Patent Publication Number: US-2021178315-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. The fuel tanks generally define an interior ullage space between the liquid fuel and the interior of the fuel tank. The ullage space is typically occupied by a mixture of fuel vapor and ambient air. Such fuel vapor-air mixtures can present a fire hazard concentration of oxygen within the ullage space 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, that 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 a canister having an inlet end and an outlet end arranged along a canister axis, a separator supported within the canister and configured to separate a compressed air flow received at the air separation module into an oxygen-depleted air flow fraction and an oxygen-enriched air flow fraction, and an inlet cap. The inlet cap is seated about the inlet end of the canister, contains therein a portion of the separator, and has an oxygen-enriched air outlet port fluidly separated from the outlet end of the canister by the separator for diverting the oxygen-enriched air flow fraction to the external environment. 
     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 an oxygen-enriched air duct, the oxygen-enriched air duct extending tangentially from the inlet cap. 
     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 and the canister define between one another an annular oxygen collection plenum, the annular oxygen collection plenum fluidly coupling the separator with the oxygen-enriched air outlet port. 
     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 an inlet cap flange connecting the inlet cap to the canister, and further including a face seal member arranged axially between the inlet cap flange and 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 separator includes a resin body portion coupled to a canister portion by an inlet cap portion, the resin body portion and the canister portion of the separator contained within the inlet cap. 
     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 portion of the separator is contained within the canister, and that the inlet cap portion of the separation is radially overlapped by the inlet cap. 
     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 separator includes a hollow fiber mat supported within the inlet cap by the resin body portion of 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 resin body portion of the separator is contained within the inlet cap and bounds an inlet cap plenum defined axially between the inlet cap and the resin body portion of the separator, and further that the air separation module further include a radial seal member radially compressed between the inlet cap and the resin body portion of 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 canister is a one-piece body including a perforated portion, the canister and the performed portion 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 a compressed air source fluidly coupled to the separator by the inlet cap, and therethrough disposed in fluid communication with the oxygen-enriched air outlet port. 
     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 perforated portion, the perforated portion of the canister fluidly coupling the separator with the oxygen-enriched air outlet port. 
     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 perforated portion of the canister is contained within the inlet cap. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include an outlet cap seated on the outlet end of the canister, wherein the outlet cap has an outlet cap axial length, wherein the inlet cap has an inlet cap axial length, and wherein the inlet cap axial length is greater than the outlet cap axial length 
     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 extending about the canister, the canister inlet flange connecting the inlet cap to the canister, the canister inlet flange arranged axially between the perforated portion of the canister and the outlet end of 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 contains a tube sheet locating feature, the tube sheet locating feature contained within the canister and radially separated from the inlet cap 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 in fluid communication with the outlet end of the canister, the separator fluidly coupling the fuel tank to the inlet cap, the separator fluidly separating the fuel tank from the oxygen-enriched air outlet port. 
     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 extending about the inlet end of the canister, that the canister has a canister outlet flange extending about the outlet end of the canister, and that the canister extends continuously and without a port between the canister inlet flange and the canister outlet flange. 
     A nitrogen generation system is also provided. The nitrogen generation system includes an air separation module as described above. The inlet cap and the canister define between one another an annular oxygen collection plenum, the annular oxygen collection plenum fluidly coupling the separator with the oxygen-enriched air outlet port. A compressed air source is fluidly coupled to the separator by the inlet cap, and therethrough is disposed in fluid communication with the oxygen-enriched air outlet port. A fuel tank is in fluid communication with the outlet end of the canister, the separator fluidly coupling the fuel tank to the inlet cap, the separator fluidly separating the fuel tank from the oxygen-enriched air outlet port. 
     In addition to one or more of the features described above, or as an alternative, further examples of the nitrogen generation system may include the canister has a perforated portion, the perforated portion of the canister fluidly coupling the separator with the oxygen-enriched air outlet port; and that the separator includes a resin body portion coupled to a canister portion by an inlet cap portion, the resin body portion and the canister portion of the separator contained within the inlet cap. 
     In addition to one or more of the features described above, or as an alternative, further examples of the air separation module may include an ozone converter supported by the inlet cap; an inlet temperature sensor fluidly coupling the ozone converter to the separator; an oxygen sensor fluidly coupled to the inlet temperature sensor by the separator; an outlet temperature sensor fluidly coupled to the separator by the oxygen sensor; and a flow control valve fluidly coupled to the oxygen sensor by the outlet temperature sensor. 
     A method of making an air separation module includes defining a canister having an inlet end and an outlet end arranged along a canister axis; supporting a separator within the canister, the separator arranged to separate a compressed air flow received at the air separation module into an oxygen-depleted air flow fraction and an oxygen-enriched air flow fraction; seating an inlet cap about the inlet end of the canister such that the inlet cap contains therein a portion of the separator; and fluidly separating an oxygen-enriched air outlet port from the outlet end of the canister with the separator for diverting the oxygen-enriched air flow fraction to the external environment. 
     In addition to one or more of the features described above, or as an alternative, further examples of the method may include compressing a face seal member axially between the canister and the inlet cap; compressing a radial seal member radially between the separator and the inlet cap; defining an annular oxygen collection plenum between the canister and the inlet cap; and fluidly coupling the separator with the oxygen-enriched air outlet port with the annular oxygen collection plenum. 
     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 inlet caps having oxygen-enriched air output ports. In accordance with certain examples air separation modules have inlet caps containing a portion of the separator, allowing the separator to be larger than the canister containing the separator. It is also contemplated that, in accordance with certain examples, air separation modules include canisters with perforated portions in communication with the oxygen-enriched air outlet port for diverting oxygen-enriched air, separated from compressed air received by the separator, to the ambient environment. Diversion can be accomplished, for example, via a collection annulus defined by the inlet cap. 
    
    
     
       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 a nitrogen generation system constructed in accordance with the present disclosure, showing air separation module having an inlet cap with an oxygen-enriched air outlet port diverting oxygen-enriched air separated from a compressed air flow to the ambient environment; 
         FIG. 2  is a perspective view of the air separation module of  FIG. 1  according to an example, showing the inlet cap and an outlet cap seated on axially opposite ends of a canister; 
         FIG. 3  is a longitudinal cross-sectional view of a portion of the air separation module of  FIG. 1  including the inlet cap, showing a resin portion and an inlet cap portion of a separator contained within the inlet cap; and 
         FIG. 4  is a block diagram of method of making an air separation module in accordance with the present disclosure, 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 (e.g., nitrogen-enriched) 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 . 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 communicates 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 . 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 . In this respect the inlet temperature sensor  114  fluidly couples the filter module  108  to the air separation module  100  for measuring temperature of the compressed air flow  16  received from the supply conduit  106  via the filter module  108  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  (shown in  FIG. 3 ) 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  (shown in  FIG. 2 ), and an inlet cap  128  (shown in  FIG. 2 ). The canister  126  has an inlet end  130  and an outlet end  132  arranged along a canister axis  134  (shown in  FIG. 2 ). The separator  122  is supported within the canister  126  and is arranged to separate a compressed air flow, e.g., the compressed air flow  16 , received at the air separation module  100  into an oxygen-depleted air flow fraction, e.g., the oxygen-depleted air flow fraction  18 , and an oxygen-enriched air flow fraction, e.g., the oxygen-enriched air flow fraction  30 . The inlet cap  128  (e.g., an inlet end cap) is seated about the inlet end  130  of the canister  126 , contains therein a portion  136  (shown in  FIG. 3 ) of the separator  122  and has an oxygen-enriched air outlet port  138 . The oxygen-enriched air outlet port  138  is fluidly separated from the outlet end  132  of the canister  126  by the separator  122  for diverting the oxygen-enriched air flow fraction to the external environment  32 . 
     With reference to  FIG. 2 , the air separation module  100  includes the canister  126 , the inlet cap  128 , and an outlet cap  140  (e.g., an outlet end cap). The canister  126  defines the canister axis  134  and has canister inlet flange  142 , and a canister outlet flange  144 . The canister inlet flange  142  extends about the canister  126 . The canister inlet flange  142  extends about the inlet end  130  of the canister  126 . The canister outlet flange  144  extends about the outlet end  132  of the outlet end  132  of the canister  126 . In certain examples the canister  126  has no oxygen-enriched air outlet port defined between the canister inlet flange  142  and the canister outlet flange  144 , the oxygen-enriched air outlet port  138  instead defined by the inlet cap  128 . In the illustrated example the canister  126  has a band  146 , e.g., a doubler) with a canister fixation feature  147  extending laterally therefrom arranged between the canister inlet flange  142  and the canister outlet flange  144  for fixation of the air separation module  100  to vehicle structure, e.g., the vehicle  10  (shown in  FIG. 1 ), through the canister  126 . 
     The outlet cap  140  has an output cap flange  150  and an output cap fixation feature  152 . The output cap flange  150  connects the outlet cap  140  to the canister outlet flange  144  and therethrough to the canister  126 . The output cap fixation feature  152  extends laterally from the outlet cap  140  and is arranged for fixation of the air separation module  100  to vehicle structure, e.g., the vehicle  10  (shown in  FIG. 1 ), through the outlet cap  140 . In the illustrated example the oxygen sensor  118 , outlet temperature sensor  116 , and the flow control valve  120  are each supported by the outlet cap  140 . In this respect the output cap flange  150  of the outlet cap  140  and the canister outlet flange  144  of the canister  126  cooperate to communicate the load of the canister  126 , the outlet cap  140 , the oxygen sensor  118 , the outlet temperature sensor  116 , and the flow control valve  120  through the canister fixation feature  148  and the outlet cap fixation feature  152 . 
     The inlet cap  128  is similar the outlet cap  140  and additionally has an inlet cap flange  154 , an oxygen-enriched air duct  156 , a filter module mount  158 , and an inlet cap fixation feature  160 . The inlet cap flange  154  connects the inlet cap  128  to the canister inlet flange  142  and therethrough to the canister  126 . The filter module mount  158  supports the filter module  108  and fluidly couples the filter module  108  to the canister  126 . The inlet cap fixation feature  160  extends laterally from the inlet cap  128  and is arranged for fixation of the air separation module  100  to vehicle structure, e.g., the vehicle  10  (shown in  FIG. 1 ), through the inlet cap  128 . It is contemplated that the filter module  108  be supported by the inlet cap  128 , e.g., cantilevered therefrom, a portion of the load associated with the filter module  108  communicated through the inlet cap flange  154  and the canister inlet flange  142 . 
     The oxygen-enriched air duct  156  extends tangentially from the inlet cap  128  and defines the oxygen-enriched air outlet port  138 . In certain examples the inlet cap  128  and oxygen-enriched air duct  156  are monolithically formed as a one-piece body of homogeneous composition, e.g., as a casting or as an additively manufactured article, simplifying assembly of the air separation module. In accordance with certain examples the inlet cap  128 , the oxygen-enriched air duct  156 , and the filter module mount  158  can be monolithically formed as a one-piece body of homogenous composition, e.g., as a casting or as an additively manufactured article, further simplifying assembly of the air separation module  100 . As shown in  FIG. 2  the inlet cap  128  has an inlet cap axial length  161  that is greater than an outlet cap axial length  163  of the outlet cap  140 , the inlet cap  128  thereby arranged to contain therein a portion of the separator  122 . This increases the volume within the air separation module  100  available for the separator  122  for a given canister length between the canister inlet flange  142  and the canister outlet flange  144 . 
     With reference to  FIG. 3 , a portion of the air separation module  100  including the inlet cap  128  and the canister  126  is shown. The separator  122  includes a resin body portion  162 , an inlet cap portion  164 , and a canister portion  166 . The canister portion  166  is contained within the canister  126  and is connected to the resin body portion  162  by the inlet cap portion  164 . The inlet cap portion  164  of the separator  122  is contained within the canister  126 , is further contained within the inlet cap  128 , and couples the canister portion  166  of the separator  122  to the resin body portion  162  of the separator  122 . The resin body portion  162  extends axially from the canister  126  in the direction of the filter module mount  158 , is contained within the inlet cap  128  and bounds an inlet cap plenum  168  defined between the resin body portion  162  and the inlet cap  128 . In certain examples the resin body portion  162  provides structural support to the hollow fiber mat  124  of the separator  122 , e.g., by presenting a machined surface to the inlet cap plenum  168  through which hollow fibers of the hollow fiber mat  124  fluidly communicate with the inlet cap plenum  168 . In accordance the certain examples the canister  126  contains a tube sheet locating feature  194 , the tube sheet locating feature  194  contained within the canister  126  and radially separated from the inlet cap  128  by the separator  122  to axially fix the separator relative to the canister  126 . 
     The canister  126  is partially contained with the inlet cap  128  and this respect has an inter-flange portion  170 , a perforated portion  172 , and rim portion  174 . The inter-flange portion  170  of the canister  126  extends between the canister outlet flange  144  (shown in  FIG. 2 ) and the canister inlet flange  142 . The perforated portion  172  of the canister  126  extends axially from inter-flange portion  170  of the canister  126  in a direction opposite the canister inlet flange  142 , connects the inter-flange portion  170  of the canister  126  to the rim portion  174  of the canister  126 , and has a plurality of perforations  176  extending radially therethrough. In certain examples canister  126  is a one-piece body including the perforated portion  172 , the canister both homogenous in composition and monolithic in construction to provide structural strength to the canister  126 . 
     The plurality of perforations  176  fluidly couple the separator  122  with the oxygen-enriched air outlet port  138  through the oxygen-enriched air duct  156  (shown in  FIG. 2 ), and in the illustrated example are distributed circumferentially about the circumference of the canister  126 . The rim portion  174  of the canister  126  extends axially from the perforated portion  172  of the canister  126  in a direction axially opposite the canister inlet flange  142 , is contained within the inlet cap  128  and is connected to the inter-flange portion  170  of the canister  126 . In the illustrated example both the perforated portion  172  of the canister  126  and the rim portion  174  of the canister  126  are radially overlapped by the inlet cap  128 , the perforated portion  172  and the rim portion  174  thereby cooperating with the resin body portion  162  of the separator  122  to support and protect the hollow fiber mat  124  during assembly of the inlet cap  128  on the canister  126 . 
     The inlet cap  128  defines a radial seal slot  178 , a canister seat  180 , an annular oxygen collection plenum  182 , and a face seal slot  184 . The radial seal slot  178  extends circumferentially about an interior surface  186  of the inlet cap  128 , is defined axially between inlet cap plenum  168  and the canister seat  180 , and seats therein a radial seal member  188 . The radial seal member  188  is radially compressed between the resin body portion  162  of the separator  122  and the interior surface  186  of the inlet cap  128  to fluidly separate the oxygen-enriched air outlet port  138  from the inlet cap plenum  168 . The canister seat  180  is defined by the interior surface  186  of the inlet cap  128 , extends circumferentially about the rim portion  174  of the canister  126  and radially outward thereof, and receives therein the rim portion  174  of the canister  126 . 
     The annular oxygen collection plenum  182  is defined between the interior surface  186  of the inlet cap  128  and the separator  122 , and more particularly between the interior surface  186  of the inlet cap  128  and the perforated portion  172  of the canister  126 , and fluidly couples the separator  122  to the oxygen-enriched air outlet port  138  of the inlet cap  128 . The face seal slot  184  is defined within an axial face  190  of the inlet cap flange  154 , extends circumferentially about the separator  122 , and seats therein a face seal member  192 . The face seal member  192  is axially compressed between the canister inlet flange  142  and the inlet cap flange  142 , the face seal member  192  thereby fluidly separating the annular oxygen collection plenum  182  from the external environment  32  (shown in  FIG. 1 ) and thereby limiting fluid communication between the annular oxygen collection plenum  182  and the external environment  32  to the oxygen-enriched air outlet port  138 . 
     During operation the compressed air flow  16  (shown in  FIG. 1 ) enters the inlet cap plenum  168  through the filter module mount  158 . The inlet cap plenum  168  communicates the compressed air flow  16  to the separator  122 , e.g., to hollow fibers of the hollow fiber mat  124 . The hollow fibers convey the compressed air flow  16  through the resin body portion  162  of the separator  122  and therethrough to the canister portion  166  of the separator  122 . As the compressed air flow  16  traverses the canister portion  166  of the separator  122  oxygen molecules of the compressed air flow traverse (e.g., driven by pressure) walls of the hollow fibers and collect in the annular oxygen collection plenum  182 . The annular oxygen collection plenum  182  diverts the oxygen molecules to the external environment  32  (shown in  FIG. 1 ) as the oxygen-enriched air flow fraction  30  (shown in  FIG. 1 ) through the oxygen-enriched air outlet port  138 . The hollow fibers of the hollow fiber mat  124  in turn convey nitrogen molecules of the compressed air flow  16  to the outlet end  132  of the canister  126 , and therethrough to the fuel tank  20  (shown in  FIG. 1 ) as the oxygen-depleted air flow fraction  18  (shown in  FIG. 1 ) wherein the oxygen-depleted air flow fraction  18  limits concentration of oxygen within the ullage space  24  (shown in  FIG. 1 ) of the fuel tank  20 . 
     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. The method includes defining a canister with an inlet end and an outlet end arranged along a canister axis, e.g., the canister  126  (shown in  FIG. 1 ) with the inlet end  130  (shown in  FIG. 1 ) and the outlet end  132  (shown in  FIG. 1 ) arranged along the canister axis  134  (shown in  FIG. 1 ), as shown with box  210 . The method  200  also includes supporting a separator within the canister, e.g., the separator  122  (shown in  FIG. 3 ), as shown with box  220 . It is contemplated that separator be arranged to separate a compressed air flow, e.g., the compressed air flow  16  (shown in  FIG. 1 ), into an oxygen-depleted air flow fraction and an oxygen-enriched air flow fraction, e.g., the oxygen-depleted air flow fraction  18  (shown in  FIG. 1 ) and the oxygen-enriched air flow fraction  30  (shown in  FIG. 1 ), as also shown with box  220 . 
     As shown with box  230 , an inlet cap is seated about the inlet end of the canister, e.g., the inlet cap  128  (shown in  FIG. 2 ). It is contemplated that the inlet cap contains a portion of the separator, e.g., the resin body portion  162  (shown in  FIG. 3 ) of the separator  122  (shown in  FIG. 3 ) and the inlet cap portion  164  (shown in  FIG. 3 ) of the separator  122 , as also shown with box  230 . In certain examples seating the inlet cap on the canister includes defining an annular oxygen collection plenum between the canister and the inlet cap, e.g., the annular oxygen collection plenum  182 , as shown with box  232 . 
     As shown with box  240 , the method  200  also includes fluidly separating an oxygen-enriched air outlet port, e.g., the oxygen-enriched air outlet port  138  (shown in  FIG. 2 ), from the outlet end of the canister using the separator for diverting the oxygen-enriched air flow fraction to the external environment. In certain examples fluidly separating the oxygen-enriched air outlet port from the outlet end of the canister includes compressing a face seal member, e.g., the face seal member  192  (shown in  FIG. 3 ), axially between the canister and inlet cap, as shown with box  242 . In accordance with certain examples fluidly separating the oxygen-enriched air outlet port from the outlet end of the canister includes compressing a radial seal member, e.g., the radial seal member  188  (shown in  FIG. 3 ), radially between the canister and the separator and the inlet cap, as shown with box  244 . As shown with box  250  the separator is thereafter fluidly coupled with the oxygen-enriched air outlet port using the annular oxygen collection plenum, as shown with box  250 . 
     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 an inlet cap with an oxygen-enriched air outlet port. Portions of the canister and the separator are contained within the inlet cap and the canister perforated to provide fluid communication between the separator and the external environment. The fluid communication provided by the perforated portion of the canister allows oxygen-enriched air driven out of the separator by pressure of compressed air admitted to the separator to exit the air separation module through the inlet cap through oxygen-enriched air outlet port. 
     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.