The Double Check Valve Device Assembly

The double check valve device assembly (DCVA) is a backflow prevention device used for backflow prevention of low hazard non-potable water into a potable water system or to separate two potable water system. It consists of two independently acting spring load closed check valves and four test cocks. The spring loading provides the ability to bite through small debris and still seal, a protection feature not prevalent in unloaded swing check valves. The DCVA can be tested in-line to evaluate the operation of the check valves to close drip tight. The DCVA can also be repaired in-line (in-line means not having to physically remove the device). The DCVA should be tested at least annually by a certified tester. Unlike the RPZ, the DCVA will not visually indicate check value failures. Therefore, periodic testing may be required, since the only time that it is know that the DCVA is working properly is when it is tested.

If a backflow condition were to occur both check valve would close tight. If the first check valve was fouled open with debris and it could not close, the second check would hold tight and the device would still provide protection. If the second check were fouled as well under a backflow condition, the device would not offer protection. For these reasons, this device shall be tested annually and used for low hazard situations only.

The DCVA is used for direct cross-connections applications to prevent backpressure and backsiphonage situations. The DCVA is inline testable and repairable and is equipped with upstream and downstream shut-off valves. The test cocks are located on the upstream and downstream of each check valve. The DCVA may be subjected to continuous or intermittent pressure conditions, The DCVA shall comply with the American Society Sanitary Engineering 1015 Standard.