Swing / Wafer Check Valve

Overview

A check valve lets fluid pass in one direction and blocks it in the other, entirely on its own. There is no handwheel, motor, or signal: forward flow pushes the closure open, and the moment flow stalls or reverses, backpressure pushes it shut. That makes it the standard guard on a pump discharge, where it stops the column of liquid from spinning the pump backward when it trips, and at any point where reverse flow would contaminate, drain, or damage the system.

The Valve Body shapes the flow so the closure swings or lifts clear when open and lands on the Seat Ring when flow reverses. A swing design carries a hinged Swing Check Valve Disc and Hinge; a compact wafer or nozzle design uses a Spring Check Valve Poppet instead. The Access Cover gives access for service, the Arm & Stop limits how far the disc swings, and the Flange Set mounts the valve in the line.

How it works

In a swing check, the Swing Disc / Clapper hangs from a Hinge Pin set above the bore. Forward flow swings it up and out of the way until the Travel Stop catches the arm; when flow drops, gravity plus reverse pressure swings it back onto the seat, and a soft Disc Facing conforms for a drop-tight seal. The weakness of a plain swing disc is slam: if flow reverses fast, the disc accelerates shut and bangs the seat, sending a pressure spike, water hammer, back up the line.

The spring-loaded Spring Check Valve Poppet answers that. Its Poppet Disc moves only a short axial distance and a Coil Spring starts closing it the instant forward flow eases, so it reseats before the column can build reverse velocity. A Poppet Guide keeps the poppet square to the seat through that travel. The trade-off is a slightly higher cracking pressure, the small forward pressure needed to open the valve against the spring. Both designs share the same job, pass flow one way, seal it the other, and the choice between them comes down to how violently the system can reverse.