What is a pressure vacuum breaker assembly (PVB & SVB)?
A PVB is a mechanical backflow preventer that consists of an independently acting, spring-loaded check valve and an independently acting, spring-loaded, air inlet valve on the discharge side of the check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A PVB is only effective against backsiphonage and can be used to protect against health hazard and non-health hazard backsiphonage conditions in industrial plants, cooling towers, laboratories, laundries, swimming pools and lawn sprinkler systems. These must be installed 12″ above the highest piping and outlets downstream of the assembly to preclude backpressure. When installed there should be clearance for ease of repair and testing. The newest of the PVB devices is the Anti-Siphon, Spill-Resistant, Vacuum Breaker (SVB). Like the PVB, they prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage on point-of-use applications with the exceptio