The purpose of Air Valve and Vent Inflow Preventer Assemblies is to allow the release and admission of high volumes of air through air valves and air vents in water distribution systems but prevent the entry of contaminated water when the air valve outlet becomes submerged from flooding or is the target of malicious tampering.
ANSI/ASSE 1063-2009 history
2009ANSI/ASSE 1063-2009 Performance Requirements for Air Valve and Vent Inflow Preventer