A vibrating-wire instrument for simultaneous measurement of the density and viscosity of liquids under conditions of high pressure is described. The instrument is capable of operation at temperatures between 298.15 and 473.15 K at pressures up to 200 MPa. Calibration was performed by means of measurements in vacuum, air, and toluene at 298.15 K. For n-dodecane measurements were made along eight isotherms between 298.15 and 473.15 K at pressures up to 200 MPa, while for n-octadecane measurements were measured along seven isotherms between 323.15 and 473.15 K at pressures up to 90 MPa. The estimated uncertainty of the results is 2% in viscosity and 0.2% in density. Comparisons with literature data are presented.

We report the results of simultaneous measurements of the viscosity and density of five pure hydrocarbon liquids (octane, decane, 1,3-dimethylbenzene, 1,2,3,4-tetrahydronaphthalene and 1-methylnaphthalene) at temperatures between 298.15 K and 473.15 K and at pressures ranging from 0.1 MPa to approximately 200 MPa. The measurements were made with a vibrating-wire instrument and the estimated expanded relative uncertainties are ±2 % for viscosity and ±0.2 % for density with a coverage factor of 2. The densities were correlated by means of a modified Tait equation, while the viscosities were correlated both with the theory of Dymond and Assael and in terms of an empirical function of temperature and pressure. We also present correlations of the viscosity of dodecane and octadecane based on results that we published previously [Caudwell, et al., Int. J. Thermophys. 2004, 25, 1340-1352. Extensive comparisons with literature data are presented.

We report the results of simultaneous measurements of the viscosity and density of five pure hydrocarbon liquids (octane, decane, 1,3-dimethylbenzene, 1,2,3,4-tetrahydronaphthalene and 1-methylnaphthalene) at temperatures between 298.15 K and 473.15 K and at pressures ranging from 0.1 MPa to approximately 200 MPa. The measurements were made with a vibrating-wire instrument and the estimated expanded relative uncertainties are ±2 % for viscosity and ±0.2 % for density with a coverage factor of 2. The densities were correlated by means of a modified Tait equation, while the viscosities were correlated both with the theory of Dymond and Assael and in terms of an empirical function of temperature and pressure. We also present correlations of the viscosity of dodecane and octadecane based on results that we published previously [Caudwell, et al., Int. J. Thermophys. 2004, 25, 1340-1352]. Extensive comparisons with literature data are presented.

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