Check valve, a automatic working valve, can be classified into several categories that under different condition and purpose, the selection is different.

1. The check valve is generally suitable to clean fluid, and not the fluid containing of solid particle and high viscosity.

2. For the low pressure check valve under DN 50mm, it is better to choose the butterfly swing check valve, vertical lift check valve and diaphragm check valve. For the low and medium pressure check valve with DN over 200mm and under 1200mm, it is better to choose the in-gage ball valve. For the low pressure check valve with DN over 50mm and under 2000mm, it is better to choose the butterfly swing check valve and diaphragm check valve.

3. The diaphragm check valve is offen applied on the pipeline which is easily generate hydraulic shock for the diaphragm removing the hydraulic shock generated by the fluid backflow. However, because of the limited pressure, it is commonly used on the normal temperature pipeline.

4. For the pipeline with light or no hydraulic shock when be closed, it is better to choose the slow closing swing check valve or the slow closing butterfly swing check valve.