Abstract: Composite membranes having advantageous combinations of selectivity and permeability are prepared by the coating of a separation layer on a porous support layer containing a controlled amount of liquid in the range of from about 10% to about 90% by weight of the liquid present in the fully wet support layer.

Abstract: Apparatus and a process for coating continuous lengths of filaments are described. The apparatus includes a tubular vessel for applying a fluid coating to a plurality of traveling filaments which are then separated and passed through drying and curing zones in separate and appropriate ovens. The method of the invention, carried out in the apparatus of the invention, is particularly useful to apply special coatings to continuous lengths of hollow fibers to prepare composite hollow fibers useful as separatory membranes.

Abstract: A hollow filament separatory module utilizing an annulus of semi-permeable hollow filaments with open ends encased in a potting compound and a collection chamber communicating with said open ends adjacent the potting compound with access surface means formed in the potting compound wherein the open ends appear, the sum of the area of said access surface means when projected upon a plane perpendicular to the direction of internal pressure forces against the potting compound being less than 50% of the cross-section of the non access portions of said compound parallel to said plane.