Rhae, No, 8" apart is correct. This is a continuation of the ~do sidewalls need a wall discussion~ but I made it new because I don't know how to trim threads using my phone. Very interesting stuff. When looking at activation only I use a heat detector because the same RTI algorithm is used for upright, pendent, sidewall, and heat detector. It is interesting to note that the 12" deep beam affects the near sprk like an 18" draftstop affects a water curtain sprk-- it disrupts the heat flow, delaying activation a few seconds. I think an 18" draft stop is used to contain an 18" "build down" of 'cold smoke', per floor, when openings are required to be protected. On Dec 30, 2015 12:30 PM, "Rahe Loftin - 7PMC" <[email protected]> wrote:
> Brad, > Should your post say 8' apart instead of 8"? > > > > *Success Through Code Compliance* > > *Rahe Loftin, PE * > *Regional Fire Protection Engineer* > *General Services Administration* > *Region 7 - TX, OK, NM, AR, LA* > *Facilities Management & Support 7PMC* > *c - 817-371-3102* > *o - 817-978-7299* > > On Wed, Dec 30, 2015 at 11:07 AM, Brad Casterline <[email protected]> > wrote: > > > Modeled: > > (2) heat detectors, 8" below ceiling, 8" apart, with and without 12" deep > > beam centered between them. > > > > Results without-- > > Both near and far side heads activate at 90.5 seconds. > > Margin of error a few tenths of a second. > > > > Results with-- > > near side=93.8 seconds. > > far side=115.0 seconds. > > Same margin of error. > > > > Head scratching -- > > 1) I doubt in real life two heads 8" apart would activate within tenths > of > > a second of each other, my feel is more like a few, enough for one to > > cold-solder the other. > > 2) in a model the spray pattern of a sidewall can be straight out, but in > > real life I think enough would be splashed backward to cause 1). > > > > For 30 years, if I thought beyond what the book said about max deflector > > distance I thought "ok, the heat rises, hits the bottom of the deck, and > > starts coming down, and when this heat gets, say, 12" down the head > pops". > > Well, 10 years ago I realized that that is normal-- and the emergency is > > where the heated air is travelling horizontally five to ten feet per > second > > across the head. > > 10 years ago is also when I first heard "ceiling jet". I really resented > a > > Code Person telling me anything about sprinklers but, after 3 months of > > getting my sprinkler (oops i mean head) around mass and the metric system > > learning the first things about FDS, it started sinking in that the > ceiling > > jet is really where is at re: activation. > > > > Brad C > > > > Ps- this new thread is tied to the recent "can sidewalls..." thread. > > Ps2- Ron, I'm not too sick, tired (or lazy), to look stuff up-- i just > > don't have access to commentary, and I was curious, but it can wait. > > Ps3- Ron2-----please don't be a stranger > > _______________________________________________ > > 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
