Because the FDC requirements in both 13 and 14 hinge on 150 PSI as a benchmark starting pressure. NFPA 13E prescribes pumping at 150 PSI to start; if a system requires higher pressure, engineers are trained to keep raising the pressure until failure is imminent. Imminent failure is usually expressed by pinging sounds as metallic components near the fail point ... it's pretty primitive. But the standards essentially say that you have to put a sign on the FDC if the required pressure to meet demand exceeds 150 PSI. If the required pressure exceeds 175, then you have to build the system with materials that rated for the anticipated working pressure or higher. But it's pretty widely understood that you don't have to use HP components just because there's an FDC that could theoretically be pumped over 175. In part, that's why we test to 50-over.
SML -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of Travis Mack Sent: Thursday, April 28, 2016 9:43 AM To: [email protected] Subject: Re: standpipe and sprinkler pressures I thought you didn't factor FDC pressures when selecting sprinkler components. If so, why are we not using high pressure sprinklers on all jobs. Travis Mack, SET MFP Design, LLC "Follow" us on Facebook: https://www.facebook.com/pages/MFP-Design-LLC/92218417692 Send large files to MFP Design via: https://www.hightail.com/u/MFPDesign Sent from my iPhone > On Apr 28, 2016, at 9:40 AM, Ben Young <[email protected]> wrote: > > So the main answer appears to be yes, even with a wet manual > standpipe, the FD pumper pressure has to be considered for the > sprinkler system when configured in this way. > > Anyone disagree with this? > > > Benjamin Young > > On Thu, Apr 28, 2016 at 10:51 AM, Steve Leyton > <[email protected]> > wrote: > >> The simplest (though possibly not the lowest cost) solution is to run >> a separate sprinkler riser instead of a combined system and install >> two FDC's >> - one for A/S and one for standpipes. >> >> My opinion only, >> SL >> >> -----Original Message----- >> From: Sprinklerforum [mailto: >> [email protected]] On Behalf Of Ben >> Young >> Sent: Thursday, April 28, 2016 7:47 AM >> To: [email protected] >> Subject: Re: standpipe and sprinkler pressures >> >> Steve, >> >> Its in design, but its a moot point at this junction for that >> particular project, because we increased the pipe size from the FDC anyway. >> >> So this is a hypothetical that is an exaggerated real scenario. >> Basically something to keep in the back of my mind for future >> projects where sales or another entity may want to try and squeeze >> down standpipe feeds to 4" even on a job with only two standpipes. >> What's that take, a 3-way siamese that has a 4" outlet? >> >> >> Tom et al, this is only a wet automatic system, the fire pump is >> irrelevant for the standpipe pressures. since the FDC is downstream >> of the pump, you don't have to size the pump (even in GPM) to match >> the standpipe demand. A lot of people at my company thought that so >> I think its a common misconception. >> >> >> >> >> Benjamin Young >> >> On Thu, Apr 28, 2016 at 9:02 AM, Steve Leyton >> <[email protected]> >> wrote: >> >>> When you ask, "Say you have a fully sprinklered building ...", do >>> you already have this building or is it being designed? >>> >>> >>> Steve >>> >>> >>> -------- Original message -------- >>> From: Ben Young <[email protected]> >>> Date: 4/28/16 4:41 AM (GMT-08:00) >>> To: [email protected] >>> Subject: standpipe and sprinkler pressures >>> >>> So this kind of came up earlier this week, and I've been researching >>> it and mulling it about in my head to no avail. I thought this >>> would be the best place to ask! >>> >>> Say you have a fulled sprinklered building with a combined standpipe >>> and sprinkler system. Building is non-highrise so standpipe is >>> class I wet manual, five standpipes total, so 1000 GPM is required >>> at the FDC. So good so far, right? >>> >>> There's also a fire pump for the sprinkler system, but that >>> shouldn't factor into the pressures for the standpipes... >>> >>> So I know that the FDC as it pertains to the sprinkler system side >>> of things is considered supplemental, and thus I don't have to worry >>> about excess pressures as long as my pump doesn't churn over 175 PSI... >>> >>> But what about when its to pressurize the standpipes? >>> >>> >>> For this scenario, lets say that even with 6" pipe from the FDC to >>> the standpipes (the first split point where 250 GPM breaks off) you >>> still need >>> 200 PSI at the FDC to enable 100 PSI at the top of the most remote >>> standpipe, and the fire department and AHJ has allowed this. >>> >>> Do I now need to verify that my sprinkler systems aren't seeing more >>> than >>> 175 PSI (if I'm using normally rated sprinklers and other various >>> valves that are only listed to 175)? Do I also need to use a >>> pressure regulating hose valve for the first few hose valves that >>> would also see >> over 175 PSI? >>> >>> Or do you just say 'eh its a manual standpipe' and don't worry about it? >>> >>> >>> This has to have come up for others before, I've just never had to >>> deal with it I guess. >>> >>> >>> (Hmm, so apparently Tyco is the only slouch that doesn't have a >>> floor control assembly listed for pressures over 175 PSI...) >>> >>> Benjamin Young >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprin >>> kl er.org _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprin >>> kl >>> er.org >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprink >> ler.org _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprink >> ler.org > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.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
