An equation of state for the thermodynamic properties of 1,1,1,3,3,3-hexafluoropropane (HFC-236fa)

1,1,1,3,3,3-Hexafluoropropane (HFC-236fa) is widely used in industrial fields as an alternative for chlorofluorocarbons and hydrochlorofluorocarbons. In this paper, a new equation of state expressed explicitly in the Helmholtz energy with temperature and density as independent variables was developed. The equation of state is valid from 179.6 K to 400 K with pressures up to 70 MPa. The results from the equation of state were compared with the available experimental data. The uncertainties in density of the equation of state are estimated to be 0.1% in the compressed liquid region, and 0.5% in the vapor region. The uncertainties in vapor pressure are 0.2% at temperatures from 280 K to 380 K, and 0.4% at temperatures above 380 K. The uncertainty in speed of sound in the gas region is 0.1%. The extrapolation behavior of the equation of state is reasonable within the valid range and at higher pressures and temperatures.