The Principle Operation of a Dual Check Valve Backflow Prevention Device – Installation Considerations
The DuCV uses two compact replaceable check modules and is typically installed immediately downstream of the residential water meter. The DuCV can be installed in a vertical or horizontal position and can only be used to control low hazard cross-connections. The DuCV is intended to be used on cold water line but it may be used on hot water lines as specified by the manufacturer. The DuCv shall be installed where it can be easily maintained. This is not a testable backflow prevention device and should be replaced as specified by the manufacture or responsible authority. The DuCv shall be protected from freezing and shall be installed where the water temperature does not exceed 180 degrees or the water pressure does not exceed 175 psi. Servicing the DuCV involves replacing the check valve assemblies.
Some DuCV series are designed to be installed on residential fire sprinkler systems that are classified as low hazard cross-connections. The DuCV designed for potable fire sprinkler service connections have pressure drops across the DuCV of 6 psi at 30 gpm and installed to protect against possible backsiphonage conditions that could inadvertently drain the fire sprinkler system.