In addition to the requirements of section 27-75 the following shall also apply.
(a) Fire systems:
(1) Fire protection systems may consist of sprinklers, hose connections, and hydrants. Sprinkler systems may be dry or wet, open or closed. Systems consisting of fixed-spray nozzles may be used indoors or outdoors for protection of flammable-liquid and other hazardous processes. It is standard practice, especially in cities, to equip automatic sprinkler systems with fire department pumper connections.
(2) A meter (compound, detector check) should not normally be permitted as part of a backflow prevention assembly. An exception may be made, however, if the meter and backflow prevention assembly are specifically designed for that purpose.
(3) For cross-connection control, fire protection systems shall be classified on the basis of water source and arrangement of supplies as follows:
a. Class 1: 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.
b. Class 2: Same as class 1, except that booster pumps may be installed in the connections from the street mains. It is necessary to avoid drafting so much water that pressure in the water main is reduced below twenty (20) psi.
c. Class 3: Direct connection from public water supply main plus one (1) 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 are filled or connected to public water only, the water in the tanks to be maintained in a potable condition).
Otherwise, Class 3 systems are the same as class 1. Class 3 systems will generally require minimum protection (approved double check valves) to prevent stagnant waters from backflowing into the public potable water system.
d. Class 4: Directly supplied from public mains similar to classes 1 and 2, and with an auxiliary water supply on or available to the premises; or an auxiliary supply may be located within seventeen hundred (1,700) feet of the pumper connection. Class 4 systems will normally require backflow protection at the service connection. The type (air gap or reduced pressure) will generally depend on the quality of the auxiliary supply.
e. Class 5: 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. Classes 4 and 5 systems normally would need maximum protection (air gap or reduced pressure) to protect the public water system.
f. Class 6: Combined industrial and fire protection systems supplied from the public water mains only, with or without gravity storage or pump suction tanks. Class 6 system protection would depend on the requirements of both industry and fire protection, and could only be determined by a survey of the premises.
(b) Installation of assembly: When a backflow prevention assembly is required for a water service connection supplying water only to a fire system, the assembly shall be installed on the service line in compliance with standard specifications adopted by the city. (Installation of DCVA's or DDCVA's in a vertical position on the riser may be allowed on fire systems with Tucson Water approval.)
(Ord. No. 9976, § 2, 5-24-04)