Safety valve used in the pressure equipment, containers or pipes, as overpressure protection device. When the pressure in the equipment, container or pipeline exceeds the allowable value, the valve will be automatically opened and then fully discharged to prevent the pressure in the equipment, container or pipeline from rising continuously. When the pressure drops to the specified value, the valve should Automatically shut down in time to protect the safe operation of equipment, vessels or lines. The safety valve can be driven directly by the system pressure of the valve inlet, in this case by the mechanical load provided by the spring or hammer to overcome the medium pressure acting under the valve flap. They can also be pilot driven by a mechanism that opens or closes the safety valve by releasing or applying a closing force. Therefore, in accordance with the above-mentioned driving mode safety valve into direct action and pilot. The safety valve can be opened proportionally over the entire opening height range or over a relatively large opening height, or only proportionally to a slight opening height, then suddenly opened to the fully open position. Therefore, the safety valve can be divided into proportional and full swing. Safety valve structure, application and determination of the nominal pass should be subject to norms, or should be the consent of the legal authorities. Between different norms, the terms of the constraint and the definition may be different. In the application of safety valve, must comply with the requirements of its applicable specifications. As the safety valve is an automatic valve, there are many differences from the general purpose valve in terms of structural and performance parameters. Some special terminology is easy to confuse, in order to make the user more clearly understand the safety valve, and the correct selection, the following will be some of the main terminology to be explained. 1, safety valve terminology (1) safety valve. An automatic valve. Instead of using any external force, it uses the force of the medium itself to discharge a nominal amount of fluid to prevent the pressure in the system from exceeding a predetermined safety value. When the pressure returns to normal, the valve closes again and the medium continues to flow out. (2) direct load safety valve. A direct acting mechanical load, such as heavy hammer, lever weight or spring to overcome the valve pressure under the pressure generated by the force of the safety valve. (3) Safety valve with power-assisted device. The safety valve with a power-assisted device, can be opened below the normal opening pressure. Even if the auxiliary device fails, such safety valve can still meet the standard requirements. (4) Safety valve with additional load. This safety valve always maintains a pressure of increased sealing before the pressure at its inlet reaches the cracking pressure. This additional force (replenishment load) may be supplied by external energy and should be reliably released when the relief valve reaches the cracking pressure. The size should be set that is assumed that the additional force is not released, the safety valve is still in the import pressure does not exceed the national laws and regulations to open the pressure percentage under the premise of reaching the rated displacement. (5) Pilot-operated safety valve. A safety valve that is driven or controlled by draining the medium from the pilot valve. The pilot valve itself should be in line with the requirements of the standard direct load safety valve. (6) Proportional safety valve. A safety valve that opens or closes proportionally over the entire opening height range or over a substantial opening height. (7) Full-Kai safety valve. A kind of open only in the small range of opening ratio, and then suddenly opened to the fully open position of the safety valve. Open the height of not less than 1/4 runner diameter. (8) Micro-Kai safety valve. Is a direct acting safety valve for liquid media only. Open height from 1/40 ~ 1/20 diameter of the runner. (9) Opening pressure (rated pressure). Under the conditions of operation, the safety valve flap starts to have a rising inlet pressure, at which point a measurable opening height begins and the medium is continuously discharged, either visually or by auditory support. (10) discharge pressure. Valve to achieve the required opening height of the inlet pressure. The upper limit of discharge pressure is subject to the requirements of relevant national standards or codes. (11) over pressure. The difference between discharge pressure and cracking pressure, usually expressed as a percentage of cracking pressure. (12) back seat pressure. After discharge valve flap contact with again, that is, when the opening height becomes zero inlet pressure. (13) Opening and closing pressure. The difference between cracking pressure and cracking pressure, usually expressed as a percentage of cracking pressure and cracking pressure, is expressed as the difference between the two when the cracking pressure is low. (14) back pressure. Pressure relief valve outlet. (15) Rated discharge pressure. The standard specifies the upper limit of discharge pressure. (16) Seal the test pressure. The inlet pressure of the seal test was measured at which the leakage rate through the sealing surface of the closure was measured. (17) open height. The actual lift of the valve leaves the closed position. (18) Flow path area. Refers to the minimum cross-sectional area of ​​the flow path between the valve flap inlet and the closing member sealing surface, used to calculate the theoretical displacement (19) flow path diameter without any resistance effect. Corresponds to the diameter of the runner area. (20) curtain area. Cylindrical or conical shaped passage area formed between the sealing surfaces when the valve flap is above the valve seat. (21) Emissions area. The minimum cross-sectional area of ​​the fluid passage during valve discharge. For the full revelation of safety valve, the discharge area is equal to the flow area; for the micro-safety valve, the discharge area is equal to the curtain area. (22) Theoretical displacement. Is the flow channel cross-sectional area and safety valve flow channel area equal to the ideal nozzle calculation of displacement. (23) Displacement coefficient. The actual displacement and the ratio of theoretical displacement. (24) Rated displacement coefficient. The product of the displacement coefficient and the reduction factor (0.9). (25) rated displacement. That part of the actual displacement allowable as a safety valve benchmark. (26) Equivalent displacement calculation. Refers to the pressure, temperature, the nature of the media and other conditions and rated displacement of the same conditions apply, the safety valve displacement calculation. (27) Frequency hopping. Valve poppet quickly abnormal movement back and forth, in motion valve contact valve seat. (28) Flutter. Valve poppet quickly abnormal movement back and forth in motion, the valve does not contact the valve seat. 2. Selection Principle (1) steam boiler safety valve, the general use of all-spring-type safety valve. (2) liquid medium with safety valve, the general selection of micro-spring-type safety valve. (3) liquefied petroleum gas tanker truck or liquefied petroleum gas tanker truck safety valve, the general use of all Kai-type built-in safety valve. (4) oil well export (Christmas tree) with safety valve, the general selection of pilot-operated safety valve. Steam generating equipment, high pressure bypass safety valve, the general use of safety and control of the dual function of the pilot-operated safety valve.
GMP Cleanroom Engineering Project
Gmp Cleanroom Engineering Project,Sandwich Panels Cleanroom Project,Clean Room Turnkey Engineering Project,Turn-Key Pharmaceutical Cleanroom Project
Wuxi Zijing Purification Engineering Co., Ltd , https://www.zijingjh.com