Valve

An apparatus connected with the engines, boilers, etc, to permit the free pa age, or check or regulate the flow of water, air or steam. The opening of the valve is effected through the pre ure of the contained fluid against the valve, or vice vers a, or by some contrived mechanism in connection with it. Valves vary in form and mode of action, and are often named after their shape; as „Ball-valve”,..Conical-valve”, „Cap-valve”; or after their position; as „Head-valve”, „ Foot-valve”, etc.