How about a pressure recorder for a week or two to document the pressure fluctuations? Nothing worse than using 50 psi residual and finding 45 psi static on the gauge during inspection.
We are required to consider (due diligence) seasonal changes to the water supply. If the static does vary significantly from day to night or day to day or season to season the full range must be considered. I don't think imagining the worst possible extreme is due diligence but neither is ignoring the possibility. NFPA pretty well defines where the hose flow is added in so that shouldn't continue to be an issue. Ron Fletcher Aero Automatic Sprinkler Phoenix, AZ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Arthur Tiroly Sent: Monday, September 29, 2008 6:52 AM To: [email protected] Subject: FW: RE Water supply available Dear Forum, I will try this again. On several projects we are finding engineered water supply availability coming from the major chain store's [art] FP engineers. Recently the engineer used a city water flow test from a Cleveland 16" supply and assumes that the closest elevated water tank is empty and reduces static and residual by 30 ft = 13 psi. That becomes the new flow test for hydraulic calcs. He calls this the due diligence water supply for hydraulic calcs Even good water supplies become inadequate for some of the bigger box stores with flow demands of 1500-2000 gpm. This is NOT Walmart, Lowes or Home Depot. Where are these requirements to down grade a water supply coming from? Should this be the norm? Then we need a 10 psi cushion to the reduced residual. Is this the insurance company requirement? [art] Asking the engineers to back up a statement seems hopeless. "We need 1900 gpm at 50 psi at the riser flange including hose streams." But the hydrants are outside so the sprinkler demand is 1400 at the riser I say. "NO, we need the 1900 at the flange." This is an FPE. Comments please. Art Tiroly _______________________________________________ Sprinklerforum mailing list http://lists.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 http://lists.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)
