A stripping column packed with 2 in. metal Pall rings uses air at $5 \mathrm{psig}, 80^{\circ} \mathrm{C}$, to strip an impurity from an absorber oil $\left(S G=0.9\right.$, viscosity $=5 \mathrm{cP}, T=20^{\circ} \mathrm{C}$ ). If the flow rate of the oil is $500 \mathrm{lb}_{\mathrm{m}} / \mathrm{min}$ and that of the air is $20 \mathrm{lb}_{\mathrm{m}} / \mathrm{min}$, determine the following:

(a) What is the minimum column diameter that can be used without flooding?

(b) If the column diameter is $50 %$ greater than the minimum size, what is the pressure drop per ft of column height?