Chris, the way I read 23.4.4.1.1.4 is that it's optional. In your case, I'd calc 2,000 sf of dry system plus 1,900 sf of wet. Since it's all light hazard, it shouldn't get ugly.
I gotta believe there will be some tweaking to that section, though. I read the ROP and ROC - Tracey's 480 sf canopy (page 88 of the ROC) is probably being protected by 4 sprinklers, but could require a 4" supply pipe & dry valve since the phantom flow is added at the end of the dry x-main. That doesn't seem reasonable to me. Ed Kramer Lawrence, KS > -----Original Message----- > From: [email protected] [mailto:sprinklerforum- > [email protected]] On Behalf Of Cahill, Christopher > Sent: Wednesday, March 13, 2013 4:46 PM > To: [email protected] > Subject: Phantom Flow > > Not what you think by the subject. Working out of NFPA 13 '13 > 23.4.4.1.1.5. This is new and confusing us greatly. > > I have a 20,000 sq.ft. heated LH building. And a 2,000 sq.ft. area that > needs a dry system. Not an auxiliary dry system. My starting required > design is 0.1/3,900. I calc the system at 2,000 sq.ft. (cuz that's all > I have) and get for discussion sake 220 gpm. Then I subtract from 390 > (3,900 x 0.1 per 23.4.4.1.1.5) and I get 170 gpm. Then I go back to the > calc and redo but this time I add 170 at the end of the main. Now this > has the effect of overflowing all the rest of the BL's such my final > calc is more than 390. > > !@#$^# > > What if I have a 500 sq.ft. building and the next building is 20 miles > away @#$@# are we calc'ing this extra area for? > > Can someone 'splain if we got it right and then why in the world this > got into the standard? > > Chris Cahill, PE* > Senior Fire Protection Engineer, Aviation & Facilities Group Burns & > McDonnell > 8201 Norman Center Drive > Bloomington, MN 55437 > Phone: 952.656.3652 > Fax: 952.229.2923 > [email protected]<mailto:[email protected]> > www.burnsmcd.com<http://www.burnsmcd.com/> > > Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered > in: MN > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attach > ments/20130313/26a3e378/attachment.html> > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
