The wafer check valve is a kind of automatic valve which automatically open and close through the force generated by the flow of the media itself in the pipeline.
 
The function of wafer check valves is to allow the medium to flow only in one direction, and to prevent it from flowing in the opposite direction. Usually, the wafer check valves work automatically and the valve clacks open under the effects of the pressure from the fluid flowing in one direction. When the fluid flows in the opposite direction, the flow will be cut off because of the fluid pressure's and the valve clacks' effects on the valve seat.
 
Stainless steel wafer check valves just belongs to this kind of valves, which includes swing check valves and lift check valves. A swing check valve has a articulated mechanism and a valve clack like a door freely resting on the inclined valve seat surface. In order to ensure that the valve clack reaches the proper position of the valve seat each time, the valve clack is designed in the articulated mechanism so that it has enough swing space and is truly and fully accessible to the valve seat. The valve clack can be made entirely of metal, or it can be embedded in metal, leather, rubber, and synthetic coverage, depending on the performance requirements. In the fully open condition of swing check valves, the fluid pressure is almost unimpeded, so the pressure drop flowing through the valve is relatively small. The valve clacks of the lift check valves are located on the valve seats' sealing surfaces of the valve bodies. The lift check valves is as same as globe valves, except that the valve clacks of lift check valves. The fluid pressure lift the valve clacks from the valve seats' sealing surfaces. The flowing back of the media makes the valve clack come back to the valve seat and then cut off the flow. Depending on the conditions of use, the valve clacks may be of the all-metal structure or in the form of a rubber pad or rubber ring in the clack frame. Like globe valves, the passages of the fluid through the lift check valves are also narrow, so the pressure through lift check valves is larger than that through swing check valves and the flow of the swing check valves is less limited compared with that of the lift check valves.