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Pressure Relief Valve summary

Pressure reducing valve is a valve in the body of the opening of the opening and closing of regulating the flow of medium, the medium pressure is reduced, at the same time with the aid of the role of the valve after pressure adjust the opening of open-close part, keep the valve after pressure within a certain range, and the valve body or valve after the injection of cooling water, reduce the temperature of medium, the valve is called desuperheating valve to relieve stress.
The characteristics of the pressure reducing valve: the characteristics of the pressure reducing valve is in the case of constant changes in the inlet pressure, keep the outlet listening pressure and temperature value within a certain range.

Pressure Relief Valve Selection criteria

1. Within the range of the given spring pressure level, the outlet pressure can be continuously adjusted between the maximum and minimum value, and there shall be no jam and abnormal vibration;
2. For the soft sealing pressure reducing valve, there shall be no leakage within the specified time;For the metal sealing pressure reducing valve, the leakage should not be greater than 0.5% of the maximum flow;
   
3. When the outlet flow rate changes, the deviation of the outlet pressure of the direct acting type is not more than 20%, and that of the pilot type is not more than 10%.
4. When the inlet pressure changes, the deviation of the outlet pressure of the direct acting type is not more than 10%, and that of the pilot type is not more than 5%.
5. Usually, the pressure after the valve of the pressure reducing valve should be less than 0.5 times the pressure before the valve;
6. The application range of pressure reducing valve is very wide, in steam, compressed air, industrial gas, water, oil and many other liquid media equipment and pipeline can be used, the medium flow through the outlet of the pressure reducing valve, generally with mass flow or volume flow;
7. Bellows direct acting type pressure reducing valve is suitable for low pressure, medium and small caliber steam medium;
8. Film direct acting pressure reducing valve is suitable for medium and low pressure, medium and small caliber of air and water medium;
9. Pilot piston type pressure reducing valve, suitable for all kinds of pressure, all kinds of caliber, all kinds of temperature of steam, air and water media, if made of stainless acid steel, can be used for all kinds of corrosive media;
10. Pilot bellows type pressure reducing valve, suitable for low pressure, medium and small caliber steam, air and other media;
11. Pilot film type pressure reducing valve, suitable for low pressure, medium pressure, medium and small diameter of steam or water and other media;
12. The fluctuation of the inlet pressure of the pressure reducing valve should be controlled at 80% ~ 105% of the given value of the inlet pressure. If it exceeds this range, the performance of the early decompression will be affected.
13. Usually the pressure after the pressure reducing valve should be less than 0.5 times the pressure before the valve;
14. Each spring of the pressure reducing valve is only applicable within a certain range of outlet pressure, and the spring should be replaced beyond the range.
15. In the medium working temperature is relatively high occasions, generally choose the pilot piston type pressure reducing valve or the pilot bellows type pressure reducing valve;
16. Medium for air or water (liquid) occasions, generally suitable for the direct action of film type pressure reducing valve or pilot film type pressure reducing valve;
17. When the medium is steam, the pilot piston type or the pilot bellows type pressure reducing valve should be selected;
18. For the convenience of operation, adjustment and maintenance, the pressure reducing valve should generally be installed on the horizontal pipeline.