A pipeline to carry crude oil at a rate of 1 million bbl/day is constructed with $50 \mathrm{in}$. ID pipe, and it is 700 miles long. It contains the equivalent of 70 gate valves but no other fittings.

(a) What is the total power required to drive the pumps if they are $70 %$ efficient?(b) How many pump stations will be required if the pumps develop a discharge pressure of 100 psig?

(c) If the pipeline must go through hilly terrain, what is the steepest downslope grade that can be tolerated without creating slack flow in the pipe?

(crude oil viscosity $=25 \mathrm{cP}, \mathrm{SG}=0.9$ )