A method to determine the Patel-Teja equation of state (EoS) constants F and lc is presented. The method uses Wagner and Rackett equations to generate vapor pressure and liquid volume data. Constants were estimated for 498 pure substances. For 19 substances the new constants were used to predict some thermodynamical properties like vapor pressure, liquid molar volume, vapor molar volume, and enthalpy of vaporization. An extension to mixtures was done by using the Panagiotopoulous-Reid mixing rule. New constants are comparable to the original ones reported in the Patel-Teja work, and they preserve the good features of the equation of state.