scope:

Description

These devices are installed in the potable water supply lines to prevent the backflow of non-potable material into the potable water supply caused by backsiphonage only. They are not for use in any system where back pressure is applied to the device. When the system is pressurized, the vent closes to prevent a flow through the upstream check valve and to eliminate vent spillage. They are designed for installation in those portions of the domestic potable water systems that are normally under continuous pressure conditions. The device includes one check valve force-loaded closed and an air inlet vent valve force loaded open to atmosphere, positioned downstream of the check valve, and located between and including two tightly closing shut-off valves and two test cocks.