Viscosity-ratio measurements with capillary viscometers

Published

November 27, 2013

Author(s)

Robert F. Berg, Eric F. May, Michael R. Moldover

Abstract

Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium calculated ab initio. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic gas thermometry and for the most accurate redeterminations of the Boltzmann constant. Accurate viscosity ratio measurements enable the calibration of laminar flow meters with surrogate gases and their use with process gases. We review ratio viscometers that comprise one, two, and four capillaries. A single capillary is a ratio viscometer when it is used to measure multiple gases, while two- and four-capillary viscometers are instruments intended for ratio measurements. We consider gases and Newtonian liquids, with a focus on the two-capillary gas viscometer and its extension to pressures up to 100 MPa. A single-capillary viscometer could measure the ratio (viscosity of liquid water)/(viscosity of gaseous helium) thereby reducing the uncertainty of the liquid-viscosity scale relative to the international system of units.

Citation

Journal of Chemical and Engineering Data

Volume

59

Pub Type

Journals

Download Paper

https://doi.org/10.1021/je400880n

Keywords

capillary viscometer, helium gas, two-capillary capillary viscometer, gas viscosity, viscosity ratio, liquid water

Citation

Berg, R. , May, E. and Moldover, M. (2013), Viscosity-ratio measurements with capillary viscometers, Journal of Chemical and Engineering Data, [online], https://doi.org/10.1021/je400880n (Accessed September 15, 2024)