This standard applies to devices classified as atmospheric type vacuum breakers that are single
pipe-applied (does notapplytot ank ballcocksorsimilardevicest hatdepend on floatoperatedv alves
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 backsiphonageconditions. a small amount ofwater is permitted toexit through the air ports.