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Hydraulically calculated sprinkler systems shall be acceptable. Pipe friction losses shall be determined by the Hazen and Williams friction loss formula. The design area shall be the hydraulically most remote area. All sprinklers shall discharge at a flow rate at least equal to the design density times the area covered per head. The equivalent pipe length method shall be used for all fittings, valves, strainers and any other parts.
The “C” factor in the Hazen and Williams formula shall be as follows:
Pipe | “C” Factor |
Unlimited cast or ductile iron | 100 |
Black steel (dry and pre-action systems) | 100 |
Black steel (wet and deluge systems) | 120 |
Galvanized | 120 |
Cement lined cast or ductile iron | 140 |
Copper | 150 |
The design densities and area shall not be less than the following:
Occupancy | Density | Area |
Class A and B | .10 GPM square feet | 1,500 square feet |
Class C, D and E | .12 | 1,500 square feet |
Class F, G and H with ceiling heights to 14 feet | .20 | 2,000 square feet |
Class F, G and H with ceiling heights over 14 feet | .25 | 2,500 square feet |
Class I and those occupancies listed in Section 15-16-240 | .30 | 2,500 square feet |
For dry pipe sprinkler systems the area of application shall be increased 30 percent.
In buildings with mixed occupancies the design density and area of application for the different occupancies shall be applied to each occupancy. In buildings of Class A, B, C, D, or E occupancy class those areas used for storage or building maintenance shop purposes shall be sprinkled on the basis of an industrial occupancy. Spaces used for heating, ventilation, and air conditioning equipment shall have a density of .15 GPM/square feet over an area of 1,500 square feet.
Sprinkler systems using sprinklers with discharge orifices other than one-half inch in diameter shall be hydraulically calculated.
A safety factor, not less than five pounds per square inch, shall be provided between the calculated pressure requirement of a system and the water pressure available in the city water main supplying a hydraulically calculated system. The available city water pressure shall be determined by a water flow test at the site of the building conducted within the previous 12 months. The factor of safety shall be applied to the city pressure which is available at a flow of 1,000 gallons per minute or the calculated flow required for the sprinkler system whichever is greater.
(Prior code § 91-44; Amend Coun. J. 10-30-96, p. 31216, § 1)