Application of check valve

Application of check valve

The purpose of using check valve is to prevent the reverse flow of medium. Generally, check valve shall be installed at the outlet of pump. In addition, a check valve shall also be installed at the outlet of the compressor. In short, in order to prevent the reverse flow of medium, check valves should be installed on equipment, devices or pipelines.

Generally, vertical lifting check valves are selected on horizontal pipelines with a nominal diameter of 50mm. Straight through lift check valves can be installed on both horizontal and vertical pipelines. The bottom valve is generally only installed on the vertical pipeline at the pump inlet, and the medium flows from bottom to top.

Swing check valve can be made into high working pressure, PN can reach 42MPa, and DN can also be very large, up to more than 2000mm. According to the different materials of the shell and seal, it can be applicable to any working medium and any working temperature range. The medium is water, steam, gas, corrosive medium, oil, food, medicine, etc. The working temperature range of the medium is - 196 ~ 800 ℃.

The installation position of swing check valve is not limited. It is usually installed on horizontal pipeline, but it can also be installed on vertical pipeline or inclined pipeline.

Butterfly check valve is suitable for low pressure and large diameter, and the installation occasion is limited. Because the working pressure of butterfly check valve can not be very high, but the nominal diameter can be very large, which can reach more than 2000mm, but the nominal pressure is below 6.4Mpa. Butterfly check valves can be made into wafer type, which are generally installed between the two flanges of the pipeline in the form of wafer connection.

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

Diaphragm check valve is suitable for pipelines prone to water hammer. The diaphragm can well eliminate the water hammer caused by medium countercurrent. As the working temperature and working pressure of diaphragm check valve are limited by diaphragm material, it is generally used in low-pressure and normal temperature pipeline, especially suitable for tap water pipeline. Generally, the working temperature of the medium is between - 20 ~ 120 ℃ and the working pressure is less than 1.6Mpa, but the diaphragm check valve can achieve a larger diameter, and the maximum DN can be more than 2000mm.

Diaphragm check valve is widely used in recent years because of its excellent waterproof performance, simple structure and low manufacturing cost.

Because the sealing element of the spherical check valve is a sphere coated with rubber, it has good sealing performance, reliable operation and good water hammer resistance; And because the seal can be single ball or multi ball, it can be made into large diameter. However, its seal is a hollow sphere coated with rubber, which is not suitable for high-pressure pipelines, but only for medium and low-pressure pipelines.

Because the shell material of the spherical check valve can be made of stainless steel, and the hollow sphere of the seal can be coated with polytetrafluoroethylene engineering plastic, it can also be used in the pipeline of general corrosive media.

The working temperature of this kind of check valve is between - 101 ~ 150 ℃, its nominal pressure is ≤ 4.0Mpa, and the nominal diameter range is between 200 ~ 1200mm.