**AcentricFactor**

The acentric factor, w, is a thermodynamic property of a fluid that is commonly used in property correlations. It is defined by

w = -1.0 - log10(Psat/Pcrit)

where

Psat is the vapor pressure of the fluid at a temperature equal to 0.7 * Tcrit

Pcrit is the critical pressure

Tcrit is the critical temperature [R or K]

Thermophysical Property Functions