Piston check valve
A piston check valve uses a guided piston or plug that rises from its seat under forward differential pressure. As flow falls or reverses, the closure member returns to the seat and blocks reverse flow. The guided linear movement—and damping used in some piston designs—distinguishes it from compact wafer-disc and dual-plate constructions. Selection should consider the differential pressure needed to open the valve, permitted mounting orientation, pressure loss, and response to frequent flow reversals or pressure surges.
Application and duty
Backflow prevention where guided linear closure is appropriate; for rapid flow reversals or pressure surges, the need for a damped design should be evaluated separately.