5.18.1.3 Where an electric variable speed pressure limiting control driver is installed, and the maximum total discharge head adjusted for elevation with the pump operating at shutoff and rated speed exceeds the pressure rating of the system components, a pressure relief valve shall be installed.
We do not use Relief valves any more. We rely on the proper rated fittings and Pressure Reducing Valves. The relief valves we have seen do not operate quickly enough to save the system from being exposed to higher pressure and they discharge so much water that they destroy property. Plus we have never understood this section because it defeats the purpose of the relief valve in regards to the rating of the fittings. This actually traps the pressure in the system if the relief valve is slow in opening. 5.18.3 Location. The relief valve shall be located between the pump and the pump discharge check valve and shall be so attached that it can be readily removed for repairs without disturbing the piping. Greg Living Water Fire Protection, LLC 1160 McKenzie Road Cantonment, FL 32533 850-937-1850 Fax: 850-937-1852 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bobby McCullough Sent: Wednesday, March 14, 2007 8:18 AM To: [email protected] Subject: RE: pump tricks Greg: Here in Georgia we adopted NFPA 20, 2003 two months ago and we may very well adopt 2007 later this year. I'm trying to figure out the application of the main relief valve. (2007) 5.18.1.2* Pressure relief valves shall be used only where specifically permitted by this standard. Does the standard specifically allow the use of a main pressure relief valve anywhere except for use with a diesel pump and/or in combination with a variable speed drive? Bobby -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Greg McGahan Sent: Wednesday, March 14, 2007 8:28 AM To: [email protected] Subject: RE: pump tricks It is not allowed to eliminate pressure reducing valves on any pump. In the old days we did it but now we are required to provide PRV's anywhere the fittings and sprinklers working pressure is less than the greatest expected pressure on the components (churn + static - elevation loss). 5.7.6.1 The net pump shutoff (churn) pressure plus the maximum static suction pressure, adjusted for elevation, shall not exceed the pressure for which the system components are rated. 5.7.6.2* 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. Greg Living Water Fire Protection, LLC 1160 McKenzie Road Cantonment, FL 32533 850-937-1850 Fax: 850-937-1852 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bobby McCullough Sent: Wednesday, March 14, 2007 7:14 AM To: [email protected] Subject: RE: pump tricks Tony: I believe NFPA 20 2003 and 2007 limit the use of a main pressure relief valve for use with a diesel pump and/or in combination with a variable speed drive. I don't believe the relief valve is allowed with an electric pump just to chop off the high end of the pressure curve. Bobby McCullough -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of A.P.Silva Sent: Wednesday, March 14, 2007 1:37 AM To: [email protected] Subject: RE: pump tricks This is an old thread, but I'm working on two projects, a six storey and 9 storey with fire pumps and it got me thinking (not an easy feat). Most times, the problem is not when you have a large flow through the sprinklers or hose stations. It is when the flow is small or at churn pressure. When the flow is large, the pressure has dropped down below 175 psi. When the flow is small you don't need the extra pressure. So if you install a pressure relief valve set at say 160 psi, you shouldn't need the XH pipe, fittings and pressure reducing valves. I might be wrong, but I'm thinking the pressure relief valve must be costing less than a pressure reducing valve. Any thoughts? Tony -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - work Sent: February 7, 2007 7:22 AM To: [email protected] Subject: pump tricks I seem to be running into several situations lately where there is a very fine balancing act between meeting the 100 psi at the top outlet of the standpipe and not exceeding 175 psi at the base of the riser. (6 story hotels are a good example) Does anybody have any good ideas they'd care to share on making these work? I'd like to limit the use of extra-heavy pipe and fitting (especially larger sizes) and PRVs. I have several tricks up my sleeve, but I'm running out of sleeves. Todd Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut 860-535-2080 www.fpdc.com _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
