The Fire Flow value is not about sprinklers. It is about hydrant flow. Remember the majority of sprinklers are designed to control, (suppression mode aside) not necessarily extinguish the fire. So in a significant fire, the fire department is tasked with the extinguishing effort via hydrants and manual hose lines.
Depending on the conditions of the fire, the manual fire fight could take hours. Recent warehouse fire was a 13 hour fire fight due to the commodity. So if you flow 1000-1500 from a deck gun then add 3-4 hose lines at 250 -500 gpm each and you can see where a lot of water can be used rather quickly. Remember that for the most part sprinkler flow is 1 hour or 2 hours, not 4 hours. I think as fire protection engineers/designers we primarily focus on the sprinklers and often forget that when the sprinklers go off, that's only the beginning of the suppression effort. There is much more tied into this work we do. Craig L. Prahl Fire Protection Group Lead CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29303 Direct - 864.599.4102 Fax - 864.599.8439 CH2MHILL Extension 74102 [email protected] -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of Brad Casterline Sent: Thursday, August 28, 2014 9:09 AM To: [email protected] Subject: RE: 1, 2 & 3 hour stored water duration requirements That is mind-bending Craig, thanks. I do not doubt the procedure for coming up with 2 million. I guess what's bothering me is along these lines: "If a couple three thousand GPM flowing for 30 minutes doesn't do the trick, how is 10 times that going to help"? Brad -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Thursday, August 28, 2014 7:11 AM To: [email protected] Subject: RE: 1, 2 & 3 hour stored water duration requirements Fire Flow from Section 507 of the IFC is typically the driver when it comes to large aboveground tanks. This is one issue often forgotten or overlooked in fire protection design. When determining the adequacy of water supplies, both the sprinkler flow and Fire Flow must be considered. I had a project last year with 8000 gpm for 4 hour duration for fire flow. Yes it was a big honking tank, 2 million gallons. Deluge system flows were at the 7500 gpm mark. Got one right now that's a bit smaller with only 6000 gpm for 4 hours for fire flow. Rule of thumb for estimating tank cost is between .60 cents and $1.00 a gallon depending on location and installation issues. Craig L. Prahl Fire Protection Group Lead CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29303 Direct - 864.599.4102 Fax - 864.599.8439 CH2MHILL Extension 74102 [email protected] _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
