I Think you've answered your own question. "The secondary water supply shall have a duration of not less than 30 minutes as determined by the occupancy hazard classification in accordance with NFPA 13." 13 doesn't specify standpipe demands. The one I've done in the past was only required to maintain sprinkler durations, not standpipe operations.
Jamie Seidl -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Fairchild, Jack Sent: Thursday, December 22, 2011 8:39 AM To: [email protected] Subject: Pressure Requirements for Secondary Onsite Water Supply To those in urban seismic areas: When required to provide the onsite secondary water supply, is the pump/tank required to provide 100 psi at the top of a combination standpipe or just sprinkler pressure demand? I have a situation where the city/pump combination can meet the standpipe pressure demands at the top, but the tank/pump doesn't. I have two projects with new high rise buildings being constructed. Both are campus style pumping arrangements (no underground pipe). One of the projects has an existing pump/tank combination which was not designed to meet 100 psi at the top based on tank alone. The combination pump/city supply does meet the standpipe pressure demand, but not the pump/tank. The other project has a pump/city supply which I am adding a pump/tank to. The new pump is redundancy only. Adding the tank without increasing the pump size will not provide 100 psi at the top. [F] 903.3.5.2 Secondary 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 assigned to Seismic Design Category C, D, E or F as determined by this code. The secondary water supply shall have a duration of not less than 30 minutes as determined by the occupancy hazard classification in accordance with NFPA 13. Exception: Existing buildings. Jack Fairchild _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
