They already took the 10% off the available pressures so their actual margin would be around 10-11 psi without the 10% decrease, but here's another twist, the test hydrant is not on the same water main that serves the site and is several hundred to a thousand feet away. So there is some question as to the real value of the test in relation to what is actually available at the site. Calcs say test to riser is less than 10ft.
Craig L. Prahl, CET Fire Protection Specialist 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 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Steve Leyton Sent: Monday, November 30, 2009 3:14 PM To: [email protected] Subject: RE: Calcs-How much margin Did they observe a safety margin below the actual flow test result? If you take 10% off the available to start and still have 3.63 PSI, then sure. But if that's 3.63 PSI below the actual flow test result then unless the water supply is ... umm, distressed, it doesn't sound like a good idea. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, November 30, 2009 12:11 PM To: [email protected] Subject: Calcs-How much margin I've got a calc I'm reviewing, after all said and done, 3.63 psi margin between demand and available. Designer used 4.2K heads to get the flow exactly to the decimal of the required flow. This is an industrial type project. With a .15 gpm/sf density at 92 sf per head, the flow would be 13.8 gpm and he's dead on the money. The concern would be that over the years if there was any change in the water supply or decay of the piping, that the operation of half the design area would be questionable. Would you approve or reject this design? Is this cutting it just a bit close? Craig L. Prahl, CET Fire Protection Specialist 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://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) __________ Information from ESET NOD32 Antivirus, version of virus signature database 4650 (20091130) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 4650 (20091130) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
