Volume Flow our of a fire hydrant

[lord_temple]

I'm doing calculations for how much water was lost during flushing a hydrant. It is a 2.5 in. outlet and the pressure is on the system in that zone is 40 psi. It was flushing for 1.5 hours.

Q=AV

V=[(2 dP gc)/density]

density = 62.4 lb/ft^3
dP=40 psi
gc=32.2 lbm ft / lbf s^2

V=77ft/s

Q=AV=(0.0340)(77)=2.6 ft^3/s=19gal/sec

The hydrant was flushing for 1.5hrs=90mins=5400secs so...

The water lost was 19*5400=105,892.77 gals? is that right?? can you check my generals theory of my problem?? it seems to me a little bit high to loose 100,000 gals in 1.5 hours for flushing a hydrant... don't you think?

 

[FredGarvin]

This was answered on Eng-tips forum. I'd look there instead of rehashing it here as well.

 

[ravenprp]

Your calculations are correct. However, it is important to note that the volume flow out of a fire hydrant can vary depending on the size of the outlet and the pressure in the system. In this case, a 2.5 inch outlet at 40 psi would result in a high volume flow rate. It is also possible that there may have been some water loss due to leaks in the hydrant or pipes. It would be helpful to double check the pressure and outlet size to confirm the accuracy of your calculations. Additionally, it may be beneficial to compare the calculated volume with the actual volume of the hydrant to determine if there were any discrepancies. Overall, it is always important to carefully review and double check calculations to ensure accuracy in engineering projects.