Hollow fiber module built up from concentric cylinders of hollow fibers

A hollow fiber module made by the method comprising fabricating a first, generally cylindrical central sub-assembly of hollow fibers, the ends of which sub-assembly are potted said potting forming circular collars at the ends of the first central sub-assembly, and a series of additional cylindrical sub-assemblies generally equal in length to the first central sub-assembly and to each other, each such sub-assembly being of increasing diameter and fitting around a next smaller cylindrical sub-assembly in the series and inside a next larger cylindrical sub-assembly in the series, each such sub-assembly comprising hollow fibers potted at the ends, said potting forming circular collars of potting, wherein the cylindrical sub-assemblies are fitted concentrically into each other according to size and around the first central sub-assembly, the entire array of concentrically assembled sub-assemblies being glued in the spaces between the circular collars of potting at the ends of each concentrically fitted cylindrical sub-assembly and the central sub-assembly to produce a complete hollow fiber module.