Measurement of gas viscosity with a Fleisch pneumotachograph

J Appl Physiol Respir Environ Exerc Physiol. 1982 Jul;53(1):290-3. doi: 10.1152/jappl.1982.53.1.290.


A simple rapid method of measuring gas viscosity using a standard Fleisch pneumotachograph and a 3-liter hand-driven syringe is described. Comparison of pneumotachographic and predicted viscosity of five pure gases (CO2, N2, He, O2, and Ar), two binary mixtures (He-O2 and N2-O2), and one quaternary mixture (He-air) gave an overall coefficient of correlation of 0.987 and an accuracy of better than 1.7%. Our data show the well-known marked curvilinear relationship between viscosity and the concentration of helium in air and oxygen mixtures. These studies indicate that a Fleisch pneumotachograph can be used as a simple accurate gas viscometer to characterize gas mixtures in terms of viscosity.

MeSH terms

  • Gases
  • Pulmonary Ventilation*
  • Respiratory Function Tests / instrumentation*
  • Viscosity


  • Gases