Check Valve

A valve that permits the passage of a liquid or gas in one direction only. It stops, or checks, reverse flow.

Also known as a clack valve, from the noise it makes.

Photograph courtesy of

In boilers they are usually mounted halfway along the boiler drum, or else as a top feed, but away from the firebox, so as to avoid stressing it with the shock of cold water.

Types include:


The hinged closure element of a swing check valve.

See also: Ball Check Valve, Flow Control Valve, Swing Check Valve.

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Subjects: Mechanical Engineering

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