Check valve is also called one-way valve or non-return valve. Check valve on-off part depends on the medium flow and its weight to achieve the valve open and close, preventing of the medium back flow. Check valve is automatic valve. Check valve is mainly used on to the one way flow pipe, and only allows the medium flow in one direction, preventing of accidents happened.

Check valve can be divided into lift type check valve, swing type check valve and butterfly type check valve. Lift type check valve can be divided into vertical type lift check valve and horizontal type lift check valve. Swing type check valve can be divided into single disc type swing check valve, dual-plate type swing check valve and multi-plate swing check valve. Butterfly type check valve is straight-through type check valve. Check valve connection type can be threaded, flanged and welded.

Check valve should not bear the pipe weight, and large sized check valve should be supported independently. The direction of arrow on the check valve body should be in accordance with medium flow direction. Lift check valve with vertical disc should be mounted on the vertical pipe, while lift check valve with horizontal disc should be mounted on the horizontal pipe.