This field selects the equation of state used for the physical properties calculation.
- Redlich-Kwong EOS (RK): The Redlich-Kwong relation (1949), two-parameter EOS.
- Soave-Redlich-Kwong EOS (SRK): Soave modification of the RK relation (1972), including dependence on the Pitzer acentric factor in the attractive term.
- Peng-Robinson EOS (PR): (1976) A more accurate EOS, with T and acentric-factor dependence in the attractive term and a more complex repulsive term. Can be applied to some liquid regions with usable accuracy.
- Peng-Robinson-Stryjek-Vera (PRSV): The Peng-Robinson EOS with modifications to the temperature and acentric factor dependence. Improves some polar-nonpolar mixture calculations and properties at low temperatures. (Stryjek, R. and J.H. Vera, Can. J. Chem. Eng. 64 (1986), p. 323.)
A van der Waals (vdW) mixing rule is used to estimate multi-component EOS parameters.