I got it. I was thinking that you had sidewalls 8 inches apart back to back and another set 8 feet from them. Very interesting test. It is always interesting to find things in NFPA 13 that mysteriously do not work, as indicated, in real life.
*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 1:04 PM, Brad Casterline <[email protected]> wrote: > 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 > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
