The Principle Operation of a Dual Check Valve with Intermediate Atmospheric Vent – Backflow Prevention Device – No Water Out of the Box
This DCVwIV contains an intermediate atmospheric vent positioned between two spring-loaded check valves. With no water in the DCVwIV, the check valves are close by the springs and the intermediate atmospheric vent is open. The intermediate atmospheric vent closes when a diaphragm seal is activated by pressure introduced into the supply side of the check valve. The positive supply pressure holds the diaphragm seal in place to close off the atmospheric vent.
