PVT properties of sulfur-hexafluoride in the gas-liquid critical region

The PVT properties of sulfur hexafluoride in the critical region have been measured by using a combination of the Burnett and the isochoric methods. The measurement of one reference PV-isotherm at about 333 K was performed by the Burnett method of repeated expansions; the measurement of a large number of PT quasi-isochores between 313 and 333 K relied on the so-called isochoric method. An important feature of the data analysis is the application of several consistency criteria to the least-squares analysis for polynomial representation which made it possible to determine reliable values of the Burnett constants and the virial coefficients. The reference isotherm with 105 data points covers a pressure range between 1 and 100 bar and a density range up to 1.2 g cm^?3. The 21 isochoric runs with densities between 0.1 and 1.2 g cm^?3 contain 220 data points. Except for the region very close to the critical point, the accuracy of the measurements is estimated to be better than 0.01% in the pressure, 0.02% in the density and 1 mK in the temperature.