Problem 4.8.4

Water is being delivered from an open tank through a 0.5-in diameter brass pipe at a rate of 0.01 cubic foot per second. Pipe is 200 feet long. The pipe network contains a globe valve (K_V = 6.9). Entrance and exit losses can be described as K_entrance, 0.78 and K_exit, 1.0 velocity heads. What is the water level in the tank?

Solution:

Water is flowing through the pipe at a velocity of 7.334 feet per second. Reynolds number is 2.532 times 10⁴. Friction factor can be read as 0.0061. Head loss through valves is equal to 6.9 plus 0.78 plus 1.0 or 8.68 velocity heads. Replacing velocity by its value, head loss is 7.25 foot pound-force per pound-mass. Skin friction losses are 97.715 foot pound-force per pound-mass. Combined losses are 7.25 plus 97.715 or 104.97 foot pound-force per pound-mass.

Applying Bernoulli Equation, p₁ = p₂, V₁ = 0 (assuming that tank has very large tank). Water level in the tank, Z₁, is 105.8 feet.