A high-temperature oscillating-disk viscometer

Abstract

The paper describes a new, high-precision, oscillating-disk viscometer in which it is possible to make absolute determinations of the viscosity of gases at atmospheric pressure in a temperature range 20–950°C, approximately. The effect of differential thermal expansion on the spacing between the disk and the fixed plates as well as that of high internal damping in the wire, both of which precluded the use of this method at high temperatures in the past, has been eliminated by making all such parts, including the suspension strand, of fused quartz. This was made possible by a novel method of drawing the strand. Estimates of precision and tests of reproducibility suggest that the measurements are accurate to ±0.1%. Preliminary results on pure nitrogen up to 500°C are presented. Excellent agreement with the most reliable determinations, which are available up to 75°C, is obtained, thus inspiring confidence in the results at higher temperatures.