Check valve refers to the industrial valve where the opening and closing part is a circular disc and acts by its own weight and medium pressure to block the back flow of the medium. Check valve is an automatic valve, also known as one way valve, cut off valve, non return valve, isolation valve, back water valve, back pressure valve.
Check valve can be divided into lift check valve(vertical lifting type check valve and horizontal lift check valve), swing type check valve( single door swing check valve, dual door swing check valve, multi door swing check valve), wafer butterfly type check valve( single door butterfly check valve, dual door butterfly check valve), ball type check valve, rubber disc check valve, diaphragm check valve, foot valve(bottom valve), slow closing check valve, silencing check valve,etc.
For different diameters required, different type of check valves are selected:
1. For high and medium pressure check valve with nominal diameter DN<50, vertical lifting type check valve and horizontal lift check valve should be used;
2. For low pressure check valves, with DN<50, the butterfly type check valve, vertical lift check valve and diaphragm check valve should be used;
3. For high and medium pressure check valves with 50<DN<600, swing type check valve should be used;
4. For medium and low pressure check valve with 200<DN<1200, wear free rubber ball type check valve should be used;
5. For low temperature check valve with 50<DN<2000, butterfly check valve and diaphragm check valve should be used;
6. For pipelines which requires less water hammer or no water hammer when it is closing, slow closing swing type check valve and slow closing butterfly type check valve should be used;