Disregard my previous post, I wasn't current on the forum topic. But here is an exercise you could easily perform. Establish the physical parameters and calculate 3 or 4 variations using incremental "fixed" flows with a 500 GPM delta on each and determine the net change between them. i.e 75,72,500 and 8" x 1500 with a "fixed flow" of 1000, 1500, and 2000. Mark at Aero -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of Brad Casterline Sent: Thursday, June 26, 2014 10:55 AM To: [email protected] Subject: RE: Underground Piping
True! I guess the best we could do is say "IF it were one pipe, x diameter, y long, the C-factor would be z". But doing an analysis on a big yard system complex, where some pretty good plans exist, and flowing hydrants from point to point, rearranging H-W gives a pretty good idea of the condition of the underground. -----Original Message----- From: Rahe Loftin - 7PMC [mailto:[email protected]] Sent: Thursday, June 26, 2014 12:40 PM To: SprinklerFORUM Subject: Re: Underground Piping Easy to do with a dead end system but not so easy with a gridded system *Thanks* *Rahe Loftin, PE * *Regional Fire Protection Engineer* *General Services Administration* *Region 7 - TX, OK, NM, AR, LA* *Facilities Management & Support 7PMC* *c - 817-371-3102* *o - 817-978-7299* On Thu, Jun 26, 2014 at 11:58 AM, Brad Casterline <[email protected]> wrote: > Makes sense Todd. > > I believe a flow test measures the friction loss from the source to > the gauged hydrant, with a negligible amount of velocity head loss. > Say we get 75,72,500. If we know 8" X 1500 feet total, using Q^1.85 > and rearranging H-W, we can get the C-Factor=140. If we got 75,68,500 > with the same 8 by 1500, we would get C=85. Also, using Q^2 and C=140, > we would get the same 7 > pound drop. I guess what I am saying is, the flow test is a measure of > the several factors, as a whole, that are usually unknown without > doing a lot of digging, literally ;) > > Brad > > > -----Original Message----- > From: Todd - Work [mailto:[email protected]] > Sent: Thursday, June 26, 2014 10:18 AM > To: [email protected] > Subject: Re: Underground Piping > > Remember, all of our formulas are approximations. They can be more accurate > in some situations and less in others. The velocity restrictions of > years back were originally to compensate for the inaccuracies in the > formula when > velocity exceeded a certain amount. > > Todd G Williams, PE > Fire Protection Design/Consulting > Stonington, CT > www.fpdc.com > 860-535-2080 (ofc) > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
