So you have run into a sprinkler scientist (AHJ). I feel your pain. Balancing the flow in a system is a lost art completely ignored by the computer programs we use today. Computer programs bump up the end head pressure to create equal pressures at a flow split. Without knowing the particulars of the system design these suggestions may or may not make a difference.
* You could re-calc using velocity pressure if it isn't a grid it should get you a little closer. * Tweak the riser nipple diameters to better balance the pressures at the crossmain. *Use higher pressure from a sprinkler with a smaller orifice i.e. change from K11 to K8. * If the sprinklers are not equally spaced make sure your not overflowing some of the heads. Check actual flow compared to minimum required. Good Luck, Ron Fletcher Aero Automatic Sprinkler Phoenix, AZ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Joe Burtell Sent: Thursday, July 31, 2008 7:20 AM To: [email protected] Subject: RE: Water Supply The AHJ is what George said, not allowing me to extrapolate beyond the test point on the curve of 1210 gpm. Does anyone know of any sections in NFPA that would hint that I can extrapolate beyond the 1210 gpm or can't? -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of George Church Sent: Thursday, July 31, 2008 6:12 AM To: [email protected] Subject: RE: Water Supply I believe what Joe has encountered is an AHJ who doesn't realize what EXTRAPOLATION on a water supply graph is. Interpolating a point on a curve is when the demand falls between your static and residual points; extrapolation is when the demand is past the point where the residual flow was measured. Chris is 100% right on the iffy-ness of a 300 GPM flow extrapolated out to 1200. But 31 gpm past the measured point? I'd ask the AHJ to cite code to indicate where you are wrong. Probably time for a #13 committee member letter or an informal interpretation. Or a day in hydraulics class for the AHJ? glc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Cahill Sent: Wednesday, July 30, 2008 2:19 PM To: [email protected] Subject: RE: Water Supply It most certainly does in the context of lowering the residuals to a pressure less than your design pressure and providing more water at a lower pressure that is then boosted to the pressure needed. This is what we (or at least I) though Joe's problem was at first, he was 31 gpm on the wrong side of the curve. Perhaps it was the way it was implied that confusion was created. Agreed pump's don't create water but create AVAILABLE water (to a point) at a desired pressure. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [EMAIL PROTECTED] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, July 30, 2008 12:48 PM To: [email protected] Subject: RE: Water Supply SNIP And for others, adding a pump does not create more water. A pump will not add 31 gpm to the source. Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.ch2m.com _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
