Distillation 163 a 3 4 5 6 78910 15 20 30 40 50 60 70 LIQUID LOAD PER FOOT MEAN TRAY WIDTH. GPM Figure 8-110. Liquid gradient chart-cap spacing 31.25% cap diameter. Used by permission, Bolles, W. L., Pet. Pmcessing, Feb. thru May (1956).