Fig. 18 shows a comparison between Eq. (4) and all the data. Most of the data are to within ±10% errors. As already discussed, the accuracy of evaluations can be improved by taking into account the dependency of C1 and C2 on the flow regime with Eq. (5). Fig. 19 shows a comparison between Eq. (5) and the data, where most of the data are to within ±5% errors. Thus the proposed aG correlation is of great use to correlate the gas holdup data for various initial liquid heights, column geometries and diffuser configurations.