Simple correlations for saturated liquid and vapor densities of pure fluids

Two correlations for the saturated liquid and vapor densities of pure substances particularly those used as working fluids in refrigeration machines are proposed. They are shown to represent well the reduced density as a function of the reduced temperature ranging from 0.5 to 1. For about 30 pure substances with acentric factor and critical compressibility factor varying in a wide range, the correlations predict accurately the saturation densities.