Most applications for Air Valves require air to be exhausted both at start-up and while operating, in addition to incorporating vacuum protection during draining. The GA Combination Air Valve consists of an Air & Vacuum Valve and an Air Release valve. At start-up both valves exhaust air as the system is filled. Once the air is purged, the valve float is lifted by liquid closes the valve. Small pockets of air entering the valve displace the liquid and lower the float, allowing the Air Release valve to open and exhaust the air. When the system pressure drops, the float drops and opens both valves, admitting large amounts of air to prevent critical vacuum conditions.
Combination Air Valves are primarily used on water mains, transmission lines and sewage force mains. They are also used at the discharge of pumps, especially deep well turbine pumps.