The reason I ask Chris is, the calculation method sprung Not from "how fast does an accidental fire get how hot", but "if we make the second piece inch and a quarter can we reduce the main size a notch or two, and still get the same water?" And I hear the first remote areas were round! I would consider any barrier to the fire-driven heat flow, rated or not.
> On May 20, 2014, at 7:17 PM, Brad Casterline <[email protected]> wrote: > > Good water or bad? > >> On May 20, 2014, at 7:12 PM, "Cahill, Christopher" <[email protected]> >> wrote: >> >> I can't believe I'm asking this question after all these years. Anyway, >> swallowing pride and asking. >> >> 2010 NFPA 13 strict Density/Area method 11.2.3.2 and 22.4.4.1.1. Great big >> room being subdivided. Existing system with a new wall added between heads >> on a BL. Contractor had to add a head on one side to preserve the existing >> spacing (area) of the heads. Without head over 130 sq.ft. I take the 1.2 >> ^.5 of the area and get 46.5' required along the BL. Original system lets >> say calc'd 5 heads on the BL. But now in the same 46.5' there are 6 heads >> on the BL. Do I ignore the wall and require a new calc? What if the wall >> is rated 1 hour do I ignore it? >> >> I looked all over and can't seem to find anything definitive. Room design is >> out so not a consideration. 22.4.4.1.1.1 simply says all the heads in the >> 46.5'. I can't find anything that says either to count the wall as a break >> so measure 46.5' from the wall in each direction and still see if there are >> 5 head or ignore it and there are now 6 heads. I find 11.1.2 that clarifies >> to extend the density or not. I don't think that's applicable exactly. The >> question is not about whether to extend the density on either side. Let's >> just say it's all OH. >> >> It gets a little more complex as on the one side of the wall they cut a head >> in on the BL but on the other side there is a perpendicular new wall and >> they come off same BL and arm over to two more head so if I ignore the walls >> there are now 8 heads off the 1 BL. >> >> Prefer a code section or written reference 'cuz this is going to be a big >> deal if we ignore the walls. Ordinarily with unrated walls they are ignored >> in density/area (of course can't find that reference). I think I'm getting >> tripped up with the rated portion? Or maybe I'm just tired???? >> >> Chris Cahill, PE* >> Associate Fire Protection Engineer >> Burns & McDonnell >> Phone: 952.656.3652 >> Fax: 952.229.2923 >> [email protected]<mailto:[email protected]> >> www.burnsmcd.com<http://www.burnsmcd.com/> >> *Registered in: MN >> >> >> Proud to be #14 on FORTUNE's 2014 List of 100 Best Companies to Work For >> >> >> >> >> _______________________________________________ >> 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
