An air-operated valve is a type of power operated valve that uses air pressure against a piston or diaphragm to produce linear or circular movement to operate avalve. Types are 2-way, 3-way and 4-way. The 2 way air-operated valves can be either normally closed or normally opened.

Air release valves are used in pressurized pipe work systems to vent off unwantedair within them. Trapped air rises and collects within the high points of the system. … As air is vented water fills the valve, raising the float until the valve seat is pushed back against the orifice closing it off from atmosphere again.