Todd is correct. For system designs, we should evaluate the water supply around the anticipated system demand. A drop of 25% is great for site water supply, but in my opinion, for fire protection systems we should be flowing around our design demand points. I hope this helps.
*The above is my opinion and has not been processed as a formal interpretation in accordance with the NFPA Regulations Governing Committee Projects. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the **AFSA, and/or NFPA or its technical committees.**AFSA cannot provide design or consulting engineering services, and this opinion should therefore not be considered, nor relied upon, as such.* Thanks, John John August Denhardt, PE *Vice President, Engineering and Technical Services* *American Fire Sprinkler Association* m: p: 301-343-1457 214-349-5965 ext 121 w: firesprinkler.org <https://www.facebook.com/firesprinkler.org/> <https://twitter.com/afsa/status/1039528345367732224> <https://www.linkedin.com/company/american-fire-sprinkler-association-afsa-/> <https://www.instagram.com/firesprinklerorg/> *Our members are at the heart of everything we do.* Don’t miss another issue! Sign up to get your exclusive copy of the industry’s leading membership magazine Sprinkler Age delivered straight to your mailbox, inbox, or both! Subscribe <https://sprinklerage.com/subscribe> now to get the latest information you need to know and never miss another issue. On Tue, Aug 30, 2022 at 5:07 PM Fpdcdesign <[email protected]> wrote: > Chris, > > I think part of it is practicality. There are some situations where to get > a 25% drop, you are going to have to drain the water tower. Also, with > water companies that are doing their own tests with a couple of field guys, > they are not going to open a bunch of hydrants; one and done. > > Todd G Williams, PE > Fire Protection Design/Consulting > Stonington, CT > 860-535-2080 (ofc) > 860-554-7054 (fax) > 860-608-4559 (cell) > > > On Aug 30, 2022 at 5:21 PM, <Christopher Cahill <[email protected]>> > wrote: > > Good day all, it’s been a while. I’m still here for you old timers. > > > > It appears the traditional 25% drop in residual pressure for satisfactory > results has been modified to 10%, ’22 edition 4.4.6. I’ve looked in the > committee reports and can’t find why. When I look in the enhanced content > on Link it talks about 25% still. So now I’m wondering if it’s a typo. > Anyone have an idea why this changed? > > > > The option to flow system demand appears modified as well in 4.4.7 When > conducting a flow test for the purpose of fire protection system design, > the flow and pressure results should be adequate for the total demand of > the system. Like that’s practical for high demand systems, lol. > > > > Putting it together does it all mean for fire flow drop 10% and for system > design we now HAVE to go to system demand? > > > > *Chris Cahill, PE** \ Burns & McDonnell > > Sr. Associate Fire Protection Engineer > > Phone: 952.656.3652 > > [email protected] > > > > *Registered in: MN > > > > [image: A close up of a sign Description automatically generated] > <https://www.burnsmcd.com/insightsnews/industries/construction?utm_campaign=CORP_NationalConstruction&utm_source=OutlookSignatures_Web-InsightsNews-Industry-Construction> > > > _________________________________________________________ SprinklerForum > mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > [email protected] > > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > [email protected]
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