral valve annuloplasty in a 68-year-old man who had severe aortic stenosis and moderate-to-severe mitral regurgitation. Intraoperatively, we found severe calcification of the aortic root. We approached the aortic valve through a transverse aortotomy, performed in a higher position than usual, and we replaced the valve with a Sorin Perceval S sutureless prosthesis. In addition, we performed mitral annuloplasty with use of an open rigid ring. The aortic cross-clamp time was 63 minutes, and the cardiopulmonary bypass time was 83 minutes. No paravalvular leakage of the aortic prosthesis was detected 30 days postoperatively. Our case shows that the Perceval S sutureless bioprosthesis can be safely implanted in patients with aortic root calcification, even when mitral valve disease needs surgical correction.

  19. Fluid Mechanics of Heart Valves and Their Replacements

    Sotiropoulos, Fotis; Le, Trung Bao; Gilmanov, Anvar


    As the pulsatile cardiac blood flow drives the heart valve leaflets to open and close, the flow in the vicinity of the valve resembles a pulsed jet through a nonaxisymmetric orifice with a dynamically changing area. As a result, three-dimensional vortex rings with intricate topology emerge that interact with the complex cardiac anatomy and give rise to shear layers, regions of recirculation, and flow instabilities that could ultimately lead to transition to turbulence. Such complex flow patterns, which are inherently valve- and patient-specific, lead to mechanical forces at scales that can cause blood cell damage and thrombosis, increasing the likelihood of stroke, and can trigger the pathogenesis of various life-threatening valvular heart diseases. We summarize the current understanding of flow phenomena induced by heart valves, discuss their linkage with disease pathways, and emphasize the research advances required to translate in-depth understanding of valvular hemodynamics into effective patient therapies.

  20. Flow and cavitation characteristics of water hydraulic poppet valves

    廖义德; 刘银水; 黄艳; 李壮云


    Two types of poppet valves were tested, one is a poppet with a sharp-edged seats, and the other is that with a chamfered seat. During the tests, the effects of backpressure and poppet lift on flow characteristics were considered. Cavitation inception was detected by the appearance and rapid growth of a particular low frequency component of the outlet pressure fluctuation of valve when cavitation occurs. Experimental results show cavitation, back pressure, valve opening and its geometrical shape have significant effects on the flow characteristics of valve. The flow coefficient of throttle with water used as working medium is 0. 85~0. 95 when there is no cavitation. The pressure drop of flow saturation decreases with the increasing of poppet lift. The sharp-edged throttle has stronger anti-cavitation ability than the chamfered one.

  1. 47 CFR 69.727 - Regulatory relief.


    ... similarly situated customers; and (ii) The price cap LEC excludes all contract tariff offerings from price... customer. (b) Phase II relief. Upon satisfaction of the Phase II triggers specified in §§ 69.709(c) or 69... Pricing Flexibility § 69.727 Regulatory relief. (a) Phase I relief. Upon satisfaction of the Phase I...

  2. 7 CFR 1465.33 - Equitable relief.


    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Equitable relief. 1465.33 Section 1465.33 Agriculture... § 1465.33 Equitable relief. (a) If a participant relied upon the advice or action of any authorized NRCS... participant may be eligible for equitable relief under 7 CFR part 635, section 635.3. The financial or...

  3. 28 CFR 36.504 - Relief.


    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Relief. 36.504 Section 36.504 Judicial... COMMERCIAL FACILITIES Enforcement § 36.504 Relief. (a) Authority of court. In a civil action under § 36.503, the court— (1) May grant any equitable relief that such court considers to be appropriate, including...

  4. 29 CFR 553.225 - Early relief.


    ... 29 Labor 3 2010-07-01 2010-07-01 false Early relief. 553.225 Section 553.225 Labor Regulations... relief. It is a common practice among employees engaged in fire protection activities to relieve employees on the previous shift prior to the scheduled starting time. Such early relief time may occur...

  5. 29 CFR 4041.4 - Disaster relief.


    ... 29 Labor 9 2010-07-01 2010-07-01 false Disaster relief. 4041.4 Section 4041.4 Labor Regulations...-EMPLOYER PLANS General Provisions § 4041.4 Disaster relief. When the President of the United States declares that, under the Disaster Relief Act (42 U.S.C. 5121, 5122(2), 5141(b)), a major disaster exists...

  6. 29 CFR 1614.505 - Interim relief.


    ... 29 Labor 4 2010-07-01 2010-07-01 false Interim relief. 1614.505 Section 1614.505 Labor Regulations... OPPORTUNITY Remedies and Enforcement § 1614.505 Interim relief. (a)(1) When the agency appeals and the case... interim relief. (2) Service under the temporary or conditional restoration provisions of paragraph (a)(1...

  7. 7 CFR 276.5 - Injunctive relief.


    ... 7 Agriculture 4 2010-01-01 2010-01-01 false Injunctive relief. 276.5 Section 276.5 Agriculture... Injunctive relief. (a) General. If FNS determines that a State agency has failed to comply with the Food... Secretary may seek injunctive relief against the State agency to require compliance. The Secretary may...

  8. 20 CFR 627.803 - Relief.


    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Relief. 627.803 Section 627.803 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR GENERAL PROVISIONS GOVERNING PROGRAMS... Relief. In ordering relief, the ALJ shall have the full authority of the Secretary under section 164 of...

  9. 24 CFR 7.44 - Interim relief.


    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Interim relief. 7.44 Section 7.44... § 7.44 Interim relief. (a) When the Department appeals and the case involves removal, separation, or... outcome of the Department appeal. The employee may decline the offer of interim relief. (b) Service under...

  10. 7 CFR 1466.33 - Equitable relief.


    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Equitable relief. 1466.33 Section 1466.33 Agriculture... Administration § 1466.33 Equitable relief. (a) If a participant relied upon the advice or action of any... relief, to the extent it is deemed desirable by NRCS, to provide a fair and equitable treatment because...

  11. 7 CFR 1470.34 - Equitable relief.


    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Equitable relief. 1470.34 Section 1470.34 Agriculture... § 1470.34 Equitable relief. (a) If a participant relied upon the advice or action of NRCS and did not... be eligible for equitable relief under 7 CFR part 635. The financial or technical liability for any...

  12. 12 CFR 268.505 - Interim relief.


    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Interim relief. 268.505 Section 268.505 Banks... REGARDING EQUAL OPPORTUNITY Remedies and Enforcement § 268.505 Interim relief. (a)(1) When the Board appeals... offer of interim relief. (2) Service under the temporary or conditional restoration provisions of...

  13. 7 CFR 636.20 - Equitable relief.


    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Equitable relief. 636.20 Section 636.20 Agriculture... AGRICULTURE LONG TERM CONTRACTING WILDLIFE HABITAT INCENTIVES PROGRAM § 636.20 Equitable relief. (a) If a... as meeting program requirements and grant relief because of the good-faith reliance on the part of...

  14. 7 CFR 795.24 - Relief.


    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Relief. 795.24 Section 795.24 Agriculture Regulations... PROVISIONS COMMON TO MORE THAN ONE PROGRAM PAYMENT LIMITATION General § 795.24 Relief. If a producer relied... reviewing authority makes a more restrictive determination, the Deputy Administrator may grant relief only...

  15. 32 CFR 516.19 - Injunctive relief.


    ... 32 National Defense 3 2010-07-01 2010-07-01 true Injunctive relief. 516.19 Section 516.19 National... RELATIONS LITIGATION Reporting Legal Proceedings to HQDA § 516.19 Injunctive relief. (a) General. Plaintiffs... injunctive relief: (1) Plaintiff's likelihood of success on the merits. (2) Whether plaintiff will be...

  16. 18 CFR 281.215 - Additional relief.


    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Additional relief. 281... Additional relief. If an interstate pipeline rejects (under § 281.210 or otherwise) a request for... aggrieved by such action may file a request for relief from curtailment under § 385.206 of this chapter. The...

  17. 49 CFR 1108.4 - Relief.


    ... 49 Transportation 8 2010-10-01 2010-10-01 false Relief. 1108.4 Section 1108.4 Transportation Other... TRANSPORTATION BOARD § 1108.4 Relief. (a) Subject to specification in the complaint, as provided in § 1108.7 herein, an Arbitrator may grant the following types of relief: (1) Monetary damages, to the extent...

  18. Distortion of the CoreValve during transcatheter aortic valve-in-valve implantation due to valve dislocation

    Souteyrand, Geraud, E-mail: [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Wilczek, Krzysztof [Department of Cardiology, Medical University of Silesia, Silesian Centre for Herat Diseases, Zabrze (Poland); Innorta, Andrea; Camilleri, Lionel [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Chodor, Piotr [Department of Cardiology, Medical University of Silesia, Silesian Centre for Herat Diseases, Zabrze (Poland); Lusson, Jean-René; Motreff, Pascal [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Laborde, Jean-Claude [St. George' s Hospital, London (United Kingdom); Chabrot, Pascal; Durel, Nicolas [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France)


    Nowadays transcatheter aortic valve implantation (TAVI) is an accepted alternative to surgical aortic valve replacement for high-risk patients (pts). Successful TAVI procedures for failed aortic surgical bioprosthesis (TAV-in-SAV) have already been reported. In the presented two cases of TAV-in-SAV implantation a strut distortion of the stent was revealed on angiographic imaging and confirmed on control CT scan. In both procedures, a dislocation of the medtronic core valve (MCV) prosthesis during implantation led to valve retrieval, with a necessity of reloading it in the 18F introducer before subsequent implantation of the same valve in correct position.

  19. An electrochemical active valve

    Neagu, C.R.; Gardeniers, J.G.E.; Elwenspoek, M.; Kelly, J.J.


    A novel electrochemical microactuator was developed, which operates as an active valve. The microactuator consists of an electrochemical cell and a membrane that deflects because of the pressure of oxygen gas generated by electrolysis. Relatively large pressures (up to tens of bars) can be reached w

  20. Thermostatic Radiator Valve Evaluation

    Dentz, J.; Ansanelli, E.


    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  1. Heart valve surgery - discharge

    ... ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  2. Analysis of air motion in a rotary valve. Measurement of static coefficient of discharge and numerical analysis of air motion for the columnar-notch type rotary valve; Rotary valve ni yoru kyunyu uki ryudo no kaiseki. Enchugata kirikaki shiki rotary valve no seiteki ryuryo keisu no sokutei oyobi kuki ryodo no kaiseki

    Muroki, T.; Moriyoshi, Y.; Suzuki, M. [Chiba University, Chiba (Japan). Faculty of Engineering


    Characteristic test and numerical analysis were performed of the prototype notch type rotary valve prepared as intake and exhaust valve for 4-cycle internal combustion engines. In experiment, a model cylinder and cylinder head were mounted on a surge tank, and the static coefficient of discharge was determined by measuring an intake flow rate and the differential pressure between an intake pipe and surge tank pipe while reducing static pressure in a surge tank to -20mmHg. As an experimental result, the static coefficient of discharge of the notch type rotary valve was dependent on opening shape of a valve air passage, and was higher in the second half of intake-stroke than the first one at the same minimum opening area. Prediction of the relation between an opening angle and flow rate was possible by numerical analysis of flow in the valve. The fact that the static coefficient of discharge of rotary valves is smaller than that of poppet valves at smaller opening area, seemed to be caused mainly by separation of air flow in the passage of rotary valves. 2 refs., 8 figs.

  3. Effect of permanent pacemaker on mortality after transcatheter aortic valve replacement

    Engborg, Jonathan; Riechel-Sarup, Casper; Gerke, Oke


    OBJECTIVES: Transcatheter aortic valve implantation (TAVI) is an established treatment for high-grade aortic valve stenosis in patients found unfit for open heart surgery. The method may cause cardiac conduction disorders requiring permanent pacemaker (PPM) implantation, and the long-term effect...

  4. Free-floating left atrial ball thrombus early after mitral valve replacement.

    Sanae, T; Kazama, S; Nie, M; Miyoshi, Y; Machii, M; Ohara, K; Yoshimura, H


    A 61-year-old woman was found to have a free-floating ball, thrombus in the left atrium on echocardiographic examination 2 weeks after mitral valve replacement and tricuspid, annuloplasty. The free-floating thrombus was successfully, removed by an open-heart procedure without clinical sequelae. The diagnostic value of routine echocardiography on follow-up of valve surgery is emphasized.

  5. Service Learning Through Disaster Relief

    Donna J. Duerst


    Full Text Available The Rock County 4-H Disaster Relief Committee raised $1,550 to aid tsunami victims in Sri Lanka and then turned its attention to Hurricane Katrina relief efforts. Thirty-one 4-H youth participated in a service learning trip to the South with the objectives of helping hurricane victims, learning about new cultures and achieving personal growth during three days of service projects in Louisiana and Mississippi. Their written reflections and other evaluative measures revealed they learned about southern culture, gained a greater appreciation for their lives, gained self confidence and developed a desire to help others more often. The trip was a valuable developmental experience for the youth, and information from the trip could be utilized to create similar experiences based on service learning. This article provides an overview of the trip and describes the evaluation methods used to measure learning and assess personal growth.

  6. Enhancing detailed haptic relief for real-time interaction

    Theoktisto, Víctor


    The present document exposes a different approach for haptic rendering, defined as the simulation of force interactions to reproduce the sensation of surface relief in dense models. Current research shows open issues in timely haptic interaction involving large meshes, with several problems affecting performance and fidelity, and without a dominant technique to treat these issues properly. Relying in pure geometric collisions when rendering highly dense mesh models (hundreds of thousands ...

  7. CPR1000全厂断电叠加蒸汽发生器安全阀误开启事故引起的严重事故分析%Analysis of CPR1000 Severe Accident Induced by SBO With SG Safety Valve Stuck Open

    李龙泽; 王明军; 田文喜; 苏光辉; 秋穗正


    The CPR1000 severe accident caused by station blackout (SBO) with the SG safety valve stuck open was modeled and analyzed using MELCOR code ,and the simula-tion of CPR1000 severe accident process was preliminarily achieved . Three assump-tions ,namely without shaft sealing leakage and auxiliary feed water ,with shaft sealing leakage and auxiliary feed water ,and with shaft sealing leakage but without auxiliary feed water ,were analyzed .The results imply that SG safety valve stuck open has great influence on the accident sequences .According to the calculation results ,without shaft sealing leakage and auxiliary feed water ,pressure vessel will fail at 9 576 s .When auxil-iary feed water supplies ,pressure vessel failure delays nearly 30 000 s .When the leak-age of the shaft sealing system exists ,pressure vessel failure will delay about 50 s .The results show that the auxiliary feed water and the leakage of the shaft sealing system have great mitigation effect on the severe accident induced by SBO with SG safety valve stuck open .%利用MELCOR程序对CPR1000全厂断电叠加蒸汽发生器(SG)安全阀误开启事故引发的严重事故进行建模与分析,初步实现了对CPR1000严重事故进程的仿真计算与模拟。文中重点分析了无轴封泄漏和辅助给水、有轴封泄漏和辅助给水、有轴封泄漏但无辅助给水3种不同假设条件下CPR1000全厂断电严重事故的响应进程和结果。计算结果显示,SG安全阀误开启对事故进程有重要影响。在无轴封泄漏和辅助给水的情况下,压力容器在9576 s失效;当存在辅助给水时,压力容器失效延后近30000 s;而当存在轴封泄漏时,压力容器失效延后50 s左右。结果证明了发生全场断电叠加SG安全阀误开启事故情况下辅助给水和轴封泄漏对事故起到有效缓解作用。

  8. Developments in mechanical heart valve prosthesis

    Kalyani Nair; C V Muraleedharan; G S Bhuvaneshwar


    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the performance of mechanical heart valves. The clinical performance of mechanical heart valves is also addressed. Efforts made in India in the development of mechanical heart valves are also discussed.

  9. Experimental and Analytical Study on the Lift Check Valve

    Kim, J. H.; Song, C. S.; Kim, H. S.; Hong, S. C. [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of); Lee, W. H. [Samshin Limited Co., Chonan (Korea, Republic of)


    In general, the check valve mounted on the flow line is used for the purpose of protecting the pump and the related facility, making the flow path, and maintaining the pressure boundary during the operation mode change in steam power plant and nuclear power plant. Fig. 1 shows the example of check valve in nuclear power plant. Especially, the check valve mounted on safety feed system and nuclear safety system is operated to open state and has a role of acquiring enough fluid such as safety feed and auxiliary feed water in the Design Basis Accident. And the check valve is operated with enough sealing and with protecting steam hammer in normal operational mode. For this purpose, the check valve can be open easily and be maintained in the open state in case of small flow velocity. In this research, the experimental and analytical study on the check vale was performed. The flow coefficient and closure time were compared between the experimental and the analytical result by numerical simulation. The validation of the analytical method was performed.

  10. Optimum design of seat region in valves suitable for digital displacement machines

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.


    is optimised considering both the mechanical strength during pressure loading and fluid flow restriction in the open valve state. Material stresses are modelled using finite element (FE) analysis including non-linear material behaviour, contact elements and fluid pressure penetrating load, closely reflecting...... the actual load of the seat valve connected to a fluid pressure chamber. Valve pressure losses are modelled using computational fluid dynamics (CFD). On basis of an overall physical size requirement and material specification, optimum valve geometry and stroke length are given as function of a defined...... normalised flow coefficient directly related to the machine efficiency....

  11. Surgical Bailout Therapy after Implantation of a Medtronic CoreValve Bioprosthesis

    Rita Calé


    Full Text Available Moderate-to-severe paraprosthesic leak causing hemodynamic deterioration and left ventricular remodeling can occur after transcatheter aortic valve implantation (TAVI. We present the case of a 75-year-old woman who underwent TAVI with a 26 mm CoreValve prosthesis complicated with an acute left ventricle dilatation due to a severe paravalvular leak. Patient was unresponsive to elective balloon post-dilatation, and therefore she was successfully treated with open-heart surgery to remove the malfunctioning CoreValve bioprosthesis and perform standard aortic valve replacement.

  12. Advance relief under the Cape Town Convention and its Aircraft Protocol: Aa comment on Gilles Cuniberti's interpretative proposal

    Veneziano, A.


    In the inaugural issue of this journal Gilles Cuniberti addressed the question of the nature of the relief pending final determination under the Cape Town Convention. One of his contentions is that the Convention leaves open the question of the nature of the relief provided in Article 13, which has

  13. Building relations with women's organisations in relief work.

    Gell, F


    An Oxfam Emergency Team arrived in Ingushetia in the Northern Caucasus region of the former Soviet Union in August 1996 to set up a program of shelter, rehabilitation, and relief in response to the large influx of people displaced by conflicts in the neighboring republics of Chechnya and North Ossetia. The team was also tasked with contacting community organizations such as women's groups and developing a relationship with them through joint relief work. The Chechen population was comprised of mainly women, children, and the elderly. The internally displaced population of 100,000 people is now scattered throughout the republic in collective centers and host families. Small committees of women were formed to help identify the most vulnerable residents and to distribute winter clothing. It was found during the relief work that fledgling women's groups are establishing themselves as vehicles for change, increasingly open to work with and learn from international organizations such as Oxfam. The Chechen branch of the Union of North Caucasian Women and the Ingushetian ALMOS played leading roles in peacemaking, human rights observance, and humanitarian relief.

  14. Percutaneous tricuspid valve replacement in childhood

    Mathias Emmel


    Full Text Available Percutaneous replacement of the tricuspid valve with a bovine jugular venous valve (melody valve was successfully undertaken in a 9-year-old boy. The patient had a previous history of bacterial endocarditis of the native tricuspid valve in infancy. Initially, a pericardial patch valve was created, followed by surgical replacement of the valve using a biological tissue valve at 4 years of age. Progressive stenosis and regurgitation of the biological valve, with severe venous congestion and resulting hepatic dysfunction prompted percutaneous valve replacement.

  15. Design and analysis of a new high frequency double-servo direct drive rotary valve

    Zhu, Muzhi; Zhao, Shengdun; Li, Jingxiang


    Researchers have investigated direct drive valve for many years to solve problems, such as fluid force imbalance and switching frequency. The structure of the rotary valve has received considerable research interest because of its favorable dynamic properties and simple structure. This paper studied the high frequency doubleservo direct drive rotary valve (DDRV), and proposed a novel structure and drive method satisfying high reversing frequency and adequate quantity of flow. Servo motors are integrated into the valve by the innovative structure, which is designed to equilibrate the unbalanced radial fluid force with the symmetric distributed oil ports. Aside from the fast reversing function of the valve, the DDRV presented high performance in linearity of the flow quantity and valve opening as a result of the fan-shaped flow ports. In addition, a computational fluid dynamics (CFD) method based on Fluent was conducted to verify the flux regulation effect of the height change of the adjustable boss.

  16. Drive piston assembly for a valve actuator assembly

    Sun, Zongxuan (Troy, MI)


    A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

  17. Development of a novel parallel-spool pilot operated high-pressure solenoid valve with high flow rate and high speed

    Dong, Dai; Li, Xiaoning


    High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system. However, traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously. A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system. A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design. Mathematical models of the opening process and flow rate of the valve are established. Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response. Corresponding formulas to solve 4 parts of the response time are derived. Key factors that influence the opening response time are analyzed. According to the mathematical model of the valve, a simulation of the opening process is carried out by MATLAB. Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve. Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool. The experimental results are in agreement with the simulated results, therefore the validity of the theoretical analysis is verified. Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa. The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s. According to the result of the load driving test, the valve can meet the demands of the driving system. The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.

  18. Development of a Novel Parallel-spool Pilot Operated High-pressure Solenoid Valve with High Flow Rate and High Speed

    DONG Dai; LI Xiaoning


    High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system. However, traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously. A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system. A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design. Mathematical models of the opening process and flow rate of the valve are established. Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response. Corresponding formulas to solve 4 parts of the response time are derived. Key factors that influence the opening response time are analyzed. According to the mathematical model of the valve, a simulation of the opening process is carried out by MATLAB. Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve. Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool. The experimental results are in agreement with the simulated results, therefore the validity of the theoretical analysis is verified. Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa. The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s. According to the result of the load driving test, the valve can meet the demands of the driving system. The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.

  19. Image-based mass-spring model of mitral valve closure for surgical planning

    Hammer, Peter E.; Perrin, Douglas P.; del Nido, Pedro J.; Howe, Robert D.


    Surgical repair of the mitral valve is preferred in most cases over valve replacement, but replacement is often performed instead due to the technical difficulty of repair. A surgical planning system based on patient-specific medical images that allows surgeons to simulate and compare potential repair strategies could greatly improve surgical outcomes. In such a surgical simulator, the mathematical model of mechanics used to close the valve must be able to compute the closed state quickly and to handle the complex boundary conditions imposed by the chords that tether the valve leaflets. We have developed a system for generating a triangulated mesh of the valve surface from volumetric image data of the opened valve. We then compute the closed position of the mesh using a mass-spring model of dynamics. The triangulated mesh is produced by fitting an isosurface to the volumetric image data, and boundary conditions, including the valve annulus and chord endpoints, are identified in the image data using a graphical user interface. In the mass-spring model, triangle sides are treated as linear springs, and sides shared by two triangles are treated as bending springs. Chords are treated as nonlinear springs, and self-collisions are detected and resolved. Equations of motion are solved using implicit numerical integration. Accuracy was assessed by comparison of model results with an image of the same valve taken in the closed state. The model exhibited rapid valve closure and was able to reproduce important features of the closed valve.

  20. Aortic valve stenosis: non-invasive preoperative evaluation using 64-slice CT angiography.

    Ciolina, F; Sedati, P; Zaccagna, F; Galea, N; Noce, V; Miraldi, F; Cavarretta, E; Francone, M; Carbone, I


    In patients affected by aortic valve stenosis (AS) it is mandatory to rule out coronary artery disease (CAD). The role of retrospectively ECG-gated 64-slice CT angiography (64-SCTA) was assessed in patients with AS referred for surgical valve replacement. Forty-two patients with AS underwent ECG-gated 64-SCTA of thoracic aorta, including the heart and coronary arteries, before surgical valve replacement. Images were evaluated by two independent readers and compared with surgical findings in terms of aortic valve calcification grading, valvular morphology, aortic valve annulus and sino-tubular junction diameters, and valvular area planimetry. Quantitative evaluation of cusps opening was also performed. Finally, the presence of CAD, thoracic aortic aneurysm and left ventricle hypertrophy were assessed. Visualization of the aortic valve without motion artefacts was possible in 38 patients (90.5%). Valvular morphology was correctly assessed in all cases (100%). 64-SCTA correctly determined aortic valve calcification grading and the aortic valve annulus and sinotubular junction diameters in 100% of cases. The aortic valve planimetric area was assessed in 38 cases (90.5%). Ascending aortic aneurysms requiring surgical replacement were detected in 12 patients (28.6%). Significant left ventricle hypertrophy was found in 30 patients (71%). Preoperative evaluation of patients undergoing surgical replacement for AS with 64-SCTA is feasible. 64-SCTA can rule out CAD and evaluate the status of the aortic valve and thoracic aorta in the same examination, obtaining relevant information for surgical planning.

  1. Tricuspid Valve Replacement, Mechnical vs. Biological Valve, Which Is Better?

    Haitham Akram Altaani


    Full Text Available Background: The initial trial in tricuspid surgery is repair; however, replacement is done whenever the valve is badly diseased. Tricuspid valve replacement comprises 1.7% of all tricuspid valve surgeries. Materials and Methods: The present retrospective study was performed using the medical records of 21 cases who underwent tricuspid valve replacement from January 2002 until the end of December 2010. The mean age of the participants was 52.3±8.8 years and 66.7% were females. In addition, tricuspid valve replacement was associated with mitral valve surgery, aortic valve surgery, and both in 14.3%, 4.8%, and 33.3% of the cases, respectively. Yet, isolated tricuspid valve replacement and redo surgery were performed in 10 cases (47.6% and 8 cases (38.1%, respectively. Besides, trial of repair was done in 14 cases (66.7%. Moreover, biological and mechanical valves were used in 76.2% and 23.8% of the patients, respectively. Results: According to the results, early mortality was 23.8% and one year survival was 66.7%. Moreover, early mortality was caused by right ventricular failure, multiorgan failure, medistinitis, and intracerbral bleeding in 42%, 28.6%, 14.3%, and 14.3% of the cases, respectively. In addition, 57.1% of the deaths had occurred in the cases where the biological valve was used, while 42.9% of the deaths had taken place where the mechanical one was utilized. Conclusions: The patients who require tricuspid valve replacement are usually high risk surgical candidates with early and long term mortality. The findings of the current study showed no significant hemodynamic difference between mechanical and biological valves.

  2. Transcatheter Replacement of Failed Bioprosthetic Valves

    Simonato, Matheus; Webb, John; Kornowski, Ran


    Background-Transcatheter valve implantation inside failed bioprosthetic surgical valves (valve-in-valve [ViV]) may offer an advantage over reoperation. Supra-annular transcatheter valve position may be advantageous in achieving better hemodynamics after ViV. Our objective was to define targets fo...

  3. Performance Characteristics of an Isothermal Freeze Valve

    Hailey, A.E.


    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  4. "Vanishing" pulmonary valve stenosis

    Nofil I Arain


    Full Text Available Objective: Both spontaneous resolution and progression of mild pulmonary valve stenosis (PS have been reported. We reviewed characteristics of the pulmonary valve (PV to determine factors that could influence resolution of mild PS. Methods: Fifteen asymptomatic pediatric patients with spontaneous resolution of isolated mild PS were retrospectively reviewed. Results: There was no correlation between the PV gradient, clinical presentation, age at diagnosis, or PV morphology. The PV annulus was small at initial presentation, which normalized at follow up. When corrected for the body surface area (z-score, the PV annulus was normal in all patients, including at initial evaluation. Conclusions: Based on our observation, neither age at diagnosis, nor PV-morphology-influenced resolution of mild PS. The variable clinical presentation makes it difficult to categorize and observe mild PS by auscultation alone. The PV annulus z-score could be a useful adjunct to determine the course and serial observation of mild PS.

  5. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    Dvir, Danny; Webb, John G; Bleiziffer, Sabine


    IMPORTANCE: Owing to a considerable shift toward bioprosthesis implantation rather than mechanical valves, it is expected that patients will increasingly present with degenerated bioprostheses in the next few years. Transcatheter aortic valve-in-valve implantation is a less invasive approach......, stroke, and New York Heart Association functional class. RESULTS: Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation...

  6. Minimally Invasive Mitral Valve Replacement and Transfemoral Aortic Valve Implantation.

    Rustenbach, Christian; Baumbach, Hardy; Hill, Stephan; Franke, Ulrich F W


    The case is reported of a symptomatic elderly patient with severe mitral regurgitation, severe aortic valve stenosis, and coronary heart disease. The coronary artery disease had been interventionally treated four years previously with stent implantation into the right coronary artery. Published studies have shown that a combination of mitral and aortic valve surgery is associated with a significantly increased risk of mortality and morbidity, particularly in elderly patients. In the present patient, both valvular malformations were successfully treated with a single-step interdisciplinary approach, namely an initial surgical mitral valve replacement followed by transfemoral transcatheter aortic valve replacement.

  7. Posterior Urethral Valves

    Steve J. Hodges


    Full Text Available The most common cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although the incidence has remained stable, the neonatal mortality for this disorder has improved due to early diagnosis and intensive neonatal care, thanks in part to the widespread use of prenatal ultrasound evaluations. In fact, the most common reason for the diagnosis of posterior urethral valves presently is the evaluation of infants for prenatal hydronephrosis. Since these children are often diagnosed early, the urethral obstruction can be alleviated rapidly through catheter insertion and eventual surgery, and their metabolic derangements can be normalized without delay, avoiding preventable infant mortality. Of the children that survive, however, early diagnosis has not had much effect on their long-term prognosis, as 30% still develop renal insufficiency before adolescence. A better understanding of the exact cause of the congenital obstruction of the male posterior urethra, prevention of postnatal bladder and renal injury, and the development of safe methods to treat urethral obstruction prenatally (and thereby avoiding the bladder and renal damage due to obstructive uropathy are the goals for the care of children with posterior urethral valves[1].

  8. Balloon-expanding stent and delivery system for transcatheter aortic valve implantation:An animal study

    Xiang Chen; Fei-Yu Wang; Guo-Jun Chu; Yu-Feng Zhu; Hong-Wen Tan; Xian-Xian Zhao; Yong-Wen Qin; Jun-Bo Ge


    Objective: To evaluate the feasibility and satefy of transcatheter aortic valve implantation in animals by using a new balloon-expanding valved stent. Methods: The balloon-expandable stent is made from cobalt-based alloy material and designed with a tubular, slotted structure. Fresh bovine pericardium was treated, sutured and fixed on the balloon-expandable stent. Ten healthy sheep (five males and five females), weighing an average of (25.16 ± 1.83) kg, were selected to undergo transcatheter implantation of the valve stents. The function of the valve stent was evaluated by angiography, echocardiography, and histology six months after the procedure. Results: Of the ten experimental sheep, two sheep died during the operation because the higher position of the artificial valve affected the opening of the coronary artery. We successfully implanted the aortic valve stent in other eight sheep;however, one sheep died of heart failure two weeks after the operation due to the lower position of the valve stent. The valve stents were implanted in the desired position in seven sheep. Ascending aortic angiographic and autoptic findings immediately after the operation confirmed the satisfactory location and function of the valved stent. Echocardiography, angiography, and histology at six post-operative months confirmed the satisfactory location and function of the valve stent. Conclusion: We successfully implanted our new valve stent as a replacement of native aortic valve via the transcatheter route with satisfactory outcome. Copyright © 2015, Chinese Medical Association Production. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (

  9. Internal Acoustics of a Pintle Valve with Supercritical Helium Flow

    Fishbach, Sean R.; Davis, R. Benjamin


    Large amplitude flow unsteadiness is a common phenomenon within the high flow rate ducts and valves associated with propulsion systems. Boundary layer noise, shear layers and vortex shedding are a few of the many sources of flow oscillations. The presence of lightly damped acoustic modes can organize and amplify these sources of flow perturbation, causing undesirable loading of internal parts. The present study investigates the self-induced acoustic environment within a pintle valve subject to high Reynolds Number flow of helium gas. Experiments were conducted to measure the internal pressure oscillations of the Ares I Launch Abort System (LAS) Attitude Control Motor (ACM) valve. The AGM consists of a solid propellant gas generator with eight pintle valves attached to the aft end. The pintle valve is designed to deliver variable upstream conditions to an attache( converging diverging nozzle. In order to investigate the full range of operating conditions 28 separate tests were conducted with varying pintle position and upstream pressure. Helium gas was utilized in order to closely mimic the speed of sound of the gas generator exhaust, minimizing required scaling during data analysis. The recordec pressure measurements were interrogated to multiple ends. The development of root mean square (RMS) value! versus Reynolds Number and Pintle position are important to creating bounding unsteady load curves for valve internal parts. Spectral analysis was also performed, helping to identify power spectral densities (PSD) of acoustic natural frequencies and boundary layer noise. An interesting and unexpected result was the identification of an acoustic mode within the valve which does not respond until the valve was over 60% open. Further, the response amplitude around this mode can be as large or larger than those associated with lower frequency modes.

  10. Mitral Valve Prolapse in Pregnancy

    Shi-Min Yuan

    Full Text Available Abstract Mitral valve prolapse is a benign condition. Mitral regurgitation is only complicated in patients with severe mitral valve prolapse. Women with mitral valve prolapse in the absence of other cardiovascular disorders tolerate pregnancy well and do not develop remarkable cardiac complications. Nevertheless, serious complications of mitral valve prolapse, including arrhythmia, infective endocarditis and cerebral ischemic events, can be present in pregnancy. Debates remain with regard to the use of prophylactic antibiotics and β-blockers in the pregnant women with mitral valve prolapse. The prognosis of the pregnant patients might be closely related to the pathological and (or functional changes of the mitral valve. Non-myxomatous mitral valve prolapse poses no or little obstetric risks in terms of pregnancy, labor and neonatal complications; whereas myxomatous mitral valve prolapse is a major etiology of valvular heart disease in women of childbearing age. In the pregnant patients with mitral valve prolapse progressing into major complications, surgical interventions are considered. Medicinal treatment of such patients with β-blockers should be a concern for the fetal safety.

  11. Innovative Stemless Valve Eliminates Emissions


    Big Horn Valve Inc. (BHVI), of Sheridan, Wyoming, won a series of SBIR and Small Business Technology Transfer (STTR) contracts with Kennedy Space Center and Marshall Space Flight Center to explore and develop a revolutionary valve technology. BHVI developed a low-mass, high-efficiency, leak-proof cryogenic valve using composites and exotic metals, and had no stem-actuator, few moving parts, with an overall cylindrical shape. The valve has been installed at a methane coal gas field, and future applications are expected to include in-flight refueling of military aircraft, high-volume gas delivery systems, petroleum refining, and in the nuclear industry.

  12. Influence of blast furnace gas flow speed on dust deposition characteristics in butterfly valve region

    Lixin WANG


    Full Text Available The blast furnace gas contains plenty of dust, which deposits easily on the bottom of seat sealing surface of the tri-eccentric butterfly valve in the pipeline, causing stuck and damage to the valve plate, thereby affects the production of the blast furnace and brings great economic loss. To derive the influence mechanism of effects of the blast furnace gas flow speed within the pipeline on the dust deposition laws in the butterfly valve region, a 3D model of the butterfly valve and its regional flow field is built with Pro/E software. Based on FLUENT module of ANSYS Workbench, along with standard k-ε turbulence model and DPM model, simulation analysis of moving trajectories of dust particles in butterfly valve region under 3 blast furnace gas flow speeds is conducted. Results show that the deposition mass of dust particles decreases firstly, then increases with the enlargement of valve plate opening angle under the blast furnace gas flow speed of 8 m/s, while decreases with the enlargement of valve plate opening under the blast furnace gas flow speeds of 12 m/s and 16 m/s. In the case of the valve plate opening angle of 15°, the deposition rate of dust particles increases with the growing of blast furnace gas flow speed, while decreases with the growing of blast furnace gas flow speed under the cases of valve plate opening angle of 45° and 75°. The research results provide a theoretical reference for the development of automatic dust removal system in the butterfly valve region of the blast furnace gas pipeline.

  13. Fluid-dynamic design optimization of hydraulic proportional directional valves

    Amirante, Riccardo; Catalano, Luciano Andrea; Poloni, Carlo; Tamburrano, Paolo


    This article proposes an effective methodology for the fluid-dynamic design optimization of the sliding spool of a hydraulic proportional directional valve: the goal is the minimization of the flow force at a prescribed flow rate, so as to reduce the required opening force while keeping the operation features unchanged. A full three-dimensional model of the flow field within the valve is employed to accurately predict the flow force acting on the spool. A theoretical analysis, based on both the axial momentum equation and flow simulations, is conducted to define the design parameters, which need to be properly selected in order to reduce the flow force without significantly affecting the flow rate. A genetic algorithm, coupled with a computational fluid dynamics flow solver, is employed to minimize the flow force acting on the valve spool at the maximum opening. A comparison with a typical single-objective optimization algorithm is performed to evaluate performance and effectiveness of the employed genetic algorithm. The optimized spool develops a maximum flow force which is smaller than that produced by the commercially available valve, mainly due to some major modifications occurring in the discharge section. Reducing the flow force and thus the electromagnetic force exerted by the solenoid actuators allows the operational range of direct (single-stage) driven valves to be enlarged.

  14. Whitey Gauge and Root Valves (VPS)

    MISKA, C.


    These valves are 1/2 inch ball valves fabricated of 316 stainless steel: Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the Vacuum Pumping and Helium System.

  15. Controller Development for a Separate Meter-In Separate Meter-Out Fluid Power Valve for Mobile Applications

    Nielsen, Brian

    by a single pump the fluid is distributed through valves. A valve works by controlling a fluid stream through the valve by varying the opening of an orifice. The disadvantage by this is that when controlling the fluid flow rate a pressure drop is created across the orifice. This results in a throttle loss......, which is commonly used in many types of mobile applications, is a 4-way proportional valve. In this type of valve two fluid streams are controlled: One fluid stream from a pump to a fluid consumer and one fluid stream from the fluid consumer to a fluid reservoir. In a 4-way proportional valve...... it is necessary to use a separate control of the two fluid streams to minimise the throttling losses. The purpose of the research documented in this dissertation is to investigate how a 4-way proportional valve may be build to fulfil the increasing demands with regard to energy efficiency and functionality...

  16. Passively operated spool valve for drain-down freeze protection of thermosyphon water heaters. Final technical report



    The work done to extend the existing drain-down valve technology to provide passive drain-down freeze protection for thermosyphon-based solar water heaters is described. The basic design of the existing valve model is that of a spool valve, employing a cylindrical spool which moves axially in a mating cartridge to open and close o-rings at the two operating extremes (drain and operate) to perform the valving function. Three passive actuators to drive the basic valving mechanism were designed, fabricated, and tested. Two piping configurations used to integrate the spool valve with the thermosyphon system are described, as are the passive actuators. The three actuator designs are: photovoltaic driven, refrigerant-based bellows, and heat motor cable-drive designs. Costs are compared for the alternative actuator designs, and operating characteristics were examined for the thermosyphon system, including field tests. The market for the valve for thermosyphon systems is then assessed. (LEW)

  17. 安全阀阀芯传感器的标定理论与验证技术%Research on Theoretical and Verifiable Technology of Calibration of Valve Disc Sensor of Safety Valve

    郭崇志; 张清懿


    安全阀在线检测技术最重要的功能实现就是要解决大型生产装置运行周期不断延长,而安全泄放装置检验周期却有一年一检的严格限制之间的矛盾.安全阀是承压设备上的重要安全附件之一,作为生产装置安全的最后一道防线,本身具有很苛刻的性能要求,因此如何实现其在线检测,是生产装置实现长周期连续可靠运行的关键技术之一.为此,在专利技术指导下,设计研制了内嵌阀瓣膜传感器形式的新型安全阀.本文对安全阀中传感元件的布置、选择及标定技术原理等方面进行了理论和试验研究,结果表明这种带有阀芯薄膜传感器的新型安全阀运行稳定可靠,开启、回座迅速,密封性好,并且具有很好的检测灵敏度.%Safety valve on-line detection technology's most important function is used to solve large - scale production plant operation cycle which has been increasing, while the safety relief device there has strict limits of one-year inspection cycle. Safety valve is a one of the important security accessories of pressure vessel, asa production of the safety of last line of defense, itself has a very demanding performance of requirements,and how to take on - line detection is one of the key technology of a continuous operation of the plant. Therefore,under the guidance of patent technology ,we design and develop a new valve disc sensor in safety valve. In this paper, patch location, the choice of strain gauges, and the patch after the calibration has been studied in theory and experimental way. The results show that the sensor operates stably ,open and seat back quickly ,its sealing is good,very good spool membrane sensor output signal.

  18. Aortic Annular Enlargement during Aortic Valve Replacement

    Selman Dumani


    Full Text Available In the surgery of aortic valve replacement is always attempted, as much as possible, to implant the larger prosthesis with the mains goals to enhance the potential benefits, to minimise transvalvular gradient, decrease left ventricular size and avoid the phenomenon of patient-prosthesis mismatch. Implantation of an ideal prosthesis often it is not possible, due to a small aortic annulus. A variety of aortic annulus enlargement techniques is reported to avoid patient-prosthesis mismatch. We present the case that has submitted four three times open heart surgery. We used Manouguian technique to enlarge aortic anulus with excellent results during the fourth time of surgery.

  19. Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve Disease

    Mylotte, Darren; Lefevre, Thierry; Søndergaard, Lars


    BACKGROUND: Limited information exists describing the results of transcatheter aortic valve (TAV) replacement in patients with bicuspid aortic valve (BAV) disease (TAV-in-BAV). OBJECTIVES: This study sought to evaluate clinical outcomes of a large cohort of patients undergoing TAV-in-BAV. METHODS...

  20. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    Olsen, Niels Thue; De Backer, Ole; Thyregod, Hans G H


    risk factors. METHODS AND RESULTS: Observational single-center study of 509 consecutive patients treated with a transcatheter implanted self-expandable aortic valve prosthesis (Medtronic CoreValve). We identified 18 patients diagnosed with TAVI-PVE during a median follow-up period of 1.4 years...

  1. A sigh of relief or a sigh of expected relief: Sigh rate in response to dyspnea relief.

    Vlemincx, Elke; Meulders, Michel; Luminet, Olivier


    Research has suggested that sighs may serve a regulatory function during stress and emotions by facilitating relief. Evidence supports the hypotheses that sighs both express and induce relief from stress. To explore the potential role of sighs in the regulation of symptoms, the present study aimed to investigate the relationship between sighs and relief of symptoms, and relief of dyspnea, specifically. Healthy volunteers participated in two studies (N = 44, N = 47) in which dyspnea was induced by mild (10 cmH2 O/l/s) or high (20 cmH2 0/l/s) inspiratory resistances. Dyspnea relief was induced by the offset of the inspiratory resistances (transitions from high and mild inspiratory resistance to no resistance). Control comparisons included dyspnea increases (transitions from no or mild inspiratory resistance to high inspiratory resistance) and dyspnea continuations (continuations of either no resistance or a high resistance). In Experiment 1, dyspnea levels were cued. In Experiment 2, no cues were provided. Sigh rate during dyspnea relief was significantly higher compared to control conditions, and sigh rate increased as self-reported dyspnea decreased. Additionally, sigh rate was higher during cued dyspnea relief compared to noncued dyspnea relief. These results suggest that sighs are important markers of dyspnea relief. Moreover, sighs may importantly express dyspnea relief, as they are related to experiential dyspnea decreases and occur more frequently during expected dyspnea relief. These findings suggest that sighs may not only be important in the regulation of stress and emotions, but also may be functional in the regulation of dyspnea. © 2017 Society for Psychophysiological Research.

  2. VALVE: Volcano Analysis and Visualization Environment

    Cervelli, D. P.; Cervelli, P.; Miklius, A.; Krug, R.; Lisowski, M.


    Modern volcano observatories collect data using a wide variety of instruments. Visualizing these disparate data on a common time base is critical to interpreting and reacting to geophysical changes. With this in mind, the Hawaiian Volcano Observatory (HVO) created Valve, the Volcano Analysis and Visualization Environment. Valve integrates a wide range of both continuous and discontinuous data sources into a common, internet web-browser based interface that allows scientists to interactively select and visualize these data on a common time base and, if appropriate, in three dimensions. Advances in modern internet browser technology allow for a truly interactive user-interface experience that could previously only be found in stand-alone applications--all while maintaining client platform independence and network portability. This system aids more traditional in-depth analysis by providing a common front-end to retrieving raw data. In most cases, the raw data are being served from an SQL database, a system that lends itself to quickly retrieving, logically arranging, and safely storing data. Beyond Valve's visualization capabilities, the system also provides a variety of tools for time series analysis and source modeling. For example, a user could load several tilt and GPS time series, estimate co-seismic or co-intrusive deformation, and then model the event with an elastic point source or dislocation. From the source model, Coulomb stress changes could be calculated and compared to pre- and post-event hypocenter distribution. Employing a heavily object-oriented design, Valve is easily extensible, modular, portable, and remarkably cost efficient. Quickly visualizing arbitrary data is a trivial matter, while implementing methods for permanent, continuous data streams requires only minimal programming. Portability is ensured by using software that is readily available on a wide variety of operating systems; cost efficiency is achieved by using software that is open

  3. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    National Aeronautics and Space Administration — Cryogenic fluid valves are subject to harsh exposure and actuators to drive these valves require robust performance and high reliability. DSM's piezoelectric...

  4. Bioprosthesis valve replacement in dogs with congenital tricuspid valve dysplasia: technique and outcome.

    Arai, Shiori; Griffiths, Leigh G; Mama, Khursheed; Hackett, Timothy B; Monnet, Eric; Boon, June A; Carter, Leslie; Orton, E Christopher


    To describe the surgical technique and report outcome of dogs undergoing bioprosthesis valve replacement for severe tricuspid regurgitation (TR) secondary to congenital tricuspid valve dysplasia (TVD). Twelve client-owned dogs (19-43 kg) with TVD underwent tricuspid valve replacement with a bovine pericardial or porcine aortic bioprosthesis with the aid of cardiopulmonary bypass. Anticoagulation with warfarin was maintained for 3 months after surgery and then discontinued. Ten of 12 (83.3%) dogs survived surgery and were discharged from the hospital. Seven dogs were alive with complete resolution of TR for a median period of 48 months (range 1-66 months) after surgery. Two dogs underwent euthanasia because of bioprosthesis failure due to inflammatory pannus at 10 and 13 months after surgery. Two dogs experienced valve thrombosis that was resolved by tissue plasminogen activator. One dog developed suspected endocarditis after surgery that was resolved with antibiotics. Serious cardiac complications included atrial fibrillation and flutter, right-to-left shunt through an uncorrected patent foramen ovale, complete atrioventricular block, and sudden cardiac arrest. Postoperative atrial fibrillation or flutter did not occur in 7 dogs treated prophylactically with oral amiodarone before surgery. Curative intermediate-term outcomes are possible in dogs undergoing open tricuspid valve replacement with a bioprosthesis. Prosthesis-related complications include inflammatory pannus, thrombosis, and endocarditis. Postoperative atrial fibrillation or flutter can be reduced or prevented by prophylactic preoperative treatment with amiodarone. Several identified complications are avoidable or can be reduced with increased awareness and experience with these techniques. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Analysis of Water Hammer with Different Closing Valve Laws on Transient Flow of Hydrogen-Natural Gas Mixture

    Norazlina Subani; Norsarahaida Amin


    Water hammer on transient flow of hydrogen-natural gas mixture in a horizontal pipeline is analysed to determine the relationship between pressure waves and different modes of closing and opening of valves. Four types of laws applicable to closing valve, namely, instantaneous, linear, concave, and convex laws, are considered. These closure laws describe the speed variation of the hydrogen-natural gas mixture as the valve is closing. The numerical solution is obtained using the reduced order m...

  6. Chimney technique for mitral valve replacement in children.

    González Rocafort, Álvaro; Aroca, Ángel; Polo, Luz; Rey, Juvenal; Villagrá, Fernando


    Severe mitral stenosis is unusual in children, but it represents an important challenge for surgeons because of the scarcity of solutions. Several mitral percutaneous and surgical valvuloplasties are performed repetitively to delay mitral valve replacement. Most of the time these procedures show discouraging results. When mitral valve replacement is performed, the annulus may not be large enough to fit a substitute. We present, to our best knowledge, a new technique to implant a large prosthesis in a small annulus without negatively affecting the opening of the leaflets.

  7. Surge-damping vacuum valve

    Bullock, Jack C.; Kelly, Benjamin E.


    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  8. Mitral valve surgery - minimally invasive

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Mitral Valve Prolapse Browse the Encyclopedia A.D. ...

  9. Valve-"Health"-Monitoring System

    Jensen, Scott L.; Drouant, George J.


    A system that includes sensors and data acquisition, wireless data-communication, and data-processing subsystems has been developed as a means of both real-time and historical tracking of information indicative of deterioration in the mechanical integrity and performance of a highgeared ball valve or a linearly actuated valve that operates at a temperature between cryogenic and ambient.

  10. Combination throttle and shutoff valve

    Carriker, J. W.


    Combination of translating sleeve throttle valve and conventional poppet valve provides capability of shutting off flow completely by poppet and sleeve control of the rate of flow. Integration of the two concepts can be accomplished without difficulty and in a manner that requires a minimum of development.

  11. Oxycodone combinations for pain relief.

    Raffa, R B; Pergolizzi, J V; Segarnick, D J; Tallarida, R J


    No single analgesic drug provides the perfect therapeutic/adverse effect profile for every pain condition. In addition to convenience and possibly improved compliance, a combination of analgesic drugs offers the potential, requiring verification, of providing greater pain relief and/or reduced adverse effects than the constituent drugs when used individually. We review here analgesic combinations containing oxycodone. We found surprisingly little preclinical information about the analgesic or adverse effect profiles of the combinations (with acetaminophen, paracetamol, nonsteroidal anti-inflammatory drugs, morphine, gabapentin or pregabalin). Clinical experience and studies suggest that the combinations are safe and effective and may offer certain advantages. As with all combinations, the profile of adverse effects must also be determined in order to provide the clinician with the overall benefit/risk assessment.

  12. Exercise Based- Pain Relief Program

    Zadeh, Mahdi Hossein

    in the current study was to use exercise induced- muscle damage followed by ECC as an acute pain model and observe its effects on the sensitivity of the nociceptive system and blood supply in healthy subjects. Then, the effect of a repeated bout of the same exercise as a healthy pain relief strategy......Exercise-based pain management programs are suggested for relieving from musculoskeletal pain; however the pain experienced after unaccustomed, especially eccentric exercise (ECC) alters people´s ability to participate in therapeutic exercises. Subsequent muscle pain after ECC has been shown...... to cause localized pressure pain and hyperalgesia. A prior bout of ECC has been repeatedly reported to produce a protective adaptation known as repeated bout effect (RBE). One of the main scopes of the current project was to investigate the adaptations by which the RBE can be resulted from. The approach...

  13. Pain relief can be painful

    Ashish Bindra


    Full Text Available Mandibular nerve block is periodically used procedure used to treat neuralgic pain in the distribution of trigeminal nerve. It is a commonly performed block in outpatient settings at our institute. We present a case of an elderly edentulous patient with trigeminal neuralgia who suffered recurrent temporomandibular joint (TMJ dislocation following mandibular nerve block. The patient presented with complaints of severe pain, inability to close mouth, and eat food since 2 days. Anterior closed reduction of TMJ resulted in reduction of joint and immediate pain relief. However, the maneuver failed due to recurrent dislocation of the joint. A Barton dressing was applied to prevent another dislocation. This was followed by autologous blood injection into the joint. This case focuses on the preponderance of clinical evaluation and accentuates the need for additional forethought to be taken during pain procedures, particularly in the geriatric population.

  14. Numerical simulation on a throttle governing system with hydraulic butterfly valves in a marine environment

    Wan, Hui-Xiong; Fang, Jun; Huang, Hui


    Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve. It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.

  15. Fluid mechanics of artificial heart valves.

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P


    1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird's-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10-15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage.

  16. 安全阀的调试与维修%Debugging and Maintenance of Safety Valve



    This paper briefly describes the SY type safety valve application in petrochemical industry, as well as the role of the relief valve in the production unit is responsible for. Relief valve set point of the set is a dangerous and necessary work very much, because the work of specific data, will reflect to the relief valve in the device usage, directly determines the safety valve will be able to have the corresponding security protection. The thesis gives a set of production site pressure setting debugging methods, combined with field using the process of maintenance and repair work experience, summed up the various common faults and fault processing methods, some and illustrates the maintenance process should pay attention to the aspects.%本文简要叙述了SY型安全阀在石油化工行业中的一些应用,以及安全阀在生产装置中所担负的作用。安全阀设定值的现场设定是一项危险且非常必要的工作,因为这一工作得出的具体数据,将体现到其在装置中的使用情况,且直接决定了其是否能够起到相应的安全保护作用。本文详细给出了生产现场压力设定值的设定调试的具体方法,结合现场使用过程中运行维护和检修的工作经验,总结了各种常见故障及其针对一些故障的处理方法,并说明了检修过程中应该注意的方面。

  17. 44 CFR 68.12 - Relief.


    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Relief. 68.12 Section 68.12 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY... Relief. The final determination may be appealed by the appellant(s) to the United States district court...

  18. 24 CFR 220.753 - Forbearance relief.


    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Forbearance relief. 220.753 Section 220.753 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... and Obligations-Projects Project Mortgage Insurance § 220.753 Forbearance relief. (a) In a case where...

  19. 47 CFR 1.6009 - Relief.


    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Relief. 1.6009 Section 1.6009 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Implementation of Section 325(e) of the... Carriers for Retransmission Without Consent § 1.6009 Relief. If the Commission determines that a satellite...

  20. 24 CFR 236.255 - Forbearance relief.


    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Forbearance relief. 236.255 Section 236.255 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... Insurance § 236.255 Forbearance relief. (a) In a case where the mortgage is in default, the mortgagor and...

  1. 24 CFR 221.761 - Forbearance relief.


    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Forbearance relief. 221.761 Section 221.761 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... § 221.761 Forbearance relief. (a) In a case where the mortgage is in default, the mortgagor and the...

  2. Robotic mitral valve surgery.

    Kypson, Alan P; Nifong, L Wiley; Chitwood, W Randolph


    A renaissance in cardiac surgery has begun. The early clinical experience with computer-enhanced telemanipulation systems outlines the limitations of this approach despite some procedural success. Technologic advancements, such as the use of nitinol U-clips (Coalescent Surgical Inc., Sunnyvale, CA) instead of sutures requiring manual knot tying, have been shown to decrease operative times significantly. It is expected that with further refinements and development of adjunct technologies, the technique of computer-enhanced endoscopic cardiac surgery will evolve and may prove to be beneficial for many patients. Robotic technology has provided benefits to cardiac surgery. With improved optics and instrumentation, incisions are smaller. The ergometric movements and simulated three-dimensional optics project hand-eye coordination for the surgeon. The placement of the wristlike articulations at the end of the instruments moves the pivoting action to the plane of the mitral annulus. This improves dexterity in tight spaces and allows for ambidextrous suture placement. Sutures can be placed more accurately because of tremor filtration and high-resolution video magnification. Furthermore, the robotic system may have potential as an educational tool. In the near future, surgical vision and training systems might be able to model most surgical procedures through immersive technology. Thus, a "flight simulator" concept emerges where surgeons may be able to practice and perform the operation without a patient. Already, effective curricula for training teams in robotic surgery exist. Nevertheless, certain constraints continue to limit the advancement to a totally endoscopic computer-enhanced mitral valve operation. The current size of the instruments, intrathoracic instrument collisions, and extrathoracic "elbow" conflicts still can limit dexterity. When smaller instruments are developed, these restraints may be resolved. Furthermore, a working port incision is still required for

  3. Valve-related complications after mechanical heart valve implantation.

    Misawa, Yoshio


    The number of heart valve surgeries is increasing, and 19,164 patients underwent heart valve surgery in Japan in 2011. The early mortality rate has remained stable for more than 10 years. Many patients now survive for many years, with a reported 10-year survival rate of at least 60 %. However, unfavorable complications can occur after valve surgery. Valve-related complications include thromboembolisms, bleeding complications and prosthetic valve endocarditis, followed by structural and nonstructural prosthetic valve dysfunctions. Our review of studies published after 2000 revealed that the rate of all valve-related complications was 0.7-3.5 % per patient-year. Thromboembolisms occur at a rate of approximately 1 % per patient-year, and bleeding complications occur at almost 0.5 % per patient-year. Thromboembolic and hemorrhagic events related to anticoagulant therapy should be considered during life-long follow-up. The occurrence rate of endocarditis reaches 0.5 % per patient-year, with a poor postoperative survival. Structural dysfunctions have been largely overcome, and the nonstructural dysfunction rate is 0.4-1.2 % per patient-year. The nonstructural dysfunctions induced by paravalvular leaks and pannus ingrowth are also issues that need to be resolved.

  4. Patents and heart valve surgery - II: tissue valves.

    Cheema, Faisal H; Kossar, Alexander P; Rehman, Atiq; Younas, Fahad; Polvani, Gianluca


    Valvular heart disease affects millions of Americans yearly and currently requires surgical intervention to repair or replace the defective valves. Through a close-knit collaboration between physicians, scientists and biomedical engineers, a vast degree of research and development has been aimed towards the optimization of prosthetic heart valves. Although various methods have made fantastic strides in producing durable prostheses, the therapeutic efficacy of prosthetic valves is inherently limited by a dependency upon lifelong anticoagulant regimens for recipients - a difficult challenge for many in clinical setting. Thus, biological tissue valves have been developed to circumvent vascular and immunemediated complications by incorporating biological materials to mimic native valves while still maintaining a necessary level of structural integrity. Over the past decade, a multitude of patents pertaining to the refinement of designs as well as the advancement in methodologies and technologies associated with biological tissue valves have been issued. This review seeks to chronicle and characterize such patents in an effort to track the past, present, and future progress as well as project the trajectory of tissue valves in the years to come.

  5. Improvements in valve devices for use in mining

    Dettmers, M.; Weirich, W.


    A multi-way electromagnetically operated valve device for use in electro-hydraulic control systems of mining equipment employs a series of cylindrical inserts fitted into a bore in a housing. These inserts provide and locate the functional components of the valves and define connections between internal chambers and bores. To seal the inserts against the bore, O-rings are provided. The end most inserts accommodate O-rings in grooves while the other intermediate inserts have open recesses at their ends for receiving the other O-rings. To close the recesses and locate the O-rings in place use is made of axial collars on the inserts and a separate locking ring. This enables the valve device to be assembled without damaging the O-rings.

  6. Percutaneous mitral valve repair with MitraClip.

    Cilingiroğlu, Mehmet; Salinger, Michael


    Over the last decade, several technologies have been developed for percutaneous repair of the mitral valve for patients with severe mitral regurgitation (MR) and at high-risk for the traditional open-heart mitral valve repair or replacement. Among them, MitraClip has emerged as the only clinically safe and effective method for percutaneous mitral valve repair. It is adapted from the surgical technique that was initially described by Dr. Alfieri and his group by placement of a suture approximating the edges of the mitral leaflets at the origin of the MR jet, leading to creation of so-called bow-tie or double orifice with significant reduction in the MR jet. Here, we review the details of the technology, its procedural perspective as well as currently available data for its safety and effectiveness on a case-based report.

  7. Anatomic, histopathologic, and echocardiographic features in a dog with an atypical pulmonary valve stenosis with a fibrous band of tissue and a patent ductus arteriosus.

    Yoon, Hakyoung; Kim, Jaehwan; Nahm, Sang-Soep; Eom, Kidong


    Congenital pulmonary valve stenosis and patent ductus arteriosus are common congenital heart defects in dogs. However, concurrence of atypical pulmonary valve stenosis and patent ductus arteriosus is uncommon. This report describes the anatomic, histopathologic, and echocardiographic features in a dog with concomitant pulmonary valve stenosis and patent ductus arteriosus with atypical pulmonary valve dysplasia that included a fibrous band of tissue. A 1.5-year-old intact female Chihuahua dog weighing 3.3 kg presented with a continuous grade VI cardiac murmur, poor exercise tolerance, and an intermittent cough. Echocardiography indicated pulmonary valve stenosis, a thickened dysplastic valve without annular hypoplasia, and a type IIA patent ductus arteriosus. The pulmonary valve was thick line-shaped in systole and dome-shaped towards the right ventricular outflow tract in diastole. The dog suffered a fatal cardiac arrest during an attempted balloon pulmonary valvuloplasty. Necropsy revealed pulmonary valve dysplasia, commissural fusion, and incomplete opening and closing of the pulmonary valve because of a fibrous band of tissue causing adhesion between the right ventricular outflow tract and the dysplastic intermediate cusp of the valve. A fibrous band of tissue between the right ventricular outflow track and the pulmonary valve should be considered as a cause of pulmonary valve stenosis. Pulmonary valve stenosis and patent ductus arteriosus can have conflicting effects on diastolic and systolic dysfunction, respectively. Therefore, beta-blockers should always be used carefully, particularly in patients with a heart defect where there is concern about left ventricular systolic function.

  8. 42 CFR 84.137 - Inhalation and exhalation valves; check valves; minimum requirements.


    ... 42 Public Health 1 2010-10-01 2010-10-01 false Inhalation and exhalation valves; check valves... PROTECTIVE DEVICES Supplied-Air Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a) Inhalation and exhalation valves shall be provided where necessary and protected...

  9. 49 CFR 195.116 - Valves.


    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 195.116 Section 195.116 Transportation... PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with the following: (a) The valve must be of a sound engineering design. (b) Materials subject to...

  10. 14 CFR 125.133 - Fuel valves.


    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 125.133 Section 125.133....133 Fuel valves. Each fuel valve must— (a) Comply with § 125.155; (b) Have positive stops or suitable... operation or from accelerated flight conditions are not transmitted to the lines connected to the valve....

  11. 49 CFR 192.145 - Valves.


    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 192.145 Section 192.145 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Design of Pipeline Components § 192.145 Valves. (a) Except for cast iron and plastic valves, each valve must meet the minimum requirements of API...

  12. 14 CFR 125.137 - Oil valves.


    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  13. Cavitation guide for control valves

    Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)


    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

  14. Mitral valve repair: an echocardiographic review: Part 2.

    Maslow, Andrew


    Echocardiographic imaging of the mitral valve before and immediately after repair is crucial to the immediate and long-term outcome. Prior to mitral valve repair, echocardiographic imaging helps determine the feasibility and method of repair. After the repair, echocardiographic imaging displays the new baseline anatomy, assesses function, and determines whether or not further management is necessary. Three-dimensional imaging has improved the assessment of the mitral valve and facilitates communication with the surgeon by providing the surgeon with an image that he/she might see upon opening up the atrium. Further advancements in imaging will continue to improve the understanding of the function and dysfunction of the mitral valve both before and after repair. This information will improve treatment options, timing of invasive therapies, and advancements of repair techniques to yield better short- and long-term patient outcomes. The purpose of this review was to connect the echocardiographic evaluation with the surgical procedure. Bridging the pre- and post-CPB imaging with the surgical procedure allows a greater understanding of mitral valve repair.

  15. Electromagnetic Exhaust Valve Event Optimization for Enhancing Gasoline Engine Performance

    Fan Xinyu


    Full Text Available Variable exhaust valve events have the potential to further improve the engine power output, fuel economy and decrease the NOX emissions. Based on the moving coil electromagnetic valve train applied to engine exhaust system, effects of variable exhaust valve events are analyzed in detail and the optimization approaches are carried out. Also with the fully variable intake and exhaust valve train, different internal EGR strategies can be achieved and the contrastive analyses are carried out between combustion chamber recirculation and exhaust port recirculation strategies at same operational condition. Results show that, the optimal exhaust valve opening motion can strengthen both power performance and fuel economy at engine part loads. And two principal EGR strategies are applied in a good combination under variable engine loads. At the engine speed of 2000 r/min, BMEP is about 0.3 MPa and with 30%~35% exhaust port recirculation rate, the BSFC and NOX emissions have decrease over 10% and 85% respectively compare with initial condition.

  16. Deformation of Congenital Bicuspid Aortic Valves in Systole

    Szeto, Kai; Pastuszko, Peter; Nigam, Vishal; Lasheras, Juan


    Clinical studies have shown that patients with congenital bicuspid aortic valves (CBAVs) develop degenerative calcification of the leaflets at young ages compared to normal tricuspid aortic valves (TAVs). It has been hypothesized that the asymmetrical geometry of the leaflets in CBAVs and the associate changes in flow shear stresses and excessive strain rate levels are possible causes for the early calcification. Central to the validation of this hypothesis is the need to quantify the differences in strain rate levels between the BAVs and TAVs. We simulate the CBAVs by surgically stitching two of the leaflets of a porcine aortic valve together. To quantify strain differences, we performed in-vitro experiments in both BAVs and TAVs by tracking the 3-D motion of small dots marked on each leaflet surface. We then used phase-locked stereo photogrammetry to measure the strain rates in both radial and circumferential directions during the whole cardiac cycle. In the BAVs' case, the fused leaflet experiences an almost 30% increase in the radial stretching when fully open. RNA profiling of human aortic valve interstitial cells exposed to cyclic stretch shows that the increased stretch experienced by the BAVs results in increased levels of INTERLEUKINS (ILs) and other known inflammatory markers associated with aortic valve calcification. Together, these observations suggest that the abnormal stretch experienced by BAVs activates inflammation gene expression.

  17. New Observer-based Fuzzy H∞ Control Approach for Steam Valve Opening of Multi-machine Power Systems%基于观测器的多机系统气门开度的模糊 H∞控制新方法

    刘鑫蕊; 孙秋野; 谢志远; 侯欣明


    研究了汽轮发电机组成的多机电力系统气门开度的模糊观测 H∞控制器设计问题。首先对多机电力系统建立 T -S 模糊模型,由于实际电力系统的状态有时不能作为模糊规则的前件变量,基于观测状态给出了多机电力系统具有 H∞性能指标的条件,但它不是基于线性矩阵不等式(LMIs)的,只能通过两步法求解。因此又提出仅需一步就能求解的基于 LMIs 的条件,克服了两步法求解带来的保守性。最后采用局部线性化方法对两机无穷大母线的气门开度控制系统建立 T -S 模糊模型,并验证了控制方法的有效性。%The observer-based fuzzy H∞ controller design problem was considered for steam valve opening of multi-machine power systems which is consisting of turbo-generators.Firstly,T-S fuzzy model was used to establish the model for multi-machine power systems.Because sometimes the measurable state variables of actual power systems may not be used as the premise variables of the fuzzy rules,the observer-based conditions were derived to guarantee the H∞ performance. However,the conditions are not based on the linear matrix inequalities (LMIs),which can only be solved by a two-step method.Then the LMIs-based conditions by only one step were proposed,in which the conservativeness of the conditions was reduced.Finally,the T-S fuzzy model was established for the steam valve opening of two-machine infinite bus power systems with local linearization method,and effectiveness of the proposed controller design was verified by the simulation results.

  18. Proportional valve with a piezoelectric actuator

    Laski, Pawel Andrzej


    The article concerns a slotted proportional valve for use in pneumatic and hydraulic systems. There is a growing demand for both hydraulic and pneumatic ultrafast proportional valves. The conducted analysis of literature confirms the lack of such solutions for proportional valves. The currently used pneumatic systems for selection and segregation of parts and objects require ultrafast valves. The presented solution for the proportional valve can significantly improve and accelerate this type of technological processes. Furthermore, fast proportional valves can be successfully used for positional control of pneumatic and hydraulic drives. The article presents the design of a slotted divide valve and sets the maximum mass flow rate for service roads.

  19. Proportional valve with a piezoelectric actuator

    Laski Pawel Andrzej


    Full Text Available The article concerns a slotted proportional valve for use in pneumatic and hydraulic systems. There is a growing demand for both hydraulic and pneumatic ultrafast proportional valves. The conducted analysis of literature confirms the lack of such solutions for proportional valves. The currently used pneumatic systems for selection and segregation of parts and objects require ultrafast valves. The presented solution for the proportional valve can significantly improve and accelerate this type of technological processes. Furthermore, fast proportional valves can be successfully used for positional control of pneumatic and hydraulic drives. The article presents the design of a slotted divide valve and sets the maximum mass flow rate for service roads.

  20. Double prosthetic aortic valve. Case report.

    Liddicoat, J E; Bekassy, S M; De Bakey, M E


    A 55-year-old man underwent insection of a Hufnagel valve into his descending thoracic aorta for aortic valve insufficiency 18 years ago. He remained asymptomatic for 16 years. Because of progressive left ventricular failure his incompetent aortic valve was replaced with a De Bakey carbon ball aortic valve prosthesis 2 years later. Currently, 21 months after the operation, he is doing well with two aortic valves. Review of the literature suggests that he is the first patient reported with two aortic valves functioning concomitantly and one of the longest surviving patients with a Hufnagel valve.


    Krešimir Osman


    Full Text Available This paper presents the development of the MOTORI 2004 computing tool that calculates the distance, speed and acceleration of a car engine valve train’s oscillating mass m, which is reduced to the valve axis. Distance diagrams, speed and accelerations are provided in dependence on the camshaft twist angle at a constant rotational speed in several consecutive revolutions. The computing tool implements a mathematical description and numerical solution for the motion of mass m of a valve gear dynamic model. Valve lift h is given numerically using a series of equidistant points in the period of one camshaft revolution. The variabilities of camshaft rotation and spring thread vibration as a result of cam lift harmonic excitation. The computing solutions were tested at valve opening points and in imaginary extreme operating conditions (soft/hard spring, low/high damping, low/high rotational speed and increased clearance.

  2. Considerations Regarding the Stresses and the Deformations of the Butterfly Valve Body

    Florin Peris-Bendu


    Full Text Available In the present paper it is analyzed the “von Mises” equivalent stress distribution, respectively strains, which appear in the body of a butterfly valve with nominal diameter (DN of 2800 mm and operates at a nominal pressure (PN 19 bar. The paper examines the body of a butterfly valve using finite element method and the followings data is considered to be known: boundary conditions for which the analysis is made in both positions, the valve disk in the closed position and the open position, mechanical characteristics and resistance of the materials for valve body components and loads to which it is subject. The result of the analysis obtained allow optimization of the valve body size by highlighting the oversized areas respectively areas where efforts are maximized.

  3. In-plane cost-effective magnetically actuated valve for microfluidic applications

    Pugliese, Marco; Ferrara, Francesco; Bramanti, Alessandro Paolo; Gigli, Giuseppe; Maiorano, Vincenzo


    We present a new in-plane magnetically actuated microfluidic valve. Its simple design includes a circular area joining two channels lying on the same plane. The area is parted by a septum lying on and adhering to a magneto-active polymeric ‘floor’ membrane, keeping the channels normally separated (valve closed). Under the action of a magnetic field, the membrane collapses, letting the liquid flow below the septum (valve open). The valve was extensively characterized experimentally, and modeled and optimized theoretically. The growing interest in lab on chips, especially for diagnostics and precision medicine, is driving researchers towards smart, efficient and low cost solutions to the management of biological samples. In this context, the valve developed in this work represents a useful building-block for microfluidic applications requiring precise flow control, its main features being easy and rapid manufacturing, biocompatibility and low cost.

  4. Enhanced rhamnolipids production via efficient foam-control using stop valve as a foam breaker.

    Long, Xuwei; Shen, Chong; He, Ni; Zhang, Guoliang; Meng, Qin


    In this study, a stop valve was used as a foam breaker for dealing with the massive overflowing foam in rhamnolipid fermentation. As found, a stop valve at its tiny opening could break over 90% of the extremely stable rhamnolipid foam into enriched liquid when foam flows through the sharp gap in valve. The efficient foam-control by the stop valve considerably improved the rhamnolipid fermentation and significantly enhanced the rhamnolipid productivity by 83% compared to the regular fermentation. This efficient foam breaking was mainly achieved by a high shear rate in combination with fast separation of air from the collapsed foam. Altogether, the stop valve possessed a great activity in breaking rhamnolipid foam, and the involving mechanism holds the potential for developing efficient foam breakers for industrial rhamnolipid fermentation.

  5. Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

    Harish Ramakrishna


    Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

  6. Thermostatic Radiator Valve Evaluation

    Dentz, J. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States); Ansanelli, E. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States)


    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  7. Mathematical multi-scale model of the cardiovascular system including mitral valve dynamics. Application to ischemic mitral insufficiency

    Moonen Marie


    Full Text Available Abstract Background Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models would offer the ability to better understand these dynamics and thus optimize diagnosis, as well as surgical and other interventions. Methods A cardiovascular and circulatory system (CVS model has already been validated in silico, and in several animal model studies. It accounts for valve dynamics using Heaviside functions to simulate a physiologically accurate "open on pressure, close on flow" law. However, it does not consider real-time valve opening dynamics and therefore does not fully capture valve dysfunction, particularly where the dysfunction involves partial closure. This research describes an updated version of this previous closed-loop CVS model that includes the progressive opening of the mitral valve, and is defined over the full cardiac cycle. Results Simulations of the cardiovascular system with healthy mitral valve are performed, and, the global hemodynamic behaviour is studied compared with previously validated results. The error between resulting pressure-volume (PV loops of already validated CVS model and the new CVS model that includes the progressive opening of the mitral valve is assessed and remains within typical measurement error and variability. Simulations of ischemic mitral insufficiency are also performed. Pressure-Volume loops, transmitral flow evolution and mitral valve aperture area evolution follow reported measurements in shape, amplitude and trends. Conclusions The resulting cardiovascular system model including mitral valve dynamics provides a foundation for clinical validation and the study of valvular dysfunction in vivo. The overall models and results could readily be generalised to other cardiac valves.

  8. Human tissue valves in aortic position: determinants of reoperation and valve regurgitation

    T.P. Willems (Tineke); E.W. Steyerberg (Ewout); V.E. Kleyburg-Linkers; E. Bos (Egbert); L.A. van Herwerden (Lex); J.R.T.C. Roelandt (Jos); J.J.M. Takkenberg (Hanneke)


    textabstractBACKGROUND: Human tissue valves for aortic valve replacement have a limited durability that is influenced by interrelated determinants. Hierarchical linear modeling was used to analyze the relation between these determinants of durability and valve

  9. Comparison of outcomes after aortic valve replacement with a mechanical valve or a bioprosthesis using microsimulation

    J.P.A. Puvimanasinghe (John); M.B. Edwards; M.J.C. Eijkemans (René); E.W. Steyerberg (Ewout); L.A. van Herwerden (Lex); K.M. Taylor; G.L. Grunkemeier (Gary); J.D.F. Habbema (Dik); A.J.J.C. Bogers (Ad); J.J.M. Takkenberg (Hanneke)


    textabstractBACKGROUND: Mechanical valves and bioprostheses are widely used for aortic valve replacement. Though previous randomised studies indicate that there is no important difference in outcome after implantation with either type of valve, knowledge of outcomes after aortic va

  10. Application of stereolithography for scaffold fabrication for tissue engineered heart valves.

    Sodian, Ralf; Loebe, Matthias; Hein, Andreas; Martin, David P; Hoerstrup, Simon P; Potapov, Evgenij V; Hausmann, Harald; Lueth, Tim; Hetzer, Roland


    A crucial factor in tissue engineering of heart valves is the functional and physiologic scaffold design. In our current experiment, we describe a new fabrication technique for heart valve scaffolds, derived from x-ray computed tomography data linked to the rapid prototyping technique of stereolithography. To recreate the complex anatomic structure of a human pulmonary and aortic homograft, we have used stereolithographic models derived from x-ray computed tomography and specific software (CP, Aachen, Germany). These stereolithographic models were used to generate biocompatible and biodegradable heart valve scaffolds by a thermal processing technique. The scaffold forming polymer was a thermoplastic elastomer, a poly-4-hydroxybutyrate (P4HB) and a polyhydroxyoctanoate (PHOH) (Tepha, Inc., Cambridge, MA). We fabricated one human aortic root scaffold and one pulmonary heart valve scaffold. Analysis of the heart valve included functional testing in a pulsatile bioreactor under subphysiological and supraphysiological flow and pressure conditions. Using stereolithography, we were able to fabricate plastic models with accurate anatomy of a human valvular homograft. Moreover, we fabricated heart valve scaffolds with a physiologic valve design, which included the sinus of Valsalva, and that resembled our reconstructed aortic root and pulmonary valve. One advantage of P4HB and PHOH was the ability to mold a complete trileaflet heart valve scaffold from a stereolithographic model without the need for suturing. The heart valves were tested in a pulsatile bioreactor, and it was noted that the leaflets opened and closed synchronously under subphysiological and supraphysiological flow conditions. Our preliminary results suggest that the reproduction of complex anatomic structures by rapid prototyping techniques may be useful to fabricate custom made polymeric scaffolds for the tissue engineering of heart valves.

  11. Simpler valve for reciprocating engines

    Akkerman, J. W.


    Simpler design eliminating camshafts, cams, and mechanical springs should improve reliability of hydrazine powered reciprocating engines. Valve is expected to improve efficiency, and reduce weight of engines in range up to 50 horsepower.

  12. Titanium in engine valve systems

    Allison, J.E.; Sherman, A.M.; Bapna, M.R.


    Titanium alloys offer a unique combination of high strength-to-weight ratio, good corrosion resistance and favorable high temperature mechanical properties. Still, their relatively high cost has discouraged consideration for widespread use in automotive components. Recent demands for increased fuel economy have led to the consideration of these alloys for use as valve train materials where higher costs might be offset by improvements in performance and fuel economy. Lighter weight valve train components permit the use of lower spring loads, thus reducing friction and increasing fuel economy. Camshaft friction measurements made on a typical small displacement engine indicate that a two-to-four percent increase in fuel economy can be achieved. Valve train components are, however, subject to a severe operating environment, including elevated temperatures, sliding wear and high mechanical loads. This paper discusses the details of alloy and heat treatment selection for optimizing valve performance.

  13. Diseases of the Tricuspid Valve

    ... Kawasaki Disease Long Q-T Syndrome Marfan Syndrome Metabolic Syndrome Mitral Valve Prolapse Myocardial Bridge Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden ...

  14. What Causes Heart Valve Disease?

    ... a heart attack or injury to the heart. Rheumatic Fever Untreated strep throat or other infections with strep bacteria that progress to rheumatic fever can cause heart valve disease. When the body ...




    Two patients with a quadricuspid aortic valve are described, one of them with concomitant juxtaposed coronary orifices facing the right hand facing sinus. The etiology and incidence of this congenital anomaly will be discussed.

  16. Minimally invasive aortic valve replacement

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K


    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy....... The 30-day mortality rate for the 98 patients was zero, although 14 of the 98 mini-sternotomies had to be converted to complete sternotomies intraoperatively due to technical problems. Such conversion doubled the operative time over that of the planned full sternotomies. In the group of patients whose...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  17. The spin-valve transistor

    Monsma, Douwe Johannes


    High density magnetic recording, magnetic random access memories, displacement and current detection, contactless switching and electronic compass applications all require magnetic field sensors with unprecedented sensitivity. The spin-valve effect (giant magnetoresistance) found in 1988 in magnetic

  18. Effect of Flow Characteristics in the Downstream of Butterfly Valve on the Flow Rate Measurement using Venturi Tube

    Yoon, Seok Ho; Lee, Jungho; Yu, Cheong Hwan; Park, San-Jin; Chung, Chang-Hwan


    For testing large-capacity pump, the accurate flow rate measurement is needed in the test loop. As a measuring method of flow rate, venturi tube is recommended due to its low pressure loss. However, upstream disturbance of loop component such as valve has an effect upon the accuracy of flow rate measurement. For controlling flow rate in case of high flow rate and large-scale piping system, butterfly-type valve is generally used due to its compactness. However, butterfly valve disturbs downstream flow by generating turbulence, cavities, or abrupt pressure change. In this study, the effect of downstream disturbance of butterfly valve on the flow rate measurement using venturi tube is investigated. Test loop consists of circulation pump, reservoir, butterfly valve, venturi tube, and reference flow meter. The test is conducted with regard to a different valve opening angle of butterfly valve. PIV system is used to visualize and analyze flow in the downstream region of butterfly valve. According to valve opening angle, the flow characteristics and the accuracy of flow rate measurement are investigated.

  19. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.


    It is advantageous for gas-fed pulsed electric thrusters to employ pulsed valves so propellant is only flowing to the device during operation. The propellant utilization of the thruster will be maximized when all the gas injected into the thruster is acted upon by the fields produced by the electrical pulse. Gas that is injected too early will diffuse away from the thruster before the electrical pulse can act to accelerate the propellant. Gas that is injected too late will miss being accelerated by the already-completed electrical pulse. As a consequence, the valve must open quickly and close equally quickly, only remaining open for a short duration. In addition, the valve must have only a small amount of volume between the sealing body and the thruster so the front and back ends of the pulse are as coincident as possible with the valve cycling, with very little latent propellant remaining in the feed lines after the valve is closed. For a real mission of interest, a pulsed thruster can be expected to pulse at least 10(exp 10) - 10(exp 11) times, setting the range for the number of times a valve must open and close. The valves described in this paper have been fabricated and tested for operation in an inductive pulsed plasma thruster (IPPT) for in-space propulsion. In general, an IPPT is an electrodeless space propulsion device where a capacitor is charged to an initial voltage and then discharged, producing a high-current pulse through a coil. The field produced by this pulse ionizes propellant, inductively driving current in a plasma located near the face of the coil. Once the plasma is formed, it can be accelerated and expelled at a high exhaust velocity by the electromagnetic Lorentz body force arising from the interaction of the induced plasma current and the magnetic field produced by the current in the coil. The valve characteristics needed for the IPPT application require a fast-acting valve capable of a minimum of 10(exp 10) valve actuation cycles. Since

  20. 57. Aortic valve replacement with sutureless valve and mitral valve repair in patient with infected aortic homograft

    A. attia


    Full Text Available The approach of implanting aortic sutureless valve inside the calcific homograft is suitable in redo surgery especially if associated with mitral valve surgery. Aortic valve replacement in patients who have undergone previous aortic root replacement with an aortic homograft remains a technical challenge because of homograft degeneration and the need for a redo Bentall operation. We report a case of redo aortic valve replacement (valve in valve with a sutureless valve and mitral valve repair by miniband annuloplasty in a female patient aged 64 years old who underwent aortic valve replacement with homograft 14 years ago and presented by sever aortic valve regurge and sever mitral valve regurge because of infective endocarditis. This technique allows rapid aortic valve replacement in a heavily calcified aortic root. It also avoids aortic valve size affection after mitral valve repair by ordinary methods especially in patients with small aortic annulus. This technique is particularly suitable in redo procedures for homograft degeneration, it avoids performing a redo Bentall operation with its known problems as well as to avoid patient prosthesis mismatch.