13.4 An air-ammonia mixture, containing 1.5 volume percent NH3, at 95 °F and 1.0 atm is scrubbed in a packed tower with pure water at 95 °F. The outlet NH3 concentration must be no more than 0.1% to meet EPA regulations. a. What volume of this gas in acfm can be processed in a 2-ft diameter column packed with 1-in. ceramic Raschig rings if the gas-to-liquid mass flow ratio is 1.0? b. What height of packing is necessary if Hoy is 1.85 ft?