The viscosity of nonpolar gases at normal pressures



Experimental viscosity data available in the literature for fifty-two nonpolar gases have been utilized in conjunction with a dimensional analysis approach to relate the viscosity at atmospheric pressure to temperature. The substances investigated are both simple and complex and include the inert and diatomic gases, carbon dioxide, carbon disulfide, carbon tetrachloride, and the hydrocarbons up to n-nonane, including normal and isoparaffins, olefins, acetylenes, naphthenes, and aromatics. The dependence of the product μ*ξ on reduced temperature was found to be the same for all of these substances, except helium and hydrogen.

Both theoretical considerations and dimensional analysis indicate that the viscosity product of a gas might depend on the compressibility factor at the critical point. However the results of this study show that for these nonpolar substances this viscosity product at normal pressure is independent of zc and depends only on temperature.

The only information required for the calculation of viscosity with the relationships developed in this study is the molecular weight, critical temperature, and critical pressure of the substance. Values calculated with these relationships have been compared with 785 experimental points from all reliable sources of experimental data and produced an average deviation of 1.77%. Comparisons have also been made with the values calculated with the Licht-Stechert and Bromley-Wilke equations.