NFPA 24 makes no mention of a minimum pressure requirement, NFPA 20 only requires a positive gauge pressure at the suction flange and most water purveyors jurisdiction/minimum pressure requirements stop at your tie in. I'm not sure if any other codes such as IFC have anything to say but NFPA codes wouldn't bar your design. Also if your water purveyor likes to come witness tests a lot of them get bent out of shape over the suction gauge readings and don't consider all the losses leading up to the fire pump, so it may still lead to a fight. Mike Morey, SET, CFPS Sprinkler Designer BMW Constructors, Inc. O: 317.651.0596 | C: 317.439.2695 www.bmwc.com
________________________________ From: [email protected] on behalf of Todd Williams Sent: Wed 8/24/2011 8:20 AM To: [email protected] Subject: Minimum pressures in water supply I am working on a new school project, where the building is 65 ft above the water supply in the road and 760 ft horizontally. The water supply is 54-46-1130. There is a pump planned, which I have to size. The total pressure loss in the underground between the supply and the pump house is approximately 30 psi. I know the general consensus (and some water company requirements) is that the water pressure not be drawn down below 20 psi. A 500 gpm at 60 psi pump would be a good fit for this project, but the suction pressures at the pump would end up being below 20 psi. The supply in the public mains would remain above 20 (due to the elevation), but would be below that in the private main at the pump room. Any thought if this would be acceptable? Todd G. Williams, PE Fire Protection Design/Consulting Stonington, CT 860.535.2080 www.fpdc.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum -------------- next part -------------- A non-text attachment was scrubbed... Name: winmail.dat Type: application/ms-tnef Size: 4494 bytes Desc: not available URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments/20110824/6bb66913/attachment.bin> _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
