Selection Criteria for Check Valves

1. The spherical check valve is suitable for medium and low pressure pipelines and can be made into a large diameter; 

2. The shell material of the spherical check valve can be made of stainless steel, and the hollow sphere of the seal can wrap polytetrafluoroethylene engineering plastics, so it can also be applied to the pipeline of general corrosive media, and the working temperature is -101--150 ℃, the nominal pressure is ≤4.0MPa, and the nominal passage range is between 200-1200; 

3. When selecting check valves for incompressible fluids, the first step is to evaluate the required closing speed. The next step is to select the type of check valve that may meet the required closing speed; 

4. Regarding the selection of check valves for compressible fluids, the selection can be made according to the similar method of check valves for incompressible fluids. If the medium flow field is large, check valves for compressible fluids can be used A deceleration device, if the medium flow is stopped and started quickly and continuously, such as the outlet of the compressor, use a lift check valve; 

5. The check valve should determine the corresponding size, and the valve supplier needs to provide material data of the selected size, so that the valve size when the valve is fully opened at a given flow rate can be found;

6. For high and medium pressure check valves below DN50mm, vertical lift check valves and straight-through lift check valves should be used; 

7. For low-pressure check valves below DN50mm, butterfly check valves, vertical lift check valves and barrier check valves should be selected; 

8. For high and medium pressure check valves with DN greater than 50mm and less than 600mm, swing check valves should be selected; 

9. For medium and low pressure check valves with DN greater than 200mm and less than 1200mm, non-wear spherical check valves should be used; 

10. Regarding low-pressure check valves with DN greater than 50mm and less than 2000mm, Iraq chooses butterfly check valves and barrier check valves;