Jeremy, Remember that you are trying to contain the fire and not extinguish it. If you can get water on both sides of an obstruction you can limit growth to under the obstruction. Being able to throw water over the obstruction (duct for instance) gets water on both sides. If the fire is developed enough you will go beyond pooling as the water falls as the inrush of air will carry small droplets into the fire. While these may never get to the seat of the fire they will have an overall cooling effect helping to slow development until the FD arrives for overhaul.
Brad, Perhaps the concern about EC has to do with actual testing. The four foot. 18 inch rules for standard spray is based on observed, empirical success. Perhaps in the development of EC that scenario was tested and failed. On Fri, Jul 25, 2014 at 5:59 AM, Brad Casterline <[email protected]> wrote: > Nice analysis Jeremy. > I still have my fingers crossed that some heavy lifters will weigh in on, > not necessarily the difference between open or closed at the top, but why > 4' > max for Standard Coverage and 2' max for Extended Coverage. This is 13-2013 > FIGURE A.8.6.5.1.2 (pg 309 in the Handbook) and FIGURE A.8.8.5.1.2 (pg 338 > in the Handbook), respectively. > > Brad > > -----Original Message----- > From: Jeremy Frazier [mailto:[email protected]] > Sent: Tuesday, July 22, 2014 3:31 PM > To: [email protected] > Subject: RE: stepped obstructions > > I believe they put that section in the code to deal with a code logic error > that gets made when applying the obstruction rules. (2007 edition > referenced) If you had a 4'-0" obstruction against the wall with 18" of > clearance, generally people would try and make you put sprinkler heads > underneath it because spray does not reach both sides of the obstruction. > They try and apply 8.6.5.1.2 (b) or 8.6.5.1.2. The error occurs when they > reference 8.6.5. Which should not be applied because of 8.5.5.2 & 8.5.5.3. > 8.5.5.2 only applies to obstructions within the 18" plane and tells you to > go to 8.6. The correct section to apply would be 8.5.5.3. As far as the > water on the floor, what you seeing makes a lot of sense to me. I never > understood why if its open on top everything is fine. If its solid up to > the > ceiling/deck, somehow the area doesn't get enough water. Which shouldn't > really happen, because the sprinkler head cannot spray underneath the > obstruction no matter if it's open above or solid, so it's just the > "pooling" effect that reaches the hazard. > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > -- Ron Greenman Instructor Fire Protection Engineering Technology Bates Technical College 1101 So. Yakima Ave. Tacoma, WA 98405 [email protected] http://www.bates.ctc.edu/fireprotection/ 253.680.7346 253.576.9700 (cell) Member: ASEE, SFPE, ASCET, NFPA, AFSA, NFSA, AFAA, NIBS, WSAFM, WFC, WFSC They are happy men whose natures sort with their vocations. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) A problem well stated is a problem half solved. -Charles F. Kettering, inventor and engineer (1876-1958) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
