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-firesprinkler.org > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.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
