Is it just 150psi or is it 150 + city supply?
Jerry Van Kolken Millennium Fire Protection (760) 722-2722 From: Sprinklerforum [mailto:[email protected]] On Behalf Of Bruce Verhei Sent: Monday, September 12, 2016 2:19 PM To: [email protected] Subject: Re: Fire Truck Supply @ FDC 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 <http://bvssystemsinc.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 <http://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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