Wafer check valves are in-line pipe valves used to control the direction of flow of fluids and reduce or completely prevent potential backflow in piping systems. Wafer check valves are also known as reflux valves, non-return valves, and one-way valves. This type of valve is designed to automatically eliminate the backflow of fluids that can occur when a process system is shut down.
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These valves have a hinged, valve-like disc (the wafer) that is used to admit and restrict fluid flow. This disc opens in one direction only and closes under back pressure to seal the valve against an opposing fluid flow.
Wafer check valves require a minimum amount of system fluid pressure to operate. The check valve opens when the upstream pressure is greater than the downstream pressure and closes when the downstream pressure is greater than the upstream pressure.
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Although at first glance this may seem like just a matter of space, the presence of a valve body, unlike the bare wafer check valve, makes a big difference in the valve's functionality. As flanged check valves sit in place, there is not much room for the disc to open in the pipe. This means that flow in the check valve is often restricted.
Wafer check valves, on the other hand, have a molded body that creates space for the disc to swing fully open, allowing full flow. As you can imagine, this is very important if your application requires full flow.