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 612.5.3.2 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.