I'm not seeing a conflict they work together. 23.4.4.1.1.4 sends you to 11.1.2. If you have a barrier capable of preventing heat from one area fusing heads in another (2) you don't need to extend the area 15' beyond (1). So is the loading dock separate?
For discussion I'm assuming it is. Sounds like you need to calc two areas, the attic traditional not considering the loading dock and not worry about 23.4.4.1.1.4 and then calculate the few heads in the loading dock with a total flow of 507 (OHII@2525) or 390 (OHII@1950 if the slope doesn't extend to the dock. For discussion I'm assuming it isn't. Sounds like you need to calc two areas, the attic traditional not considering the loading dock and not worry about 23.4.4.1.1.4 and then calculate the few heads in the loading dock plus whatever gets you 15' beyond (presumably in the attic) with a total flow of 507 (OHII@2525). At least that's the way I read it. I guess I'm close to you choice 2. I read the background on the changes and still don't understand why it got in there. Seemed like a solution searching for a problem that didn't exist. But now with your example I'm thinking the reasoning was to lessen the total requirements? Couple interesting questions I don't have answers for really. What is said barrier need to be and how long does it need to last? When calc'ing the attic without a barrier do you have to extend 15' into the loading dock? If so does it balance in or does it need to meet the presumed OHII density? See when you have a high hazard and balance in the lower hazard the minimum for the lower hazard is almost always met, not necessarily the other way around. It's been a few days and not a lot of discussion hopefully there will be more. Chris Cahill, PE* Associate Fire Protection Engineer Burns & McDonnell 8201 Norman Center Drive Bloomington, MN 55437 Phone: 952.656.3652 Fax: 952.229.2923 [email protected] www.burnsmcd.com Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered in: MN -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of IPA Sent: Thursday, February 13, 2014 12:20 PM To: [email protected] Subject: NFPA 13: 11.1.2 VS. 23.4.4.1.1.4 2013 EDITION NFPA 13 Is 23.4.4.1.1.4 just another option to those already listed in 11.1.2? I'm trying to figure out if one takes precedence over the other. My case is: Dry pipe system in unused attic (light hazard). Dry pipe system continues from attic to a small adjacent loading dock outside. The two options I'm pondering are: 1.) I can calc 2535 sq. ft. (dry system increase + roof pitch increase) and start out at the loading dock (ordinary group II) and include the attic (LH) in the remainder of the square footage, calculating each with their appropriate densities but obviously resulting in a lot of the attic having larger branchlines than necessary. per NFPA 13: 11.1.2 OR 2.) Per 23.4.4.1.1.4 it looks like I could just calculate the few sprinklers in the loading dock at ordinary group 2, compare it to the required flow for 2,535 sq. ft. and tack the difference on at the branchline farthest from the source (which would happen to be at the loading dock anyway) and call it good. Does one take precedence in this case? Thanks for any insight... _______________________________________________ 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
