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# Water flow equation

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 skdesigner (Mechanical) 20 Aug 12 11:35
 I had it written down, lost it and for the life of me I can't remember how it goes. Equation to figure out flow at a certain pressure when given static and residual. For example, I do a flow test and come up with x static and y residual pressure at some flow. I need to determine how much flow will be available at 20 psi. I know that I can just use 1.85 graph paper, but for the sake of precision, does anyone have this equation handy? Thanks in advance! Steve
 cdafd (Specifier/Regulator) 20 Aug 12 11:53
 maybe: sorry cannot copy but: Qr = Qf x hr(.54) power divided by hf (.54) power where: QR = flow predicted at desired residual pressure QF = total flow measured during test hr = pressure drop to desired residual pressure hf = pressure drop measured during test check this link for the formula::: http://developmentservices.cityofoxnard.org/Upload...
 cdafd (Specifier/Regulator) 20 Aug 12 11:54
 skdesigner (Mechanical) 20 Aug 12 11:57
 Much appreciated!
 NewtonFP (Automotive) 20 Aug 12 12:02
 Qf=Qr((Hr^0.54/Hf^0.54) Qf=flow at desired pressure (gpm) Qr=flow at residual pressure (gpm) Hr=(static - desired pressure) (psi) Hf=(static - residual pressure) (psi)
 cdafd (Specifier/Regulator) 20 Aug 12 12:17
 TravisMack (Mechanical) 20 Aug 12 13:59
 Hey SK, shoot me an email and I will send you a flow test form in MS Excel that does the graphs and also gives you the flows at 20 psi. I got it from OSU's website long ago, so I don't believe it is an proprietary information or spreadsheet. Travis Mack MFP Design, LLC www.mfpdesign.com

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