You must install a piping system to drain $\mathrm{SAE} 10$ lube oil at $70^{\circ} \mathrm{F}(\mathrm{SG}=0.928)$ from tank $\mathrm{A}$ to tank B by gravity flow. The level in tank A is $10 \mathrm{ft}$ above that in tank B, and the pressure in tank A is 5 psi greater than that in tank B. The system will contain $200 \mathrm{ft}$ of Sch. 40 pipe, eight standard elbows, two gate valves, and a globe valve. What size pipe should be used if the oil is to be drained at a rate of $100 \mathrm{gpm}$ ?