I made some 'coarse-grained' approximations (fires in the middle of a 65'x65'x32' space):
1) For 'Jimmy's perimeter opening', the heat does not go out from the wall and up, but down the wall and up- the down heat is what your original MOMENTUM post said! The lower the ceiling the more it moves back toward the middle at the floor too. 2) X varied very little as Z1 and Z2- over time, it was seconds, not minutes, as heat release rates varied from 1000 to 5000 Kw/m^2. 3) Steve's 'case for 15' in', and Thom's 'code of 24' in' looked uncannily good. The more the width exceeded 30', the more the velocity and temp difference between the middle and the sides became. 4) Being from Missouri I had to see it. At the Rite Of Passage meeting early Feb, concerning if the gap is max 6" wide then full coverage above would not be required: what if we sprinklered gaps like this-- center the head on the gap, at 12" max above the gap. For the spacing, we could simply stagger them with the pendents below. I know a 5' deflector distance is scary- 'we can't let the heat flow right past the head'! But heat at the activation temp flowing ON a head is what sets it off, and the faster the better. I modeled a water curtain with and without a draft stop- w/o, the heads activated a few seconds earlier than with, because the draft stop slowed the heat a little. Some gaps are too much like flue spaces formed by rack commodities to NOT feel ok about big deflector distances. If we sprinkler all gaps and make the pendents cover the entire floor on thier own, then the question "what is the max width of the gap before we need full coverage above" would be easier to define, and maybe a curve could be found, based on ceiling height, that would be as valid as the QR Reduction curve. With so few variables, a very decent 'standard' might be derived. We submitted a proposal attempting to get the TC to define how big a gap is too big. We started with allowing no more than 6 inches without sprinklers above the drop ceiling. The ROP meeting is early Feb. Roland _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
