Frans, caught between a rock and a hard place. If you really want to control your flow with the least likelihood of failure you have a stored water supply adequate for the duration with an automatic replenishment feature, and a variable speed pump with a qualified operator. Now start counting those Euros and begin the compromising. I'd say a regulator is better built, suggesting more reliable, than a pressure relief though either can fail. But if you start enumerating all the things that can fail where do you stop, and that applies in either direction? Risk versus cost as always. Apparently the good folks at NFPA consider reducing less risky than relieving. Or is it that the guys making reducing valves have more woof on the committee than those that make relief valves?
On Wed, Apr 7, 2010 at 8:06 AM, Frans Stoop <[email protected]> wrote: > Lamar, > > I agree with you that the codes allow an approved PRV on the system > side (= downstream) the fire pump discharge valves. > The system side of the fire pump discharge valves is where NFPA 20 > ends and NFPA 13 (or 14) takes over. > So NFPA 20 - 2007 par. 5.7.6.2 ( = 2010 par. 4.7.7.2) does not apply. > And NFPA 13 allows PRV's. > Design everything upstream the PRV for 250 or 300 psi and everything > downstream for 175 psi. > > My fellow technical advisors in this country would ripost that there > is no good reason to reject a Pressure Relief Valve on one side and > accept a Pressure Regulating Valve on the other side. Both can fail. > A relief valve can fail in open position as easy as a regulating > valve can fail in closed position. In both cases there is too little > or no water downstream. > So, if the codes accept a pressure regulating/reducing valve, then a > pressure relief valve should be equaly acceptable. > > A pressure relief valve that fails with the valve in open position > means -> too little water to the sprinklers. > A pressure reducing/regulating valve that fails in closed position > means -> no water to the sprinklers. > Do we really want a pressure reducing/regulating valve? > > Frans Stoop > TOS architecture & fire protection > Netherlands <[email protected]> > Tel. +31-24-324 0112 > > At 13:51 6-4-2010 -0400, you wrote: >>Another way to deal with this issue is to use an approved pressure >>"REGULATING" valve in the pump discharge line.Granted this will take >>a lot more space and probably is more expensive,but,is an accepted >>method to achieve the shut-off pressure needed for the system. >> >>Lamar Vaughn , SET > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > -- Ron Greenman Instructor Fire Protection Engineering Bates Technical College Tacoma, WA Member: SFPE, ASCET, NFPA, AFSA, NFSA AFAA, NIBS, WSAFM, WFC _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
