Ralphy,
Please enumerate where the safety margins are in Hazen-Williams in terms of
water supply. In fact, what are all of the safety margins and
conservatives that Hazen-Williams provides?
Thank You
Rahe Loftin, P.E.
Region 7 - GSA
Office - 817-978-7299
Fax - 817-978-8644
Cell - 817-371-3102
Ralphy Henderson
<ralphbuccan...@y To
ahoo.com> [email protected]
Sent by: cc
sprinklerforum-bo
un...@firesprinkl Subject
er.org RE: Inadequate Water
09/24/2009 11:10
AM
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sprinklerfo...@fi
resprinkler.org
Isn't an issue of 5 psi really a non issue? I mean, you generally have an
AHJ mandated safety factor (or should) of 5-10%, a hose allowance that may
or may not be used, plus calculations that are based upon Hazen-Williams
which in itself is not as accurate as other methods and provides an
additional safety margin.
Not only that but there are usually design options as well. Perhaps the
remote area could be re-evaluated - maybe there's that head in the closet
that really doesn't need to be included in the calcs, maybe looping a few
of the branchlines in the most demanding area would solve things, changing
BFP to a more friendly friction loss model, did the hydraulics program use
the modified equivalent lengths based upon NFPA #13 or were these
considerably rounded up by default (I've seen that)? Could changing
sprinklers to larger / smaller orifice help, sliding up and down the design
density curve to meet actual calculated sq. ft'g (if no reductions are
taken) etc..
Even without consideration of the above it would seem that 5 psi is not
lawsuit material - at least to me. As long as this is not storage or extra
hazard I don't see what the big deal is.
-Ralphy
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