Results are presented of total reflux distillation experiments conducted with Montz-pak B1-250MN at Fractionation Research Inc. in a 1.22 m internal diameter column using a paraxylene/orthoxylene (p/o-xylene) system at 0.1 bar and a cyclohexane/n-heptane (C6/C7) system at 0.31 and 1.62 bar. The same efficiencies were obtained at vacuum and above atmospheric pressure with the C6/C7 system, and these were slightly lower compared to those measured with the close boiling, p/o-xylene system. The Delft model, which accounts for packing geometry modifications as employed in this case, proved to be capable of approaching the closely measured efficiency as well as the measured pressure drop both qualitatively and quantitatively.