Chris, I hope you meant for this to go to The Forum, not just me so I am trying my hand at re-directing it. Isn't it time we start seeing where semantics might be trying to over-ride physics?
> On May 20, 2014, at 7:44 PM, "Cahill, Christopher" <[email protected]> > wrote: > > Trust me, my opinion is the same, damn near any wall will stop the heat flow > long enough to get the right heads to operate. This is strictly a code > question. I'm OK and good at separating Code from opinion or even reality in > many cases. Reality is wall will stop the heads on the other side for an > hour but Code seems to be silent. OK when the unrated steel holding up wall > falls in 15 minutes assuming the sprinkler don't actually operate reality is > the 1 hour wall falls in 15 minutes. OK the valve is open, sprinklers operate > and the wall never fails until the municipal water supply runs out so all > this is moot in the real reality. I sleep better following Code. > > Chris > > -----Original Message----- > From: Sprinklerforum [mailto:[email protected]] > On Behalf Of Brad Casterline > Sent: Tuesday, May 20, 2014 7:33 PM > To: [email protected] > Subject: Re: Area/Density Method and Walls > > 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
