Ammonia is being absorbed in a column using pure water at 25 C and 1.0 atm pressure. The feed flow rate is 1440lb/h and contains 3.0 mol% ammonia in air. The process design specifies a liquid to gas mall flow rate ratio " / " GL of 2.0. 1.0-in metal pall rings are used as the packing materials and the allowable pressure drop of this packing materials is 0.5-in H2O/ft. Calculate the column diameter.