Viscosity Measurements on Gaseous Argon, Krypton, and Propane1

A new vibrating-wire viscometer was designed to perform quasi-absolute mea- surements of very high precision on gases. It was applied to determine the viscosity of argon at temperatures of 298.15, 348.15, and 423.15 K and pressures up to 20 MPa, and the viscosity of krypton at 298.15 and 348.15 K and pressures up to 16 MPa. Furthermore, several isothermal series of viscosity measurements on gaseous propane were carried out. The subcritical isotherms at 298.15, 323.15, 348.15, and 366.15 K were restricted to 950 of the saturated vapor pressure, the supercritical isotherms at 373.15, 398.15, and 423.15 K to 20 MPa. In general, the measurements are characterized by a reproducibility of \0.050 and an accuracy of \0.20. However, close to the critical point an accuracy of \30 has to be accepted, mainly due to the uncertainty of the density. In this coIntext the influence of the equation of state used for propane is discussed.