(1) Air gap. The unobstructed vertical distance through the free atmosphere between the opening of the pipe or faucet supplying potable water to a tank, plumbing fixture, or other device. An approved air gap shall be at least double the diameter of the supply pipe or faucet and in no case less than one inch.
(2) Reduced pressure principle assembly (hereinafter “RPA”). An assembly containing two independent acting approved check valves together with a hydraulically operating, mechanically independent pressure differential relief valve located between the check valves, and at the same time below the first check valve. The assembly shall include properly located test cocks and tightly closing shut-off valves located at each end of the assembly and fitted with properly located test cocks.
(3) Double check valve assembly (hereinafter “DCVA”). An assembly composed of two independently acting, approved check valves, including tightly closing shut-off valves located at each end of the assembly and fitted with properly located test cocks.
(4) Pressure vacuum breaker assembly (hereinafter “PVB”). An assembly containing an independently operating, loaded check valve and an independently operating, loaded air inlet valve located on the discharge side of the check valve. The assembly shall be equipped with properly located test cocks and tightly closing shut-off valves located at each end of the assembly.
(B) A backflow prevention assembly may be approved by the Department if it has received the approval of the Foundation for Cross-Connection Control and Hydraulic Research of the University of Southern California and has conformed to the 1991 Edition of the UPC.
(C) The Department shall maintain a list of approved backflow prevention assemblies, by type and manufacturer. The list shall be available to any customer required to install a backflow prevention assembly.
(Prior Code, § 14-10-4)