Since many people use the Katz compressibility factor chart, the question is often asked how it may be extended to gases containing H₂S and CO₂. There are two methods available for this application.

1. 1. The approach proposed by Robinson et al.
2. 2. The approach proposed by Wichert and Aziz.

In this Tip of the Month (TOTM) we will demonstrate the accuracy of the second approach.
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