Porous membrane cartridge and method of manufacturing the same

A method of manufacturing a porous membrane cartridge comprising the steps of:

• providing an injection mold having a cavity which corresponds to a tubular-shaped barrel member having a weld portion at an outer peripheral surface positioned adjacent to one end of the barrel member;
• molding a tubular cap member having a weld portion and a sandwiching surface facing to an open edge portion of the weld portion of the barrel member, wherein the weld portion of the cap member contacts the weld portion of the barrel member at its inner peripheral surface and a ratio of its height (H) and its diameter (D), defined by H/D, is equal to or greater than 0.07;
• positioning the cap member and the porous membrane within the cavity such that the weld portion of the cap member contacts the weld portion of the barrel member at the inner peripheral surface while positioning the sandwiching surface of the cap member in a manner facing to the open edge portion of the weld portion of the barrel member and setting the porous membrane with its peripheral edge abutting on the sandwiching surface of the cap member;
• and
• injecting molding material into the cavity.