In this paper, some thermophysical properties at low pressure of sulphur hexafluoride (SF$_6$) fluid are modelled and predicted. Also, by comparing the obtained results with experimental data, the correlation performance of virial coefficients to predict thermodynamic properties over a wide temperature range is evaluated. Studied properties consist of Joule–Thomson coefficient, enthalpy, deviation function, fugacity coefficient, thermal expansion, Boyle temperature and Boyle volume. The studied correlation function is the one suggested by Zarkova et al and compared with correlation of Meng et al. The obtained results show that the correlation equation presented has a good ability to predict the thermophysical properties of sulpur hexafluoride and its deviation from the idealstate over a wide range of temperatures. Average absolute deviations (AAD) of thermophysical properties of SF$_6$ calculated by this approach is mainly below 5%.

In this research, some thermodynamic properties of small alkanes are estimated and modelled to evaluate the performance of the correlation equation of their second virial coefficient at low density and pressure. The studiedfluids are CH$_4$ to n-C$_5$H$_{12}$. The correlation equation used is the one suggested by Zarkova et al. Thermodynamic properties measured are: Joule–Thomson coefficient, enthalpy, fugacity coefficient, thermal expansion and bulk modulus. In addition, Boyle temperature and Boyle volume are also estimated using the correlation. By using virial coefficients and virial equation of state, which is based on theoretical studies and statistical mechanics, a bridge iscreated between the microscopic and macroscopic properties that can show the non-ideal behaviour of real fluids. The obtained results show that the thermodynamic properties of the studied molecules and their deviation from theideal state have been predicted and modelled very well by the correlation equation presented in a wide range of temperatures.