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(A) An approved backflow prevention assembly of the type designated shall be installed on each fire protection service to any premises where the fire protection system contains any of the following components unless the Public Works Department determines that no real or potential hazard to the public water system exists. Fire systems may be divided into six general classes. The following are typical:
Direct connections from public water mains only; no pumps, tanks, or reservoirs; no physical connection from other water supplies; no antifreeze or other additives of any kind; all sprinkler drains discharging to atmosphere, dry wells, or other safe outlets.
DCVA or DDCVA
Same as Class 1, except that booster pumps may be installed in the connections from the street mains (booster pumps do not affect the potability of the system). It is necessary, however, to avoid drawing so much water that pressure in the water main is reduced below 20 psi.
DCVA or DDCVA
Direct connection from public water supply mains, or plus one or more of the following: elevated storage tanks; fire pumps taking suction from above ground covered reservoirs or tanks; and pressure tanks. (All storage facilities that are filled or connected to public water only, the water in the tanks are to be maintained in a potable condition. Otherwise, Class 3 systems are the same as Class 1.)
DCVA or DDCVA
Directly supplied from public mains, similar to Class 1 and Class 2, with an auxiliary water supply dedicated to fire department use and available to the premises, such as an auxiliary supply located within 1700 ft. (518 m) of the pumper connection.
Directly supplied from public mains and interconnected with auxiliary supplies, such as pumps taking suction from reservoirs exposed to contamination, or rivers and ponds; driven wells; mills or other industrial water systems; or where antifreeze or other additives are used.
Combined industrial and fire protection systems supplied from the public water mains only, with or without gravity storage or pump suction tanks.
(B) Special considerations for fire systems or fire-fighting equipment.
(1) Pressure in the public potable water main shall not be reduced below 20 PSI as a result of the fire fighting activities.
(2) Foam trucks or fire-fighting vehicles shall not be able to contaminate the public potable water supply. Necessary precautions shall be taken and BFP assemblies should be used where feasible.
(3) Pressure loss across BFP assemblies can be as much as 14 psi. The design of new fire systems should incorporate this pressure loss. Existing fire systems retrofitting BFP assemblies should determine if pressure loss across the BFP device will cause the fire system to become ineffective or non-functional for fire-fighting activities.
(Ord. 1212, passed 9-7-06)