the main point is that almost all (redundant) system components, fiittings, banging on hangers (if you've ever witnessed a system in "flow" mode) and piping are rated for a working pressure of 175 psi A FIRE PUMP IS SERIOUS FLOW..just go hold a 2 1/2" line..I dare ya
On 4/5/10, Johnson, Duane (NIH/OD/ORS) [C] <[email protected]> wrote: > Although I don't have any specifics, I heard there have been cases where the > main relief valve was improperly set and thus hindering fire fighting > operations. The handbook to section 5.7.6.2 (2007 edition) states the > reason for excluding them is because they are maintenance intensive. > > Ken Isman, from that 'other' association, may have more information. I know > he was heavily involved with the re-write of this section of code and has > been involved with the fire pump handbook in the past. > > Duane Johnson, PE > Program Manager > Division of the Fire Marshal (Support Contractor) > Office of Research Services > National Institutes of Health > 301-496-0487 > > > -----Original Message----- > From: Frans Stoop [mailto:[email protected]] > Sent: Friday, April 02, 2010 11:55 AM > To: [email protected] > Subject: Pressure relief valves to flatten the pump curve > > Forumites, > > NFPA 20 - 2007 par. 5.7.6.2 ( = 2010 par. 4.7.7.2) says: > "Pressure relief valves and pressure regulating devices in the fire > pump installation shall not be used as a means to meet the > requirements of 5.7.6.1." (= 2010 par. 4.7.7.1) > > I ask this question because it seems to be not unusual in my country > to fit fire pumps with a pressure relief valve to limit the churn > pressure below 175 psi in systems that need a high pressure (e.g. 165 > psi) in the point of operation. Thus flattening the first part of the > curve up to the point of operation. > This happens to both, engine driven as well as electric driven fire pumps. > In engine driven pumps they use for this purpose the same relief > valve as mentioned in section 5.18 "Relief Valves for Centrifugal > Pumps" (= 2010 section 4.18). > > Can anyone tell me why this par. 5.7.6.2 says: "shall not be used" ? > Why did the committee put this in the code ? > I remember times when it was not in there. > Is this based on bad experiences? > > When I point other technicians to this rule a common response is "Why > ? We do it all the time! " > > Can anyone of you shed some light on this issue? > > Frans Stoop > TOS architecture & fire protection > Netherlands <[email protected]> > Tel. +31-24-324 0112 > > _______________________________________________ > 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) > _______________________________________________ > 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) > _______________________________________________ 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)
