The Double Check Valve Device Assembly – Flow or Dynamic State with Backsiphonage First and Second Check Valve Fouled Open
During the normal operations of a DCVA, the springs loaded check valves are closed when there is no demand downstream. When there is a demand downstream, the spring loaded check valves will open except when there is a backsiphonage backflow occurrence in the inlet water supply piping system. When this occurs, pressure upstream of the first check valve is sup-atmospheric. Because of the backsiphonage situation in the inlet water piping system, the DCVA is in a static state and the first and second check valves will close tight, if not fouled or not working properly. If the first and second check valves are both not holding tight non-potable water in entering the potable water system. The open check valves are preventing non-potable from siphoning back into the potable water system. The DCVA is NOT providing protection. A DCVA that is not operating as designed will not show any noticeable symptoms. The status or condition of the check valves can only be determined at the time that the DCVA is tested.