a valve having a hinged flap permitting flow only in the direction in which the flap opens.

How does a clack valve work?

Steam locomotives use non-return valves, usually called 'Clack Valves', to allow fluid to pass in one direction only. Clack valves are most commonly inserted in the water feed to the boiler, allowing pressurised water to enter the boiler but preventing steam and hot water from escaping.

What is a clack valve water softener?

A Clack water softener is a device designed to be installed onto your home's incoming water supply that will remove minerals, such as calcium and magnesium, found in hard water that cause scale. ... By removing these minerals, soft water is available from outlets.