Correct selection of Special Material Valve and precautions

Special Material Valve have a wide range of applications, including steam, compressed air, industrial gas, water, oil and other liquid media. Therefore, in view of the many possible structural changes, when considering the selection of Special Material Valve, the main thing is the exact performance of the valve. First of all, full testing should be carried out to ensure good use results.

(1) Selection principles
1. The fluctuation of the inlet pressure of the Special Material Valve should be controlled within 80%-105% of the given value of the inlet pressure. If it exceeds this range, the performance of the Special Material Valve will be affected.
2. Usually, the valve outlet pressure Pc of the Special Material Valve should be less than 0.5 times the valve outlet pressure, that is, Pc<0.5P1. Each spring of the Special Material Valve is only applicable within a certain outlet pressure range. If it exceeds the range, the spring should be replaced.
3. In situations where the working temperature of the medium is relatively high, pilot piston Special Material Valve or pilot bellows Special Material Valve are generally selected.
4. When the medium is air, water or liquid, it is generally advisable to use direct-acting diaphragm Special Material Valve or pilot diaphragm Special Material Valve.
5. When the medium is steam, it is advisable to use pilot piston Special Material Valve or pilot bellows Special Material Valve.
6. For the convenience of operation, adjustment and maintenance, Special Material Valve should generally be installed on horizontal pipes.
(2) Selection precautions
1. Within the given spring pressure level range, the outlet pressure should be able to be adjusted continuously between the maximum and minimum values, and there should be no jamming and abnormal vibration.
2. When the outlet flow changes, the outlet pressure deviation value is not more than 20% for the direct-acting type and not more than 10% for the pilot type.
3. For soft-sealed Special Material Valve, there should be no leakage within the specified time. For metal-sealed Special Material Valve, the leakage should not be more than 0.5% of the maximum flow.
4. When the inlet pressure changes, the outlet pressure deviation value is not more than 10% for the direct-acting type and not more than 5% for the pilot type.
5. For unused Special Material Valve, the spring should be adjusted to keep them in a free state. The inlet and outlet should be closed with plugs.
6. The flow rate of Special Material Valve is related to the properties of the fluid and the pressure ratio. The smaller the pressure ratio, the greater the flow rate; but when the pressure ratio is reduced to a certain value, the flow rate no longer increases as the pressure ratio decreases.