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

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

4. The straight lift check valve can be installed on both horizontal and vertical pipelines;

5. For the inlet pipeline of the water pump, a bottom valve should be selected. The bottom valve is generally only installed on the vertical pipeline of the pump inlet, and the medium flows from bottom to top;

6. The lifting and rotating type has good sealing performance and high fluid resistance. It is recommended to install it on horizontal pipelines for horizontal installations and vertical pipelines for vertical installations;

7. The installation position of the swing check valve is not limited. It can be installed on horizontal, vertical, or inclined pipelines. If installed on vertical pipelines, the flow direction of the medium should be from bottom to top;

8. The swing check valve should not be made into a small diameter valve, but can be made into a high working pressure. The PN can reach 42MPa, and the DN can also be large, with a maximum of 2000mm or more. According to the different materials of the shell and sealing components, it can be suitable for any working medium and any working temperature range. The media include water, steam, gas, corrosive media, oil products, drugs, etc. The working temperature range of the medium is between -196-800 ℃;

9. Applicable occasions are low voltage and large caliber, and installation occasions are limited;

10. The installation position of butterfly check valves is not limited and can be installed on horizontal pipelines, as well as vertical or inclined pipelines;

11. Diaphragm check valves are suitable for pipelines that are prone to water hammer. Diaphragms can effectively eliminate water hammer caused by reverse flow of media. They are generally used in low-pressure and normal temperature pipelines, especially in tap water pipelines. Generally, the working temperature of the media is between -12 and 120 ℃, and the working pressure is less than 1.6MPa. However, diaphragm check valves can achieve larger diameters, with a maximum DN of 2000mm or more;

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

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

14.When selecting check valves for incompressible fluids, the first step is to evaluate the required closing speed, 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, the selection can be based on a similar method of using a 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 quickly and continuously, such as at the outlet of a compressor, a lift check valve can be used;

16. The response size of the check valve should be determined, and the valve supplier must provide information and 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 through lift check valves should be selected;

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

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

20. For medium and low pressure check valves with DN greater than 200mm and less than 1200mm, it is advisable to choose a wear free spherical check valve;

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

22. For pipelines that require low water hammer or no water hammer during closure, slow closing swing check valves and slow closing butterfly check valves should be selected.