AIR RELEASE VALVE

An air release valve, used in a system containing liquid with gas above it, has a float chamber connected to the system and containing a float which normally closes a primary orifice leading through a vertically movable springloaded piston to an upper chamber. When the piston is raised by gas pressure in the float chamber to open the primary orifice, a seal pad, spring-mounted above the piston, closes a secondary orifice from the top chamber to atmosphere until the increased pressure in the top chamber moves the piston down to open the secondary orifice. When liquid entering the float chamber causes the float to rise, closing the primary orifice and lifting the piston, the seal pad closes the secondary orifice, trapped gas lowers the liquid and float, and the primary orifice opens.