Question: how do you calculate water velocity in a pipe?
Answer: Calculate the value of the average velocity V of the flow by plugging in the values you determined for n, S and Rh into V = (k ÷ n) x Rh ^2/3 x S^1/2. For instance, if we found S = 3, Rh = . 125 ft, n = 0.024 and k = 1.486, then V will equal (1.486 ÷ 0.024s/(ft^1/3)) x (. 125 ft^2/3) x (3^1/2) = 26.81 ft/s.