Just a quick retort: Hose stream, hose allowance are not fire flow requirements. Fire flow is set in the IFC and this building (is not a LH occupancy S-2) only is eligible for a 50% reduction in fire flow under the exception to B105.2. This would limit the total building area of V-B construction to 13400 SF. If the building is larger than that they don't meet fire flow even with the reduction. The reduction itself is "allowed" but should not be applied unless the AHJ approves of the lower flows.
In closing if this is a 2-story building with 10000SF per floor, the required fire flow would be 2750 GPM/2HR. With the reduction of 50% "if allowed" the fire flow would be 1875GPM/3HR. (note the 3 HR duration, the exception allows for a reduction in the flow for fire sprinklers, not in the duration.) -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ron Greenman Sent: Thursday, June 30, 2011 3:48 PM To: [email protected] Subject: Re: Hose Stream Thom, This does relate to a real building, 2-story, B & S-2, V-B, fully sprinklered and could have 1000 gpm total fire flow @ 20 psi but the FM wants 1500 @ 20. The pump is fine and the civil just over spec'd the tank size and included capacity for simultaneous full flow of hydrant and sprinks for 1 hour. The question though is theoretical because of the extra water and that if that amount of water were present in separate tanks the outside hose stream allowance for the sprinks wouldn't be required but is since it's in a single tank. And I couldn't remember the flow when I first asked the question and used 450 + hose just as a number. Actual flow for the building is 550 plus 250 but doesn't change the question since I could just be putting it as A=sprink, B=Hose allowance, C=Hydrant. Tank capacity = A + C. A + B < C so OK. C < Tank so OK. A + C = Tank so why do I need to include B in the A calc at all? On Thu, Jun 30, 2011 at 12:22 PM, Thom <[email protected]> wrote: > Brett: Be careful how you phrase that. The outside Hyd. May be the sole > water supply for fire flow, in which case depending on building > construction > and occupancy and size could require up to 8,000 GPM for 4 hours, "Fire > Flow" per the IFC appendix "B" table B105.1. > We need a lot more info before we can definitively say that a 1500GPM hose > allowance on top of sprinkler calc is adequate. Is the building fully > sprinklered per 13? What is the construction, total area, height, > occupancy, > who is AHJ and What is response time? > > So many questions?? So Little time! > I'm not trying to start a new thread, So please don't go off on specific's, > I'm just saying absolutes are rare. > > Subject: RE: Hose Stream > > I would say that your system demand is 450 gpm and you have included a > hose > stream allowance of 1,500 gpm which is above and beyond the minimum > requirement. > Brett Foreman > > > > _______________________________________________ > 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) > -- Ron Greenman Instructor Fire Protection Engineering Technology Bates Technical College 1101 So. Yakima Ave. Tacoma, WA 98405 [email protected] http://www.bates.ctc.edu/fireprotection/ 253.680.7346 253.576.9700 (cell) Member: ASEE, SFPE, ASCET, NFPA, AFSA, NFSA, AFAA, NIBS, WSAFM, WFC They are happy men whose natures sort with their vocations. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) _______________________________________________ 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) _______________________________________________ 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)
