Single / Double / Kinetic Cast Iron
Size Range (dia.) : 20mm to 250mm
Air Valves are regularly used to provide the following requirements on water mains :
(1) To release air when the Main is being filled , and to close and remain closed when the pipe is full to prevent loss of water. Also, to open and admit air when the main is being emptied.
(2) To release air accumulating under pressure during normal working conditions in the pipe, again without loss of water.
In case of
(a) a relatively large orifice is employed giving a high rate of discharge. The valve, a buoyant ball in water, seals the orifice when main filling is complete and is held there by the line pressure until such times as the main is shut for emptying.
For
(b) the ball leaves its seating under pressure when water in the chamber is displaced by a accumulated air. A comparatively small-sized orifice is used, of a diameter sufficient to ensure reliable working, while allowing of convenient ball and casting dimensions for an ample range of regular working pressures.
