The theoretical model for foam drainage and overflow, which was developed earlier, was tested in detail against experimental data. This data was gathered from foam fractionation columns, the operation of which included reflux, no reflux, pool feed, and foam feed. The test yielded good agreement. The theory was also tested against experimental data for stationary foam draining at steady state. This too yielded good agreement. The theoretical model was then extended to stationary foam in unsteady state drainage by combining it with a differential mass balance and suitable boundary conditions. A comparison of theoretical prediction with experimental measurement indicated that the effect of bubble coalescence in the foam can be very important in this situation. (Author)