Oil with a viscosity of $25 \mathrm{cP}$ and $\mathrm{SG}$ of 0.78 is stored in a large open tank. A vertical tube made of stainless steel with an ID of $1 \mathrm{in}$. and a length of $6 \mathrm{ft}$ is attached to the bottom of the tank. You want the oil to drain from the tank at a rate of $30 \mathrm{gpm}$.

(a) How deep should the oil in the tank be for the oil to drain at this rate?

(b) If a globe valve is installed in the tube, how deep must the oil in the tank be for it to drain at the same rate, with the globe valve wide open?