What is meant by approved backflow preventer?
An approved backflow preventer means one of the following: Approved air gap An air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. An air gap is considered the maximum protection available against back pressure backflow or back siphonage, but is not always practical and can easily be bypassed. Double check backflow assembly (DC) A DC is a testable mechanical backflow preventer that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks (required to be tested annually by a State Licensed Tester) against back pressure backflow and back siphonage, but should be used only on non-health hazards. Reduced pressure principle backflow assembly (RP) An RP is a testable mechanical backflow preventer that consists of
