The minimum air gap to afford backflow protection shall be in accordance with the following chart:
A. Atmospheric Vacuum Breaker (AVB): An atmospheric vacuum breaker consists of a body, a checking member and an atmospheric opening.
B. Double Check Valve Backflow Prevention Assembly (DC): A double check valve backflow prevention assembly consists of two (2) independently acting internally loaded check valves, four (4) properly located test cocks and two (2) isolation valves.
C. Pressure Vacuum Breaker Backflow Prevention Assembly (PVB): A pressure vacuum breaker backflow prevention assembly consists of a loaded air inlet valve, an internally loaded check valve, two (2) properly located test cocks and two (2) isolation valves.
D. Reduced Pressure Principle Backflow Prevention Assembly (RP): A reduced pressure principle backflow prevention assembly consists of two (2) independently acting internally loaded check valves, a differential pressure relief valve, four (4) properly located test cocks and two (2) isolation valves. (Ord. 938, 6-3-1991)