George, Why not simply plot the curve on paper from static pressure/zero flow all the way down to 20psi residual/maximum flow. (If your water purveyor follows AWWA M31, 20psi is the minimum residual). Do that on everyjob, really how much longer does it take one to extend the line. No extrapolation needed, any demand point that falls on or under the plotted curve is acceptable. In plain speak explain its like an umbrella. From a plan review standpoint you have to show me the people under it and the size of the umbrella so as to make sure everyones under the umbrella, from an inspection standpoint if your getting wet the umbrellas too small or theres too many people.
John -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of George Church Sent: Thursday, July 31, 2008 8:12 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) CONFIDENTIAL AND PROPRIETARY: This email message is intended only for the use of the individual or entity to which it is addressed and may contain information that is privileged and confidential, nor is it, unless specifically stated, intended to be relied upon by any person or persons other than the individual or entity named above and no warranties or representations are made or intended to persons or entities not named above. If the reader is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by telephone, return this message to the address above and delete all copies. Thank you. _______________________________________________ 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)
