Abstract:
A filter apparatus and filter element therefore are provided. The filter apparatus includes a filter head including an inlet port, a main flow outlet port and a drain flow outlet port. The filter element includes a ring of filter media defining an internal cavity. The filter element defines a main flow passage and a drain flow passage through the internal cavity. Each flow passage has an inlet on a clean side of the filter media directly fluidly communicating with the internal cavity. The main flow passage is fluidly coupled to the main flow outlet port. The drain flow passage (or air bleed passage) is fluidly coupled to the drain flow outlet port and includes (i) a restriction  154  sized large enough to allow air flow and small enough to prevent substantial liquid flow and (ii) a check valve  912  limiting flow to a single direction. The filter media separates the inlet port from the main flow and drain flow outlet ports.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This patent application claims the benefit of U.S. Provisional Patent Application No. 61/428,337, filed Dec. 30, 2010, the entire teachings and disclosure of which are incorporated herein by reference thereto. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to fluid filters and assemblies, and more particularly to liquid filters and assemblies. 
     BACKGROUND OF THE INVENTION 
     Many liquid systems, such as fuel systems for engines, utilize replaceable filters for filtering particulate out of the liquid system. Once the filter becomes spent, i.e. its serviceable life has been used, the filter is replaced by removing the old filter and replacing it with a new filter. 
     In many systems, such as fuel systems, it is beneficial to avoid entraining air into the liquid system to avoid a reduction in performance of the downstream engine. However, during replacement of the filters, the filters are typically empty and filled with air. Once the system is started, as fuel is pumped into the filter, this air can be forced through the rest of the system affecting the downstream components. 
     As such, steps to evacuate this air have been tried. For instance, in U.S. Pat. No. 7,147,110 to Clausen et al. includes a vent orifice in an end cap of the replaceable filter element which allows air that is trapped within the filter to be evacuated through the filter element and vented back to the fuel tank. Unfortunately, the vent orifice of Clausen is directly exposed to the dirty fuel side of the filter and can be easily clogged preventing the evacuation of air through the vent orifice. 
     The present invention relates to improved systems for facilitating venting air from a filter, such as at maintenance intervals. 
     BRIEF SUMMARY OF THE INVENTION 
     A filter apparatus and filter element therefore are provided. The filter apparatus and filter element are configured to improve venting of air from the filter apparatus during maintenance intervals or when the system runs empty of fluid. 
     The filter apparatus includes a filter head including an inlet port, a main flow outlet port and a drain flow outlet port. The filter element includes a ring of filter media defining an internal cavity. The filter element defines a main flow passage and a drain flow passage through the internal cavity. Each flow passage has an inlet on a clean side of the filter media directly fluidly communicating with the internal cavity. The main flow passage is fluidly coupled to the main flow outlet port. The drain flow passage is fluidly coupled to the drain flow outlet port. The filter media separates the inlet port from the main flow and drain flow outlet ports. 
     In one embodiment, the filter head further includes a standpipe including an inner cylindrical tube defining the main flow outlet port and an outer cylindrical tube surrounding the inner cylindrical tube. The inner and outer cylindrical tubes define the drain flow outlet port therebetween. The filter element further includes a first seal member sealing with the outer cylindrical tube and a second seal member sealing with the inner cylindrical tube. 
     In one embodiment, the second seal member seals with the inner cylindrical tube such that it separates the main flow passage from the drain flow passage. 
     In one embodiment, the second seal member has a smaller inner diameter than the first seal member. 
     In one embodiment, both the inner and outer cylindrical tubes extend through the first seal member and only the inner cylindrical tube extends through the second seal member. 
     In one embodiment, the drain flow passage includes a restriction sized to permit gas flow but that is sized to substantially prohibit liquid flow. 
     In one embodiment, the first seal member seals the main flow outlet port to the main flow passage, the first and second seal members seal the drain flow passage outlet to the drain flow outlet port, and the second seal portion prevents fluid from circumventing the filter media. 
     In one embodiment, no fluid exiting the filter head via either the drain flow outlet port or the main flow outlet port circumvents the filter media. 
     In one embodiment, the filter element further includes a check valve limiting fluid flow through the drain flow passage in a direction extending from the inlet thereof to the drain flow outlet port. 
     In a particular embodiment of the filter element, the filter element includes a ring of filter media defining an internal cavity. The filter element further includes a main flow passage and a drain flow passage through the internal cavity. Each flow passage has an inlet on a clean side of the filter media directly fluidly communicating with the internal cavity. The filter element also includes a first seal portion defining an outlet from the internal cavity and a second seal portion separating the main flow passage from the drain flow passage. 
     In one embodiment, the second seal portion defines a main flow passage outlet for the main flow passage; and the first and second seal portions define a drain flow passage outlet therebetween. 
     In one embodiment, the second seal portion is downstream of both the main flow outlet and drain flow outlet. 
     In one embodiment, the first seal portion has an inner diameter that is smaller than an inner diameter of the second seal portion. 
     In one embodiment, the first and second seals are formed from separate discrete seal members that are axially spaced apart. 
     In one embodiment, the drain flow passage includes a restriction between the drain flow passage inlet and drain flow outlet. In one embodiment, the restriction is sized large enough to allow sufficient air flow while small enough to prevent significant liquid flow. 
     In one embodiment, the filter element is configured such that fluid passing through both of the main flow passage and drain flow passage does not circumvent passing through the ring of filter media. 
     In one embodiment, the filter element further includes a central support. The central support defines, at least in part, the main flow passage and the drain flow passage. The central support is positioned, at least in part, within the internal cavity. 
     In one embodiment, the second seal is carried by the central support. The filter element further includes a first end cap secured to a first end of the filter media. The first end cap carrying the first seal. 
     In one embodiment, the filter element further includes a second end cap. The second end cap is secured to a second end of the filter media. The second end is opposite the first end. The second end cap being imperforate. 
     In one embodiment, the second seal is axially positioned between a first abutment portion of the central support and a retaining member affixed to the central support. 
     In one embodiment, the first seal is axially positioned between a second abutment portion of the central support and a first end cap secured to an end of the filter media. 
     In one embodiment, the filter element further includes a check valve arrangement in line with the drain flow passage limiting fluid flow through the drain flow passage in a single direction. In a more particular embodiment, the filter element includes a central support within at least a portion of the internal cavity. The central support defines, at least in part, the drain flow passage. The check valve arrangement includes a floating valve member positioned adjacent an outlet end portion of the drain flow passage. 
     Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is a simplified cross-sectional illustration of a filter apparatus according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional illustration of the filter element of  FIG. 1 ; 
         FIG. 3  is a simplified cross-sectional illustration of the standpipe of  FIG. 1 ; 
         FIG. 4  is a cross-sectional illustration of a further embodiment of a filter element according to an embodiment of the invention; 
         FIG. 5  is a cross-sectional illustration of the filter element o  FIG. 4  installed into a filter housing; 
         FIG. 6  is a further embodiment of a filter element according to an embodiment of the present invention; 
         FIGS. 7-10  are cross-section illustrations of a further embodiment of a filter element according to an embodiment of the present invention; 
         FIGS. 11 and 12  are cross-sectional illustrations of a further embodiment of a filter element according to the present invention; 
         FIG. 13  is a cross-sectional illustration of a further embodiment of a filter element according to an embodiment of the present invention; 
         FIGS. 14-17  are cross-sectional illustrations of a further embodiment of a filter element according to an embodiment of the present invention; 
         FIGS. 18 and 19  are cross-sectional illustrations of a further embodiment of a filter element according to an embodiment of the present invention; and 
         FIGS. 20 and 21  are cross-sectional illustrations of a further embodiment of a filter element according to an embodiment of the present invention. 
     
    
    
     While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an embodiment of a filter assembly  100  according to the teachings of the present invention. The filter assembly  100  generally includes a replaceable filter element  102  that is removably mounted to a filter head. The filter head is illustrated in simplified form as a housing  106  and a stand pipe  108 . 
     The housing  106  includes a shell  110  and removable lid  112 . The removable lid  112  and shell  110  define an interior cavity  114  in which the filter element  102  is housed. The removable lid  112  is threadedly secured to shell  110  to provide selective access to interior cavity  114  to allow for replacement of filter element  102 . 
     In the schematic illustration, dirty fuel, illustrated as arrow  116 , enters filter assembly  100  through inlet  118  in standpipe  108 . In other embodiments, the dirty fuel inlet  118  could be formed from other components and need not pass through stand pipe  108 . Clean fuel, illustrated as arrow  120 , exits the filter assembly  100  through clean fuel outlet  122  formed in standpipe  108 . The filter assembly  100  also includes a drain outlet  124  that allows air  126  trapped in the filter assembly  100 , such as at maintenance intervals or if the system were to be run empty of fuel, to be evacuated from the filter assembly  100 . Typically, the drain outlet  124  is operably fluidly coupled to the fuel tank such that this air  126  will be evacuated back to the fuel tank. However, it could be evacuated to other locations as appropriate. 
     With additional reference to  FIG. 2 , the filter element  102  is illustrated removed from housing  106 . The filter element  102  generally includes a ring of filter media  128  extending axially between first and second opposed ends  130 ,  132 . The ring of filter media  128  generally bounds, at least in part, an internal cavity  134 . In this embodiment, the internal cavity  134  is a clean fuel side of the filter element  102  because fuel flows radially inward through the ring of filter media  128  as it is filtered. 
     An open end cap  136  is affixed to first end  130  of the filter media  128 . The end cap  136  includes an outlet opening  138 . The outlet opening  138  carries a seal member  140 . In this embodiment, seal member  140  radially seals on a radially outer surface of a radially outer portion  141  of standpipe  108  and prevents dirty fuel  116  from bypassing the filter element  102 . The seal member  140  provides an exit path from the internal cavity  134 . As will be more fully developed below, both the clean fuel  120  and the air  126  exit the filter element  102  by passing through, seal member  140  such that two separate flow paths pass through the seal member  140  are generated. 
     The filter element  102  is closed at the opposite end. The filter element  102  includes a closed end cap  142  affixed to second end  132  of the filter media  128  to close that end  132  of the filter element  102 . 
     The end caps  136 ,  142  can be sealingly attached to the ends  130 ,  132  of the filter media in any known way, such as using plastisol, urethane, embedding the media into the end caps  136 ,  142 , foaming or molding the end caps  136 ,  142  to the filter media  128 , etc. 
     A center tube  144  is carried within internal cavity  134  of the filter media  128 . The center tube  144  provides radial support for the ring of filter media  128 . The center tube  144  is perforated and permits clean fuel  120  to pass radially therethrough. The center tube  144  extends axially between an inner surface  146  of open end cap  136  and an inner surface  148  of closed end cap  142 . In this embodiment, the ends  147 ,  149  of the center tube  144  are sealed to the corresponding end caps  136 ,  142  to avoid fluid by pass. 
     To provide the venting features, the filter element  102  defines a pair of flow passages through internal cavity  134 . 
     A first flow passage is clean fuel flow passage  150  that allows clean fuel  120  that has passed through the ring of filter media  128  to flow toward downstream components of the fuel system, when the filter element  102  is mounted to stand pipe  108 . 
     A second flow passage is air bleed passage  152  that, when the filter element  102  is mounted to stand pipe  108 , allows air trapped within the filter assembly  100  to be evacuated to drain outlet  124 , and ultimately back to tank. The clean fuel flow passage  150  and air bleed passage  152  extend through the internal cavity  134  of the filter element  102  in a generally parallel manner. 
     The air bleed passage  152  includes a restriction  154  that is generally sized to oppose or limit fluid flow by fuel but sized to generally allow fluid flow by air. As such, air that is evacuated from the filter assembly  100  after maintenance intervals can be evacuated through air bleed passage  152 , without the air otherwise being trapped within the rest of the fuel system. However, large quantities of filtered fuel will not escape back to tank after being filtered through the air bleed passage  152 . 
     The air bleed passage  152  includes an inlet  156  that is housed entirely within the internal cavity  134  of the filter element  102 . When the filter element  102  is mounted to the stand pipe  108 , the only way for air to pass through air bleed passage  152  is for the air to first pass through the filter media  128 . This arrangement provides a significant benefit over prior designs in that the inlet  156  of the air bleed passage  152  is only exposed to the clean side of the filter element  102 . This arrangement prevents dirty fuel and potential contaminants carried thereby from plugging the restriction  154 . 
     Center tube  144  carries a second seal member  158 . The second seal member  158  separates the clean fuel flow passage  150  from the air bleed passage  152 . The second seal member  158  generally defines the clean fuel flow passage  150 . The second seal member  158  radially seals with a clean fuel portion  160  of stand pipe  108 . The clean fuel portion  160  of stand pipe  108  is fluidly coupled to clean fuel outlet  122 . As such, clean fuel  120  that enters internal cavity  134  of filter element  102  by passing through media  128 , flows through the clean fuel flow passage  150  by flowing through clean fuel portion  160  of stand pipe  108  to clean fuel outlet  122  and then to downstream components of the fuel system. 
     With reference to  FIG. 1 , the radially outer portion  141  of stand pipe  108  and the clean fuel portion  160  of the stand pipe  108  define an air bleed channel  162  therebetween, which is fluidly connected to air bleed passage  152  when filter element  102  is mounted to stand pipe  108 . 
     With the filter element  102  mounted to stand pipe  108 , the second seal member  158  seals on radially outer surface  164  of clean fuel portion  160  and the first seal member  140  seals on a radially outer surface  166  of radially outer portion  141  of stand pipe  108 . This sealed relationship allows the air bleed passage  152  to be coupled to air bleed channel  162  of the stand pipe  108  via a passage formed between the clean fuel portion  160  of stand pipe  108  and an imperforate portion  168  of center tube  144 . 
     The air bleed passage  152  of the center tube  144  exits axially between the first and second seal members  140 ,  158  at the imperforate portion  168  of center tube  144 . When the filter element  102  is mounted to the stand pipe  108 , the air bleed passage  152  exits on a downstream side  170  of second seal member  158  and a clean fuel side  172  of first seal member  140 . 
     The second seal member  158  is carried by a radially inward projecting flange  173  of center tube  144 . The second seal member  158  fluidly communicates the imperforate portion  168  of center tube  144  with a perforated portion  171  of center tube  144  when the filter element  102  is not mounted to the stand pipe  108 . Similarly, the air bleed passage  152  fluidly communicates the perforated portion  171  of center tube with the imperforate portion  168 . This communication, however, occurs whether or not the filter element  102  is mounted to the stand pipe  108 . 
     The first seal member  140  has a diameter D 1  that is greater than the diameter D 2  of the second seal member  158 . This relationship permits both the radially inner clean fuel portion  160  of the stand pipe  108  as well as the radially outer portion  141  of stand pipe  108  to pass through first seal member  140 . Preferably, the first and second seal members  140 ,  158  are concentric, but axially offset. 
     With reference to  FIG. 3 , the outer surface  166  of radially outer portion  141  of stand pipe  108  has a diameter D 3  that is greater than the diameter D 4  of outer surface  164  of the inner clean fuel portion  160  of stand pipe  108 . Diameters D 3  and D 4  are sized to provide a good sealing fit with seal members  140 ,  158  while allowing the filter element  102  to be mounted onto stand pipe  108 . In other embodiments, these radial seals could be provided by axial seals. 
     The stand pipe  108  includes a third cylindrical portion  176  that has a diameter D 5  which is greater than both diameter D 3  and D 4 . 
     Other arrangements could be provided that eliminate one or more of the cylindrical portions of the stand pipe  108  (i.e. clean fuel portion  160 , radially outer portion  141  and third cylindrical portion  176 ). 
     With reference to  FIG. 2 , the first seal member  140  is axially spaced further away from second end  132  than second seal member  158 . 
     The first and second seal members  140 ,  158  are preferably recessed axially into the internal cavity  134  defined by the ring of filter media  128  such that the seal members  140 ,  158  are circumferentially surrounded by filter media  128  and axially positioned between first and second ends  130 ,  132  of the filter media  128 . 
     The air bleed passage  152  and clean fuel flow passage  150  both have inlets  156 ,  180 , respectively, that are on a clean fuel side of the filter media  128 . In this embodiment, both inlets  156 ,  180  are downstream from a perforate portion of the center tube  144 . 
     Further, when not mounted to a filter head, these passages  150 ,  152  have outlets  182 ,  184  that fluidly communicate with one another via a chamber  169  bounded by the imperforate portion  168  of center tube  144 . Chamber  169  is generally axially bounded by flange  173  and open end cap  136 . The imperforate portion  168  of center tube  144  circumferentially bounds the chamber  169 . Because end  147  of the center tube  144  is operably sealed to open end cap  136 , the only way for fluid to enter or exit this chamber  169  is via the air bleed passage  152 , first seal member  140  or second seal member  158 . 
     In operation, filter element  102  is mounted within housing  106 . Lid  112  can be threadedly removed from shell  110  to provide access to central cavity  114 . If a spent filter element is already stored within filter housing  106 , this filter element can be removed and discarded. A new clean filter element  102  is then inserted into cavity  114 . 
     As the clean filter element  102  is inserted into shell  110 , the filter element  102  is axially mounted over stand pipe  108 . At least a portion of stand pipe  108  will generally pass through both the first and second seal members  140 ,  158 . 
     Once the filter element  102  is mounted on stand pipe  108 , the lid  112  is threadedly secured to shell  112 . 
     With the filter element  102  mounted over stand pipe  108 , the radially outer portion  141  will pass through and form a seal with first seal member  140 . This seal prevents dirty fuel from bypassing the filter media  128  and passing through clean fuel portion  160  of the stand pipe  108  to downstream components of the system or through air bleed channel  162  and, for example, returning back to the tank. 
     The clean fuel portion  160  axially passes through both the first and second seal members  140 ,  158  and forms a seal with second seal member  158 . This sealing arrangement prevents clean fuel from passing through drain outlet  124 . 
     With primary reference to  FIG. 1 , during initial startup, dirty fuel  116  is pumped into cavity  114 . If air is housed within the cavity  114 , it is pumped through media  128  and through air bleed passage  152 . The air is passed through cavity  169  and exits the filter element  102  through the opening  138  that is bounded by first seal member  140  via air bleed channel  162  in stand pipe  108 . This air is typically then passed back to the tank. Typically, the passage back to tank will be at a lower pressure than through the clean fuel portion  160 . 
     Once internal cavity  114  fills with fuel, the clean fuel  120  will generally close air bleed passage  152 . Additionally, the clean fuel  120  that has passed through filter media  128  will exit internal cavity  134  of the filter element  102  via clean fuel portion  160  of stand pipe  108  and pass through both the second seal member  158  and first seal member  140 . 
     This operation illustrates that there are two parallel flow paths, one for the entrapped air to be bled from the filter assembly  100 , and one for clean fuel to be passed on to downstream components, within internal cavity  134  of the filter element  102 . When the filter element  102  is mounted to the stand pipe  108 , both flow paths ultimately pass through the first seal member  140 . However, as they pass through the first seal member  140 , they remain separated as they pass through separate portions of stand pipe  108 . Further, these flow paths are separated from one another as they pass through fluidly separated portions of the center tube  144 . 
       FIG. 6  illustrates a further embodiment of a filter element  302 . This embodiment is substantially similar to the prior embodiment in  FIGS. 1-3 . However, in this embodiment, the filter element  302  includes a different seal. Rather than including a seal member like first seal member  140 , this embodiment includes seal member  304 . 
     Here, the seal member  304  is a gasket affixed to end cap  306 . Seal member  304  may be a felt gasket. However, other embodiments may use rubber or soft plastic to form seal member  304 . In this embodiment, the seal member  304  forms the axial end of filter element  302 , as opposed to being recessed into end cap  140  of the prior embodiment. 
     This seal member  304  can be used to form a radial seal such as illustrated in the prior embodiment. Alternatively, the seal member  304  could be used to form an axial seal depending on the stand pipe and filter head configuration. 
       FIGS. 4 and 5  illustrate a further embodiment of a filter element  202 . Many features of this filter element  202  are similar to the features of filter element  102  discussed previously and thus, only the differences will be discussed below. 
     This filter element includes a ring of filter media  204  that extends axially between a first open end cap  206  and a second open end cap  208 . The filter element  202  also includes an outer wrapper  210  that surrounds the ring of filter media  204 . 
     An attachment member  212  is provided. The attachment member  212  is attached to end cap  208  and is used to attach the filter element  202  to a filter housing lid  214 . Attachment member  212  may be releasably or permanently attached to end cap  208 . 
     In this embodiment, air  216  will pass through a perforated wrapper  210  and then an air flow gap  218  formed between the attachment member  212  and second annular end cap  208 . Either the second end cap  208  or the attachment member  212  may include axial standoffs  222  that space the end cap  208  from attachment member  212  to assist in maintaining air flow gap  218 . Air  216  will then pass through center tube  224  into an air bleed passage  226 . Again, air bleed passage  226  includes a restriction  228  sized to permit air passage but to inhibit or substantially prevent fuel flow. 
     The inlet of the air bleed passage  226  as well as the restriction  228  is downstream from wrapper  210  which assists in preventing larger contaminants from blocking restriction  228  and the wrapper  210  forms a pre-filter media for the filter element  202 . 
     A first seal member  230  is carried between first end cap  206  and center tube  224 . The first seal member  230  is axially positioned between a radially inward step  232  of end cap  206  and an axial abutment portion  234  of the center tube  224 . 
     A second seal member  236  has a diameter that is smaller than first seal member  230 . The second seal member  236  is axially positioned relative to a stepped portion  237  of center tube  224  that forms an axial abutment portion and a retaining element, in the form of washer  238  that is affixed to center tube  224 . Washer  238  may be affixed to center tube  224  by snapping into a recess formed in the center tube  224 , adhesively bonded to center tube  224 , ultrasonically bonded/welded to center tube  224  or otherwise secured to center tube  224 . With the washer  238  secured to the center tube  224 , the washer  238  and stepped portion  237  form a channel that receives seal member  236  and that has a radially inward directed mouth that seal member  236  extends radially inward beyond for engagement with a stand pipe of a corresponding filter head. 
     The radially outward facing surface of seal member  236  has radially outward projecting ribs that facilitate improved sealing between the seal member  236  and center tube  224 . 
     These seal members  230 ,  236  seal on stand pipe  240  much like the prior embodiment of  FIGS. 1-3 . These seal members  230 ,  236  in combination with an imperforate portion  242  of the stand pipe  224  operate much like chamber  169  of the prior embodiment. 
     In this embodiment, the air bleed passage  226  has its inlet upstream of the ring of filter media  204 , however, it is located internal to the cavity defined by the filter media  204 . This is because the center tube  224  includes imperforate portion  250  through which the air  216  passes after it passes through air flow gap  218 . The center tube  224  also includes perforate portion  252  through which clean fuel  254  flows after the fuel has passed through filter media  204 . 
       FIGS. 7-10  are cross-sectional illustrations of a further filter element  402  according to an embodiment of the present invention. The filter element  402  is similar to the embodiments of  FIGS. 1 and 4 . 
     With reference to  FIGS. 7 and 9 , in this embodiment, the filter element  402  includes a restriction  404  that is downstream of filter media  406 . As such, any air  408  that must be evacuated must pass through filter media  406 . Further, the filter element  402  includes first and second seal members  410 ,  412  that are substantially similar to those of  FIG. 4 . 
     In this embodiment, the restriction  404  is formed in a generally imperforate portion  413  of a cylindrical sidewall portion  414  of the center tube  416 . After air  408  passes through restriction  404 , the air  408  enters an internal cavity  419  formed by end cap  420  and cylindrical sidewall portion  414  of the center tube  416 . From there, the air  408  enters air bleed passage  422 . 
     In this embodiment, the clean fluid passage  430  is defined by second seal member  412 . Clean fuel will pass through perforate portion  432  of center tube  416  prior to passing through second seal member  412 . Perforate portion  432  generally defines an inlet to the clean fluid passage of this embodiment As such, the inlet to both the clean fluid passage and the air bleed passage are on the interior and clean fluid side of the filter media. 
     Like prior embodiments, the clean fuel will typically flow through a portion of a stand pipe passing through the second seal member  412  as the clean fuel flows through the clean fuel flow passage  430 . 
       FIG. 11  illustrates a further embodiment of a filter element  502 . This embodiment is substantially similar to the embodiment of  FIGS. 4-5 . However, as also illustrated in  FIG. 12 , this embodiment has a different arrangement between the upper end cap  504  and center tube  506 . 
     This embodiment includes a seal element  508  positioned radially between an inner skirt  510  of the end cap  504  and an outer surface  512  of the cylindrical sidewall portion  514  of center tube  506 . 
     Further, the center tube  506  includes a radially outward projecting flange  516  that extends radially over inner cylindrical skirt  510 . 
     A further embodiment of a filter element  602  is illustrated in  FIG. 13 . This filter element  602  is substantially similar to the embodiment of  FIGS. 1 and 6 . 
     In this embodiment, the center tube  604  is not a one-piece construction. Instead, the center tube  604  includes a restriction plate  606 . 
     The restriction plate  606  defines a restriction  608  that allows air flow  610  but inhibits fuel flow therethrough. The restriction  608  is formed in a generally cylindrical projection  612  that extending into passage  614  formed in center tube  604 . The combination of restriction  608  and passage  614  forms an air bleed passage as discussed previously. 
     The restriction plate  606  includes an opening  616  that permits the air to flow through restriction  608  after it has passed through the filter media of the filter element  602 . 
       FIG. 14  illustrates a further embodiment of a filter element  702  useable in a filter assembly according to the teachings of the present invention. For instance, the filter element  702  could be used with a stand pipe similar to that of stand pipe  240  of prior embodiments. The filter element  702  includes a vent arrangement that is typically vented through the filter media  728  via restriction  704 , much like prior filter element  402 , described above. 
     This embodiment further includes a check valve arrangement  780  for preventing back flow of fluid into the filter element  702  through air bleed passage  722  defined by center tube  716 . In the illustrated embodiment, the check valve arrangement  780  is provided by a valve member illustrated in the form of a floating ball  782  that cooperates with the center tube  716  and particularly outlet end portion  784  of the air bleed passage  722  defined by center tube  716 . 
     The outlet end portion  784  defines a seat  786  with which the outer surface of floating ball  782  operably sealingly interacts to prevent back flow or to allow fluid flow depending on the pressure differential across the check valve arrangement  780 . In  FIGS. 14 and 15 , air (illustrated by arrow  788 ) creates a higher pressure upstream of floating ball  782  and is flowing through the air bleed passage  722 . As such, the floating ball  782  is axially spaced away from the seat  786  into an open state permitting the air  788  to flow through the check valve arrangement  780  and onto tank as discussed above. 
     However, as illustrated in  FIG. 16 , the pressure on the downstream side of the check valve arrangement  780  is higher than upstream of the upstream side of the check valve arrangement  780 , illustrated by arrow  790 . This high pressure is the result of a potential back flow and causes the check valve arrangement  780  to transition to a closed state preventing back flow of fluid through the check valve arrangement  780 . This prevents potential contaminants in the vent passage from passing back through the air bleed passage  722  and restriction  704  preventing contaminants from being exposed to a clean filter side of the filter element  702 . 
     The floating ball  782  is preferably a low density plastic or rubber, however other alternative materials may be used such as metal. 
     The seat  786  preferably has a chamfered or generally conical profile in which the floating ball  782  is located. The conical profile of the seat  786  preferably widens in the downstream direction, i.e. fluidly away from the restriction  704 . The narrowest portion of the seat  786 , i.e. inlet throat  792 , has a dimension that is smaller than the outer diameter of floating ball  782 . 
     The floating ball  782  is axially secured proximate seat  786  by a retaining element, in the form of washer  738 , which also functions to axially secure the second seal member  736  to the center tube  716 . 
       FIGS. 18 and 19  illustrate a further embodiment of a filter element  802  for use in a filter assembly according to the present invention. 
     Once again, the filter element  802  allows for venting of the filter assembly through the filter media  828  via the included restriction  804  that functions as a return air vent that allows air to pass through return air bleed passage  822  rather than through a clean fluid outlet during initial priming. This again assists in preventing undesirable air to enter the fuel system during maintenance activities. 
     Filter element  802  functions in substantially a same manner as filter element  402  described above. However, filter element  802  further includes a plastic wrapper  894  that provides support for the filter media  828 . 
       FIGS. 20 and 21  illustrate a further embodiment of a filter element  902  for use in a filter assembly according to the present invention. This embodiment is similar in many respects to the embodiment of  FIG. 13 . This embodiment utilizes a check valve  912  within the air bleed passage  914  that prevents back flow of fluid through the air bleed passage  914  to the clean fluid side of the filter media of the filter element  902 . 
     The check valve  912  of the illustrate embodiment is a duck-billed valve that is formed from a resilient material, typically a resilient rubber. However, other flexible materials may also be used. 
     The check valve  912  is illustrated in  FIG. 20  in the open state permitting fluid to flow therethrough, illustrated by arrows  910 . This is during normal operation, such as during an initial priming step after initial installation to remove air from within the filter assembly.  FIG. 21  illustrates the check valve  912  in a closed state where back pressure generated by reverse flowing fluid, illustrated by arrows  913  attempt to pass through the check valve  912 . 
     The check valve  912  extends axially into the air bleed passage  914 . A retainer plate  906  axially locates the check valve  912  within the air bleed passage  914 . The retainer plate  906  includes at least one passage  916  that allows fluid to pass therethrough toward the check valve  912 . The check valve  912  includes a radially extending annular flange portion  917  that rests on an axial abutment surface  919  of the center tube  904 . The annular flange portion  917  is axially sandwiched between the abutment surface  919  and an inner surface of the retainer plate  906 . The interactions between the annular flange portion  917  and retainer plate  906  as well as annular flange portion  917  and the abutment surface  918  provide seals that prevent fluid bypass. 
     The check valve  912  aligns with a second aperture  921  passing through the retainer plate  906  to permit the desired fluid flow, such as is illustrated in  FIG. 20 . 
     The retainer plate  906  generally has an axially extending annular sidewall  924  that has a radially outward extending mounting flange portion  926 . Opposite the mounting flange portion  926 , the annular sidewall  924  is attached to a disc portion  928  that defines apertures  816 ,  921 . The annular sidewall  924  and disc portion  928  give the retainer plate a generally cup shape. The radially outward extending mounting flange portion  926  axially abuts a distal end of center tube  904  to axially limit the compression of annular flange portion  917 . The radially outward extending mounting flange portion  926  is axially located between an inner surface of end cap  930  and the distal end of the center tube  914 . 
     All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.