Gas Compressibility (Z) Formulas
This sheet formulas to calculate gas compressibility (Z). The formula was developed by curve fitting actual Z data obtained from the chemical engineers handbook. The formula can be copied into other spreadsheets which may require automatic calculation of Z. The first formula can be used for any gas provided you have the reduced temperature and pressure, which can be obtained from critical temperature and pressure. Sample Tc and Pc are provided above. The second formula can be used to determine Z for hydrocarbon gases if you have the MW of the gas and actual temperature and pressure.