Viscosity of organic liquids at elevated temperatures and the corresponding vapour pressures

Abstract

This work involved the measurement of the viscosities of pure organic liquids at temperatures ranging from 353.15 K to 463.15 K and at the corresponding vapour pressures. A rolling ball viscometer was used where considerable emphasis was given to achieve simplicity and rapidity in obtaining results, without sacrificing the accuracy. Considering the forces affecting the motion of the ball inside the viscometer tube, an equation for the calibration of the viscometer at the same working temperature was derived. The constants of this equation were determined using benzene as the reference liquid, and the dependency of the constants on the temperature was also established. Comparing the derived equation with published ones demonstrated its adequacy in both the streamline and transition flow conditions. The liquids studied were toluene, methanol and n‐hexane. In some cases, the results compared reasonably well with published data while in others, deviations of up to 15% were found. Nine equations were tested with the experimental results for the prediction of the viscosity of these liquids. It was found that the 3‐constant Agrawal and Thodos empirical equation gave the least average deviation. Copyright © 1977 Canadian Society for Chemical Engineering