John Sometimes not that easy: This printer was allowed to tap into an 18" trunkmain, as that was the only reliable main within 1 mile. We started the flowtest with 250 gpm, then went to 500 gpm, 750 gpm, 1000 gpm, 1250 gpm, and hit 1500 gpm, (this was 125% of total demand for sprinklers and hoses) just to see a pressure drop, the pressure dropped from 98 psi to just 95 psi. The water utility said to drop the pressure by 25% we need to follow hell of a lot more, we may flood some streets and he would not allow this full-stop.
Cheers Jack C Kilavuz Assistant Director Managing Consultant - RMS Royal & Sun Alliance Insurance - Singapore 77 Robinson Rd #17-00, Singapore 068896 DID: (+65) 6423 0552 Fax: (+65) 6423 0798 Mobile (+65) 9277 5741 Website: www.rsagroup.com.sg Note new e-mail address: [EMAIL PROTECTED] Please consider the environment before printing this e-mail! "John Drucker" <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] 01/08/2008 03:38 AM Please respond to [email protected] To <[email protected]> cc Subject RE: Water Supply Eric, Good point. In order to be accurate sufficient water must be flowed to attain a 25% drop in pressure. (NFPA 291-4.3.6) As a plan reviewer I've seen plenty of flat tests and back they go. Wheres that stick. John Drucker -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of LONGMAN Eric G (AREVA NP INC) Sent: Thursday, July 31, 2008 3:12 PM To: [email protected] Subject: RE: Water Supply Joe, Although I am fairly convinced of the correct answer to this issue, I looked back through the NFPA Handbook (18th Ed.) and found an interesting statement with respect to this issue... "It is not necessary [in the example given in the text] nor should it become common practice, to extrapolate much beyond the maximum flow point, because tests from networks often produce supply curves that flatten out as the rate of flow increases." [Section 6 Chapter 7] If you have plotted several test points that all lead to a straight line, indicating an assurance of such an extrapolation out an additional 31 gpm, I would agree that 31 gpm would typically not be considered an extreme extrapolation of this curve. This can get back in to a discussion of the absolute exactness of hydraulic calculations in the first place, which has been hashed out on here previously. Anyway, just my $0.02 on the subject. Eric -------------------------------------------------------------- Eric G. Longman AREVA NP Inc. Fort Worth, Texas -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Drucker Sent: Thursday, July 31, 2008 1:44 PM To: [email protected] Subject: RE: Water Supply Joe, Its appears as though you have more then enough water (then again you already knew this). I didn't ask you about pressure because that can be resolved with a fire pump. I know other code officials who have complained about some computer programs that don't draw the traditional curve merely marking points with stars, I connect the dots, others don't. 2002 NFPA-13 14.3.4 doesn't need any further explanation, the operative term is "complete hydraulic calculation. So plot the curve from 0 to 0, yea you read that correctly, draw a line down at 20 psi and shade the area beyond 20 if you choose. 15.1.2 Capacity, 15.2.1.2 Connections are the other applicable sections of the standard. If all else fails an appeal may be in order. John Drucker Fire Protection Subcode Official (AHJ) Red Bank, NJ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Joe Burtell Sent: Thursday, July 31, 2008 12:02 PM To: [email protected] Subject: RE: Water Supply About 2100 GPM. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Drucker Sent: Thursday, July 31, 2008 9:45 AM To: [email protected] Subject: RE: Water Supply Joe, What is GPM (Q) at 20psi residual (R20) on your supply curve ? John -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Joe Burtell Sent: Thursday, July 31, 2008 10:20 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. 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