Reduced Pressure Principle Backflow Prevention Assembly (RP) shall be tested at intervals not exceeding six (6) months (annually, if installed on an irrigation system) to ensure that both check valves are drip tight under all pressure differentials and that the pressure differential relief valve will maintain pressure in the center chamber of at least two pounds per square inch below that of the inlet chamber.ĭefinition: A device composed of two tightly closing shut-off valves surrounding two independently acting pressure reducing check valves that, in turn, surround an automatic pressure differential relief valve, and four test cocks, one upstream of the five valves and one between each of the four check and shut-off valves. An approved air gap shall be at least double the diameter of the supply pipe measured vertically above the overflow rim of the vessel ? in no case less than one inch. Air Gaps (AG) shall be inspected at intervals not exceeding one (1) year to ensure that they continue to meet the requirements.ĭefinition: A physical separation between the free flowing discharge end of a potable water supply pipeline and an open or non-pressure receiving vessel.
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