This app calculates the gas compressibility factor Z with five differents correlation with:

- Papay
- Dranchuk-Purvis-Robinson
- Hall-Yarborough
- Bill-Beggs
- Dranchuk-Abou Kassem

Using three parameters: pressure, temperature and gas specific gravity it calculate the pseudocritical properties with the Standing correlations that expressed mathematicaly the graphical correlation of Brown et al.