Oil with a viscosity of 25 cP and SG of 0.78 is contained in a large open tank. A vertical tube made of commercial steel, with a 1 in. ID and a length of 6 ft, is attached to the bottom of the tank....

Oil with a viscosity of 25 cP and SG of 0.78 is contained in a large open tank. A vertical tube made of commercial steel, with a 1 in. ID and a length of 6 ft, is attached to the bottom of the tank. You want the oil to drain through the tube at a rate of 30 gpm.

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

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