The principle and function of pneumatic check valve

Pneumatic check valve is a valve driven by compressed air. When purchasing pneumatic valves, the practice of only specifying specifications, categories, and pressures to meet the purchasing needs is imperfect in the current market economy environment. We need to know more about the general requirements and principles of pneumatic check valves.

 

 

General requirements for pneumatic check valves

1. The specifications and types of pneumatic actuated valves produced should meet the requirements of the pipeline design documents.

 

2. The model and manufacturing standard of pneumatic butterfly valve should be marked with the national standard number requirement. If it is a corporate standard, the relevant description of the model should be indicated.

 

3. The working pressure of the pneumatic actuated ball valve is required to be greater than the working pressure of the pipeline. On the premise of not affecting the price, the working pressure that the valve can withstand should be greater than the actual working pressure of the pipeline;

 

 

Material of pneumatic check valve

1. The material of the valve body should be mainly ductile iron, and the grade and actual physical and chemical test data of the cast iron should be indicated.

2. Stem material, strive for stainless steel stem (2CR13), large diameter valve should also be stainless steel embedded stem.

3. The nut material is made of cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the valve stem.

4. The material of the valve stem bushing should be less than the valve stem in hardness and strength, and will not form electrochemical corrosion with the valve stem and valve body under water immersion.

 

 

Performance testing of pneumatic check valve

1. When an air actuator valve is manufactured in batches of a certain specification, an authoritative organization should be entrusted to perform the following performance tests:

① The opening and closing torque of the valve under working pressure;

②Under working pressure conditions, the continuous opening and closing times of the valve can be guaranteed to close tightly;

③The detection of the flow resistance coefficient of the valve under the condition of pipeline water delivery.

 

2. The valve should be tested as follows before leaving the factory:

① When the air actuated ball valve is open, the valve body should withstand the internal pressure test that is twice the valve working pressure;

②When the valve is closed, both sides bear 1.1 times the valve working pressure value, and there is no leakage; however, the leakage value of the metal-sealed butterfly valve is not greater than the relevant requirements.

③Comprehensive anti-corrosion is required for the inside of the valve body and the various parts of the valve plate. On the one hand, it will not rust when immersed in water and will not produce electrochemical corrosion between the two metals; on the other hand, the surface is smooth to reduce water resistance.