Honestly, how many water purveyors could guarantee their system pressures would NEVER fluctuate 5 psi, none.
That is why some won't even give you the data, they don't want to be held to an assumed guaranteed value. Craig L. Prahl, CET Fire Protection Specialist Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [email protected] http://www.ch2m.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ralphy Henderson Sent: Thursday, September 24, 2009 1:26 PM To: [email protected] Subject: RE: Inadequate Water I believe I read that in Mark Brommans' book but I could be wrong. From what I understand the Hazen-Williams formula is not the most accurate in the world and actually produces results which are more demanding than the actual situation. If such is the case, and given a few of the other factors that I mentioned, I don't see the reason to hem and haw over 5 psi in a LH or OH situation. --- On Thu, 9/24/09, [email protected] <[email protected]> wrote: From: [email protected] <[email protected]> Subject: RE: Inadequate Water To: [email protected] Date: Thursday, September 24, 2009, 4:16 PM 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 Please respond to 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 _______________________________________________ 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) _______________________________________________ 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) _______________________________________________ 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) _______________________________________________ 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)
