• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.4 no.2
• /
• pp.7-12
• /
• 2008

The purpose of this study is to present a methodology to estimate the capacity of the pressure relief valve which prevents overpressure of the pressure vessel in a cold state. In this methodology, the transient behavior of the flow rate through the pressure relief valve and the pressure inside the pressure vessel are considered. The result of this study shows the followings; The more the relief valve capacity is considered in excess, the more the initial relief flow rate and the initial pressure inside the pressure vessel are high and low respectively. When the relief valve capacity is determined properly, the pressure inside the pressure vessel maintains almost the same value, so the ASME code requirement will be met.

• Journal of Drive and Control
• /
• v.15 no.4
• /
• pp.61-66
• /
• 2018

Almost every hydraulic system is equipped with a pressure relief valve, to maintain working pressure of the system at a pre-determined level. Thus, dynamic characteristics of such a relief valve, in conjunction with other hydraulic components, are important in designing the hydraulic control system. The single stage pressure relief valve is dynamically undesirable, due to relatively low viscous damping, that causes high frequency oscillations. This problem is overcome by introducing orifices in the inner pilot line, and drain line. In this study, for the single stage spool type pressure relief valve, the system equations were derived through an adequate linearisation and several simplifications were made, to use the transfer function formulation technique. All coefficients were evaluated and used, to make some results by using Matlab software. Results of analysis are compared with experimental results. In this study, parameters affecting stability of valve design are determined and suggested relative to the design.

• Journal of Hydrogen and New Energy
• /
• v.20 no.3
• /
• pp.179-187
• /
• 2009

This paper presents a static and dynamic characteristics of the relief valve which is a kind of direct operated pressure control valve for hydrogen compressor. The valve is consisted of a main poppet, a spring, an adjuster and a valve body. The purpose of this study is development of the simulation model for relief valve by using commercial AMESlM$^{(R)}$ tool. Poppet with sharp edge seat type and ball poppet with sharp edge seat type compare for P-Q characteristic. The dynamic simulation results are presented the operating pressure characteristics of relief valve. High pressure power unit of which maximum pressure control range is 100MPa was manufactured, and the pressure control valve was experimented using the above-mentioned power unit. The new model of pressure control valve from this results was suggested. It was confirmed that the suggested valve has a good control performance from experimental setup.

• Journal of Drive and Control
• /
• v.13 no.4
• /
• pp.7-13
• /
• 2016

This paper presents the meter-out and meter-in speed control characteristics of a pneumatic cylinder with relief valve type cushion device. The piston displacement and velocity are measured to investigate high speed driving performance with variation of the pressure setting in relief valve, air supply pressure, load mass, the supply and exhaust flow rate from the cylinder. Also, the internal pressures and temperatures driving pressure and cushion chamber are measured. The piston displacements and velocities of meter-out and meter-in control are compared experimentally determined data. A comparison experimental data meter-out and meter-in control show that a relief valve type cushion device is suitable for high speed pneumatic cylinders. The desired response characteristics of piston displacement and velocity are satisfactory adjust the pressure setting of a relief valve with varying system parameters such as air supply pressure, load mass and controlled flow rate.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.1 no.2
• /
• pp.65-72
• /
• 1977

Major problems in the design and use of refief valve are (a) chattering because of instability, (b) excessive pressure differential which makes the valves crack far below maximum pressure diminishing useful flow in the system. In this study, A magnet-coupled relief valve is investigated theoretically and experimentally in order to improve the performance of a conventional direct type reliefvalve. A theory is developed to predict the performance, response, and stability of the magnet-coupled valve taking into account the delivery line response. In the experiment, a typical magnet-coupled relief valve is designed on the basis of the analytical results; the discharge rates are measured varying the supply pressure, and both the pressure-time curves and valve displacament-time curves are recorded providing the supply pressures greater than the setting pressure. The measured override characteristic curves are then compared with those of conventional pilot type and direct type releif valves. It is showm that the excessive pressure differential of a magnet-coupled relief valve becomes less than that of a conventional direct type valve. It is also shown that the most important chatacteristic of a magnet-coupled relief valve is to eliminate valve chattering due to instability regardless of the magnitude of setting pressures and discharge rates, which suggests wide applications of the idea of the use of a magnet in the design of hydraulic valves.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.629-636
• /
• 2003

The purpose of this study is localization of safety relief valves for Nuclear Service through technical development with overall design, fabrication, inspection, capacity certification test and functional qualification test of safety relief valves in accordance with ASME Section III and KEPIC Code. Safety relief valve is the important equipment used to protect the pressure vessel, the steam generator and the other pressure facility from overpressure by discharging the operating medium when the pressure of system is reaching the design pressure of the system. But we're depending on technology of the other country up to the present time. Because we don‘ have our own technologies, we have been spent the great time and money on installing and repairing safety relief valve at nuclear power plant. Therefore we have to achieve the development of safety relief valves for Nuclear Service with our own technologies.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.508-511
• /
• 2008

The most landing gear use oleo-pneumatic shock strut to absorb the impact energy during touchdown. The shock strut is composed of the oil damper and the gas spring, especially the oil damper provides resistance force which is proportional to the square of landing speed. In case of high landing speed, the abnormal peak load can be occurred and transferred to the airframe structure. To prevent this, the pressure-relief valve is used to limit the damping force under the specific level. In this paper, it is presented the design process to find optimal damping and analysis results using pressure-relief valve.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.3
• /
• pp.263-269
• /
• 2015

Growing concerns regarding air pollution have recently increased the demand for liquefied natural gas (LNG) fueled ships. LNG-fueled ships are equipped with an explosion relief valve in the crankcase to relieve excessive pressure and stop flames from emitting from the crankcase. In this study, a finite element analysis was conducted to evaluate the crankcase relief valve disk spring design using an ANSYS Workbench, v.15. The setting pressure, leak and explosion test performed by european standard EN14797 to evaluate function and mechanical integrity of crankcase relief valve. The tests results indicate that the pressure of the crankcase relief valve is 3.05 bar, with no air leakage at 2.97 bar. Finally, the mechanical integrity of the crankcase relief valve was confirmed through an explosion test in which the valve plate assembly, flame arrester, and other parts were safe from fracturing.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.12
• /
• pp.729-734
• /
• 2017

A safety relief valve is a device that relieves excessive pressure in piping lines or tanks and maintains pressure at the appropriate pressure level for use. The (pressure in the) safety valve is directly influenced by the change in the back pressure, depending on whether the vents in the spring bonnet are vented to the atmosphere or to the outlet. The back pressure is divided into the built-up back pressure and the superimposed back pressure, and the back pressure characteristics vary according to the usage conditions. The safety valve used in this study is a Conventional Safety Relief Valve. The blowdown of the safety valve is predicted by establishing the equilibrium equation between the opening force and spring force considering the back pressure characteristics. Its reliability is secured by using CFX17.1. In addition, the safety of the safety valve trim was examined through fluid-structure interaction analysis.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1552-1564
• /
• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.