Todd, if I recall correctly from your earlier posts, the BFP is downstream of the fire pump. What does your calibrated gauge read on the suction side of the pump before starting the pump? Comparable to the hydrant static?
Dave David A. de Vries, P.E., CSP Firetech Engineering Incorporated 2715 Harrison St. Evanston, IL 60201 Tel: 847-733-0944 Fax: 847-866-6255 --- On Tue, 12/30/08, Ed Kramer <[email protected]> wrote: From: Ed Kramer <[email protected]> Subject: RE: suction pressure dilemma - part 2 To: [email protected] Date: Tuesday, December 30, 2008, 9:51 AM Todd, your theory rings a bell, albeit a distant one. Reading your post reminded me of high school or college physics class and Bernoulli's principal (the name of the theory may not be correct, it's been a while!!) The basis for the theory is that the total energy in a stream is a constant, so as kinetic energy (velocity) increases, potential energy (pressure) decreases. Or something similar to that. Now whether that can account for 12 psi in your situation is the kicker. I'd volunteer to do the math, but I can guarantee it would melt my brain. An observation - if the relief valve operates at 'churn' testing, then it really isn't a churn test. For purposes of testing the pump, has anyone temporarily disabled the relief valve long enough to get true churn readings? A true churn suction pressure reading might be more in-line with the static flow test reading. Or not. Keep us updated. Ed Kramer Littleton, CO > > I posted a problem about a month ago regarding a situation where the > suction pressure at churn of a pump was 12 psi less than the static > pressure during a flow test. Both were read at no-flow conditions and > there is no elevation difference. I was looking for an explanation, > as yet, none has emerged. The pump is a diesel drive and has a relief > valve that is piped back into the suction line. Could this be the > culprit? > > Todd G. Williams, PE > Fire Protection Design/Consulting > Stonington, Connecticut > www.fpdc.com > 860.535.2080 _______________________________________________ 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)
