The Double Check Valve Device Assembly – Flow or Dynamic State with Backsiphonage First and Second Check Valves Holding Tight
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 static state and the first check valve will close tight if not fouled or not working properly. There is positive pressure downstream of both check valves.The second check valve will close tight holding back pressurized non-potable water. If the check valves are closed tight, a siphoning situation of the non-potable water is prevented. The closed check valves prevents non-potable from siphoning back into the potable water system. The DCVA is providing protection. If the second check valve was fouled with debris and could not close tight, the first check would hold tight and the device would still provide protection. If the first check were fouled as well under a backsiphonage condition, the device would not offer protection.
