Abstract: A gas separation module 25 is disclosed for separating air into nitrogen 27 and oxygen 26 enriched fractions. The nitrogen enriched fraction 27 may be used to inert an atmosphere inside a fuel tank 32. The air is separated into nitrogen 27 and oxygen 26 enriched fractions by providing a plurality of strands of gas separation membrane wound around a core and maintaining a pressure difference across the walls of the strands of membrane. A low pressure difference of?30 psi maintained across the membrane is able to effect gas separation and provide highly nitrogen enriched air. The membrane has preferably been subjected to a modification technique to increase its gas permeability.

Abstract: A method of supplying oxygen rich air to the passengers and crew on board a passenger aircraft by use of a highly permeable oxygen enrichment unit, wherein the fiber tubes of the hollow fiber membranes used to separate normal air into oxygen rich and nitrogen rich fractions in the oxygen enrichment unit are subjected to a modification technique before the tubes are coated with a selective polymer.

Abstract: A method of producing composite, hollow fibre gas separation membranes, wherein external surfaces of the porous hollow fibre tubes used in the construction of the membranes are subjected to a modification technique before the external surfaces are coated with a thin layer of selective polymer so as to increase the number of pores in the fibre surface.

Abstract: A method of producing composite, hollow fibre gas separation membranes, wherein external surfaces of the porous hollow fibre tubes used in the construction of the membranes are subjected to a modification technique before the external surfaces are coated with a thin layer of selective polymer so as to increase the number of pores in the fibre surface.