Selection Criteria For Check Valves

The selection criteria of Lined Check Valve are as follows:

1. In order to prevent the backflow of the medium, check valves should be installed on equipment, devices and pipelines;

2. Check valves are generally suitable for clean media, and should not be used for media containing solid particles and high viscosity;

3. Generally, vertical lifting check valves should be used on horizontal pipelines with a nominal diameter of 50mm;

4. Straight-through lifting check valves can be installed on both horizontal and vertical pipelines;

5. For the inlet pipeline of the water pump, a foot valve should be used. The foot valve is generally only installed in the vertical pipeline at the pump inlet 6. The lifting type has better sealing than the swing type, and the fluid resistance is large. The horizontal type should be installed on the horizontal pipeline, and the vertical type should be installed on the vertical pipeline; 7. The installation position of the swing check valve is not restricted. It can be installed on the horizontal, vertical or inclined pipeline. If it is installed on the vertical pipeline, the medium should flow from bottom to top; 8. The swing check valve should not be made into a small-diameter valve. It can be made into a very high working pressure. The PN can reach 42MPa, and the DN can also be very large, up to 2000mm. According to the different materials of the shell and the seal, it can be used for any working medium and any working temperature range. The medium is water, steam, gas, corrosive medium, oil, medicine, etc. The working temperature range of the medium is between -196--800℃;

9. The applicable occasion is low pressure and large diameter, and the installation occasion is limited;

10. The installation position of the butterfly check valve is not restricted. It can be installed on the horizontal pipeline, or on the vertical or inclined pipeline;

11. The diaphragm check valve is suitable for pipelines that are prone to water hammer. The diaphragm can well eliminate the water hammer caused by the backflow of the medium. It is generally used on low-pressure and normal temperature pipelines, especially for tap water pipelines. The general medium working temperature is between -12--120℃, and the working pressure is <1.6MPa, but the diaphragm check valve can be made of larger diameter, and the maximum DN can reach to more than 2000mm;

12. Ball check valves are suitable for medium and low pressure pipelines and can be made into large diameters;

13. The shell material of the ball check valve can be made of stainless steel, and the hollow sphere of the seal can be wrapped with polytetrafluoroethylene engineering plastics, so it can also be used in pipelines of general corrosive media. The working temperature is between -101--150℃, its nominal pressure is ≤4.0MPa, and the nominal diameter range is between 200-1200;

14. When selecting a check valve for incompressible fluids, the required closing speed must be evaluated first, and the second step is to select the type of check valve that may meet the required closing speed;

15. When selecting a check valve for compressible fluids, you can choose it in a similar way to the check valve for incompressible fluids. If the medium flow range is large, a deceleration device can be used for the check valve for compressible fluids. If the medium flow stops and starts rapidly continuously, such as the outlet of a compressor, a lift check valve is used;

16. The check valve should determine the corresponding size. The valve supplier must provide data on the selected size, so that the valve size can be found when the valve is fully open at a given flow rate;

17. For high and medium pressure check valves below DN50mm, vertical lift check valves and straight lift check valves are suitable;

18. For low-pressure check valves below DN50mm, butterfly check valves, vertical lifting check valves and diaphragm check valves should be used;

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

20. For medium and low pressure check valves with DN greater than 200mm and less than 1200mm, wear-free ball check valves should be used;

21. For low-pressure check valves with DN greater than 50mm and less than 2000mm, butterfly check valves and diaphragm check valves should be used;

22. For pipelines that require relatively small or no water hammer when closing, slow-closing swing check valves and slow-closing butterfly check valves should be used