The check valve can also be used to supply a line in which the pressure may rise to an auxiliary system that exceeds the system pressure. The check valve can be mainly divided into a swing type check valve (rotation according to the center of gravity) and a lift check valve (moving along the axis).

Check Valves The role of this type of valve is to allow only the medium to flow in one direction and to prevent flow in the opposite direction. Usually, the valve is automatically operated, and the valve flap is opened by the fluid pressure flowing in one direction; when the fluid flows in the opposite direction, the fluid pressure and the self-reclosing valve flap of the valve disc act on the valve seat to cut off the flow.

Among them, the check valve belongs to this type of valve, which includes a swing check valve and a lift check valve. The swing check valve has a hinge mechanism and a door-like flap that rests freely against the inclined seat surface. In order to ensure that the valve flap can reach the proper position of the valve seat surface each time, the valve flap is designed in the hinge mechanism, so that the valve flap has enough swinging space and the valve flap is truly and comprehensively in contact with the valve seat. The flaps can all be made of metal, or they can be inlaid with leather, rubber, or synthetic coverings depending on the performance requirements. With the swing-open check valve fully open, the fluid pressure is almost unimpeded, so the pressure drop across the valve is relatively small. The valve flap of the lift check valve is located on the valve seat sealing surface of the valve body.