And Carrol, to further thank my friends for watching my back, I'd like to make sure that you were NOT asking about the "room design method" (11.2.3.3) but that you ARE asking about the "Special Design Approach" known as "Residential Sprinklers" in NFPA 13 (11.3.1). You did ask specifically about the room design method in the subject of your question! However, I am only referring to the residential method (because you are using residential sprinklers). Please, I beg you.... I do not have many electrons left! (As my good friend Ron Greenman so kindly points out....) I must know, was my post appropriate for your situation or have you really been asking about the "room design method" (also known as the largest room rule) all along??? Still, even if you were talking about the "Room Design Method" (wherein you should be using QR sprinklers in the largest room of your building and not residential sprinklers)...... you could use the "small room rule" square footage allowance (room area divided by the number of sprinklers) to determine the "design area" for the purposes of calculating minimum flow required from a sprinkler. Help.... need electrons..... Anxiously, Cecil Bilbo
> Date: Sat, 30 Oct 2010 19:59:50 -0700 > Subject: Re: Residential "Room Design Method"? > From: [email protected] > To: [email protected] > > And because I'm so in to "proper" language (see my rant yesterday > about design area) and because cecil and I watch each other's back I'm > going to mention that everyone keeps saying "small room" when they're > talking about "room design method." Small room refers to the s"small > room rule" which is a completely different thing. I've noticed after > playing on this Forum for years that we all, at one time or another, > spend lots of electrons answering questions that weren't asked because > the question was confusing. > > On Sat, Oct 30, 2010 at 7:11 PM, Sprinkler Academy - C Bilbo > <[email protected]> wrote: > > > > Carrol, > > > > Hopefully, you caught Ron's reference to 11.3.1.2 and not solely the > > requirement for a 20x20 spacing. Specifically, take a look at Ron's > > inferred reference to 11.3.1.2 item number 2: > > > > > > 11.3.1.2* Unless the requirements of 11.3.1.3 are met, the minimum > > required discharge from each of the four hydraulically most demanding > > sprinklers shall be the greater of the following: > > (1) In accordance with minimum flow rates indicated in individual listings > > (2) Calculated based on delivering a minimum of 0.1 gpm/ft2 (4.1 mm/min) > > over the design area in accordance with the provisions of 8.5.2.1 or > > 8.6.2.1.2 > > > > Item Number One requires us to examine the listing. The sprinkler listing > > for a residential sprinkler likely delivers .05 gpm/sq ft (or just a bit > > more) and do not try to "back in" to this density because it is based on a > > listed area of 20 x 20 in your case because you are 10 feet off the wall. > > This means the listing requires 20 gpm or a little more. > > > > Item Number Two says to use regular spacing requirements and deliver .10 > > gpm/sqft. The question is whether or not the "design area" is the SxL > > rule(8.5.2.1) or the "Small Room Rule" (8.6.2.1.2). > > > > IF (and I mean IF) your room meets the definition of a "small room", then > > you may divide the room by the number of sprinklers and deliver .10 > > gpm/sqft over THAT "design area". This would meet the requirements of > > 11.3.1.2, item number two. In the example you have given to us, you would > > be able to flow .10 gpm over the 256 sq ft of "design area" if your room > > meets the definition of a small room. The flow from the sprinkler would > > need to be a minimum of 25.6 gpm under this method. > > > > The last step is to compare the flows required by Item One and Item Two. > > This is called for in the charging sentence of 11.3.1.2 ("shall be the > > greater of the following"). That would mean that your sprinkler must > > flow the greater of the listed flow of 20 gpm or the "design area" flow of > > 25.6 gpm. Therefore, your sprinkler must flow 25.6 gpm! > > > > Now go rock on! And have your AHJ call Ron Greenman if he has any further > > questions. > > > > Sincerely, > > > > A SprinklerGeek named Cecil > > > > > > > > > > > > > > > >> Date: Sat, 30 Oct 2010 09:49:29 -0700 > >> From: [email protected] > >> Subject: Re: Residential "Room Design Method"? > >> To: [email protected] > >> > >> That was exactly what I was hoping to hear. Now, hopefully, I can > >> convince the > >> AHJ of this. I have INCREDIBLE pressure and flow and it seems crazy that > >> I > >> can't get 4 heads to flow. > >> > >> > >> Thanks everyone! > >> > >> Carrol > >> > >> > >> > >> > >> ________________________________ > >> From: Ron Greenman <[email protected]> > >> To: [email protected] > >> Sent: Sat, October 30, 2010 9:25:04 AM > >> Subject: Re: Residential "Room Design Method"? > >> > >> 2007/11.3.1 > >> > >> see > >> 11.3.1.1 > >> and > >> 11/.3.1.2 > > > > > > _______________________________________________ > > 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: > AFSA, SFPE, ASCET, NFPA, NFSA, AFAA, ASEE, 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)
