Crude oil with a viscosity of $12.5 \mathrm{cP}$ and $\mathrm{SG}=0.88$ is to be pumped through a $12 \mathrm{in}$. Sch. 30 commercial steel pipe at a rate of $1900 \space \mathrm{bbl} \space \mathrm{h}$. The pipeline is 15 miles long, with a discharge that is $125 \mathrm{ft}$ above the inlet, and contains 10 standard elbows and 4 gate valves.

(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 psi each?

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