AIRCRAFT FUEL TANK FLAMMABILITY REDUCTION METHODS AND SYSTEMS AND AIR SEPARATION METHODS USING MEMBRANES

A gas separation method includes contacting a membrane filter with gas feed, permeating the gas from the gas feed through the membrane, and producing filtered gas from the filter. The filtered gas is produced from the filter as a result of the membrane removing any hydrocarbons containing six or more carbon atoms to produce a total of 0.001 ppm w/w or less. A gas separation method includes feeding gas into a filter containing a hollow fiber membrane that exhibits the property of resisting degradation due to exposure to hydrocarbons containing six or more carbon atoms. The filter exhibits a pressure drop across the membrane of less than 5 psi. The method includes feeding the filtered gas into a gas separation module that exhibits a susceptibility to degradation from exposure to hydrocarbons containing six or more carbon atoms.