The Principle Operation of a Hose Connection Dual Check Valve Vacuum Breaker – Backflow Prevention Device – General Specifications
The hose connection dual check valve (HCDCV) is a backflow prevention device that is equipped with two independently acting spring loaded check valves, force loaded to normally closed and an atmospheric vent located between the check valves. The HCDCV is threaded on the inlet and outlet for hose connections and can be screwed directly to the sill cock. The inlet and outlet connections are ¾ inch standard female and male hose thread. Some HCDCV are equipped with break-away set screws located on the inlet side while other are equipped with a non-removable thread design. The HCDCV is designed to be used to control high hazard cross-connections and can be used to control a backsiphonage or low-head backpressure condition not greater than 4.33 psi associated with hose connections. The HCDCV is not suitable for continuous pressure condition for more than 12 hours. Since the HCDCV is equipped with an atmospheric vent mechanism similar to that of a hose bibb vacuum breaker, the HCDCV should not be used for continuous pressure because the atmospheric vent diaphragm may stick to the vent openings, making the potable water system vulnerable to backflow hazards.
The HCDCV can be tested in-line without the use of test gauges or instruments. The HCDCV shall comply with ASSE Standard 1052.