CEE 371 Fall 2009

# Homework #2

Hydraulics and Flow in Pipes

1.      Water Pressure

a) What is the hydraulic head in ft equivalent to a pressure of 30 lbs per square inch (psi)?

b) What is the pressure in psi equivalent to 80 ft of head?

2.      Use the Darcy Weisbach equation to choose a pipe size (diameter in inches) given the following information: ductile iron pipe with roughness (ε) of 2x10-4 ft, flow of 600 gpm, pipe length of 3000 ft, and frictional head loss as close to 12 ft as feasible but do not exceed.  Choose a pipe diameter that is a common nominal pipe diameter.

3.      Do Problem #2 but now use the Hazen Williams equation with a C of 140.  Compare your answer to that obtained in Problem #2.

4.      Water is pumped 8 miles from a reservoir at an elevation of 120 ft to a second reservoir at an elevation of 280 ft.  The pipeline connecting the reservoirs is 54 inches in diameter. It is concrete with a C of 100, the flow is 25 MGD, and the pump efficiency is 82%.  What is the monthly power bill if electricity costs 8.5 cents per kilowatt-hour? (ignore minor losses)

Assigned: 18 Sept 09

Due: 28 Sept 09