Cliff, I believe that reference refers to crossing the main/cross-main to add heads, not a gap due to feeding from separate mains/cross-mains. There is always a most demanding area for every system cum hazard area, and sometimes more if two areas are mirrored. The trick is deciding which is most demanding. When it's not obvious you do as many as you think there are in question (as you've done). I don't think there is a reference with a single, specific answer that addresses this scenario as you could have a higher demand across the peak in one instance and a different result in the other configuration depending on pipe sizes. Now all that said, how I'd interpret this is you need to maintain at least the 1:1.2 ratio (unless the building configuration makes that impossible--single side feed with not enough building) between branch lines:along branch lines and that would take you across the peak. That those across the peak heads are not fed from the same main is what creates the question, and that is what suggests calcing both ways. That at least would be the critical path analysis I'd use.
On Thu, Aug 23, 2012 at 8:48 AM, Brad Casterline <[email protected]>wrote: > I do not believe "insufficient number of heads..." applies in this case, > nor > that the most demanding scenario is obvious, especially if C=100, and you > have Pe differences. > > -----Original Message----- > From: Cliff Whitfield [mailto:[email protected]] > Sent: Thursday, August 23, 2012 10:39 AM > To: [email protected] > Subject: RE: Remote Area Question > > Thanks David! Just what I was looking for and apparently overlooked. > > Have a great day! > > Cliff Whitfield, SET > President > Fire Design, Inc. > Ph: 337-261-8807 > Fx: 337-261-8808 > > > > [email protected] > www.fire-design.com > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of David Autry > Sent: Thursday, August 23, 2012 10:34 AM > To: [email protected] > Subject: RE: Remote Area Question > > 2007 Edition > 22.4.4.1.1.3 > > Stay on one side of the peak. It should be the most demanding (If all the > pipe sizes are the same) > > > David Autry > > Meininger Fire Protection Inc. > 2521 W L St. Suite No.4 > Lincoln, Ne 68522 > Voice (402) 466-2616 > Fax (402) 466-2617 > [email protected] > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Travis Mack > Sent: Thursday, August 23, 2012 10:29 AM > To: [email protected] > Subject: Re: Remote Area Question > > 13 does address this. I am out so I can't find the exact section right now. > But, stop at your peak and pick up additional heads on the same cross main. > > Since you use AS, just put both remote areas on and see which is most > demanding. > > Travis Mack, SET > MFP Design, LLC > > Sent from my iPhone > > On Aug 23, 2012, at 8:20 AM, "Cliff Whitfield" <[email protected]> > wrote: > > > Forumites, > > > > I have a question regarding a remote area on a 'skinny' building and > > since we can't include a 'snapshot' I will do my best to describe the > > situation in question. > > > > Picture a 80' x 400' building with a 1/12 slope and the peak at the > > center of the building (40'). This is a dry system on a loading dock > > for a trucking company. I have a main on both sides of the building > > (but not connected in a loop) with lines running up the slope so > > everything will drain properly, thus my lines are approx 40' each and > > do not connect in the middle (not a grid - it's dry). My remote area > > is to be 1.2 x the sq root of 1950 (just using this as an example) so > > I will need at least 53' of branch line. > > > > Since my branch lines are only 40' wide, obviously I have to cross the > > peak to pick up the proper number of heads for a line. Herein lies the > problem. > > I don't believe this is clearly spelled out in NFPA 13 (if it is, > > please forgive me but also tell me where it is!). Do you cross the > > peak and pick up heads on lines that are connected to the opposite > > main or do you stop at the peak, widen the remote area to include more > > branch lines and make all of the heads flow thru the single main back to > the riser? > > > > This can arise in a similar fashion in an office building, especially > > if you are looping the system on the floor. > > > > The question I have is - which solution is required/correct in > > accordance with the way NFPA 13 is written. > > > > Thanks, > > > > Cliff Whitfield, SET > > President > > Fire Design, Inc. > > Ph: 337-261-8807 > > Fx: 337-261-8808 > > > > [email protected] > > www.fire-design.com > > > > > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > -- 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, WFSC They are happy men whose natures sort with their vocations. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments/20120823/4a9d36f5/attachment.html> _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
