@wikipedia

Synonyms: Compressibility factor = Z-factor

Dimensionless multiplier describing the deviation of a fluid density from ideal gas estimate under the same pressure & temperature conditions:

Z = \frac{p  \, V_m}{R \, T} = \frac{p}{\rho} \cdot \frac{M}{R \, T}

where

Z-factor is related to fluid density  as:

\rho(T, p) =\frac{p}{Z(T, p)} \cdot \frac{M}{R \, T}

Z-factor is related to fluid compressibility  as:

c(p) = \frac{1}{p} - \frac{1}{Z} \frac{dZ}{dp}

Z(p) = \frac{Z_0}{p_0} \cdot p \cdot \exp \left[ - \int_{p_0}^p c(p) dp  \right]

The Z-factor value is trending towards unit value () for incompressible fluids and linear pressure dependence () for strongly compressible Fluids.

Modelling Z-factor  as a function of fluid pressure  and temperature  is based on Equation of State.

There is also a good number of explicit Z-factor Correlations @models.

See also

Natural Science / Physics / Thermodynamics / Equation of State

[ Fluid Compressibility ][ Gas compressibility ]

References