# Thread: Question re water velocity and flow rate

1. ## Question re water velocity and flow rate

Hello!

"What is the water flow rate in a 10 inch diameter pipe in gallons per minute when the flow velocity is 1.8 feet per second?"

I know I first need to calculate the area of the pipe, which I believe is .54 sq ft.
Can anyone help with the next step?

Thank you.

2. Originally Posted by Greg999
Hello!

"What is the water flow rate in a 10 inch diameter pipe in gallons per minute when the flow velocity is 1.8 feet per second?"

I know I first need to calculate the area of the pipe, which I believe is .54 sq ft.
Can anyone help with the next step?

Thank you.
Volume per second is Area times Speed and if these are in sq ft and fps the volume rate will be in cubic feet per second

CB

3. Area times speed. That would make the answer .54 times 1.8?

4. Originally Posted by Greg999
Area times speed. That would make the answer .54 times 1.8?
No, the area is incorrectly rounded (and state the units)?

CB

5. Originally Posted by Greg999
Area times speed. That would make the answer .54 times 1.8?
More correctly, it is .54 square feet times 1.8 feet per second which will give a result in "cubic feet per second"- but you want gallons per second. Both "cubic feet" and "gallons" are volume measures. You will need to look up how many gallons there are in a cubic foot. Then multiply "cubic feet per second" times "gallons per cubic foot" to get "gallons per second".