The Lee–Kesler method [1] allows the estimation of the saturated vapor pressure at a given temperature for all components for which the critical pressure Pc, the critical temperature Tc, and the acentric factor ω are known.
with The prediction error can be up to 10% for polar components and small pressures and the calculated pressure is typically too low.
For pressures above 1 bar, that means, above the normal boiling point, the typical errors are below 2%.
It is important to use the same absolute units for T and Tc as well as for P and Pc.
The unit system used (K or R for T) is irrelevant because of the usage of the reduced values Tr and Pr.