Patent Publication Number: US-2021178302-A1

Title: Air separation modules, nitrogen generation systems, and methods of making air separation modules

Description:
BACKGROUND 
     The present disclosure generally relates to nitrogen generation systems, and more particularly to air separation modules for generating oxygen-depleted air in nitrogen generating systems. 
     Vehicles, such as aircraft, commonly carry liquid fuel in fuel tanks. Fuel tanks typically have an ullage space occupied by a mixture of fuel vapors and ambient air. Such fuel vapor-air mixtures are potentially hazardous when concentration of oxygen is sufficient to support combustion. To limit (or eliminate entirely) the combustion risk posed by such fuel vapor-air mixtures some vehicles employ inerting systems to control oxygen concentration with the vehicle fuel tank. Examples of inerting systems include nitrogen generation systems with air separation modules. The air separation modules in such inerting system can be employed to communicate oxygen-depleted air flows to the vehicle fuel tank to limit oxygen concentration within the fuel tank ullage space. 
     Air separation modules typically separate pressurized air into an oxygen-depleted fraction and an oxygen-enriched fraction. The oxygen-depleted air flow is generally communicated to the vehicle fuel tank, wherein the oxygen-depleted air flow limits concentration of oxygen within the fuel tank. The oxygen-enriched air flow is typically diverted to the external environment. The oxygen-depleted air flow generation capacity of the air separation module is typically limited by external support structure and/or framing employed to structurally support the air separation module. 
     Such systems and methods have generally been acceptable for their intended purpose. However, there remains a need for improved air separation modules, nitrogen generation systems, and methods of making air separation modules for nitrogen generation systems. 
     BRIEF DESCRIPTION 
     An air separation module is provided. The air separation module includes canister, a separator, and a band. The canister has an inlet end, an axially opposite outlet end, and an oxygen-enriched air flow fraction outlet port between the inlet end and the outlet end of the canister. The separator is supported within the canister and is arranged to separate compressed air flow into an oxygen-depleted air flow fraction and an oxygen-enriched air flow, provide the oxygen-depleted air flow fraction to the outlet end of the canister, and divert the oxygen-enriched air flow fraction to the oxygen-enriched air flow outlet port. The band is fixed to the canister and extends about the separator at a location axially between the oxygen-enriched air flow fraction outlet port and the inlet end of the canister to support the air separation module. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include that the band and the canister are formed as a one-piece canister body. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include that the band is fastened to the canister. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include that the band is welded or bonded to the canister. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include that the canister has a canister inlet flange and an axially opposite canister outlet flange, the band evenly spaced between the canister inlet flange and the canister outlet flange. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a supply conduit fluidly coupled to the outlet end of the canister, the supply conduit supported by the canister. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include the band has a standoff and that the supply conduit is supported by the standoff. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a band member extending about the canister axially between the oxygen-enriched air outlet and the band, the band member supporting the supply conduit. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a canister fixation feature connected to the band and arranged for fixation of the air separation module to a vehicle structure. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a one-piece inlet cap connected to the inlet end of the canister and having an inlet end fixation feature, the inlet end fixation feature arranged for fixation of the air separation module to a vehicle. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a one-piece outlet cap connected to the outlet end of the canister and having an outlet end fixation feature, the outlet end fixation feature arranged for fixation of the air separation module to a vehicle. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include the canister fixation feature includes a clevis structure arranged to seat therein a tie rod. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a compressed air source fluidly coupled to the inlet end of the canister and fluidly coupled to the outlet end of the canister by the separator. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include a fuel tank fluidly coupled to the outlet end of the canister and fluidly coupled to the inlet end of the canister by the separator. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include that the inlet cap has a one-piece inlet cap body, the one-piece inlet cap body and inlet end fixation feature being homogenous in composition and monolithic in construction. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include that the outlet cap has a one-piece outlet cap body, the one-piece outlet cap body and inlet end fixation feature being homogenous in composition and monolithic in construction. 
     A nitrogen generation system is also provided. The nitrogen generation system includes an air separation module described above. The canister has a canister inlet flange and an axially opposite second flange and the band is evenly spaced between the canister inlet flange and the second flange. A compressed air source fluidly is coupled to the inlet end of the canister and is in turn fluidly coupled to the outlet end of the canister by the separator. A fuel tank fluidly is coupled to the outlet end of the canister and fluidly coupled to the inlet end of the canister by the separator. 
     In addition to one or more of the features described above, or as an alternative, further examples of the nitrogen generator may include a canister fixation feature fixed to the band and arranged for fixation of the air separation module to a vehicle structure; a one-piece inlet cap connected fixed to the inlet end of the canister and having an inlet end fixation feature, the inlet end fixation feature arranged for fixation of the air separation module to a vehicle structure; and a one-piece outlet cap connected fixed to the outlet end of the canister and having an outlet end fixation feature, the outlet end fixation feature arranged for fixation of the air separation module to a vehicle structure. 
     In addition to one or more of the features described above, or as an alternative, further examples of the nitrogen generation system may include that the band and the canister are formed as a one-piece canister body, and further comprising a canister fixation feature fixed to the band and arranged for fixation of the air separation module to a vehicle structure. 
     A method is additionally provided. The method includes defining a canister having an inlet end, an axially opposite outlet end, and an oxygen-enriched air outlet port between the inlet end and the outlet end of the canister; supporting a separator within the canister to separate a compressed air flow into the oxygen-depleted air flow fraction and the oxygen-enriched air flow, provide the oxygen-depleted air flow fraction to the outlet end of the canister, and divert the oxygen-enriched air flow fraction to the oxygen-enriched air flow outlet port; and fixing a band to the canister, wherein the band extends about the canister at a location axially between the oxygen-enriched air outlet and the outlet end of the canister to strengthen the canister and support the air separation module. 
     In addition to one or more of the features described above, or as an alternative, further examples of the method may include connecting a one-piece inlet cap to the inlet end of the canister, the one-piece inlet cap having an inlet end fixation feature for fixation of the air separation module to a vehicle structure; connecting a one-piece outlet cap to the outlet end of the canister, the one-piece outlet cap having an outlet end fixation feature for fixation of the air separation module to a vehicle structure; and connecting a canister fixation feature to a band, the canister fixation feature arranged for fixation of the air separation module to a vehicle structure. 
     In addition to one or more of the features described above, or as an alternative, further examples may include connecting a standoff to the band, supporting a supply conduit with the standoff, and fluidly connecting the supply conduit to the oxygen-depleted air outlet of the canister. 
     Technical effects of the present disclosure include air separation modules having relatively large oxygen-depleted air flow generating capacity (inerting capability) relative to space occupied by the air separation module. In certain examples air separation modules described herein include strengthened canisters, limiting (or eliminating entirely) the need for framing. In accordance with certain examples, air separation modules described herein include a band extending about the canister and having canister fixation features, the band stiffening the canister and allowing the band to at least in part transfer the load of the air separation module to vehicle structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a schematic view of an air separation module constructed in accordance with the present disclosure, showing a nitrogen generation system including the air separation module carried by an aircraft and providing an oxygen-depleted air flow to a fuel tank; 
         FIG. 2  is a perspective view of the air separation module of  FIG. 1  according to an example, showing a canister with a band connecting an inlet cap to an outlet cap of the air separation module; 
         FIGS. 3A-3D  are a partial perspective view and partial cross-sectional views of the air separation module of  FIG. 1  according to the example, showing a band extending about the canister of the air separation module; and 
         FIG. 4  is a block diagram of a method of making an air separation module, showing operations of the method according to an illustrative and non-limiting example of the method. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an example of an air separation module constructed in accordance with the disclosure is shown in  FIG. 1  and is designated generally by reference character  100 . Other examples of air separation modules, nitrogen generation systems, and methods of making air separation modules, are provided in  FIGS. 2-4 , as will be described. The systems and methods described herein can be used for generating oxygen-depleted air flows for inerting fuel tanks, such as fuel tanks carried by aircraft, though the present disclosure is not limited to inerting fuel tanks on aircraft or to fuel systems in general. 
     Referring to  FIG. 1 , a vehicle  10 , e.g., an aircraft is shown. The vehicle  10  includes a fuel system  12 , a compressed air source  14 , and a nitrogen generation system  102 . The nitrogen generation system  102  includes the air separation module  100 , a source conduit  104 , and a supply conduit  106 . The source conduit  104  fluidly connects the compressed air source  14  to the air separation module  100  to communicate a compressed air flow  16  to the air separation module  100 . The air separation module  100  is configured to separate an oxygen-depleted air flow fraction  18  from the compressed air flow  16 . The supply conduit  106  fluidly connects the air separation module  100  to the fuel system  12  to provide thereto the oxygen-depleted air flow fraction  18 , e.g., a nitrogen-enriched air flow fraction. In certain examples the nitrogen generation system  102  is an onboard inert gas generation system (OBIGGS) for an aircraft. 
     The fuel system  12  includes a fuel tank  20 . The fuel tank  20  is fluidly coupled to the air separation module  100  by the supply conduit  106  and contains within its interior a liquid fuel  22 . The liquid fuel  22  and the interior of the fuel tank  20  define between one another an ullage space  24 . The ullage space  24  harbors an atmosphere with a mixture including a fuel vapor  26  and nitrogen  28 . The fuel vapor  26  is combustible in the presence of oxygen in concentration above a combustion threshold. The nitrogen  28  is provided by the oxygen-depleted air flow fraction  18  and is maintained in concentration sufficient to maintain concentration of oxygen with the ullage space below the combustion threshold of the fuel vapor  26 . Limiting oxygen concentration limits (or prevents entirely) possibility of combustion of the fuel vapor  26  in the event that an ignition source comes into communication with the fuel vapor  26 . 
     The compressed air source  14  is configured to provide the compressed air flow  16  (or pressurized air flow) using air ingested from the external environment  32 . In certain examples the compressed air source  14  includes an engine, such as the compressor section of gas turbine engine carried by an aircraft. In accordance with certain examples the compressed air source  14  includes an external compressed air source, such as a ground support equipment cart or facility compressed air source. 
     The nitrogen generation system  102  includes the air separation module  100 , a filter module  108  containing a debris filter  110  and an ozone converter  112 , and an inlet temperature sensor  114 . The nitrogen generation system  102  also includes an outlet temperature sensor  116 , an oxygen sensor  118 , and a flow control valve  120 . 
     The filter module  108  fluidly couples the source conduit  104  to the inlet temperature sensor  114  to communicate thereto the compressed air flow  16 . The debris filter  110  is configured to impound debris entrained within the compressed air flow  16  to prevent the debris from reaching and/or reducing reliability of air separation module  100 . The ozone converter  112  is also to convert ozone molecules included within the compressed air flow  16  into dioxygen molecules, preventing the entrained ozone molecules from reaching the air separation module  100 . As will be appreciated by those of skill in the art in view of the present disclosure, entrained debris and/or ozone can limit the reliability of the air separation module  100 . 
     The inlet temperature sensor  114  is configured to measure temperature of the compressed air flow  16  provided to the air separation module  100  and fluidly couples the filter module  108  to the air separation module  100 . In this respect the inlet temperature sensor  114  receives the compressed air flow  16  from the supply conduit  104  via the filter module  108  and communicates the compressed air flow  16  to the air separation module  100  subsequent to filtering and ozone conversion. In certain examples the inlet temperature sensor  114  is disposed in communication with a controller, which adjusts temperature of the compressed air flow  16  to maintain the compressed air flow  16  within a predetermined inlet temperature range. 
     The air separation module  100  includes a separator  122 . The separator  122  is configured to separate the compressed air flow  16  into the oxygen-depleted air flow fraction  18  and an oxygen-enriched air flow fraction  30 . The oxygen-enriched air flow fraction  30  is diverted from the fuel system  12  by the air separation module  100 , e.g., is dumped overboard. The oxygen-depleted air flow fraction  18  is communicated by the air separation module  100  to the fuel system  12  via the outlet temperature sensor  116 , the oxygen sensor  118 , and the flow control valve  120 . In certain examples the separator  122  includes a hollow fiber mat  124  configured to separate the compressed air flow  16  into the oxygen-depleted air flow fraction  18  and the oxygen-enriched air flow fraction  30 . Examples of suitable hollow fiber mats include PEEK-Sep™ hollow fiber mats, available from Air Liquide Advanced Separations of Woburn, Mass. 
     The outlet temperature sensor  116  is configured to measure temperature of the oxygen-depleted air flow fraction  18  prior to the oxygen-depleted air flow fraction  18  reaching the fuel system  12 . In this respect the outlet temperature sensor  116  fluidly couples the air separation module  100 , and therein the separator  122 , to the oxygen sensor  118  to measure temperature of the oxygen-depleted air flow fraction  18 . It is contemplated the outlet temperature sensor  116  provide a signal to a controller indicative of temperature of the oxygen-depleted air flow fraction  18 , the controller thereby able to control of the oxygen-depleted air flow fraction  18  communicated to the fuel system  12 . 
     The oxygen sensor  118  is configured to measure concentration of oxygen within the oxygen-depleted air flow fraction  18  prior to the oxygen-depleted air flow fraction  18  reaching the fuel system  12 . In this respect the oxygen sensor  118  fluidly couples the outlet temperature sensor  116  to the flow control valve  120 , and therethrough to the supply conduit  106 , to measure oxygen concentration within the oxygen-depleted air flow fraction  18  received from the separator  122  as the oxygen-depleted air flow fraction  18  traverses the air separation module  100 . It is contemplated that the oxygen sensor  118  provide a signal to a controller indicative of oxygen concentration within the oxygen-depleted air flow fraction  18 , the controller thereby able to monitor performance of the air separation module  100 . 
     The flow control valve  120  is configured to control flow rate, e.g., mass flow rate, of the oxygen-depleted air flow fraction  18  to the supply conduit  106 . In this respect the flow control valve  120  fluidly couples the oxygen sensor  118  to the supply conduit  106  throttle flow of the oxygen-depleted air flow fraction  18  to the fuel system  12 . It is contemplated that the flow control valve  120  be operatively associated with a controller to throttle the flow rate of the oxygen-depleted air flow fraction  18  according to the inerting requirements of the fuel system  12  and/or according to the operating requirements of the vehicle  10 . 
     As will be appreciated by those of skill in the art in view of the present disclosure, the inerting capability provided by air separation modules generally corresponds to the weight and size of the air separation module. To limit weight and size per unit inerting capability the air separation module  100  is provided. 
     The air separation module  100  generally includes the separator  122 , a canister  126 , and a band  128  (e.g., a doubler). The canister  126  has an inlet end  130 , an axially opposite outlet end  132 , and an oxygen-enriched air flow fraction outlet port  134  between the inlet end  130  and the outlet end  132  of the canister  126 . The separator  122  supported within the canister  126  and is arranged to separate compressed air flow  16  into the oxygen-depleted air flow fraction  18  and the oxygen-enriched air flow fraction  30 , provide the oxygen-depleted air flow fraction  18  to the outlet end  132  of the canister  126 , and divert the oxygen-enriched air flow fraction  30  to the oxygen-enriched air flow fraction outlet port  134 . The band  128  is fixed to the canister  126  and extends about the separator  122  at a location  136  longitudinally, e.g., axially relative a direction of flow through the canister  126 , between the oxygen-enriched air flow fraction outlet port  134  and the inlet end  130  of the canister  126  to support the air separation module  100 . 
     With reference to  FIG. 2 , the air separation module  100  is shown according to an example. The air separation module  100  includes the canister  126 , an inlet cap  138  (e.g., an inlet end cap), and an outlet cap  140  (e.g., an outlet end cap). The inlet cap  138  has a one-piece inlet cap body  142  with a filter module mount  144 , an inlet temperature sensor mount  146 , an inlet end flange  148 , and an inlet end fixation feature  150 . The filter module mount  144  seats thereon the filter module  108  and fluidly couples the filter module  108  therethrough to the inlet end  130  of the canister  126 . The inlet temperature sensor mount  146  seats thereon the inlet temperature sensor  114  and fluidly couples the inlet temperature sensor  114  to the inlet end  130  of the canister  126 . The inlet end flange  148  extends about the inlet cap  138  and receives therethrough a plurality of inlet cap fasteners  152 , which rigidly fix the inlet cap  138  to the inlet end  130  of the canister  126 . It is contemplated that inlet cap  138  fluidly coupled the source conduit  104  to the canister  126  to communicate thereto the compressed air flow  16  (shown in  FIG. 1 ). 
     The inlet cap  138  has a one-piece inlet cap body  142 . As used in herein the term “one-piece” means that various portions, e.g., mounting feature, flange, and/or mount, of the associated “one-piece” element are homogenous in composition and monolithic in construction. For example, it is contemplated that the inlet cap  138  be homogenous in composition and monolithic in construction, e.g., as formed using an investment casting technique, an additive manufacturing technique, or machined from a common piece of stock. As will be appreciated by those of skill in the art in view of the present disclosure, other manufacturing techniques and/or combinations of the aforementioned techniques are possible and are within the scope of the present disclosure. 
     The outlet cap  140  has a one-piece outlet cap body  154 . The one-piece outlet cap body  154  has an oxygen sensor mount  156 , an outlet temperature sensor mount  158 , and a flow control valve mount  160 . The one-piece outlet cap body  154  also has an outlet cap flange  162  and an outlet end fixation feature  164 . The oxygen sensor mount  156  seats thereon the oxygen sensor  118  and fluidly couples the outlet end  132  of the canister  126  to the oxygen sensor  118 . The outlet temperature sensor mount  158  seats thereon the outlet temperature sensor  116  and fluidly couples the oxygen sensor  118  to the outlet temperature sensor  116 . The flow control valve mount  160  seats thereon the flow control valve  120  and fluidly couples the outlet temperature sensor  116  to the flow control valve  120 , and therethrough to the supply conduit  106 . The outlet cap flange  162  extends about the outlet cap  140  and receives therethrough a plurality of outlet cap fasteners  166 , which rigidly fix the outlet cap  140  to the outlet end  132  of the canister  126 . 
     The canister  126  defines the oxygen-enriched air flow fraction outlet port  134  and has a canister inlet flange  168  and a canister outlet flange  170 . The canister inlet flange  168  extends about the inlet end  130  of the canister  126  and defines therein a canister inlet flange fastener pattern  172 . The canister inlet flange fastener pattern  172  receives therein the plurality of inlet cap fasteners  152  for rigid fixation of the inlet cap  138  to inlet end  130  of the canister  126  at the canister inlet flange  168 . The canister outlet flange  170  is similar to the canister inlet flange  168  and additionally extends about the outlet end  132  of the canister  126 , defines therein a canister outlet fastener pattern  174 , and receives therein the plurality of outlet cap fasteners  166  for rigid fixation of the outlet cap  140  to the outlet end  132  of the canister  126  at the canister outlet flange  170 . 
     The compressed air source  14  (shown in  FIG. 1 ) is fluidly coupled to the inlet end  130  of the canister  126  and is fluidly coupled to the outlet end  132  of the canister  126  by the separator  122  to communicate thereto the compressed air flow  16  (shown in  FIG. 1 ). The fuel tank  20  (shown in  FIG. 1 ) is fluidly coupled to the outlet end  132  of the canister  126  and is fluidly coupled to the inlet end  130  of the canister  126  by the separator  122  to receive therefrom the oxygen-depleted air flow fraction  18  (shown in  FIG. 1 ). 
     The band  128  is arranged longitudinally between the canister inlet flange  168  and the canister outlet flange  170 . In certain examples the double  128  is equally spaced between the canister inlet flange  168  and the canister outlet flange  170 . In accordance with certain examples the band  128  can be arranged longitudinally between the oxygen-enriched air flow fraction outlet port  134  and the canister outlet flange  170 , which allows to canister  126  to be positioned in an inclined orientation relative to gravity when the vehicle  10  (shown in  FIG. 1 ) is straight and level flight such that the oxygen-enriched air flow fraction  30  (shown in  FIG. 1 ) flushes condensate from within the canister  126 . 
     With reference to  FIGS. 3A-3D , a portion of the air separation module  100  is shown including the canister  126  and the band  128 . The band  128  extends circumferentially about the exterior of the canister  126  and includes a canister fixation feature  174 . More specifically, the band  128  extends circumferentially about the canister  126  at a location between the canister inlet flange  168  (shown in  FIG. 2 ) and the canister outlet flange  170  (shown in  FIG. 2 ). In certain examples the band  128  is evenly spaced between the canister inlet flange  168  and the canister outlet flange  170 . 
     As shown in  FIG. 3B , in certain examples the band  128  and the canister  126  are formed as a one-piece canister body  176 . Forming the canister  126  and the band  128  as a one-piece canister body  176  increases strength of the canister  126 , allowing the canister  126  to support itself without an external frame and/or to fix the air separation module  100  to vehicle structure through the canister  126 . As shown in  FIG. 3C , in accordance with certain examples, the band  128  is fixed to the canister with one or more canister fastener  178 . Fastening the band  128  to the canister  126  simplifies fabricating the air separation module  100  allows the band  128  to support the air separation module  100 . As shown in  FIG. 3D , it is also contemplated that the band  128  can be fixed to the canister  126  with a weld or bond  180 . Welding or bonding the band  128  to the canister  126  simplifies fabrication of the air separation module  100  while allowing the band to both provide strength to the canister  126  and support the air separation module  100 . 
     The canister fixation feature  174  is configured for fixation of the air separation module  100  to the vehicle  10  (shown in  FIG. 1 ). More specifically, the canister fixation feature  174  is configured to support the air separation module  100  in the vehicle  10  through the canister  126 , limiting size and/or weight of the air separation module  100  by limiting (or eliminating entirely) the need for additional structure to support the air separation module  100 . In certain examples the canister fixation feature  174  is coupled to the canister  126  by the band  128 . In accordance with certain examples canister fixation feature  174  extends laterally from the band  128 . It is contemplated that, in accordance with certain examples, the canister fixation feature  174  can include one or more clevis  180  to seat therein a tie rod  34  for fixation of the air separation module  100  to the vehicle  10 . 
     In certain examples the band  128  includes a standoff  182 . The standoff  182  is coupled to the canister  126  by the band  128 , extends laterally from the band  128 , and is arranged to support the supply conduit  106  (shown in  FIG. 1 ). In the illustrated example the standoff  182  seats therein a bracket  184  (shown in  FIG. 2 ). The bracket  184  is fastened to the standoff  182 , seats therein the supply conduit  106 , and is supported therethrough by the canister  126 . 
     In accordance with certain examples the air separation module  100  includes a band member  186 . The band member  186  extends about the canister  126  at a location between the band  128  and the oxygen-enriched air flow fraction outlet port  134  of the canister  126 , and seats thereon the supply conduit  106 . This allows the canister  126  to support the supply conduit  106  while conforming the supply conduit  106  to the fuel system  12  (shown in  FIG. 1 ) carried by the vehicle  10  (shown in  FIG. 1 ). 
     With reference to  FIG. 4 , a method  200  of making an air separation module, e.g., the air separation module  100  (shown in  FIG. 1 ), is shown. As shown with box  210 , the method  200  includes defining a canister, e.g., the canister  126  (shown in  FIG. 1 ), having an inlet end, an axially opposite outlet end, and an oxygen-enriched air flow fraction outlet port between the inlet end and the outlet end of the canister. As shown with box  220 , the method  200  also includes supporting a separator, e.g., the separator  122  (shown in  FIG. 1 ), within the canister to separate a compressed air flow into the oxygen-depleted air flow fraction and the oxygen-enriched air flow. As shown with box  230 , the method  200  additionally includes fixing a band to the canister, e.g., the band  128  (shown in  FIG. 1 ), the band extending about the canister at a location axially between the oxygen-enriched air outlet and the outlet end of the canister to strengthen the canister and support the air separation module. 
     As shown with box  240 , the method  200  includes connecting a canister fixation feature for fixation of the canister to a vehicle, e.g., the canister fixation feature  174  (shown in  FIG. 2 ), to the band. A one-piece inlet cap having an inlet cap fixation feature for fixation of the inlet cap to the vehicle, e.g., the inlet cap  138  (shown in  FIG. 2 ), is connected to the to the inlet end of the canister, as shown with box  250 . A one-piece outlet cap having an outlet cap fixation feature for fixation of the outlet cap to the vehicle, e.g., the outlet cap  140  (shown in  FIG. 2 ), is fixed to the outlet end of the canister, as shown with box  260 . Connection can be with fasteners, e.g., the plurality of inlet cap fasteners  152  (shown in  FIG. 2 ) and/or the plurality of outlet cap fasteners  166  (shown in  FIG. 2 ), the fasteners rigidly fixing the inlet cap and the outlet cap to the canister. 
     It is contemplated that the air separation module be supported in a vehicle, e.g., the vehicle  10 , with the fixation structures and without an intervening bracket or frame. In this respect it is contemplated that the air separation module be fixed to the vehicle with the canister fixation feature, as shown with box  242 . It is also contemplated that that the air separation module be fixed to the vehicle with the inlet cap fixation feature and the outlet cap fixation feature, as shown with box  252  and box  262 . 
     In certain examples the method  200  can include connecting a standoff to the band, e.g., the standoff  182  (shown in  FIG. 2 ), as shown with box  270 . A supply conduit, e.g., the supply conduit  106  (shown in  FIG. 1 ), can supported by the standoff, as shown with box  280 . The supply conduit is fluidly connected to the outlet end of the canister by the outlet cap to receive therefrom an oxygen-depleted air flow fraction from the canister, e.g., the oxygen-depleted air flow fraction  18  (shown in  FIG. 1 ), as shown with box  290 . 
     Fuel tanks, such as fuel tanks used to store liquid fuel in vehicles like aircraft, commonly contain fuel vapors within the ullage space of the fuel tank. Because such fuel vapors can present a fire hazard some vehicles include nitrogen generation systems with air separation modules. The air separation module is typically arranged to provide a flow of oxygen-depleted air to the fuel tank ullage space, limiting concentration of oxygen within the fuel tank ullage space and reducing (or eliminating entirely) the fire hazard potentially posed by the fuel vapors. The volume of nitrogen enriched air is generally constrained by the size of the air separation module and space allocated to the air separation module within the vehicle. 
     In examples provided herein air separation modules are provided having a band fixed to the canister of the air separation module. The band is arranged between the inlet end and the outlet end of the canister, e.g., equally spaced therebetween, to allow the air separation module to be supported by the canister and the band. In certain examples the band and the canister are formed as a one-piece canister body, the band thereby providing strength to the canister to limit (or eliminate entirely) the need for an external frame or support. In accordance with certain examples the band can be welded or bonded to the canister to provide strength to the canister. In accordance with certain examples the band couples a canister fixation feature to support the air separation module to a vehicle carrying the air separation module. It is also contemplated that the band can support a supply conduit through a standoff, conforming the air separation module the arrangement of a fuel system carried by the vehicle. 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary example or examples, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular example disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all examples falling within the scope of the claims.