All it would take is one failure at the wrong time and your water is in the parking lot instead of coming out the sprinklers.
Clarke doesn't have PLDs in the UK market? 189-229 Lomond Road, Coatbridge, ML5 2, GB Tel: 44-0-1236-429-946 Todd, swapping the controller out for a variable speed one could easily be $75k for the controller on an electric; makes a break tank economically feasible. Might could swap out a diesel for a one with a listed PLD that is also listed with that pump. #20 has guidance on sizing break tanks, it's not just what you need minus what you got = what ya store. We did a "green" 3,000 GPM diesel pump last year, flowmeter to pump suction. I don't like to pump to suction, but they were adamant so that's what they got. glc -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Frans Stoop Sent: Monday, April 05, 2010 3:50 PM To: [email protected] Subject: RE: Pressure relief valves to flatten the pump curve George, Actually, what you mention is what I hear whispering by manufacturers of relief valves and fire pumps. Using diesels pump sets with Variable Speed Pressure Limiting Control is one option, although importing Clark diesel driven fire pump sets to Europe is not an easy thing to do. It becomes even more difficult when the client insists on having one diesel driven and one electric driven fire pump. In particular when all the involved technicians, including other fire protection specialists, see no reason why not to limit the maximum pressure with the pressure relief valve. Maybe there have not been that many failures of pressure relief valves? Frans Stoop TOS architecture & fire protection Netherlands <[email protected]> Tel. +31-24-324 0112 At 13:56 2-4-2010 -0400, you wrote: >I believe another reason was fear of main relief valve sticking OPEN as >flows increase, so the water that should go to 10 open heads is out in the >parking lot. > >We address by using Clarke diesels w/PLD, 170 pSI output from churn to >demand. About as good as it gets at base of riser. Sometimes your water >delivery has a "need for speed". > >Glc > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of Roland >Huggins >Sent: Friday, April 02, 2010 12:43 PM >To: [email protected] >Subject: Re: Pressure relief valves to flatten the pump curve > >doing a very bad thing all the time is not grounds for continuing to >do it. NFPA 20 did not allow it in the past although the sloppy >wording lead many to jump to that conclusion. The problem is during >the weekly churn test, you are dumping a boat load of water in the >parking lot etc. It now emphasizes that one is to design the system >appropriately and account for higher pressures by selection of >components (including not casually going to a bigger pump just to get >a little more pressure and down size the pipes just a touch more). >That's about as bright a light as I can shine. > >Roland > >On Apr 2, 2010, at 8:54 AM, Frans Stoop wrote: > > > 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)
