How many gallons per minute (gpm) flow can be expected from a 12-inch pipe at a velocity of 4 feet per second?

To determine the expected flow in gallons per minute from a 12-inch pipe at a velocity of 4 feet per second, it is essential to apply the equation for flow rate, which is the product of the cross-sectional area of the pipe and the velocity of the flow.

First, calculate the cross-sectional area of the pipe. The area ( A ) of a circle is given by the formula:

[ A = \pi \times r^2 ]

Where ( r ) is the radius. For a 12-inch pipe, the diameter is 12 inches, and the radius is 6 inches. Converting inches to feet (since the velocity is in feet per second):

[ r = 6 \text{ inches} = \frac{6}{12} = 0.5 \text{ feet} ]

Now we can calculate the area:

[ A = \pi \times (0.5)^2 = \pi \times 0.25 \approx 0.7854 \text{ square feet} ]

Next, to find the flow rate in cubic feet per second (cfs):

[ \text{Flow Rate} = A \times \text{Velocity} = 0.