A water system of 2 in.(inside diameter) pipe, having a length of 1/4 mile, is to be flushed with a volume of water equal to twice that contained in the system. how much water (gallons) must be flushed through the system? (note: one cubic foot=7.481gal.)

Answer 1

if the pipe is full, it contains

pi * 2^2 * 1/4 * 5280 * 12 = 199051 in^3 = 115.19 ft^3

So, we want twice that, or

230.38 * 7.481 = 723.5 gal

Answer 2

rats. divide that by 4, since I was using radius=2, not diameter