You wrote, " ... using two pressure reducing valves in series. Then run two standpipes, one low pressure and the other, high pressure and use additional pressure reducing valves at each floor where the pressure exceeds 175 psi." Taken literally, your statement could mean that you would create two zones using master PRV's and then use PRV's again at each floor after that. You didn't specify that you would only use floor PRV's on the upper zone. If that's not the intent then disregard.
What I would instead is create zones based on where the break occurs between pressure above and below 175psi. Where higher floors are not exposed to ≥175psi, you don't need any more pressure regulating equipment so figure out where that break occurs. -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of T. Silva Sent: Tuesday, May 26, 2015 10:29 AM To: [email protected] Subject: Re: Highrise Steve, thanks for your valued comments. I'm not sure if I understand your statement "PRV inside PRV". My concern was whether a single PRV can be used on each floor to reduce pressure to both sprinklers and non-pressure reducing hose valve. I normally see PRV for sprinklers and separate pressure reducing hose valve. As this must be more costly than using a single PRV for both sprinklers and hose, there must be a reason why that is the normal method. At least that is what I think. Any comments? Thanks, Tony ----- Original Message ----- From: "rongreenman ." <[email protected]> To: [email protected] Sent: Tuesday, May 26, 2015 10:46:32 AM Subject: Re: Highrise I'm going to agree MOST DEFINITELY with Steve's arguments, pro and con, and his conclusion. On Tue, May 26, 2015 at 6:55 AM, Steve Leyton <[email protected]> wrote: > For the sake of both reliability and maintenance, I think you want to > pick one or the other basis of design, i.e. create a lower zone with a > double reducing valve manifold or (assuming the building isn't so tall > as to preclude this) make the building a single zone and use point of > connection reducing valves at each hose connection and sprinkler floor > control assembly. I would not want PRV's inside of PRV's. > > PR hose and control valves are either spring (totally field > adjustable) or piston type and these designs will fail in the open > state if they do. I prefer this type of valve because even if it > hasn't been maintained and isn't working properly, water is still available > to fire fighters. > Pilot-type valves can fail open or closed, and the prospect of a > full-close fail state is of highest concern, hence the NFPA 14 > requirement for redundancy. (Sidebar note: if you pursue this > approach, remember that you also need to account for the lowest flow > of one or two sprinklers, so two smaller PRV's are likely also > required.) > > The most critical element of all is the issue of maintenance - > regardless of which approach, will these valves be ITM'd by the owner > to assure functionality? Zone-by-PRV is likely the less expensive > approach and there are fewer valves to test, but in a fire fight there > is a higher (albeit still very low) chance of interruption of the > water supply. Point of connection valves are more expensive and there > are more of them to test and maintain, but are considered more > reliable (again, the % chance of failure overall is very low in any > case) and will fail open. But there is a critical difference and that > is that POC valves can be ordered that are completely field-adjustable > in flow and no-flow conditions, allowing firefighters the most > flexibility during an operation. For me - as a consultant who isn't > spending his own money - and knowing what I know about the available > product technologies, I prefer the POC approach because at the end of > the day a standpipe system is about r eliability of the water supply and > firefighter safety. > > The preceding is MOST DEFINITELY my opinion only and does not > represent the NFPA 14 Technical Committee or AFSA in that or any other regard. > > Steve > > > -----Original Message----- > From: Sprinklerforum on behalf of T. Silva > Sent: Mon 5/25/2015 10:44 PM > To: [email protected] > Subject: Highrise > > Can you share your strategies for highrise buildings? Or direct me to > a source for information? > > I am planning to reduce the pressure after the fire pump, using two > pressure reducing valves in series. Then run two standpipes, one low > pressure and the other, high pressure and use additional pressure > reducing valves at each floor where the pressure exceeds 175 psi.This > PRV at each floor will reduce the pressure (only where it exceeds 175) > to both the sprinkler zone and hose connection. Any problem with that? > Or do I have to use a PRV for only the sprinkler zone and a pressure > reducing hose valve for the hose connection? The hose connections are > 2 1/2" with 2 1/2" x 1 1/2" reducers. > > Any feedback will be appreciated. Thanks. > > Tony > > > > Call > Send SMS > Add to Skype > You'll need Skype Credit Free via Skype > _______________________________________________ > 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-firesprinkl > er.org > -- Ron Greenman Instructor Fire Protection Engineering Technology Bates Technical College 1101 So. Yakima Ave. Tacoma, WA 98405 [email protected] http://www.bates.ctc.edu/fireprotection/ 253.680.7346 253.576.9700 (cell) Member: ASEE, SFPE, ASCET, NFPA, AFSA, NFSA, AFAA, NIBS, WSAFM, WFC, WFSC They are happy men whose natures sort with their vocations. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) A problem well stated is a problem half solved. -Charles F. Kettering, inventor and engineer (1876-1958) _______________________________________________ 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
