A Karr column is to be sized to extract 99.95% of the methyl vanillin in water using o-xylene. The feed rate is 6 m³/hr with a vanillin concentration of 40 kg/m³. The average partition coefficient is 5.6, defined as the concentration in xylene to the concentration in water. Experiments with a Karr column of 2-inch diameter and 1.5- meter plate-stack height give the optimal conditions as 610 mL/minute of feed and 270 mL/minute of xylene, for a stroke height of 19.1 mm and 250 strokes/min. Scale-up this data to determine the diameter and plate-stack height of a commercial Karr column.