The Double Check Valve Device Assembly (DCVA) – Flow or Dynamic State with Backpressure Second and First Check Valve Fouled Open
During a normal flow condition with a demand downstream, the check valves are open. If a backpressure condition were to occur, the second and first check vales would close if they were not fouled or not operating properly. If the second check was fouled open, it would not close and the high-pressure backpressure water would be introduced downstream of the first check through the fouled second check valve and close the first check valve. If the first check was fouled open, as well, no protection would be provided and non-potable water will be introduced into the potable water system. The amount of non-potable water entering the potable water system is depending on the degree of the fouled check valves. If the check valves were fouled by a small amount of debris a small amount of non-potable water would enter the potable water system. If the check valve disks were badly damaged a large amount of non-potable may enter the potable water system. The DCVA is not providing protection and the status or condition of the check valves can only be determined at the time that the DCVA is tested.