Experimental work on a 229-mm-dia. air/liquid distillation simulator shows that the surface tension of a given liquid can affect the total tray pressure drop, which normally consists of the sum of dry tray pressure drop clear liquid head, and residual pressure drop. Both the dry tray pressure drop and clear liquid head values establish correlations in the literature for their prediction. The residual pressure drop, however, has been regarded as a constant value. This is not the case and the residual pressure drop is a dynamic variable. Three different surface-tension liquids (water, benzyl alcohol, and n-Propanol) are used to isolate this effect. Results presented correlate the residual pressure drop in terms of the gas F-factor, the clear liquid head, and the traditional residual head loss definition.