This guideline provides a formulation based on the virial equation for the fugacity of water in humid air, and recommends correlations for the necessary virial coefficients as a function of temperature.
The range of validity is from 193 K to 473 K at pressures up to 5 MPa.
The development of the formulation is described in detail in a scientific article.
This Guideline is the product of the Working Groups "Thermophysical Properties of Water and Steam" (TPWS) and "Subcommittee on Seawater" (SCSW) of the International Association for the Properties of Water and Steam (IAPWS).
This page updated May 29, 2018