Fire flow question 1

[leadfeet]

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

 

[leadfeet]

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

 

[cvg]

try the following link:

http://www.firehydrant.org/info/ftest4.html

 

[LHA]

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