High‐Temperature Viscosity Ratios for Hydrogen, Helium, Argon, and Nitrogen

The temperature dependency of the coefficient of viscosity relative to its value at 283°K has been determined for hydrogen, helium, argon, and nitrogen at atmospheric pressure. The method used is a variation of the usual capillary viscometry scheme in that no attempt is made to obtain absolute viscosity values. The measurements provide the ratio of the viscosity of a gas at temperature T to its viscosity at the reference temperature, 283°K. The value of T ranges from 1100°K to 2150°K and is measured by a disappearing filament pyrometer. In this relative method there is cancellation of most noncontrolled experimental variables so that the measurements are of high reproducibility, ±0.1%, and apparently accuracy, ±0.4%, is limited only by the uncertainties in the international temperature scale in the optical pyrometer range. These results are higher by 3%‐8% compared with the results of previous workers. However, extrapolation of lower‐temperature viscosity measurements by Kestin and Leidenfrost, and more recently by DiPippo, gives excellent agreement with the values reported here.