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Fire flow question

Fire flow question

Fire flow question

(OP)
I have been given a table of fire flows at various hydrants by a city. A column provides a calculated flow rate for the given hydrant at 20 psi, the max fire flow if you will. I cant remember the equation used to determine this rate. I seem to remember it is a form of the energy equation. As with standard  fire flow tests, I have static and flowing pressures at two hydrants. I dont want to solve it graphically. Does anyone have this worked out with the conversion factors to get it in standard units? thanks

RE: Fire flow question

(OP)
Nothing better than answering your own question...

The equation is

Available water = Q mutliplied by  square root(D2/D1)

where available water is flow rate in gpm
Q = flow rate of flowing hydrant in gpm
D2 = static pressure - assumed residual pressure of 20 psi
D1 = static pressure - actual residual pressure

leadfeet

RE: Fire flow question

Thanks, cvg.  I had gotten used to using the .54 log graph method at my other job.  I don't have any of that paper here, and I needed a quick, no-frills refresher.

If anyone else needs a summary, this is a page or two that cuts to the chase.

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve

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