Difference and difference of pressure reducing valve, safety valve, pressure stabilizing valve and pressure relief valve

Pressure reducing valve, safety valve, pressure stabilizing valve and pressure relief valve are all pressure valves, which are mainly functional differences.

The pressure reducing valve is a device that reduces the medium with high pressure to medium with low pressure. The characteristic of the valve is to keep the outlet pressure and temperature within a certain range when the inlet pressure is constantly changing.
Safety valve is used to prevent boiler, pressure vessel and other equipment or pipeline from damage due to overpressure. When the pressure is slightly higher than the normal working pressure, the safety valve will automatically open to reduce the pressure. When the pressure is slightly lower than the normal working pressure, the safety valve will automatically close, stop discharging the fluid and keep the seal.
The pressure relief valve is mainly used in the case of excessive pressure. When the pressure is greater than the set value, the valve inner piece is pushed open to release the pressure in time, and the pressure will return to the original position after reducing. It is not different from the safety valve. The pressure relief valve is mostly used for liquid, and the safety valve is mostly used for gas and steam.

Pressure stabilizing valve is a device that keeps the medium in a certain pressure range.

20210625082159 74012 - Difference and difference of pressure reducing valve, safety valve, pressure stabilizing valve and pressure relief valve

Difference between pressure stabilizing valve and pressure reducing valve

Pressure reducing valve: no matter how the inlet pressure changes, the outlet pressure is reduced to the rated value to reduce the pressure (One is to stabilize the pressure in its proper state.)
Regulator valve: no matter how the downstream pressure and demand change, maintain a constant upstream pressure (One is to reduce the pressure from a high place to its proper state.)

20210625082740 69384 - Difference and difference of pressure reducing valve, safety valve, pressure stabilizing valve and pressure relief valve

Safety valve and pressure reducing valve are two types of valves, which are special valves. Among them, the safety valve belongs to the safety relief device, which is a special valve. It only acts when the working pressure exceeds the allowable range to protect the system. The pressure reducing valve is a process valve, which can reduce the pressure of high-pressure logistics to meet the pressure requirements of the post system. Its working process is continuous.

Design standard table of pressure reducing valve

Standard code Standard name
JIS B3372-1982 Pressure reducing valve for compressed air
JIS B8410-1990 Pressure reducing valve for Waterway
GB/T 10868-1989 Technical specification for desuperheating and pressure reducing valve of power station
GB/T 12244-1989 General conditions for pressure reducing valves
GB/T 12245-1989 Test method of Xineng for pressure reducing valve
GT/T 12246-1989 Pilot-operated reducing valves
GB/T 3656-1994 Water pressure reducing valve
GB/T 3656-1994 Marine air pressure reducing valve
ASTM F1370-1992 Pressure reducing valve of marine water supply system
JB/T 53265-1994 Product quality classification of pilot type pressure reducing valve
AWWA C511-1992 Pressure relief and backflow prevention valve assembly

Working principle of pressure reducing valve

Serial number Name Working principle
1 Direct acting diaphragm pressure reducing valve When the outlet pressure increases, the film moves upward, the valve opening decreases, the flow rate increases, the pressure drop increases, the pressure behind the valve decreases, and the outlet pressure decreases. When the film moves downward, the opening of the valve increases, the flow rate decreases, the pressure drop decreases and the pressure behind the valve increases. The outlet pressure behind the valve always keeps the constant pressure set by the setting adjusting screw.
2 Direct acting bellows pressure reducing valve The pressure at the outlet side increases, the bellows moves upward, the valve opening decreases, the flow rate increases, the pressure drop should be larger, the pressure behind the valve decreases and the outlet side pressure decreases. The bellows move downward, the valve opening increases, the flow rate decreases, the pressure drop decreases, and the back pressure increases. The outlet pressure behind the valve always keeps the constant pressure set by the setting adjusting screw.
3 Pilot piston pressure reducing valve Screw the adjusting screw to open the pilot valve disc, and the medium enters the piston from the inlet side. Because the piston area is larger than the main valve disc area, it pushes the piston downward to open the main valve. The pressure behind the valve is balanced, and the pressure of the adjusting spring changes the opening of the pilot valve, so as to change the pressure on the piston, control the opening of the main valve disc, and keep the pressure behind the valve constant.
4 Pilot diaphragm pressure reducing valve The working principle is the same as above. The pressure of the upper chamber of the membrane is controlled by the bypass regulating valve.
5 Pilot diaphragm pressure reducing valve When the adjusting spring is in a free state, the main valve and the pilot valve are closed. When the hand wheel is turned clockwise, the pilot valve diaphragm is pushed downward to open the pilot valve, and the medium flows to the upper part of the main diaphragm through the pilot valve, so as to push the main valve to open, and the medium flows to the outlet, and at the same time enters the lower part of the pilot valve diaphragm, and the outlet pressure rises to keep balance with the adjusted spring force. If the outlet pressure increases, the pilot valve diaphragm will move upward and the pilot valve opening will decrease. At the same time, the flow of the medium under the main diaphragm decreases, the pressure decreases, and the outlet pressure decreases to reach a new balance, and vice versa.
6 Combined pressure reducing valve The pressure reducing valve is composed of main valve, pilot valve and stop valve. When the adjusting spring is in free state, the main valve and pilot valve are closed. Turn the adjusting screw, and the medium pushes the pilot valve. At the same time, the pressure entering the rubber membrane chamber of the main valve keeps balance with the pressure of the adjusting spring. Enter the rubber membrane chamber of the main valve to make the rubber membrane upward. The main valve opens, and the medium flows to the outlet (at this time, the stop valve opens to maintain a certain pressure in the chamber). The outlet medium feeds back to the chamber above the rubber membrane and the chamber below the pilot valve. When the outlet pressure increases, the diaphragm of the pilot valve moves up, the opening of the pilot valve decreases, and the medium pressure of the chamber decreases. At the same time, the chamber pressure decreases, and the rubber membrane of the main valve moves down, and the opening of the main valve decreases, and the outlet pressure decreases, reaching a new balance; vice versa.
7 Lever type pressure reducing valve At this time, the pressure reducing valve is balanced by the weight on the lever. Its action principle: when the lever is in the free state, the disc and seat of the double seat are in the closed state. Under the action of the inlet pressure, push the valve disc upward, and the pressure is formed at the outlet end. Through the counterweight on the lever, the important adjustment is transmitted to the required outlet pressure. When the outlet pressure exceeds the given pressure, the force of medium pressure acting on the upper valve seat is greater than that on the lower valve seat, forming a certain pressure difference, which makes the valve disc move downward, reduces the throttle area, and the outlet pressure also decreases, reaching a new balance; vice versa.
8 Pilot bellows pressure reducing valve The structure principle is the same as the pilot piston pressure reducing valve.

Source: Network Arrangement – China Valve Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@metallicsteel.com

Please notice that you might be interested in the other technical articles we’ve published:

Related News

العربيةБългарски简体中文繁體中文DanskNederlandsEnglishFrançaisDeutschBahasa IndonesiaItaliano日本語한국어LatinPortuguêsРусскийEspañolதமிழ்ไทยTürkçe