You are correct my ski-bumming amigo. Because we're in seismic country, the building code has long required an on-site auxiliary water supply equal to 30 minutes of sprinkler demand. Every large metro FD (i.e. San Francisco, Sacramento, LA and San Diego) has had ordinance in place for years that stretches the capacity to 30 minutes or more of standpipe demand, or sprinklers with hose stream whichever is greater; that's always been the standpipes in my experience. So with two standpipes, we store 21,500 usable gallons; for three risers it would be 30K, and so forth. Since we already have to store a large amount of water, the common practice has been to pour a cistern-like tank monolithically with walls and or floors, and that generally is at the lowest level of a parking basement on grade. Not always, but usually on grade. It being a break tank, we then draft directly from the reservoir using the pump discharge flange as the "flow test", based on the pump rating exclusively (no NPSH).
Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Thom McMahon Sent: Wednesday, September 23, 2009 7:33 AM To: [email protected] Subject: RE: draft line from suction tank. What I've heard from my SOCAL friends, is that they usually install the storage in the parking garage as you suggest, but also put the pump down there, eliminating the "Draft" issue. Am I describing this correctly Mr. Leyton? Thom McMahon, SET Firetech, Inc. 2560 Copper Ridge Dr P.O. Box 882136 Steamboat Springs, CO 80488 Tel: 970-879-7952 Fax: 970-879-7926 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of R Richardson Sent: Wednesday, September 23, 2009 7:19 AM To: [email protected] Subject: RE: draft line from suction tank. This issue came up here with respect to secondary water tanks required for high rise buildings in seismic zones. There was significant resistance from the "building owner community" for two main reasons. Firstly, there is a limit to how much negative draft is feasible, which results in a prohibition of placing the tanks deep down in the underground parking, which is where the architects typically desire to locate the tank. The second reason for resistance is the fact that the tank requirement is based on the premise that a seismic event disabled the city water supply. The owners were not happy with the possibility that the emergency water for their fire sprinkler system (plus hose use) would be used for someone else's building, leaving their building now unprotected. We ended up not requiring the draft line. Probably quite a bit different scenario than what you are involved in, but something to consider. Rich Richardson Seattle Fire Department _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) __________ Information from ESET NOD32 Antivirus, version of virus signature database 4450 (20090923) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 4450 (20090923) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
