Available values of the surface tension of 81 common fluids were fitted by using the same model presently used in the REFPROP program V9.0 by NIST. A set of data was built for every fluid by including mainly those values given in the DIPPR and DETHERM databases. For some fluids, other available sources of data were added in order to obtain adequate sets. For every fluid, we checked the accuracy of the REFPROP program and we made a new fit in order to improve the performance of the correlation. We found good general agreement between the REFPROP predictions and the data for 44 fluids, and therefore only very slight improvements are made for them. For the other 37 fluids, the REFPROP correlation can be more clearly improved. In particular, our new correlation is significantly more accurate for ammonia, deuterium, ethanol, and neon, because the version of REFPROP used gives values in clear disagreement with other data sources.

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Nine empirical correlations for the calculation of the liquid saturation density of pure fluids are studied for their accuracy and applicability. All of them are based on the corresponding states principle, and we have included very recent proposals. The first model requires only the knowledge of critical parameters, the following seven need the critical parameters and acentric factor as inputs, and the last requires the Lennard-Jones molecular parameters and the acentric factor as input data. As a reference, we take the numerical values for the liquid saturation density accepted by the DIPPR project for 552 fluids, grouped into 30 families. Recommendations are given for the use of each model and for the choice of the adequate model for each family of fluids, including for particular fluids.

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