Oh, and starting at something lower than eventual EP is more than adequate to let you find open standpipe ports, and close them. Why flood the stairwell more than necessary?
BV > On Sep 12, 2016, at 14:06, Bruce Verhei <[email protected]> wrote: > > Most FD's use 150 psi as a near universal starting point. It's what an FDC > basically says "start me at". > > If nozzle is not too high above FDC this isn't too bad. If nozzle is a number > of floors up the operator will be ready to provide water before its needed. > And it gets all of the now compressed air out of the system. > > But once water is flowing, the pump operator will do field calc's to get the > appropriate real pressure. Our standard 1 3/4 hose packs used 135 psi for > friction loss and nozzle pressure. I suspect cities with bigger footprint > buildings would use a 200' instead of 150' hose pack, getting you back to > ~150 psi at gated wye (2 1/2" X 1 1/2" X 1 1/2") I know an alternative is 50' > 2 1/2" then wye, then standpipe bundles. > > Our standard was for head pressure was 5 psi per floor. For all you three > significant digit folks, this actually works out pretty close for 10-12' > storeys. > > Field calc also includes friction loss between engine and FDC. > > And our standard calc included 25 psi for friction loss in the standpipe > system. I later decided that this was way too much, but fire experience > belied the numbers. The scheme we used did not result in too high nozzle > pressure. Usually more pressure was requested by radio. Eventually I decided > that hose lines were much more liable to have kinks in this setting compared > to homes, restaurants, repair garages and so on. Compare a kink to a 1" 90 in > a 1 1/2" sprinkler line. Lots of friction loss in a very short run. > > So I didn't send a note to Training telling them no, we weren't seeing 25 psi > f.l. in a five story standpipe at 200 gpm. > > NP + attack line FL + HP + 25 for standpipe and FDC + FL from engine to FDC = > EP > > To recap, > -150 psi to get water flowing, > -connect second 2 1/2" line to FDC and get it charged, > -do field hydraulics, increase engine pressure, and reset relief valve ( or > governor) > -adjust up 20 psi per each request from attack companies. 20 psi is about > minimum that is noticeable. During active fire fighting you will not get a > request for less. > > After control, at some point pressure will be adjusted way down, per request. > > This is one FD's practice. It works well in low rise. > > Best > > Bruce Verhei > > On Sep 12, 2016, at 13:00, Brian Harris <[email protected]> wrote: > >> Thanks guys, much appreciated. >> >> Brian Harris, CET >> BVS Systems Inc. >> bvssytemsinc.com >> >> From: Sprinklerforum [mailto:[email protected]] >> On Behalf Of Brian Harris >> Sent: Monday, September 12, 2016 3:21 PM >> To: [email protected] >> Subject: Fire Truck Supply @ FDC >> >> Is there a “standard” GPM @ PSI used for a standpipe calc with regard to >> what the fire truck will provide? I called the local AHJ and all he would >> say is they provide 150psi, didn’t know the gpm or even the hose size for >> that matter. Any help would be greatly appreciated. >> >> Brian Harris, CET >> BVS Systems Inc. >> Design Manager >> bvssystemsinc.com >> Phone: 704.896.9989 >> Fax: 704.896.1935 >> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
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