Atmospheric vacuum breakers from T&S Brass prevent siphoning and back-flow of non-potable liquids into the drinking water line. Atmospheric vacuum breakers have a vented hood cover on top that allows air to enter if siphoning occurs. A plunger inside the assembly is held up by the water pressure as it flows though, blocking the hood air entrance. If the water pressure is reduced to atmospheric pressure or below, air enters and causes the plunger to drop - successfully stopping the siphon.
