Steve, I understand the argument but I think that eliminates having two supplies to the fire pump, if you are only filling the tank and using the tank as the sole supply to the fire pump then you only have on supply, what happens if in the case of some type of event you actually lose the tank but have city water supply, you need the the city supply supplying the fire pump as well as the tank or you essentially are still looking at only one supply to the fire pump and assuming that the tank will never fail as opposed to having city supply and tank supply to the pump which would be 2 independent sources.
Thanks Brett Peters General Manager Installation & Design Proudline Fire Protection Services Ltd. br...@proudline.ca 780 490 7602 office ext 202 780 490 7605 fax 780 777 0568 cell 780 718 2676 24h Visit us at www.proudline.ca Proudline now offers ULc listed monitoring services, please contact a...@proudline.ca for more information On Mon, Sep 25, 2023 at 1:05 PM Steve Leyton <st...@protectiondesign.com> wrote: > Respectfully don’t concur. > > > > The point of the tank is to store a reserve of standpipe water or > sprinkler water, whichever volume is highest given demand x duration. > This requirement is intended to mitigate interruption of the primary water > supply (city main) due to a cataclysmic seismic event that might damage the > service lateral or public system. Assuming it’s sized correctly, you start > with a full tank and the pump begins drafting and almost immediately, the > autofill opens. We use 6” fill lines, so once its open, the fill line will > either maintain the tank level or augment it. If at some point the supply > to the tank is interrupted, you at least have tank water for the calculated > duration at full demand. > > > > Even if the public (fill) supply is interrupted before the pump operates, > you still have a full tank at the start. Which is the point, to assure an > adequate water supply for the duration of an activation. Not two separate > (and potentially concurrent) water supplies, just a back-up to assure that > you have one reliable one. And you won’t have that if you’re drafting > just from the city main and it gets interrupted, so I think this > arrangement is consistent with the intent. And all the AHJ’s out here in > Earthquake Country seem to agree, as this is a fairly standard > arrangement. > > > > The foregoing is my opinion only and does not represent NFPA or the NFPA > 14 Technical Committee, nor intended to serve as an interpretation of the > standard. > > > > *Protection Design and Consulting* > > Steve Leyton, President > > T *|* 619.255.8964 x 102 *| * > *www.protectiondesign.com <http://www.protectiondesign.com/> *2851 Camino > Del Rio South *|* Suite 210 *|* San Diego, CA 92108 > Fire Protection System Design *|* Consulting *|* Planning *|* Training > > > > > > > > > > > > > > > > *From:* Travis Mack <t.m...@mepcad.com> > *Sent:* Monday, September 25, 2023 9:47 AM > *To:* Discussion list on issues relating to automatic fire sprinklers < > sprinklerforum@lists.firesprinkler.org> > *Subject:* [Sprinklerforum] Re: Standpipe PRV Question > > > > In my opinion, that is not dual water supplies. If the tank is down your > water supply is down. You need one connected to the city and one connected > to the tank. Yes. It can be quite tough to balance that calc. I’ve had to > put a PRV on the incoming line so as to basically kill most of the supply > pressure. > > > > Travis Mack, SET > > *M.E.P.CAD* | > > 181 N. Arroyo Grande Blvd. #105 I Henderson, NV 89074 > > www.mepcad.com | *m: 480.547.9348* > > > > *AutoSPRINK | AutoSPRINK FAB | AutoSPRINK RVT | AlarmCAD* > > > > Book appointment time in my calendar > > https://calendly.com/t_mack_mepcad > > > ------------------------------ > > *From:* Micah Davis <micah...@gmail.com> > *Sent:* Monday, September 25, 2023 9:17:40 AM > *To:* Discussion list on issues relating to automatic fire sprinklers < > sprinklerforum@lists.firesprinkler.org> > *Subject:* [Sprinklerforum] Re: Standpipe PRV Question > > > > Thank you for the response, Steve! Does the redundant fill valves for the > tank satisfy the secondary supply requirement of the IBC without an > additional tank? I was interpreting the city main connected to the pump as > the primary supply and the tank as the secondary supply (or vice versa). > If my interpretation is wrong and the tank with redundant fill valves meets > BOTH the primary and secondary water supply requirements, I can NOT connect > the city water main to the fire pump, and the problem is solved using your > method above. > > > > Am I tracking correctly? > > > > My thought is that if the city main stays connected to the pump and my > demand calcs and PRV settings are based on the supply from the tank (which > I think is correct), how do we avoid overpressurization with the added > pressure from the city? I'm probably overthinking this somewhere! That > tends to be my M.O.! > > > > Micah Davis > > Ferguson Fire Design > > micah.da...@ferguson.com > > > > > > On Mon, Sep 25, 2023 at 12:02 PM Steve Leyton <st...@protectiondesign.com> > wrote: > > Micah: > > The best way to stabilize the pump discharge pressure and give yourself a > (nearly) straight line suction pressure curve is to arrange the required > secondary water supply as a break tank. Fill the tank with city water > (recommend to manifold at least one automatic plus one manual fill; in my > neck of the woods we use two automatic and one manual) and base your > calculations on the lowest potential water level in the tank. We simply > use the pump’s performance curve as a water supply assuming 0 psi suction > head. Depending on water column height, your actual discharge pressure > variation will be ≤ 5 psi, unless the tank is uniquely configured and > multi-story. > > > > > > The foregoing is my opinion only and does not represent NFPA or the NFPA > 14 Technical Committee, nor intended to serve as an interpretation of the > standard. > > > > *Protection Design and Consulting* > > Steve Leyton, President > > T *|* 619.255.8964 x 102 *| * www.protectiondesign.com > 2851 Camino Del Rio South *|* Suite 210 *|* San Diego, CA 92108 > Fire Protection System Design *|* Consulting *|* Planning *|* Training > > > > > > > > > > > > > > > > *From:* Micah Davis <micah...@gmail.com> > *Sent:* Monday, September 25, 2023 8:55 AM > *To:* SprinklerForum <sprinklerforum@lists.firesprinkler.org> > *Subject:* [Sprinklerforum] Standpipe PRV Question > > > > Good morning, Forum! > > > > I've got a head-scratcher and am interested in the Forum's collective > opinion! Important project parameters are as follows. > > > > - 42-story high rise with an automatic standpipe > > - Seismic Design Category - C > > - IBC 2018 > > - Fire pump supplied by city water supply > > - Secondary supply, as required by IBC 403.3.3, is a tank of adequate size > > - 305 psi @ 1000 gpm pump sized based on the feed from tank > > - Direct-acting pressure reducing valves on each floor > > > > Here is my issue. If I base my PRV settings on city supply, I cannot get > 100 psi at the remote valves when calculating tank as supply. If I base my > PRV settings on tank supply, I am over 175 psi discharge on the valve when > calculating city as supply. If I try to get my settings using the city as > static and the tank as residual pressures, there is no PRV setting that > works. > > > > I have my opinions about what I think should happen here, but I want to > see what the Forum thinks. I will not bother the group with what the > design team is suggesting I do. > > > > Micah Davis > > Ferguson Fire Design > > micah.da...@ferguson.com > > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > sprinklerforum-le...@lists.firesprinkler.org > > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > sprinklerforum-le...@lists.firesprinkler.org >
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