Performance Requirements for Atmospheric Type Vacuum Breakers (ANSI approved 2009)
Applies to atmospheric type vacuum breakers that are single pipe-applied (does not apply to tank ball cocks or similar devices that depend on float operated valves to control flow). The purpose of these devices is to provide protection of the potable water supply against pollutants or contaminants that enter the system due to backsiphonage through the outlet. Under backsiphonage conditions, a small amount of water is permitted to exit through the air ports.
A downloadable version of this standard is also available.