Tim, Here is my two cents worth (it was worth a dime before the current economic crisis!) Also, could you answer a few questions so a better analysis could be made?
(1) Did you do the proper two-hydrant flow test? (2) What was the full flow test for the area (static, residual, and flow) (3) How far away from the pressure reading hydrant did you do the pitot (flow) reading? (4) What size underground line was this test taken from? (5) Was it dead-end or a circulating (looped/gridded) main? (6) Was there any significant elevation change between the flow and pressure hydrants? (7) If it is a dead-end line, did you flow the hydrant on the end of the line or take the pressure readings from the end hydrant? All things being equal, a pitot reading should be pretty much the same as the residual pressure reading minus the elevation difference between the hydrants, any friction loss in the piping system associated with the distance between the two hydrants, the friction loss thru the type of hydrant in place, and the actual coefficient of the tested opening. Typically, when you have such a dicrepency between the residual pressure and the pitot readings there is an obstruction somewhere in the line, or a valve is closed (or partially closed) somewhere in the piping system and you are not getting the proper available flow thru the test hydrant. I am also not getting the warm and fuzzies regarding the flow test paper information either, just based on the numbers you indicate. It is entirely possible the flow test you are referencing is also incorrect or was not performed properly. Ray Vance - SET Chief Sales Designer Wayne Automatic Fire Sprinklers, Inc. www.waynefire.com (407) 877-5563 office (321) 436-2184 cell -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Forest Wilson Sent: 2008-10-14 21:43 To: [email protected] Subject: FLOW / PITOT READINGS Am I ignorant on this subject? Please let me know. If you flow a 2 1/2" hydrant, and the pitot reading is 55 psi the gpm will always be 1250. Right? (I understand you factor in the coefficient of the hydrant nozzle). My pitot gauge manufac tured by Potter shows BOTH gpm AND psi. I'm looking at a flow test paper. Through a 2.5" hydrant outlet. Residual is 90 psi @ 840 GPM. Is this possible? Forest Wilson Cherokee Fire Pro. a _______________________________________________ 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)
