A method is proposed of correcting the design of countercurrent sepn. columns for the impact of axial-dispersion effects. After computing the required no. of transfer units (NTU) employing conventional procedures based on the plug-flow assumption, the method permits the estn. of a correction factor accounting for deviations from plug flow. This factor is used to correct the NTU for such effects. The procedure also works in correcting height-of-transfer-unit data that are affected by axial dispersion. The method is straightforward and simple to use, and the results agree in simple cases within a few percent with those obtained from a rigorous soln. of the model of axial dispersion. [on SciFinder (R)]