!EXACTLY! Ron :)
I never try to predict anything, per se, I try to find the DIFFERENCE
between scenarios, in this case the same Ceiling Height and Heat
Release Rate versus sprinkler Temp and RTI. For a benchmark, I found
the steady state HRR that would activate a 286 SR in ~180 seconds,
with the head centered on the plume. This turned out to be 1072
kilowatt/173 sec (about half a couch actually, but maybe scalable to a
whole couch centered between two heads.) But steady state means 0 to
1072 in 1 sec, not very realistic (even though it is similar to the
"plunge test" used to establish RTI experimentally) so I ramped the
HRR from 0 to 1072 in 90 sec and calculated the 4 scenarios SEPERATELY
as posted.
Your talk about innermost ring, next ring out, etc has inspired me to
model some "SPRINKLER SKIPPING". My understanding of 'skipping' is
that it is the water in the vapor state equivalent of water in the
liquid state "COLD SOLDERING", IOW, vapor from activated heads in ring
1 might cool heads in ring 2 and delay their activation so that heads
in ring 3 activate before heads in ring 2! Thank goodness there is no
minimum in 13 to avoid sprinkler skipping ;).
Thanks for requesting some details in that instructor type of way of
yours. You know how much I enjoy talking sprinklers.
Brad
Quoting Ron Greenman <rongreen...@gmail.com>:
So....High release vertical heat plume hitting ceiling and starting to
spread out, immediate ring opens starts to cool fire but intermediate heads
in second ring open, dropping flow to first ring, but doing nothing to cool
fire, the third ring with even worse results. My understanding of QR
standard spray is mostly for low heat release horizontal spreading fires
(and mostly where people are likely to be present), fast response links in
special heads used as listed, SR/SS, high temp. where you might want to
slow down the opening of heads in places where you have a high heat release
vertical fire or where you will have a retarded (OK, everyone do a Beavis
and Butthead now, and then get over it) water delivery but quickly
spreading ceiling jet, as in a dry system. Then again, I've been known to
misinterpret the purpose for things being the way they are.
On Sun, Sep 30, 2012 at 9:07 AM, <bcasterl...@fsc-inc.com> wrote:
all i got is some numbers:
27' ceiling height, 9" deflector distance, couch on fire in the middle of
a large, open furniture showroom---
286F, standard response- activation time = 188 seconds
286F, quick response- activation time = 172 seconds
212F, standard response- activation time = 97 seconds
212F, quick response- activation time = 80 seconds
(details available upon request)
regards,
Anyone...?
:)
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Ron Greenman
Instructor
Fire Protection Engineering Technology
Bates Technical College
1101 So. Yakima Ave.
Tacoma, WA 98405
rgreen...@bates.ctc.edu
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)
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