Hollow fiber membrane modules. (a) End views of a full-scale module, showing the fibers potted in an epoxy resin;(1) cross-section of the whole module; (2) closeup showing individual hollow fibers. (1B) Side view of a laboratory-scale module,showing the outside of the fibers and the opening on the shell side where feed enters for outside-in flow, and permeate exits for insideout flow.