Method of improving the effectiveness of an oxygen removal unit for a fuel supply system and the resulting oxygen removal unit

A method of improving the effectiveness of an oxygen removal unit for a fuel supply system and having an inlet, the method comprising:

• placing a tube bundle in the oxygen removal unit, the tube bundle including a microporous support structure covered by an air permeable, non-porous layer;
• introducing a repair liquid into the oxygen removal unit though the inlet;
• drawing the repair liquid through the oxygen removal unit and the tube bundle such that it passes through the microporous support structure and the air permeable, non-porous layer, wherein the repair liquid is drawn through the bundle under pressure and at 20 to 40° C. for less than two hours, wherein the repair liquid comprises a solvent and a curable thermoset material;
• wherein drawing results in deposition of the repair liquid in the pinhole defects of the air permeable, non-porous layer;
• draining the tube bundle of excess repair liquid;
• evaporating the solvent;
• and
• curing the curable thermoset material located in the pinhole defects of the air permeable, non-porous layer;
• wherein the solvent comprises a hydrocarbon having 5 to 7 carbons or a mixture of hydrocarbons having 5 to 7 carbons.