CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/904,657, filed May 29, 2013, which claims the benefit of U.S. Provisional Patent Application No. 61/653,240, filed May 30, 2012 and U.S. Provisional Application No. 61/754,266, filed Jan. 18, 2013. The entire disclosures of these applications are incorporated by reference herein in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention concerns a portable container intended for holding and dispensing flammable fuels. More particularly, it is concerned with an improved fuel container design which seeks to inhibit even the possibility of explosions by intentionally retaining a quantity of fuel proximate to an opening in order to provide a fuel-air mixture within the container that is too rich to support combustion. 
         [0004]    2. Description of the Prior Art 
         [0005]    Portable fuel containers as used herein are intended to refer to containers which hold about 6 gallons (about 26.43 liters) or less of fuel. Such portable fuel containers have traditionally been constructed of metal or synthetic resin and configured to permit stored fuel to be dispensed from an opening for use. Existing portable fuel containers are safe and effective for their intended purpose when properly used. Unfortunately, notwithstanding warning labels, common sense and safety instruction, as well as the experiences of others, users are known to have improperly used fuel containers. Bad judgment or practically no judgment is occasionally exercised by those users who ignore safe practices and instead recklessly pour liquid fuel from a portable container into a smoldering campfire or brush pile, or even onto an open flame. The resulting consequences are predictable but tragic when the fuel which is being poured and the fuel vapors ignite and burns the user and others in the vicinity of the fuel container. 
         [0006]    Most children are taught at a young age that fire or explosion may result from a combination of fuel (e.g., gasoline or other inflammable liquids), oxygen (such as is present in the atmosphere) and a source of ignition. Most safety measures concentrate on eliminating one of these elements. Thus, modern EPA approved portable fuel containers include warnings and provide closures that enclose the fuel container to shut off the source of fuel. These fuel containers work well under normal circumstances where the user exercises even a minimum of care. It is believed that even under conditions of abuse as described herein, fuel containers of recent manufacture will not explode. However, explosions within fuel containers have been induced by researchers in highly-controlled, extreme laboratory environments. While it is believed that it is only possible to produce an explosion within a fuel container under such extreme laboratory conditions, there has developed a need for a new approach to inhibiting combustion within portable fuel containers. 
         [0007]    Attempts have been made to eliminate the possibility of portable fuel container explosions. Some portable fuel containers made of metal (specifically safety cans) employ a metal flame arrestor. A flame arrestor is a metal screen that is fitted inside the neck of the tank and attempts to keep an ignition source such as a flame or spark from entering the tank of the portable fuel container. While such flame arrestors may be beneficial in a safety can, there are difficulties using them in common plastic fuel containers. For example, while filling a portable fuel container at a gas station, pumping gasoline through a flame arrestor screen could cause the fuel to splash back out of the container and mix with air, thereby creating a mixture ready for combustion. Moreover, pumping gasoline through a metal screen may cause a static spark with obvious catastrophic consequences. Metal safety cans offer a grounding tab to prevent this static electricity discharge, but this is not possible nor practical in a synthetic resin (plastic) tank as ordinary consumers are not familiar with this apparatus or practice. Furthermore, the presence of a metal flame arrestor may give the user a false sense of security or safety to the consumer and user and, if positioned just inside the neck of the container (as they are in such metal safety cans) they can be easily removed, thus defeating the intent of protecting against even irresponsible use. 
         [0008]    Thus, while the use of existing flame arrestors may have benefits, its limitations, especially in the context of use in a synthetic resin portable fuel container, still presents problems and far outweigh any benefits. A flame arrestor&#39;s intent is to keep the flame or spark from entering a portable fuel container, but this may not prove sufficient to defeat combustion when a user removes the flame arrestor or pours fuel directly onto fire. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention seeks to accomplish these goals by employing a method and apparatus which run contrary to conventional thinking, in that rather than cutting off a source of liquid fuel or ignition sources, an overly rich fuel-to-air ratio is provided within the portable fuel container, thus preventing the possibility of combustion. 
         [0010]    As noted above, it is accepted scientific fact that when fuel and air are present and their mixture is within a given combustible range, combustion will occur if the mixture is ignited. If the mixture of fuel and air is perfect (a stoichiometric mixture), complete combustion is achieved and both the fuel and the air are totally consumed during the combustion event. Combustion may also occur if the mixture is slightly lean of fuel, but if too lean (i.e., not enough fuel is present) combustion cannot occur. Similarly, combustion may occur if the mixture has slightly more fuel than a stoichiometric mix, but if the fuel-air mixture has too much fuel (becoming too rich), combustion cannot occur in this condition either. 
         [0011]    The present invention seeks to employ this latter circumstance—a situation where the fuel-air mixture is too rich—to inhibit combustion within the portable fuel container where, for example, fuel is being poured directly from the container opening onto an ignition source or within a controlled laboratory where fuel is “weathered” and maintained at an artificial temperature to establish a condition ripe for explosion. Again, the former circumstance is a highly undesirable practice which poses extreme risks to the user and others and should be avoided at all times, and the latter occurs only artificially when one intends to produce combustion within a container. The present invention seeks to minimize the risk of combustion in the portable fuel container even where the user proceeds recklessly or explosion is an intended consequence. 
         [0012]    The method and apparatus of the present invention employs structure which will be unlikely to be removed by an imprudent user because it does not impede normal usage, yet retains a sufficient quantity of fuel within the portable fuel container so as to create a mixture too rich to combust. Where there is sufficient fuel present in the container to present a risk of explosion when the contents are being poured, the present invention uses this condition to its advantage by trapping a sufficient quantity of fuel and thereby creates a “too rich” condition to inhibit combustion within the container. In some preferred embodiments, the structure of the apparatus and the method seek to cause this condition to be maintained in close proximity to the opening such that combustion may not proceed into the interior of the container but rather any explosive event will be suppressed by the retention of fuel immediately proximate the opening. In this circumstance, an incipient explosion entering the portable fuel container will encounter a circumstance where the amount of fuel in the fuel-air mixture will not support combustion. 
         [0013]    The present invention contemplates several alternate structures for providing this condition. In one approach, a neck dam is positioned in a neck of the portable container interior to the opening whereby a sufficient quantity of fuel is trapped in the neck area during pouring of fuel from the opening. In another approach, an absorbent, sponge-like material is utilized within the interior of the container either within a main body or in the neck proximate to an opening in the container. The absorbent material, by becoming substantially saturated and retaining a quantity of fuel in the area of the neck once fuel is poured therefrom, provides a “too rich” mixture for combustion and the onset of an explosion. In another approach, the container is configured to provide an inverted pocket for retaining fuel adjacent the neck area, the pocket retaining sufficient fuel during pouring from the container to provide a fuel-air mixture too rich to support combustion. A further approach is to provide a flash suppressor which is integral to the neck or tank walls and extends into the fuel-receiving chamber of the container, which accommodates the introduction of fuel into the container from a conventional gasoline pump nozzle, includes a substantially imperforate fuel-retaining wall to create a fuel-retaining pocket adjacent the opening in the container which fuel-retaining wall extends part way into the fuel-receiving chamber, and includes perforations to permit fuel to flow therethrough for filling the container and dispensing fuel therefrom. Each of these alternative structures is employed to retain a sufficient quantity of fuel within the container, and in particular in the narrowed neck area such that the fuel-air mixture is too rich to support combustion entering and/or occurring into the interior of the tank portion of the portable fuel tank—even combustion which may be occurring in the environment just exterior to the opening. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of a portable fuel container having a hollow tank body, and a fuel dispensing nozzle mounted to a neck; 
           [0015]      FIG. 2  is an enlarged side elevational view of a neck and opening of a portable fuel container according to the prior art, showing in vertical cross-section a part of the tank body adjacent the neck; 
           [0016]      FIG. 3  is an enlarged side elevational view of a neck and opening of a portable fuel container according to one embodiment of the present invention, utilizing an annular neck dam which is inwardly flared to retain fuel proximate the neck and opening 
           [0017]      FIG. 4  is an enlarged side elevational view of neck and opening of a portable fuel container according to another embodiment of the present invention, utilizing an annual neck dam which has a circumscribing and downwardly extending without flaring, and which retains an absorbent sponge-like material; 
           [0018]      FIG. 5  is an enlarged side elevational view of a neck and opening of a portable fuel container according to a further embodiment of the present invention, which utilizes and inverted fuel-retaining pocket adjacent the neck and opening; 
           [0019]      FIG. 6  is an isometric view of a vertical section through a portable fuel container as shown in  FIG. 1  with the fuel dispensing nozzle removed and showing a plurality of absorbent pads mounted interiorly of the main body for absorbing and retaining fuel within the portable fuel container; 
           [0020]      FIG. 7  is an isometric view of a flash suppressor for integrating inside the neck of a portable fuel container and having a fuel-retaining wall for creating a fuel-retaining pocket proximate the neck and opening of a fuel container; 
           [0021]      FIG. 8  is a plan view of the flash suppressor of  FIG. 7  showing an annular rim configured for engaging the inner surface of the neck of the fuel container; 
           [0022]      FIG. 9  is a bottom view of the flash suppressor of  FIG. 7  showing perforations in the bottom wall of the flash suppressor for permitting fuel to pass therethrough; 
           [0023]      FIG. 10  is a front elevation view of the flash suppressor of  FIG. 7  showing the annular rim in profile and the fuel-retaining wall adjacent the rim, the rear view being a mirror image thereof; 
           [0024]      FIG. 11  is right side elevation view of the flash suppressor of  FIG. 7  showing perforations in the sidewall of the flash suppressor below the fuel-retaining wall, the left side elevation being a mirror image thereof; 
           [0025]      FIG. 12  is an enlarged left side elevation view of the flash suppressor of  FIG. 7  placed within the neck of a fuel container prior to integration into the neck; 
           [0026]      FIG. 13  is an enlarged left side elevation view showing the interference of the annular rim of the flash suppressor of  FIG. 7  with a circumscribing bulge located on the inner surface of the neck of the fuel container prior to integration into the neck; 
           [0027]      FIG. 14  is an enlarged left side elevation view showing the flash suppressor of  FIG. 7  integrated into the neck of the container to provide a fuel-retaining pocket adjacent the neck and opening; 
           [0028]      FIG. 15  is a vertical cross-sectional view taken through a fuel container and flash suppressor after integration of the flash suppressor into the fuel container; 
           [0029]      FIG. 16  is an isometric view of a flash suppressor for integrating inside the neck of a portable fuel container having a configuration similar to that of the flash suppressor depicted in  FIG. 7 , but configured without the fuel-retaining wall, so that fuel retention is accomplished primarily by retaining fuel in the perforations of the flash suppressor; 
           [0030]      FIG. 17  is a top isometric view of a flash suppressor for integrating inside the neck of a portable fuel container having a bottom wall that is shiftable relative the sidewall, illustrating the bottom wall in a closed position; 
           [0031]      FIG. 18  is a bottom isometric view of the flash suppressor of  FIG. 17 , illustrating the bottom wall in a closed position; and 
           [0032]      FIG. 19  is a top isometric view of the flash suppressor of  FIG. 17 , illustrating the bottom wall in an open position. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0033]    Like reference numbers are used to identify the same or similar structures in the different embodiments and views. 
         [0034]    Referring now to the drawings,  FIG. 1  shows a portable fuel container  10 . The fuel container  10  is shown as an example of the variety of different fuel containers with which the present invention may be employed, it being understood that the present invention is not limited to the particular fuel container  10  as shown herein. The fuel container  10  includes a hollow tank body  12 , a collar  14  which is removably mounted to the fuel container  10  and which, in combination with a dispensing spout  16 , covers an opening which may be used for filling the fuel container  10  with fuel and from which the fuel contained therein may be selectively dispensed. The dispensing spout  16  of this example is a selectively actuatable dispensing spout biased to a non-dispensing condition, such that the user must operatively depress a button  18  in order to enable fuel to flow from the tank body  12  through the dispensing spout  16  and from a discharge outlet  20 . The dispensing spout  16  may be held by the collar  14  which is threadably attached to a neck  22  fluidically communicating with the tank body  12 , the external threading on the neck  22  being shown in  FIG. 2 . In the example shown in  FIG. 1 , both the dispensing spout  16  and the collar  14  are coupled together whereby unscrewing the collar  14  causes the collar  14  and dispensing spout  16  to be detached from the container as a unit. When the dispensing spout  16  or collar  14  are removed, an opening  24  is revealed which permits filling of the tank body  12  with fuel or, in typically undesired circumstances, through which fuel contained in the tank body  12  may be poured. The size of the opening  24  can be at least at least 2.0, 2.25, 2.75, or 3.0 square inches and/or not more than 10, 8, 6, or 4 square inches. As shown in  FIGS. 2-6  and  12 - 15 , a fuel-receiving chamber  25  is presented within the body  12 . The fuel-receiving chamber  25  can have a capacity of at least 1 gallon and/or not more than 6 gallons. The fuel container body  12 , collar  14  and spout  16  are preferably molded of synthetic resin, such as, for example, polyethylene. 
         [0035]    A typical neck  22  of a portable fuel container  10  is shown in  FIG. 2 .  FIG. 3  illustrates a first embodiment of the apparatus of the present invention. A portable fuel container  10 A may be constructed substantially identically to that shown in  FIGS. 1 and 2 . However, an annular neck dam  26  of synthetic resin material such as polyethylene or polypropylene which is resistant to degradation by exposure to fuel such as gasoline is inserted into the neck  22  proximate the opening  24 . As shown in  FIG. 3 , the annular neck dam  26  may extend around the interior surface of the neck  22  and extends downwardly toward and into the tank body  12 . The annular neck dam  26  may be flexible, and flared radially inwardly. Thus, when the portable fuel container  10 A is tipped or inverted, fuel  28  (shown by stippling) is retained in a reservoir  30  created by the neck dam  26  adjacent the opening  24  thereby increasing the fuel-air mixture in the vicinity of the neck  22 . A generally downwardly facing reservoir opening  31  allows the fuel  28  to enter the reservoir  30  when the fuel container  10 A is tipped or inverted and also allows the fuel  28  retained in the reservoir  30  during dispensing to flow back out of the reservoir  30  when the container  10 A is returned to its upright position. In certain embodiments of the invention, the reservoir  30  is sized to retain at least 6 milliliters of liquid fuel per gallon of liquid capacity of the container  10 . In other embodiments, the reservoir  30  is sized to retain at least 10 milliliters of liquid fuel per gallon of liquid capacity of the container  10 . 
         [0036]      FIG. 4  shows an alternate embodiment of the portable fuel container  10 B hereof, the portable fuel container  10 B being constructed substantially the same as that shown in  FIGS. 1 ,  2  and  3 . However in  FIG. 4 , the annular neck dam  26 B is not flared, but rather is substantially configured as a cylindrical tube fitted into the neck  22  and extending downwardly toward and into the tank body  12 . An optional pad  32  of porous compressible absorbent material which is sponge-like is provided in the reservoir  30 . The annular neck dam  26 B may thus serve to retain the pad  32  which as shown may also be annular. Alternatively, the annular neck dam  26 B may be omitted, with the pad  32  retained in position by adhesive or mechanical attachment. Fuel  28  may be retained in the reservoir  30  when the portable fuel container  10 B is tipped or inverted, thereby increasing the ratio of fuel to air in the vicinity of the neck  22  and opening  24 . 
         [0037]      FIG. 5  shows a further alternate embodiment of the portable fuel container  10 C hereof. While substantially identical to the portable fuel containers shown in  FIGS. 1-4 , the wall  34  of the tank body  12 C adjacent the neck  22  is configured with an inverted pocket  36 . The pocket  36  may be constructed so that it extends completely around and thus surrounds the neck  22 , or alternatively as shown in  FIG. 5 , may be located and configured so that it extends less than 360° around the base  38  of the neck  22 . When the portable fuel container  10 C is tipped or inverted, fuel  28  will be held in the pocket  36 , thereby increasing the ratio of fuel to air in the vicinity of the neck  22 . 
         [0038]      FIG. 6  shows a yet further alternate embodiment of the fuel container  10 D hereof.  FIG. 6  shows the tank body  12 D and neck  22 D in cross-section, with the opening enclosed but with the understanding that in practice the neck  22 D would be open so that fuel could flow into the chamber  25 D through an opening in the neck  22 D. It is to be understood that the neck  22 D would be externally threaded to receive the dispenser  16  shown in  FIG. 1 , and could have the neck dam or inverted pocket as illustrated in  FIGS. 2-5 .  FIG. 6 , however, also shows the use of absorbent pads  40 ,  42  and  44  attached to the inside surface  46  of the tank body  12 D. It is contemplated that only one such absorbent pad would be used per fuel container, but it is possible that a plurality of such pads  40 ,  42  and  44  could be used simultaneously. While the absorbent pads could be movable or even loose within chamber  25 D and still retain sufficient fuel to inhibit an explosion event within the portable fuel container  10 D, it is believed that better operating characteristics such as avoiding potential blockages at the opening will be achieved by mounting the pads  40 ,  42  and  44  to the inside surface  46  using mechanical fasteners or adhesive or bonding the pads to the inside surface  46  of the portable fuel container  10 D. Like pad  32 , the pads  40 ,  42  and  44  are preferably porous compressible absorbent material which is sponge-like, for example synthetic resin open-celled foam material. Fuel  28  is thus retained by the pads  40 ,  42  and  44  to create a mixture too rich for combustion and explosion. 
         [0039]      FIGS. 7 through 15  show a flash suppressor  50  that can be integrated into a portable fuel container  10 E. The flash suppressor  50  may have an annular rim  52 , a generally cylindrical, conical, or frustoconical suppressor sidewall  54 , and a bottom wall  56 . The flash suppressor  50  can be injection molded from a synthetic resin material such as polyethylene to be compatible with the tank body. The suppressor sidewall  54  may slightly taper inwardly from its width at the rim  52  to the bottom wall  56  to facilitate molding, for example from between about 0.5° to about 2.5° and most preferably about 1° of taper. The annular rim  52  surrounds an open area into which a gas nozzle may be inserted and may project outwardly from an upper end  58  of the suppressor sidewall  54  a sufficient distance to engage an inner surface of the neck of the portable fuel container into which it is received. The suppressor sidewall  54  may be provided with axially extending ribs  60  along an interior surface  62  of the suppressor sidewall  54 . These ribs  60  may extend substantially from the annular rim  52  to the bottom wall  56  to resist wear from the insertion of gasoline nozzles therein or deformation. 
         [0040]    As shown in  FIGS. 7 ,  10 - 15 , the suppressor sidewall  54  can include a circumferentially extending imperforate fuel-retaining wall  64  that retains some of the fuel held in the chamber  25  when the portable fuel container is tipped or inverted to position the opening  24  below the level of fuel held within the chamber  25 . The fuel-retaining wall  64  can extend axially downwardly from the upper end  58  of the sidewall  54 . In certain embodiments, the fuel-retaining wall  64  extends completely around the circumference of the sidewall and is continuous with the annular rim  52  so that fuel cannot pass between the fuel-retaining wall  64  and the rim  52 . The fuel-retaining wall  64  extends axially a sufficient distance to retain a quantity of fuel sufficient to make the fuel-air mixture adjacent the neck too rich for ignition, depending on the capacity of the container. By way of example, the imperforate fuel-retaining wall  64  may extend axially downward from the rim  52  at least about 0.25 inch, at least about 0.5 inch, or at least about 1 inch. The suppressor sidewall  54  may also include a pair of circumferentially spaced axially extending imperforate sections  66  having radially offset (relative to the remainder of the imperforate section) axially spaced circumferentially oriented bands  68  to provide rigidity, and a pair of circumferentially spaced axially extending perforate sections  70  which include an array of perforations  72  sized to permit the flow of fuel, such as liquid gasoline, and air therethrough. 
         [0041]    The suppressor sidewall  54  preferably extends downwardly to position the bottom wall  56  a sufficient distance to permit insertion of a gasoline pump nozzle past the neck  22  and into the area interior of the suppressor sidewall  54 . In certain embodiments, the flash suppressor  50  extends at least 0.5, 1, 2, or 3 inches and/or not more than 12, 8, or 6 inches downwardly into the liquid-receiving chamber  25 . Further, the flash suppressor  50  can have an internal volume (e.g., the volume of the space defined between the sidewall  54  and above the bottom wall  56 ) of at least 0.5, 1, 2, or 3 cubic inches and/or not more than 20, 15, 10, or 5 cubic inches. 
         [0042]    The bottom wall  56  of the flash suppressor  50 , seen best in  FIGS. 8 and 9 , may include transverse reinforcement  74  in a generally H shape including downwardly extending transverse flanges  76  and  78  and connecting flange  80 . The bottom wall  56  can include a plurality of perforations  72  which are sized to permit fuel such as liquid gasoline and air to flow therethrough. The number of perforations  72  and their size and positioning in the bottom wall  56  and suppressor sidewall are preferably sufficient to permit normal filling of the container at a moderate rate of flow without buildup and overflow of fuel from the container. For example, in certain embodiments, the size and positioning of the perforations  72  in the flash suppressor  50  permit at least 5, 7.5, or 10 gallons per minute of gasoline to flow therethrough under common gasoline filling conditions (e.g., atmospheric pressure and room temperature). In order to permit proper flow of liquid fuel through the flash suppressor  50 , the side and lower members (e.g., sidewall  54  and bottom wall  56 ) can be at least 5, 10, 15, 20, or 25 percent open and/or not more than 80, 70, 60, or 50 percent open, where “percent open” is the cumulative open area of all the perforations expressed as a percentage of the total internal surface area of the side and lower members of the flash suppressor. Further, each perforation can be sized to present an open area of not more than 0.1, 0.05, 0.025, or 0.015 square inches. 
         [0043]    In certain embodiments, it may be desired for the flash suppressor  50  be permanently attached (i.e., non-removable) to the body  12  by, for example, bonding or welding. One suitable welding technique is to spin-weld the flash suppressor  50  to the body  12  of the portable fuel container  10 E.  FIG. 12  shows the flash suppressor  50  inserted into the body  12  where the inner surface of the neck  22  is provided with a radially inwardly projecting circumferentially extending bulge  82 , but before integration. In  FIG. 13 , the flash suppressor  50  is pushed downwardly so that the annular rim  52 , which may have a beveled edge  84 , is in interference with the bulge  82 . The rim  52  thus engages the bulge  82 , the sizing being complementary such that the rim  52  is sufficiently resilient and preferably able to deflect upon such engagement. The flash suppressor  50  is then rotated relative to the body sufficiently to melt and weld with the bulge  82  to make the flash suppressor unitary with the body  12 , thereby creating a seal preventing air and liquid from moving between the annular rim  52  and the neck  22 . This unitization of the flash suppressor  50  with the body  12  creates a reservoir  86  or pocket between the body  12 , the rim  52  and the imperforate fuel-retaining wall  64  which retains a quantity of fuel therein when the portable fuel container is tipped or inverted. 
         [0044]      FIG. 16  depicts an alternative type of fuel retention structure, i.e., a flash suppressor  100 , that employs a plurality of perforations  102  to retain a quantity of liquid fuel at or near the opening of the portable fuel container. After liquid fuel is dispensed from the portable fuel container though the perforations  102  and the container is returned to its upright position, the perforations  102  can retain a sufficient quantity of liquid fuel to make the environment inside the flash suppressor  100  too rich in fuel for combustion to occur. Unlike the flash suppressor  50  depicted in  FIG. 7 , which includes an imperforate fuel retention wall  64  extending around the top of the sidewall  54 , the flash suppressor  100  depicted in  FIG. 16  relies primarily, and in certain embodiments exclusively, on the perforations  102  for fuel retention. Although other types of fuel retention structures (e.g., absorptive pads, retention walls, etc.) can be incorporated into or used in conjunction with the flash suppressor  100 , in certain embodiments, at least 50, 75, 90, 95, or about 100 weight percent of the liquid fuel retained by the flash suppressor  100  is retained within the perforations  102 . 
         [0045]    The dimensions of the flash suppressor  100  depicted in  FIG. 16  are chosen to permit adequate fuel flow through the perforations during filling of the fuel container and adequate retention of fuel in the perforations  102  after dispensing fuel from the fuel container through the perforations  102 . In certain embodiments, the perforations are configured in a manner such that after the liquid fuel has been dispensed from the container and the fuel retention structure is no longer submerged in the liquid fuel, a quantity of the liquid fuel is retained in the perforations due to intermolecular forces. The intermolecular forces include forces between molecules within the liquid fuel and forces between molecules of the liquid fuel and molecules of the fuel retention structure. 
         [0046]    The perforations  102  of the flash suppressor  100  must provide sufficient open area, as defined previously, to permit fuel to flow adequately through flash suppressor  102  under standard fuel filling conditions without having fuel spill out over the top of the flash suppressor  100 . In certain embodiments, the perforations  102  in the sidewall  104  and/or the bottom wall  106  of the flash suppressor  100  can cause the flash suppressor  100  to be at least 5, 10, 15, 20, or 25 percent open and/or not more than 90, 80, 70, 60, or 50 percent open, as defined previously. The total number or perforations in the flash suppressor can be at least 100, 500, 1000, or 2000 and/or not more than 40,000, 20,000, 10,000, or 5,000. 
         [0047]    In certain embodiments, the flash suppressor  100  can have an internal volume of at least 5, 10, 14, or 16 cubic inches and/or not more than 40, 30, 25, or 20 cubic inches. Further, the flash suppressor  100  can have a length (typically measured as the height of the sidewall  104 ) that allows it to extend at least 2, 3, 4, or 5 inches and/or not more than 12, 10, 8, or 7 inches downwardly into the fuel container. 
         [0048]    The specific configuration (e.g., size, length, and shape) of the perforations  102  in the sidewall  104  and/or end wall  106  of the flash suppressor  100  can affect the ability of the perforations  102  to permit adequate fuel flow therethrough during filling and dispensing, while still permitting adequate fuel retention therein after dispensing. In certain embodiments, the perforations  102  can be sized to present an average perforation open area of at least 0.0005, 0.001, 0.0015, or 0.002 square inches and/or not more than 0.1, 0.05, 0.01, or 0.005 square inches. As used herein, “perforation open area” means the minimum cross sectional area of a perforation, measured normal to the direct of extension of the perforation through the wall. As used herein, “average perforation open area” means the average of all open areas of all perforations in the flash suppressor. The perforations  102  can have an average perforation diameter of at least 0.01, 0.02, 0.03, 0.04, or 0.05 and/or not more than 0.4, 0.2, 0.1, or 0.08 inches. As used herein, “perforation diameter” means the maximum dimension across a perforation, measured normal to the direct of extension of the perforation through the wall. As used herein, “average perforation diameter” means the average of all perforation diameters of all perforations in the flash suppressor. The length of each perforation  102  can be determined by the thickness of the walls (i.e., sidewall  104  and/or end wall  106 ) of the flash suppressor  100 . In certain embodiments, the average length of the perforations  102  and/or the average thickness of the sidewall  104  and/or the end wall  106  can be least 0.01, 0.02, 0.04, 0.06, or 0.08 inches and/or not more than 0.25, 0.2, 0.15 or 0.1 inches 
         [0049]      FIGS. 17-19  show a flash suppressor  200  that is similar to the flash suppressor  100  depicted in  FIG. 16  in that is does not include an imperforate fuel retention dam near its opening; however, the flash suppressor  200  of  FIGS. 17-19  includes a bottom wall  202  that is shiftable relative to the sidewall  204  between an closed position (shown in  FIGS. 17 and 18 ) and an open position (shown in  FIG. 19 ). In certain embodiments, the bottom wall  202  is biased toward the closed position and the bottom wall  202  is configured to be shifted into the open position by contact with a conventional gasoline pump nozzle (not shown) that is inserted though the main opening of the portable fuel container for filling of the container. The bottom wall  202  can automatically shift into the closed position when the fuel pump nozzle is removed from the flash suppressor  200  and the main opening of the portable fuel container. The shiftable bottom wall  202  provides the necessary open area for filling the container with liquid fuel through the flash suppressor  200 . In contrast with the flash suppressor  100  illustrated in  FIG. 16 , liquid fuel does not have to pass through the perforations in the sidewall  204  or the bottom wall  202  of flash suppressor  200  in order to fill the container with fuel. Such a configuration allows the sidewall  204  of the flash suppressor  200  to be much shorter than the sidewall  104  of the flash suppressor  100  depicted in  FIG. 16 . 
         [0050]    As depicted in  FIGS. 17-19  the flash suppressor  200  can include a spring biased hinge  206  coupling the bottom wall  202  to the sidewall  204  and providing for the shiftability and biasing of the bottom wall  202  relative to the sidewall  204 . Of course, biasing mechanisms other than the torsion spring depicted in  FIGS. 17-19  can be employed to bias the bottom wall  202  toward the closed position. 
         [0051]    Referring again to  FIGS. 17 and 18 , because the end wall  20  of the flash suppressor  200  is closed during dispensing of liquid fuel from the container, the liquid fuel must flow through the perforations in the end wall  202  and/or sidewall  204  in order to dispense liquid fuel from the container. After liquid fuel is dispensed from the container and the flash suppressor  200  is no longer immersed in fuel, flash suppressor  200  retains a quantity of fuel in its perforations that is sufficient to cause the environment in the flash suppressor  200  to be too rich in fuel to support combustion. In order to retain fuel, the perforations of flash suppressor  200  can have substantially the same configuration (e.g., average perforation open area, average perforation diameter, and average perforation length) as the perforations of the flash suppressor  100  depicted in  FIG. 16 . However, the total number of perforations, internal volume, and sidewall height are substantially less than those of the flash suppressor  100  depicted in  FIG. 16 . 
         [0052]    In certain embodiments, the total number or perforations in the flash suppressor  200  can be at least 25, 50, 100, or 250 and/or not more than 10,000, 5,000, 2, 500, or 1,000. In certain embodiments, the flash suppressor  200  can have an internal volume of at least 2, 4, or 6 cubic inches and/or not more than 200, 15, 12, or 10 cubic inches. Further, the flash suppressor  200  can have a length (typically measured as the height of the sidewall  204 ) that allows it to extend at least 0.25, 0.5, 0.75 or 1 inch and/or not more than 4, 3, 2, or 1.5 inches downwardly into the fuel container. 
         [0053]    For each of the portable fuel containers  10 A,  10 B,  10 C,  10 D and  10 E, it is contemplated that provided that 10 ml of gasoline per 1 U.S. gallon (3.785 liters) capacity of the fuel container is retained within the portable fuel container, the fuel-air mixture within the portable fuel container will be too rich to support combustion within the portable fuel container. Moreover, it is believed that approximately 6 ml of gasoline per 1 U.S. gallon (3.785 liters) capacity of the fuel container is retained within the portable fuel container will be too rich to support combustion within the portable fuel container. This is linearly scalable to various sizes of portable fuel containers as defined herein. Thus, for a five gallon (18.927 liter) capacity portable fuel container, the neck dam alone, the absorbent pads alone, the pocket  36  alone, or the neck dam, pocket and absorbent pad(s) in any combination thereof will hold and retain at least 30 ml or at least 50 ml of gasoline within the portable fuel container  10 . Thus, the size of the neck dam  26 A or  26 B, or the pocket  36 , or the reservoir or pocket  86  formed by the body  12 , rim  52  and imperforate fuel-retaining  64 , or the absorbent pad(s) collectively should be sized corresponding to the volume capacity of the portable fuel container to retain the sufficient amount of fuel, in particular gasoline, described herein. 
         [0054]    For the portable fuel containers  10 A,  10 B,  10 C and  10 E, a portion of the fuel  28  dispensed during pouring through the opening is retained immediately proximate the neck  22  and opening  24 , thereby increasing the fuel-to-air ratio to a level whereby combustion may not occur. The positioning of the fuel retention structure in the neck proximate the opening  24  helps to inhibit the entry of flame into the chamber  25  of the container because the fuel is retained closely proximate the opening to maintain a too-rich mixture at the opening. For the portable fuel container  10 D, the fuel is absorbed by the pads and retained in the chamber  25 D within the main body  12 D of the portable fuel container  10 D to maintain the too rich fuel-air ratio for combustion. The portable fuel container  10 E provides, in addition to the increased fuel-air ratio caused by the retention of fuel in the reservoir  86  or pocket, a barrier to the passage of spark or flame attempting to enter the chamber  25  by the suppressor sidewall  54  and bottom wall  56 . The method hereof includes the steps of pouring fuel through the opening of a portable fuel container, and retaining a portion of the fuel in a retention member such as an absorbent pad or in a reservoir positioned proximate the opening so as to increase the ratio of fuel to air interiorly of the container, preferably proximate the opening.
A portable fuel container configured to prevent liquid fuel contained therein from being entirely emptied from the container. The amount of liquid fuel retained in the container can be sufficient to maintain a fuel-to-air ratio in the container at a fuel-rich level that prevents combustion within the container if the container were to be placed near an ignition source or if an ignition source were to somehow enter the container. The container can also include other safety features such as, for example, a flash suppressor located at the fill opening, an extra wide fill opening, and/or an easily controllable dispensing spout. When a flash suppressor is employed, the perforations in the flash suppressor can be configured to retain fuel therein after fuel has been dispensed from the container and the flash suppressor is no longer submerged in fuel.