403.3.1 Number of sprinkler risers and system design.

Each sprinkler system zone in buildings that are more than 300 feet (91 440 mm) in building height shall be supplied by no fewer than two risers. Each riser shall supply sprinklers on alternate floors. If more than two risers are provided for a zone, sprinklers on adjacent floors shall not be supplied from the same riser.

403.3.1.1 Riser location.

Sprinkler risers shall be placed in interior exit stairways and ramps that are remotely located in accordance with Section 1007.1.

403.3.2 Water supply to required fire pumps.

Required fire pumps shall be provided with water supplies in accordance with Section 905.2 and NFPA 14 as modified by Appendix Q of this code.

403.3.3 Secondary on-site water supply.

A secondary on-site water supply equal to the hydraulically calculated sprinkler demand, including the hose stream requirement, shall be provided for high-rise buildings in Seismic Design Category C or D as determined by this code, and in any high-rise building with occupied floors located more than 500 feet (152 m) above the lowest level of fire department vehicle access. The secondary on-site water supply shall have a duration of not less than 30 minutes as determined by the occupancy hazard classification in accordance with NFPA 13 as modified by Appendix Q of this code.

403.3.4 Fire pump room.

Fire pumps shall be located in rooms protected in accordance with Section 913.2.1.