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612.5 Sprinkler Piping Design
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The minimum flow rate and pressure for each residential sprinkler shall be in accordance with the manufacturer's published data for the specific sprinkler model based on the following:
- The area of coverage.
- The ceiling configuration.
- The temperature rating.
- Additional conditions specified by the sprinkler manufacturer.
The flow rate used for sizing the sprinkler piping system shall be based on the following:
- The flow rate for a room having only one sprinkler shall be the flow rate required for the sprinkler in accordance with Section 6188.8.131.52.
- The flow rate for a room having two or more sprinklers shall be determined by identifying the sprinkler in the room with the highest required flow rate in accordance with Section 6184.108.40.206 and multiplying that flow rate by 2.
- Where the sprinkler manufacturer specifies different criteria for ceiling configurations that are not smooth, flat, and horizontal the required flow rate for that room shall be in accordance with the sprinkler manufacturer's instructions.
- The flow rate used for sizing the sprinkler system shall be the flow required by the room with the largest flow rate in accordance with Section 6220.127.116.11(1), Section 618.104.22.168(2), and Section 622.214.171.124(3).
- For the purpose of this section, it shall be permissible to reduce the flow rate for a room by subdividing the space into two or more rooms, where each room is evaluated separately on the required design flow rate. Each room shall be bounded by walls and a ceiling. Openings in walls shall have a lintel not less than 8 inches (203 mm) in depth, and each lintel shall form a solid barrier between the ceiling and the top of the opening.
Attached garages, and carports with habitable space above shall be protected by fire sprinklers in accordance with this section and Section R313. Protection shall be provided in accordance with one of the following:
- Residential Sprinklers installed in accordance with their listing.
- Extended Coverage sprinklers discharging water not less than their listed flow rate for Light Hazard in accordance with NFPA 13.
- Quick-Response spray sprinklers at light hazard
spacing in accordance with NFPA 13 designed
to discharge at 0.05 gpm/ft2 density (minimum).
The system demand shall be permitted to be limited to the number of sprinklers in the compartment but shall not exceed two sprinklers for hydraulic calculation purposes. Garage doors shall not be considered obstructions and shall be permitted to be ignored for placement and calculation of sprinklers.
The water supply for a multipurpose or stand-alone sprinkler system shall be provided by the public water main, private water main, private well system, or storage tank. The water supply required shall be determined in accordance with Section 6126.96.36.199 at a pressure not less than that used in accordance with Section 612.5.3. Where a water supply serves both domestic and fire sprinkler systems, 5 gpm (19 L/min) shall be added to the sprinkler system demand at the point where the systems are connected, to determine the size of common piping and the size of the total water supply requirements where no provision is made to prevent flow into the domestic water system upon operation of a sprinkler.
The water supply shall have the capacity to provide the required flow rate to the sprinklers for a period of time as follows:
- Seven minutes for one story dwelling units less than 2000 square feet (185.8 m2) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.
- Ten minutes for multi-level dwelling units and one story dwelling units not less than 2000 square feet (185.8 m2) in the area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies, and patios shall not be included.
The sprinkler piping shall be sized for the flow rate in accordance with Section 612.5.1. The flow rate required to supply the plumbing fixtures shall not be required to be added to the sprinkler design flow for multipurpose or stand alone piping systems. The sizing of the water supply to the plumbing fixtures shall be determined in accordance with this chapter. For multipurpose piping systems, the largest pipe size required based on either the sprinkler piping calculations or the water distribution piping calculations shall be installed.
The sprinkler pipe shall be sized using the prescriptive method in Section 6188.8.131.52 or by hydraulic calculation in accordance with NFPA 13D. The sprinkler pipe size from the water supply source to a sprinkler shall be not less than 3/4 of an inch (20 mm) in diameter. Threaded adapter fittings at the point where sprinklers are attached to the piping shall be not less than 1/2 of an inch (15 mm) in diameter.