The disc of valve open or close by medium flow is called check valve which is a kind of automatic valve for one-way flow of the pipeline, that is only allowed medium flows in one direction of the pipeline system. The check valve is used to prevent the backflow of medium, the pump and drive motor reversal and the discharge of the container medium. Check valves should be installed in the pump outlet or front of the control valve for maintaining convenience.

According to its internal construction of the valve, check valve can be divided into swing check valve (rotating according to the center of gravity) and piston/lift check valve (moving along the axis). Swing check valves are the most commonly used types.