The influence of gas and liquid phase flow on the separation efficiency of Optiflow has been extensively studied. The tests were performed in a 1 m diameter distillation column with chloro-/ethyl-benzene as test mixture operated at total reflux. Packing heights varied between 3.8 and 6.4 m. The top pressures ranged from 25 to 960 mbar. From the experimental data a new method to determine the efficiency of Optiflow has been developed that accounts for the influence of liquid and gas flow independent of each other. The method is demonstrated for an industrial separation of aromatics.