The function of check valve is only to allow the medium to flow in one direction and prevent the direction from flowing. Usually, the valve operates automatically. The valve opens under the flow of fluid pressure in one direction; when the fluid flows in reverse direction, the fluid pressure and the self gravity valve disc of the valve act on the seat to cut off the flow.
Check valve common faults are:
The valve was broken;
The cause of the broken valve is:
The pressure in the front and back of the check valve is in a state of close balance and mutual "sawing". The valve flap is often flapped with the seat, and some brittle materials (such as cast iron, brass, etc.) are broken.
The way to prevent it is to use check valve with ductile material.
The reasons for the reflux of the medium are as follows:
Sealing surface damage;
Repairing sealing surface and cleaning impurities can prevent backflow.