GA Air & Vacuum Valves automatically exhaust large volumes of air from the system when it is being filled and admit large volumes of air when the line is emptied. When the system is filled, the fluid lifts the float until it closes the orifice. When the system is drained or a negative pressure occurs, the float drops and opens the valve, admitting air to prevent vacuum formation and protect the system from damage.
Air & Vacuum Valves are used in water transmission lines and sewage force mains. They are typically installed on the discharge side of deep well turbine pumps, between the pump and the discharge check valve, to exhaust air each time the pump starts and break the vacuum when the pump stops.