A non-return valve allowing atmospheric air into a boiler, if a cold boiler reduces its internal pressure on cooling down.

An automatic non-return valve that opens when the boiler is at less than atmospheric pressure so as to avoid any risk of vacuum collapse when a hot boiler is allowed to cool down out of service.

plural of vacuum valve

A blowdown valve mounted at the water level of a boiler, used to blow down lighter oily or foamy deposits that float on the water.

plural of scum valve

plural of heart valve

plural of semilunar valve

(anatomy) Either of the two crescent-shaped valves in the heart that prevent backflow from the arteries into the ventricles.

(anatomy) ileocecal valve

(anatomy) ileocecal valve