Abstract:
A fabric and elastomeric material (referred to as a fabric trilayer) combined with a sealant may be applied in such a fashion so as to eliminate or minimize air entrapment in an elastomeric composite structure that forms a seal-sealing volume. The performance of the self-sealing volume is dramatically improved with this minimizing of air entrapment. Surprisingly and unexpectedly, this construction approach may be accomplished without significantly adding to the weight or thickness of the volume and without affecting the outer dimension of the self-sealing volume. Thus, a method and system for forming a self-sealing volume are described. The system includes an elastomeric composite structure comprising at least one layer of an elastomeric material derived from a neat (no solvent) elastomeric material that does not substantially react at room temperature.

Description:
THE FIELD OF THE INVENTION 
     The present invention is related generally to the field of containers for materials, and more specifically related to the field of self-sealing fuel tanks. These fuel tanks are frequently preferred in applications where fuel fire and explosion risks are high, as in military, armored and racing vehicles. 
     BACKGROUND 
     Self-sealing fuel tanks currently exist in the conventional art. One problem with these conventional self-sealing fuel tanks is that they are manufactured using labor intensive hand lay up processes that require long cure times. Large numbers of self-sealing fuel tanks thus cannot be manufactured over a reasonable time period. 
     In addition, these conventional manufacturing techniques and materials do not allow for precise control of the outer dimensions of self-sealing fuel tank, a problem where tight fits are required and maximum fuel capacity is desired. A closed molding process using conventional composite construction techniques with conformable elastomeric materials may allow for precise control of the outer dimensions of self-sealing fuel tanks. But there are several challenges that must be addressed. 
     Air entrapment or air inclusion is a well known problem in the conventional fabrication of fiber-reinforced composites. Air entrapment can result in poor interlaminar adhesion between layers, poor dimensional conformity and less than optimum composite tensile, puncture and impact properties. 
     One method for making fiber-reinforced composites is the hand layup method. In this method, the fabric intermediates are laid in the impregnation mold by hand and wetted with the matrix. Air is removed from the laminate, by pressing against it with the aid of a roller. This is intended to remove from the layers of fabric not only air present in the laminate structure but also excess matrix material. The procedure is repeated until the desired layer thickness is achieved. Once all the layers have been applied, the component must cure. Curing is performed through a chemical reaction between the matrix material and a curing agent added to the matrix material. The advantage of the hand layup method is the small tool and low equipment outlay. However, this is offset against a low quality of component (low fabric content) and the high level of manual effort, which requires trained laminators. 
     Hand layup can also be performed as a closed method. The closed method is performed using a vacuum press. Once the fabric mats have been introduced into the impregnation mold, the mold is covered with a release film, a suction fleece and a vacuum film. A vacuum is generated between the vacuum film and the mold. This has the effect of compressing the composite. Any air still included is removed by suction, and the excess matrix material is absorbed by the suction fleece. This means that a higher quality of component can be achieved than with the open hand layup method. 
     The prepreg method is another closed method. In this, fabric mats which are pre-impregnated with matrix material and have thus already been wetted are laid in the impregnation mold. In this case, the resin is no longer liquid but has a solid, slightly tacky consistency. Air is then removed from the composite by means of a vacuum bag and it is then cured, often in an autoclave, under pressure and heat. Because of the operational equipment required (cooling plant, autoclaves) and the demanding process (temperature management), the prepreg method is one of the most expensive manufacturing methods. However, it also enables one of the highest levels of quality of component. 
     The vacuum infusion method is another closed method for making fabric-reinforced composites. In this method, the dry fabric layers are laid in an impregnation mold coated with release agent. A release fabric and a distribution medium are placed over this, and this facilitates even flow of the matrix material. A vacuum sealing tape seals the film to the impregnation mold, and the component is then evacuated with the aid of a vacuum pump. The air pressure presses together the parts that have been laid in the mold and fixes them. The suction applied draws the tempered liquid matrix material into the fiber material. Once the fabrics have been completely wetted, the supply of matrix material is stopped and the wetted fiber-reinforced composite material can be cured and removed from the impregnation mold. The advantage of this method is that the fibers are wetted evenly and with almost no air inclusion, and so the components produced are of high quality and there is good reproducibility. 
     Other techniques of mitigating air inclusion are known to those skilled in the art. In conventional self-sealing fuel tanks bleeder cords are added to the composite structure. These bleeder cords are built into the composite structure and fed out of the mold so as to provide a conduit for air to escape during vacuum molding. 
     Unfortunately the above conventional composite fabrication methods cannot be used for the manufacture of self sealing fuel tanks that employ a closed molding process. The infusion method cited as one of the most effective methods to prevent air inclusion cannot be used because of the viscosity and the reactive nature of the available elastomeric materials. For instance, a polyurethane reaction mixture retains a suitably low viscosity for an insufficient period of time for the resin to fully impregnate the fabric layers and drive out air. This is because the reaction mixture is primarily a solid at room temperature and unless heat is applied the viscosity will increase as it loses heat. Furthermore, heating the reaction mixture to reduce the viscosity is impractical since the reaction mixture will begin to react when heat is applied and thereby increase in viscosity as the polyurethane polymer is formed. Bleeder cords are problematic since they extend outside of the fuel tank and must be cut even with the volume surface after fabrication of the fuel tank. This generates defects in the volume that must be patched and sealed thereby creating irregular surfaces. Additional defects occur when the cut cords are inadequately patched as frequently happens, resulting in leakage pathways. This approach thus creates an irregular volume surface and is highly dependent upon operator proficiency and skill. 
     The above conventional methods of composite fabrication are further rendered impractical since the self-sealing fuel tanks contain a self-sealing layer that is impermeable to air. It is not possible for included air that is located inside the self-sealing layer to migrate out of the composite structure since it is trapped between an inner liner and the self-sealing layer, two air impermeable layers. A method to remove trapped air is therefore needed. 
     BRIEF SUMMARY OF THE INVENTION 
     It has been discovered that a fabric and an elastomeric material (referred to later as a fabric trilayer) combined with a sealant may be applied in such a fashion so as to eliminate or minimize air entrapment in an elastomeric composite structure that forms a seal-sealing volume. It has thus been realized that in doing so the performance of the self-sealing volume is dramatically improved. This construction approach usually can be accomplished without significantly adding to the weight or thickness of the volume and without affecting the outer dimension of the self-sealing volume. 
     A method for forming a self-sealing volume is described. The system includes an elastomeric composite structure comprising at least one layer of an elastomeric material. The structure further may include at least one layer of a fabric, and at least one sealing layer. A fuel impermeable inner liner may be positioned in an inner region relative to the other layers. 
     The fabric may comprise fibers made from nylon materials. The fabric and self-sealing layers are positioned relative to each other so as to create a path for air to escape when the volume is pressurized to consolidate layers. 
     The at least one sealing layer may comprise at least one of an unvulcanized or partially vulcanized natural rubber (NR), a polyisoprene (IR), a styrene butadiene (SBR), or a blend of these materials. In other exemplary embodiments, the sealing layer may comprise polyurethane. In other exemplary embodiments, the sealing layer may comprise fully vulcanized (&gt;1% sulfur) rubber. Other alternative materials for the sealing layer may include, but are not limited to, aliphatic polyurethanes. 
     Another inventive aspect of the method and system is that the preform release layer is inflated during curing of the elastomeric material layer. With this inflation of the preform release layer, the elastomeric composite layer conforms to the exact dimensions of the mold which holds the preform and the elastomeric composite sandwiched there between. At the same time air is driven out of the composite structure. This process yields a dimensionally correct/precisely built self-sealing volume. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the Figures, like reference numerals refer to like parts throughout the various views unless otherwise indicated. For reference numerals with letter character designations such as “ 102 A” or “ 102 B”, the letter character designations may differentiate two like parts or elements present in the same figure. Letter character designations for reference numerals may be omitted when it is intended that a reference numeral to encompass all parts having the same reference numeral in all Figures. 
         FIG. 1A  is a cross-sectional view of a self-sealing volume in the form of a fuel tank according to one exemplary embodiment. 
         FIG. 1B  is a cross-sectional view of a portion of a wall of a self-sealing volume according to one exemplary embodiment. 
         FIG. 2A  is a cross-sectional view of an entire wall for a self-sealing volume according to the exemplary embodiment of  FIG. 1 . 
         FIG. 2B  is a cross-sectional view of the wall of  FIG. 2A  in which a projectile has begun to penetrate the wall entering from outside of the self-sealing volume towards the inside of the volume containing a fluid, such as fuel. 
         FIG. 2C  is a cross-sectional view of the wall of  FIG. 2B  in which the projectile has continued to penetrate the wall from the outside of the self-sealing volume towards the inside of the volume containing a fluid, such as fuel. 
         FIG. 2D  is a cross-sectional view of the wall of  FIG. 2C  in which the projectile has continued to penetrate the wall from outside of the self-sealing volume towards the inside of the volume containing a fluid, such as fuel. 
         FIG. 2E  is a cross-sectional view of the wall of  FIG. 2D  in which the projectile has completely penetrated the wall and has entered into the volume containing the fluid, such as fuel, and allowing the fluid to react with the sealing layer. 
         FIG. 2F  is a cross-sectional view of the wall of  FIG. 2E  in which the fluid continues to react with the sealing layer causing the sealing layer to further expand into the close the volume containing the fluid. 
         FIG. 3A  is a diagram illustrating fibers receiving a polyurethane coating. 
         FIG. 3B  is a diagram illustrating a fabric receiving a polyurethane coating. 
         FIG. 4A  is a cross-sectional view of a preform, a release layer, and a liner. 
         FIG. 4B  is a cross-sectional view of an intermediate product that comprises the wall layers of  FIG. 1  in addition to the preform, the release layer, and liner of  FIG. 4A . 
         FIG. 4C  is a diagram illustrating how the intermediate product of  FIG. 4B  is positioned within a mold according to one exemplary embodiment. 
         FIG. 4D  is a diagram illustrating a cured intermediate product after the intermediate product is removed from the mold of  FIG. 4C . 
         FIG. 4E  is a diagram illustrating the formation of the completed product of  FIGS. 2A-2F  by removal of the preform and release layer. 
       FIG.  4 F 1  is a cross-sectional view of a self-sealing volume in the form of a fuel tank illustrating the individual composite layers along with paths of air escape according to one exemplary embodiment. 
       FIG.  4 F 2  is a cross-sectional view of a fabric trilayer that is depicted in FIG.  4 F 1 . 
         FIG. 4G  is a cross-sectional view of a corner of a self-sealing volume illustrating an alternative lay up pattern where one or more structural fabric plies are located on one side of the sealant layer. 
         FIG. 4H  is a cross-sectional view of a corner of a self-sealing volume illustrating an alternative lay up pattern where three or more structural fabric plies are separated by the sealant layer. 
         FIG. 4I  is a side view of a corner of a self-sealing volume illustrating an alternative lay-up pattern where the sealant material has been perforated with holes. The sealant is subsequently covered with fabric and the holes are covered with sealant patches that are larger than the original holes. The holes can be any shape. 
       FIG.  4 J 1  is a side view of an intermediate self-sealing volume illustrating an inner layer of the fabric trilayer. 
       FIG.  4 J 2  is a side view of an intermediate self-sealing volume illustrating the sealant applied with a gap over the fabric trilayer of FIG.  4 J 1 . 
       FIG.  4 J 3  is a side view of an intermediate self-sealing volume illustrating a breather fabric applied over the gap illustrated in FIG.  4 J 2 . 
       FIG.  4 J 4  is a side view of an intermediate self-sealing volume illustrating a sealant patch applied over the gap and breather fabric of FIG.  4 J 3 . 
       FIG.  4 J 5  is a side view of an intermediate self-sealing volume illustrating an outer layer of the trilayer fabric applied over the sealant patch and sealant of FIG.  4 J 4 . 
       FIG.  4 K 1  is a side view of an intermediate self-sealing volume illustrating an inner layer of the fabric trilayer. 
       FIG.  4 K 2  is a side view of an intermediate self-sealing volume illustrating the sealant applied with a gap over the fabric trilayer of FIG.  4 K 1 . 
       FIG.  4 K 3  is a side view of an intermediate self-sealing volume illustrating a calendared sealant patch applied over the gap and sealant of FIG.  4 K 2 . 
       FIG.  4 K 4  is a side view of an intermediate self-sealing volume illustrating an outer layer of the trilayer fabric applied over the calendared sealant patch and sealant of FIG.  4 K 3 . 
       FIG.  4 K 5  is a cross-sectional top, view of the calendared sealant patch embodiment of FIG.  4 K 4 . 
       FIG.  4 K 6  is a front view of the calendared sealant patch of FIG.  4 K 3  illustrated alone. 
       FIG.  4 K 7  is a side view of the calendared sealant patch illustrated in FIG.  4 K 6  illustrated alone. 
       FIG.  4 L 1  is a side view of an intermediate self-sealing volume illustrating an inner layer of the fabric trilayer. 
       FIG.  4 L 2  is a side view of an intermediate self-sealing volume illustrating the sealant applied with a gap over the fabric trilayer of FIG.  4 L 1 . 
       FIG.  4 L 3  is a side view of an intermediate self-sealing volume illustrating a breather fabric strips applied over the gap illustrated in FIG.  4 L 2 . 
       FIG.  4 L 4  is a side view of an intermediate self-sealing volume illustrating a sealant patch applied over the gap and breather fabric strips of FIG.  4 L 3 . 
       FIG.  4 L 5  is a side view of an intermediate self-sealing volume illustrating an outer layer of the trilayer fabric applied over the sealant patch and sealant of FIG.  4 L 4 . 
         FIG. 5A  is a flowchart illustrating a method for forming a self-sealing volume according to an exemplary embodiment. 
         FIG. 5B  is a continuation flowchart of  FIG. 5A  illustrating the method for forming a self-sealing volume according to an exemplary embodiment. 
         FIG. 5C  is a continuation flowchart of  FIG. 5B  illustrating the method for forming a self-sealing volume according to an exemplary embodiment. 
         FIG. 6  a flowchart illustrating a routine or submethod for creating a polyurethane reaction mixture according to an exemplary embodiment. 
       FIG.  7 A 1  is a cross-sectional view of a device for forming flexible molds according to an exemplary embodiment. 
       FIG.  7 A 2  is a cross-sectional view of the flexible molds formed from the device of FIG.  7 A 1  according to an exemplary embodiment. 
       FIG.  7 A 3  is a cross-sectional view of preform material positioned within the flexible molds of FIG.  7 A 2  according to an exemplary embodiment. 
       FIG.  7 A 4  is a cross-sectional view of the two halves of a gas-permeable, solid preform generated from the flexible molds of FIG.  7 A 3  according to an exemplary embodiment. 
       FIG.  7 A 5  is a cross-sectional view of the two halves of the gas-permeable, solid preform put together according to an exemplary embodiment. 
       FIG.  7 A 6  is a cross-sectional view of the two halves of the gas-permeable, solid preform after apertures or holes have been created within the preform according to an exemplary embodiment. 
       FIG.  7 B 1  is a cross-sectional view of a solid mold for forming a gas-impermeable, hollow preform according to an exemplary embodiment. 
       FIG.  7 B 2  is a cross-sectional view of the solid mold of FIG.  7 B 1  with a fixture attached to a side of the solid mold having an aperture according to an exemplary embodiment. 
       FIG.  7 B 3  is a cross-sectional view of the solid mold in which a liquid state of the preform material is poured into the solid mold via the fixture according to an exemplary embodiment. 
       FIG.  7 B 4  is a cross-sectional view of the solid mold containing the preform liquid material while the solid mold is being rotated according to an exemplary embodiment. 
       FIG.  7 B 5  is a cross-sectional view of the solid mold being opened after curing of the preform liquid material into an gas-impermeable, hollow preform according to an exemplary embodiment. 
       FIG.  7 B 6  is a cross-sectional view of the gas-impermeable, hollow preform after apertures or holes have been created within the preform according to an exemplary embodiment. 
         FIG. 7C  illustrates a cross-sectional view of a device for forming flexible molds according to an exemplary embodiment. 
         FIG. 8  is a flowchart illustrating a routine or submethod for generating the solid preform of  FIG. 7A  according to an exemplary embodiment. 
         FIG. 9  is a flowchart illustrating a routine or submethod for generating the hollow preform of  FIG. 7B  according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. 
       FIG. 1A  is a cross-sectional view of a self-sealing volume or wall system  200  in the form of a fuel tank according to an exemplary embodiment. The wall system  200  comprises a wall  100  and a liner  202  which will be described in more detail below. The wall system  200  may contain a fluid  204 , such as, but not limited to, a hydrocarbon fuel. The wall system  200  may further comprise a nut ring  509  containing an access port  405  which will be described below in connection with  FIGS. 4C-4E . The wall system  200  may comprise a composite of elastomeric material and fabric as described in further detail below. The composite of elastomeric material and fabric may include a self-healing layer for sealing after ballistic penetration. 
     Referring now to  FIG. 1B , this figure is a cross-sectional view of a portion of a wall  100  for forming the self-sealing volume or wall system  200  (of  FIG. 1A ) according to one exemplary embodiment. The wall  100  may comprise an elastomeric composite that includes a combination of layers such as, for example, a polyurethane reaction mixture layer  102 , a fabric or fiber layer  104 , and a sealant layer  106 . 
     In the exemplary embodiment illustrated in  FIG. 1B , the wall  100  may comprise an elastomeric material such as a first polyurethane reaction mixture layer  102 A, a first fabric or fiber layer  104 A, a second elastomeric material such as a polyurethane reaction mixture layer  102 B, a sealant layer  106 , a third elastomeric material such as a polyurethane reaction mixture layer  102 C, a second fabric were fiber layer  104 B, and a fourth elastomeric material such as a polyurethane reaction mixture layer  102 D. 
     Where the elastomeric materials include a polyurethane reaction mixture, each polyurethane reaction mixture layer  102  may be made by reacting an organic diisocyanate or diisocyanate prepolymer with a reactive hydrogen-containing material having a molecular weight of about 700.0 to about 4000.0 and then curing the reaction product as described below in connection with the flow chart of the method  500  illustrated in  FIG. 5 . The reactive hydrogen-containing material may comprise at least one or more of a polyester polyol, a polyether polyol, or a hydrocarbon-polyol. In other exemplary embodiments, the sealant layer may be unvulcanized (no curative) rubber or partially vulcanized (&lt;1% sulfur). The polyurethane reaction mixture layers  102  do not substantially react at room temperature, which is typically about 25.0° C. as understood by one of ordinary skill in the art. 
     Representative of the reactive hydrogen-containing materials are the broad classes of polyester polyols, polyether polyols, hydrocarbon-polyols. The polyester polyols that are preferred include the esters of adipic acid with the lower glycols such as ethylene glycol, propylene glycol, and butylene glycol, and higher glycols such as polyethylene glycol and polypropylene glycol and mixtures of these. The polyether polyols that are preferred include ethylene ether glycol, polyethylene ether, propylene ether glycol, polypropylene ether polyol, and polytetramethylene ether polyol and mixtures of these. 
     In conjunction with the polyol a short chain glycol, organic diamine or alkylanolamine may be used to increase the molecular weight of the polyurethane reaction mixture layer  102 . Representative members of these classes of glycols, organic diamines or alkylanolamines useful in the present invention include, but are not limited to, ethylene glycols, propylene glycols, butane diols, methylene bis-chloroaniline, methylene dianiline, bis-amino phenyl sulfone and amino methyl propanol. If organic amines are used, then urea linkages will be created rather than urethane linkages, resulting in a mixed polyurethane urea. 
     Normally, any of the well-known organic polyisocyanates useful for making castings may be utilized for the polyurethane reaction mixture layer  102 , with toluene diisocyanate and methylene diphenyldiisocyanate exemplifying the ones most frequently used. The polyisocyanates are normally reacted at about 0.8 to about 1.5 mols per each mol of reactive hydrogen-containing material. 
     A crosslinked elastomeric material may be used. Such a material can be used with a polyurethane by incorporating a cross-linking monomer, such as a crosslinking polyol, in the polyurethane reaction mixture layer  102  in order to improve the compression set and to minimize plastic deformation at higher temperatures. As understood by one of ordinary skill in the art, compression set is the tendency of elastomers to undergo permanent deformation. It is the tendency of some elastomers to not recover in a completely elastic manner. An addition of a crosslinking polyol such as described above may remedy this characteristic. This compression set property may be measured by ASTM D395. As understood by on of ordinary skill in the art plastic deformation at higher temperatures is the tendency of elastomers to permanently deform from their original shape when heated above the softening or melting temperature. An addition of a crosslinking polyol such as described above may remedy this characteristic. The softening or melting temperature may be measured by ASTM D3418-03. 
     Further, a rubber adhesion activator monomer, such as allyl-alchohol, also may be used in the polyurethane reaction mixture layer  102  in order to improve its adhesion properties to rubber. This adhesion activator monomer may improve the adhesion of the polyurethane reaction mixture layer  102  to the sealant layer  106  by providing an active group (alcohol) for bonding with the polyurethane reactive ingredients of the polyurethane reaction mixture layer  102  and an active group (olefin) that will react with the rubber of the sealant layer  106  during vulcanization. 
     One of ordinary skill in the art will appreciate that if the preferred elastomeric materials can be applied as a somewhat fluid layer  102 , then this elastomeric material layer  102  may more readily coat the fiber or fabric layer  104  before the elastomer has had a chance to react or cure to form an intractable polymer. This is done by selecting a polyurethane reaction mixture that has a relatively long gel time, such as on the order of about 30 minutes to about 120 minutes. The preferred gel time may comprise a period of between about 15.0 to about 90.0 minutes. A gel time comprises an interval of time required for the polyurethane reaction mixture layer  102  to become a solid or semisolid gel prior to fully reacting to form a polyurethane. 
     The polyurethane reaction mixture layer  102  may be applied by brushing, troweling, swabbing, dipping or spraying, or other ways as understood by one of ordinary skill in the art. After the polyurethane reaction mixture layer  102  has been sufficiently spread and incorporated into the fabric or fiber layer  104 , then the polyurethane reaction mixture layer  102  is ready to be cured. 
     The polyurethane reaction mixture layer  102  is selected such that heat is required for reaction and cure. Heat can be supplied from a conventional oven, an autoclave, a microwave oven or from a press, or alternative ways as understood by one of ordinary skill in the art. Once the liquid polyurethane reaction mixture layer  102  is applied onto the respective composite layers of the wall portion  100 , the entire uncured structure may be placed into a three dimensional, dimensionally correct mold  400  (as will be described below in connection with  FIG. 4 ). Curing is effected by heating the mold  400  to a sufficient temperature and for a sufficient time to cause the polyurethane reaction mixture layer  102  to react and form a solid polyurethane layer  102 . A sufficient temperature for curing is generally between about 80.0° C. to about 175.0° C., and preferably between about 100.0° C. to about 150.0° C., and more preferably at about 120.0° C. However, other temperatures may be used as understood by one of ordinary skill in the art and are within the scope of this disclosure. The time for curing is generally between about 20.0 minutes to about 360.0 minutes (min), and preferably between about 60.0 min to about 120.0 min, and more preferably for about 90.0 min. However, other times may be used as understood by one of ordinary skill in the art and are within the scope of this disclosure. As noted previously, the amount of pressure provided by the gaseous pressure source  403  is generally between about 2.0 psi to about 80.0 psi, and preferably between about 10.0 psi to about 40.0 psi, and more preferably at about 20.0 psi. However, other pressures may be used as understood by one of ordinary skill in the art and are within the scope of this disclosure. In addition to polyurethane reaction mixtures that are used as the elastomeric component of the composite other elastomeric materials may also be used. Such elastomeric materials may include but are not limited to polyurethane dispersions, solvated polyurethanes, solvated nitrile butyl rubber, solvated polychloroprene, silicones, polysulfides and other materials that can be applied at a low viscosity and then cured to form an intractable but flexible elastomer. 
     The fabric or fiber layer  104  may comprise coated polyamide, aramid, polyester, polypropylene or polyethylene fibers or coated fabrics of the same materials. The coating on the fibers or fabrics in layer  104  may comprise solvated or aliphatic polyurethane that is applied during the fiber or fabric manufacturing process. As understood by one of ordinary skill in the art, aliphatic is a general class of polyurethanes (excluding aromatic) which is typically easier to solvate than aromatic polyurethanes. The coating may also comprise a resorcinol formaldehyde (RFL) or an isocyanate. Further details of this coating for the fibers or fabric layer  104  are described below in connection with  FIGS. 3A-3B   
     As understood by one of ordinary skill in the art, polyamide is a class that includes NYLON and anisotropic aromatic polyamide (such as KEVLAR-™). As understood by one of ordinary skill in the art, polyester is a class that includes polyethylene terephthalate and anisotropic aromatic polyester. The fabric may comprise at least one of NYLON 6, NYLON 66, polyester, an anisotropic aromatic polyamide, or an anisotropic aromatic polyester from about 5.0 ounces per square yard (“oz/SY”) to about 30.0 oz/SY. It is possible to use other fibers and fabrics with the elastomeric material layer  102 , but polyamide and polyester fibers and fabrics are preferred due to their physical performance characteristics in ballistic and blast situations. 
     The sealant layer  106  typically is sandwiched between two elastomeric material layers  102  and two or more fabric or fiber layers  104  for reinforcement. Typical materials suitable for use as the sealant layer  106  may comprise unvulcanized, partially vulcanized and/or vulcanized natural rubber (NR). Other materials that may be used include polyisoprene (IR), styrene butadiene (SBR) and blends of SBR with NR or IR. In other exemplary embodiments, the sealant layer  106  may be unvulcanized. In other exemplary embodiments, the sealant layer  106  may comprise fully vulcanized (&gt;1.0% sulfur) rubber. Other alternative materials for the sealant layer  106  may include, but are not limited to, aliphatic polyurethanes 
     While the thicknesses of each of the layers illustrated in  FIG. 1  have been shown to be equivalent, one of ordinary skill in the art will recognize that the actual thicknesses of each layer may vary and may be adjusted depending upon the level of protection desired for a particular volume. Wall gauge design dimensions are usually driven by weight restrictions, ballistic needs and overall flexibility requirements. For example, the finished product for the self-sealing wall portion  100  typically has the following dimensions according to one illustrative embodiment: a first elastomeric material layer  102 A having a thickness of approximately 0.1 to approximately 1.0 mm; a first fabric or fiber layer  104 A having a thickness of approximately 0.5 to approximately 2.0 mm; a second elastomeric material layer  102 B having a thickness of approximately 0.1 to approximately 1.0 mm; a sealant layer  106  having a thickness of approximately 0.5 to approximately 13.0 mm; a third elastomeric material layer  102 C having a thickness of approximately 0.1 to approximately 1.0 mm; a second fabric or fiber layer  104 B having a thickness of approximately 0.5 to approximately 2.0 mm; and a fourth elastomeric material layer  102 D having a thickness of approximately 0.1 to approximately 1.0 mm. 
     Further, one of ordinary skill in the art will recognize that the number and size of the layers may be varied without departing from the scope of the present disclosure. That is, fewer or a greater number of layers with different thicknesses may be used for a particular embodiment without departing from the scope of the technology described herein. 
     Referring now to  FIG. 2A , this figure is a cross-sectional view of an entire wall or wall system  200  for a self-sealing volume according to one exemplary embodiment. The wall system  200  comprises all of the layers of the wall  100  described above in connection with  FIG. 1B , in addition to a liner layer  202  and the fluid  204 . 
     The liner layer  202  may comprise any elastomeric material that will have a greater resistance to hydrocarbon fuel  204  than the elastomeric material  102 . Exemplary materials include, but are not limited to, nitrile rubber, polyurethane, polysulfide and polyvinylidene fluoride, polyurea, polyvinylalchohol (PVA), Hydrogenated Nitrile Butadiene Rubber (HNBR), Epichlorohydrin rubber (ECO), or any fuel resistant elastomer. An optional barrier layer, described below, may also be used and positioned on the outside of the liner layer  202 . 
     The fluid  204  may comprise a fuel, and particularly a hydrocarbon fuel  204 , such as gasoline, diesel-based fuels, biofuels, ethanol fuels used in military crafts such as airplanes, boats, helicopters, tanks, cars, jeeps, all-terrain-vehicles (ATVs), and other similar vehicles. The wall  100  provides a self-sealing barrier and protection for the liner layer  202  in order to contain the fluid  204  within the entire wall system  200 . 
       FIG. 2B  is a cross-sectional view of the wall system  200  of  FIG. 2A  in which a projectile  206  has begun to penetrate the wall system  200  entering from outside of the self-sealing volume towards the inside of the volume containing a fluid  204 , such as fuel. The projectile  206  may comprise any type of object that is launched from a gun or ballistic system, such as a bullet or fragment, and/or fragments from high velocity vehicle accidents. In the exemplary embodiment illustrated in  FIG. 2B , the projectile  206  has already penetrated the first elastomeric material layer  102 A and is starting to enter the first fabric or fiber layer  104 A. 
       FIG. 2C  is a cross-sectional view of the wall system  200  of  FIG. 2B  in which the projectile  206  has continued to penetrate the wall system  200  from the outside of the self-sealing volume towards the inside of the volume containing a fluid  204 , such as fuel. In this exemplary embodiment, the projectile  206  has penetrated through the first elastomeric material layer  102 A, the first fabric or fiber layer  104 A, the second elastomeric material layer  102 B, the sealant layer  106 , the third elastomeric material layer  102 C, the second fabric or fiber layer  104 B, and has started to enter the fourth elastomeric material layer  102 D. 
       FIG. 2D  is a cross-sectional view of the wall system  200  of  FIG. 2C  in which the projectile  206  has continued to penetrate the wall system  200  from outside of the self-sealing volume towards the inside of the volume containing a fluid  204 , such as fuel. In this exemplary embodiment, the projectile  206  has penetrated through all the layers of the wall system  200  including the liner layer  202  and has entered the volume containing the fluid  204  itself. Specifically, the projectile  206  has penetrated through all four layers of the elastomeric material layers  102 , the two fiber or fabric layers  104 , the single sealant layer  106 , and the liner layer  202 . 
       FIG. 2E  is a cross-sectional view of the wall system  200  of  FIG. 2D  in which the projectile has completely penetrated the wall system  200  and has entered into the volume containing the fluid  204 , such as fuel, thus allowing the fluid  204  to react with the sealant layer  106 . In this exemplary embodiment, the fluid  204  which may comprise a fuel such as a hydrocarbon fuel may interact with the sealant layer  106  which may comprise unvulcanized or partially vulcanized natural rubber (NR). Other materials that may be used for the sealant layer  106 , as described above, may include but are not limited to polyisoprene (IR), styrene butadiene (SBR) or blends of SBR with NR or IR. 
     In this exemplary embodiment, the sealant layer  106  includes a first portion  106 A which has expanded into the cavity  210 A formed by the projectile  206 . The sealant layer  106  is selected from materials that are tacky in nature and which may have autoadhesion characteristics. Such materials may also swell around openings formed by projectiles that penetrate the materials. In other cases, it is believed that swelling of the sealant layer could occur due to a reaction between the sealant and a hydrocarbon liquids or any other type of liquid which may be stored in the self-sealing volume. 
     The sealant materials are generally themselves hydrocarbon elastomers such as unvulcanized or partially vulcanized, and/or fully vulcanized natural rubber (NR). Other materials that may be used for the sealant layer  106 , as described above, may include but are not limited to polyisoprene (IR), styrene butadiene (SBR) or blends of SBR with NR or IR. Generally the materials selected will serve to swell into a cavity as large as that made by common projectiles  206 , such as a 50 mm or 30 mm projectile, and smaller. The projectile  206  may comprise in-tact bullets, missiles, grenades, etc., and/or fragments thereof, and/or fragments from vehicle accidents/collisions. 
     This first portion  106 A of the sealant layer  106  prevents the fluid  204  from escaping or leaking through the wall system  200  of the cavity  210 A. Swelling of the sealant layer  106  initiates from the fuel side and proceeds in an outward direction. Fiber from the fabric layers  104 A,  104 B may also expand and fill the cavity  210  and may provide an additional, yet moderate level of sealing of the liquid  204  compared to the sealant layer  106 . Meanwhile, the two elastomeric material layers  102 C and  102 D remain broken by the projectile  206 . 
     As understood by one of ordinary skill in the art, various different sealing modalities may occur with the wall system  200 . Because of strength, cut resistance and elongation of wall materials, the wall system  200  may stretch (bow) inward by a significant amount before the projectile  206  penetrates into the volume containing the fluid  204 . When the wall system  200  recovers to essentially a flat surface, distances between materials forming the wall system  200  may shorten, and the stretched fibers and elastomeric molecular strands within the wall system  200  may provide a puckering kind of seal around the cavity/wound/opening. This seal may include the sealant layer  106  which may facilitate autoadhesion. 
       FIG. 2F  is a cross-sectional view of the wall system  200  of  FIG. 2E  in which, in some instances, it is possible the fluid  204  may react with the sealant layer  106  causing the sealant layer  106  to further expand and to close the volume containing the fluid  204 . In other instances or in addition to such a reaction between the fluid  204  and sealant layer  106 , the sealant layer  106  as well as others may be stretched from the projectile  206  and this sealant layer  106  may provide a puckering kind of seal around the cavity/wound/opening due to inelastic expansion. Layer  106  is usually a hydrocarbon elastomer such as unvulcanized or partially vulcanized, and/or fully vulcanized natural rubber (NR). Other materials that may be used for the sealant layer  106 , as described above, may include but are not limited to polyisoprene (IR), styrene butadiene (SBR) or blends of SBR with NR or IR. 
     In this exemplary embodiment, the first portion  106 B has further expanded into the cavity  210 B that was created by the projectile  206  when it passed through the wall system  200 . As noted previously, the first portion  106 B that has expanded into the cavity  210 B because of its reaction with the fluid  204 , which may comprise a hydrocarbon fuel, may prevent the fluid  204  from leaking through the cavity  210 B formed by the projectile  206 . 
     Referring now to  FIG. 3A , this figure is a diagram illustrating fibers  105  receiving a polyurethane coating  301 A. The coating  301 A on the fibers  105  used to form a fiber layer  104 C 1  of  FIGS. 1-2  may comprise solvated aliphatic polyurethane that is applied during the fiber or fabric manufacturing process. As understood by one of ordinary skill in the art, aliphatic is a general class of polyurethanes (excluding aromatic), which typically is easier to solvate than aromatic polyurethanes. Other materials in addition to polyurethanes can be used, such as a resorcinol formaldehyde latex (RFL) and an isocyanate. 
       FIG. 3B  is a diagram illustrating a fabric comprising fibers  105  receiving a polyurethane coating  301 B. The coating  301 B on the fibers  105  used to form fabric layer  104 C of  FIGS. 1-2  may comprise solvated aliphatic polyurethane that is applied during the fiber or fabric manufacturing process.  FIG. 3B  further illustrates a nozzle  305  that may be used to apply the coating  301 B of polyurethane to the fibers  105  of the fabric layer  104 C 2 . Other ways or methods for applying the coating  301  may be used other than those illustrated in  FIGS. 3A-3B , such as by applying the solvated polyurethane to the fabric layer  104 C 2  with a roller applicator or in a dip. 
       FIG. 4A  is a cross-sectional view of one-half of a gas-impermeable, hollow preform or gas permeable solid preform  304 , an elastomeric mold release layer  302 , and a liner  202 . The half-structure is noted by dashed line  402 . As noted previously, the liner  202  layer may comprise any elastomeric material that will have a greater resistance to hydrocarbon fuel  204  than a polyurethane elastomer. Exemplary materials include, but are not limited to, nylon, polyurethane, nitrile rubber, polysulfide, polyurea, polyvinylalchohol (PVA), Hydrogenated Nitrile Butadiene Rubber (HNBR), Epichlorohydrin rubber (ECO), and/or polyvinylidene fluoride. 
     The preform  304  may comprise a molded or shaped object that has the general shape and dimensions representing the inside volume of a fuel tank. The preform  304  is gas-permeable or gas impermeable and it may comprise a solid hard material, in that the preform preferably may support the weight of the wall portion  100  illustrated in  FIG. 1  during manufacturing. Suitable materials for the preform  304  may include, but are not limited to, plaster, polyurethane, polyurea, polyester or polystyrene foams. The preform  304  may be formed to have a shape suitable for a mold or it may be cut and sculpted to a desired shape. According to some exemplary embodiments, the preform  304  may comprise a gas-permeable solid structure such as illustrated in  FIG. 7A  (described below) or the preform  304  may comprise a gas-impermeable hollow structure such as illustrated in  FIG. 7B  (described below). The inventive system  200  and method  500  may also employ foam board performs  304  as understood by one of ordinary skill in the art as an alternative to the preform material  304 A,  304 B used for the gas-permeable structures of  FIG. 7A . 
     In the exemplary embodiment illustrated in  FIG. 4A , the cross-sectional shape of the gas-permeable, hollow preform  304  may comprise a rectangular shape or a more complex shape. As noted above, other cross-sectional shapes are possible and are within the scope of the disclosure described herein. Other cross-sectional shapes include, but are not limited to, oval, cylindrical, triangular, hexagonal (See  FIGS. 7A-7B ), octagonal, and other like shapes or more complex convex and/or concave shapes that may be conducive for use as fuel tanks on military crafts and/or other vehicles, such as, but not limited to, police cars, race cards, armored vehicles, etc. 
     Positioned between the liner  202  and the preform  304  is an elastomeric mold release layer  302 . The elastomeric mold release layer  302  may have at least two purposes. First, it may serve as an elastomeric bag that will allow gaseous pressurization from inside the perform  304 . The gaseous pressure serves to expand the elastomeric mold release layer  302  and subsequently push the uncured wall  100  structure against the surfaces of mold  400 A and  400 B. In most cases, it is important that the elastomeric mold release layer  302  be leak tight during pressurization. Second, the elastomeric mold release layer  302  may serve as a mold release between the preform  304  and the liner  202 . The elastomeric mold release layer  302  may comprise any conventional mold release material. Suitable mold release materials include, but are not limited to, silicone, elastomeric silicone, polyvinyl alcohol (PVA), polyolefin, or oil or grease mold release agents. 
     One of ordinary skill in the art will appreciate that the thicknesses illustrated in the cross-sectional view of  FIG. 4A  may have been exaggerated for viewing purposes. The thicknesses of the liner  202 , the elastomeric mold release layer  302 , and the preform  304  may be varied without departing from the scope of the disclosure described herein. According to one exemplary embodiment, the liner layer  202  may have a thickness of approximately 0.1 to approximately 1.0 mm, while the elastomeric mold release layer  302  may have a thickness of approximately 0.5 to approximately 2.0 mm, and the preform  304  may have a thickness of approximately 1.0 to approximately 10.0 mm. The preform  304  may be a monolithic solid structure, a hollow structure, or a layered structure, for example. 
       FIG. 4B  is a cross-sectional view of an intermediate product  300  that comprises the wall portion  100  of  FIG. 1  in addition to the preform  304 , the release layer  302 , and liner  202  as illustrated in  FIG. 4A . The intermediate product  300  is characterized as such (“intermediate”) because the preform  304  and elastomeric mold release layer  302  are not utilized in the end product for containing a fluid  204 , such as a fuel. The illustration of the intermediate product  300  of  FIG. 4A  is helpful in understanding how a completed fuel tank or final product forming the wall system  200  as illustrated in  FIGS. 2 and 4E-4E  is manufactured. 
       FIG. 4C  is a diagram illustrating how the intermediate product  300 A of  FIG. 4B  (which comprises the preform  304  and the elastomeric mold release layer  302  but no liquid  204 ) is positioned within a mold  400  and coupled to a gaseous pressure source  403  according to one exemplary embodiment. According to this exemplary embodiment, the intermediate product  300 A has a hexagonal shape compared to the rectangular cross-sectional shape illustrated in  FIG. 4B . 
     In the exemplary embodiment illustrated in  FIG. 4C , the mold  400  may comprise two halves  400 A,  400 B which are joined together. The two halves  400 A,  400  may be coupled together by any type of mechanical fastener, such as, but not limited to a hinge. Other types of molds  400 , such as a two piece compression mold  400 , as well as other molding techniques may be employed such as compression molding and vacuum bag molding. The actual number of mold sections can be more than two and is dictated by each individual volume geometry requirement. The mold section design also aids in the removal of the final product once the curing is complete. The mold  400  controls the dimension of the final product, which is the wall system/self-sealable volume  200  as illustrated in  FIG. 1A . Exemplary dimensions for the mold include, but are not limited to, about 499.00 mm by about 555.00 mm by about 96.50 mm (or about 19.65 inches by about 21.85 inches by about 3.80 inches). It is noted that the 19.65 inches measurement corresponds to the 19.79 inches measurement for the self sealing volume listed in Table 1 described below. It is further noted that the preform  304  does not control the final dimensions of the wall system/self-sealable volume  200 . 
     After curing of the intermediate product  300 A within the mold  400  and later removal of the preform  304  and elastomeric mold release layer  302 , the cured structure forms the final wall system  200  of a self-sealing volume as illustrated in  FIG. 4E  and  FIG. 2 . The mold  400  may comprise a heat source  410  for generating heat to apply to the intermediate product  300 A contained within the mold  400 . A heat source  410  may comprise any type of heat appropriate for molding or curing elastomeric structures as understood by one of ordinary skill in the art. Exemplary heat sources  410  include, but are not limited to, conventional ovens, like convection ovens, microwave ovens, attached electrical strip heaters, autoclaves or attached tubing containing heated oil. 
     The mold  400  may also comprise a gaseous pressure source  403 , like a pump, for generating gaseous pressure to apply to the intermediate product  300 A contained within the mold  400 . Specifically, the gaseous pressure source  403  may be coupled to an inlet  503 . The inlet  503  may be coupled to a metal fixture  507  that is contained within a nut ring  509 . A nut ring  509  may comprise an access port for fuel filling, venting, and a fuel pump. Each metal fixture  507  may be fitted with one nut ring  509 . Multiple metal fixtures  507  with nut rings  509  may be used for redundancy and/or for different connections to the resultant self-sealing volume  100  which is designed to contain fuel. 
     Each self-sealing volume  100  may have one or more nut rings  509 . Each nut ring  509  may be fitted with cords or fabric flanges that extend radially into the elastomeric composite  100  to provide secure attachment of the nut ring  509  to the self-sealing volume  100 . A nut ring is described and illustrated in U.S. Pat. No. 3,704,190, the entire contents of which are hereby incorporated by reference. A nut ring may have a circular shape. However, it may have other shapes too, such as, but not limited to, oval, rectangular, rectangular with rounded edges, pentagonal, octagonal, etc. 
     A gaseous pressure source  403  may comprise any type of gaseous pressure appropriate for forming a shaped part of elastomeric structures as understood by one of ordinary skill in the art. Exemplary gaseous pressure sources  403  include, but are not limited to, compressed air from a compressed cylinder or from a conventional air compressor, or compressed nitrogen, argon, carbon dioxide or helium from a compressed cylinder. 
     As noted previously, the elastomeric mold release layer  302  forms a gas tight seal around the preform  304  when the elastomeric mold release layer  302  is inflated by the gaseous pressure source  403 . The elastomeric mold release layer  302  will expand the elastomeric material layers  102  when the elastomeric mold release layer  302  is inflated with a gas from the gaseous pressure source  403 . The amount of pressure provided by the gaseous pressure source  403  is generally between about 2.0 psi to about 80.0 psi, and preferably between about 10.0 psi to about 40.0 psi, and more preferably at about 20.0 psi. However, other pressures may be used as understood by one of ordinary skill in the art and are within the scope of this disclosure. 
       FIG. 4D  is a diagram illustrating a cured intermediate product  300 C after the intermediate product  300 C is removed from the mold  400  of  FIG. 4C , disconnected from the inlet  503  and gas pressure source  403 , and after the intermediate product  300 C has been cured. The intermediate product  300 C may have any three dimensional shape including regular cubic square or rectangular cross-sectional shape or an irregular cubic quadrilateral shape or a complex multisided three dimensional shape. In the exemplary embodiment illustrated in  FIG. 4D , the intermediate product  300 C has a hexagonal shape. 
     The intermediate product  300 C is characterized as such (“intermediate”) because it comprises the elastomeric mold release layer  302  and the preform  304  (internally), which are not illustrated in this figure but are illustrated in  FIGS. 4A-4B . The view of  FIG. 4D  is an external one of the intermediate product  300 C such that the internal layers, such as the elastomeric mold release layer  302  and preform  304 , are not visible. 
       FIG. 4E  is a diagram illustrating the formation of the completed product  200  of  FIGS. 2A-2F  by removing the preform  304  and the release layer  304 . The preform  304  and release layer  302  may be removed from the intermediate product  300 C, as disclosed below. 
     The preform  304  and elastomeric mold release layer  302  may be removed after the intermediate product  300 C has been fully cured and cooled. These two structures  304 ,  302  may be removed by breaking them into small pieces or chunks, or a single extended piece, and removing them through nut ring  509  and access port  405 . The preform  304  may be smaller relative to (have outer dimensions which are less than) the finished product  200  since the preform  304  is filled with a fluid, like air, such that the mold release layer  302  expands from the fluid. The fluid may include a gas that is used while the finished product  200  is curing. The preform  304  usually does not change in size/dimensions when the fluid is provided inside the preform  304  to inflate the mold release layer  302 . 
     Usually, the elastomeric mold release layer  302  is removed with the preform  304  illustrated in  FIG. 4E . Then, the preform  304  may be removed through the nut ring  509  of the finished product  200 . The nut ring  509  usually has a round shape, but other shapes may be employed as understood by one of ordinary skill in the art. Once these structures  304 ,  302  are completely removed, the finished and completed product  200  is formed as illustrated in  FIG. 1A . 
     FIG.  4 F 1  is a cross-sectional view of a self-sealing volume  200  in the form of a fuel tank illustrating the individual composite layers along with paths  411  of air escape according to one exemplary embodiment. FIG.  4 F 1  has a breather structure  409 . The wall system/volume  200  comprises a wall  100  and a liner  202  which will be described in more detail below. The self-sealing wall system  200  may contain a fluid  204  (See  FIG. 1A ), such as, but not limited to, a hydrocarbon fuel. 
     Other layers of the wall system or volume  200  may include a release layer  302  (which is used during formation of the volume  200  but later discarded after formation of volume  200 ), a fabric trilayer  407 , and sealant layer  106 . The sealant layer  106  usually covers the entire (100%) of the surface area for the volume  200 . The sealant layer  106  is responsible for sealing any punctures in the volume  200  should a projectile strike and penetrate through the wall  100  of the volume  200 . Further details of the fabric trilayer  407  will be described below in connection with FIG.  4 F 2 . Similar to the other exemplary embodiments of the volume  200 , the volume  200  of FIG.  4 F 1  may include a nut ring  509  as described above. 
     In the exemplary embodiment illustrated in FIG.  4 F 1 , the volume  200  comprises three trilayers  407 A,  407 B,  407 C in each corner that forms the first breather structure  409 A. Specifically, the first breather structure  409 A comprises the following layers along the geometrical ray AB as follows (starting from point A extending towards point B of ray AB): the release layer  302  (which is discarded after formation of the preform and prior to filling the volume  200 ), the liner  202 , the first trilayer  407 A, a second trilayer  407 B, a sealant layer  106 , and a third trilayer  407 C. 
     The first breather structure  409  of the exemplary embodiment illustrated in FIG.  4 F 1  is formed in such a way that a first gap  479 A between points C and D located on respective different sealant layers  106  is formed and filled with the second trilayer  407 B. A fluid for manufacturing the volume  200 , such as air, may be allowed to escape the volume  200  by following fabric path  411  which exists within trilayers  407 A,  407 B, and  407 C. A second gap  479 B is formed similarly on the other side of the first breather structure by the second trilayer  407 B. 
     An edge portion or overlap portion O of the sealant layer  106  (which lies on top of a trilayer fabric  407 ) in each breather structure  409  may have a length of between about a 0.25 of an inch to about 2.00 inches. The sealant layer  106  may have a thickness of between about 0.02 of an inch to about 0.12 of an inch. The trilayer fabric layers  407  may each have a thickness between about 0.005 of an inch to about 0.03 of an inch. 
     The overall length (L) of the volume  200  may comprise a magnitude of about 20.0 inches, while the overall height (H) of the volume  200  may comprise a magnitude of about 10.0 inches. The volume  200  may have width dimension (not visible) having a magnitude of about 22.0 inches. As noted previously, the shape of the volume  200  may be varied without departing from the scope of this disclosure. Therefore, other magnitudes for the length (L), width, and height (H) may be possible with different geometrical shapes for the volume  200 . 
     Further, one of ordinary skill the art will recognize that the number and size of the layers may be varied without departing from the scope of the present disclosure. That is, fewer or a greater number of layers with different thicknesses may be used for a particular embodiment without departing from the scope of the technology described herein. 
     In each of the figures of this disclosure, the breather structure  409  may appear to have a thickness and size which are greater than a respective side of the volume  200 . In other words, each breather structure  409  may appear to be “bulging” relative to the sides of the volume  200  which do not have a breather structure  409 . However, the figures of this disclosure with respect to the breather structure  409  have been greatly exaggerated. In the actual final volume  200 , each breather structure  409  and its relative thickness are usually very difficult to detect with the naked eye. 
     FIG.  4 F 2  is a side view of a fabric trilayer  407  that is depicted in FIG.  4 F 1 . The fabric trilayer  407  may comprise three layers sandwiched together: a first elastomeric material matrix layer  102  (as described above in connection with  FIGS. 1-3 ), a fabric or fiber layer  104 , and a second elastomeric material matrix layer  102 . The first and second elastomeric materials  102  envelope or sandwich the fabric layer  104  therebetween. The elastomeric materials  102  have been described in detail above. In many embodiments, the two elastomeric materials  102  are absorbed into the fabric or fiber layer  104  instead of encasing/circumscribing the fabric layer  104 . 
     Each elastomeric material/matrix layer  102  may comprise at least one each of polyurethanes, polyureas, polyurethane ureas, epoxy, polyester, silicone. Each fabric layer  104  may comprise one or more layers of fabrics made from at least one of nylon, aramid, polyester polypropylene and polyethylene. Each fabric layer  104  may also comprises cords in which each cord has a diameter of between about 0.0624 of an inch to about 0.25 an inch. Each fabric trilayer  407  may have a weight between about 2.0 oz/square yard to about 36.0 oz/square yard. The fabric types may include, but are not limited to, woven materials, non-woven materials, and knitted materials. 
       FIG. 4G  is a cross-sectional view of a corner of a self-sealing volume  200  illustrating an alternative lay up pattern where one or more structural fabric plies are located on one side of the sealant layer  106 . The mold release layer  302  is not present in this embodiment: it has been removed. The sequence of layers for the exemplary embodiment illustrated in  FIG. 4G  are as follows using geometrical ray AB as a reference for the sequence of materials that form the breather structure  409 B of  FIG. 4G : liner  202 , a first fabric trilayer  407 A, a second trilayer  407 B, sealant layer  106 , and a third trilayer  407 C. 
     Relative to the first breather structure  409 A illustrated in FIG.  4 F 1 , the second breather structure  409 B illustrated in  FIG. 4G  has only a single gap  479  formed between the two sealant layers  106  by the second fabric  407 B for a respective corner region of the volume  200 . A fluid or gas, like air, may flow along fabric path  411 . Meanwhile, the sealant layer  106  for the first breather structure  409 A has two gaps and two fabric paths  411  per corner illustrated in FIG.  4 F 1 . 
       FIG. 4H  is a cross-sectional view of a corner of a self-sealing volume  200  illustrating an alternative lay up pattern where one of the fabric layers  407 A 1  is extended in a continuous manner around the sealant layer  106  to meet the outer fabric layer  407 A 2 . The mold release layer  302  is not present in this embodiment: it has been removed. Following the first fabric layer  407 A 1  along air escape path  411 , the first fabric layer  407 A 1  has an extension region  407 EX that continues towards the outer layer  407 A 2 . With this configuration, another single gap  479 , like the exemplary embodiment illustrated in  FIG. 4G , is formed for this breather structure  409 C. 
       FIG. 4I  is a side view of a corner of a self-sealing volume  200  illustrating a view of outside layers down to the sealant layer  106  where layers inside sealant layer  106  are not shown and provide an alternative lay-up pattern where the sealant layer  106  has been perforated with apertures  419 . The sealant layer  106  is subsequently covered with fabric trilayers  407 A and the areas where apertures  419  are located are covered with sealant patches  106 P that are larger than the original holes  419 . A final fabric trilayer  407 A (not illustrated) covers sealant patches  106 P and fabric trilayer  407 . 
     The apertures  419  can be any shape, such as, but not limited to, circular, elliptical, rectangular, square, slits and other similar geometric shapes. The size of the apertures  419 , such as diameters for round apertures  419 , may range between about 0.05 of an inch to about 1.0 inch. The sealant patches  106 P and corresponding fabric trilayer  407  covering the apertures  419  are covered with a final fabric trilayer  407  as indicated with the dashed line  407  in this  FIG. 1 . 
     FIGS.  4 J 1 - 4 J 5  are side views of the formation of a self-sealing volume  200  using a straight wall lay-up technique in which the breather structure is located in a lateral side of the volume  200  instead of a corner of the volume  200 . Any of the build configurations described in this disclosure may have breather structures located in sides of the volume  200 , in corners of the volume  200 , or in combinations thereof. 
     With a lay-up technique, the layers illustrated in each figure are applied in sequence. The elastomeric material layers  102  (part of trilayer  407 ) provide the necessary tack/adhesive to hold all structures together before curing. The layers in FIGS.  4 J 1 - 4 J 5  are applied by hand using tools such as a spatula or roller to smooth out and remove as much trapped air as possible. 
     Specifically, FIG.  4 J 1  is a side view of an intermediate self-sealing volume  200  illustrating an inner, first fabric trilayer  407  applied over a liner layer  202  (not visible in this FIG.  4 J 1  but see FIG.  4 F 1 ). After the first fabric trilayer  407  is applied over the liner  202 , then in FIG.  4 J 2 , a sealant layer  106  is applied. 
     Specifically, and referring to FIG.  4 J 2 , a side view of an intermediate self-sealing volume  200  illustrates the sealant layer  106  applied with a gap  413  over the fabric trilayer  407  of FIG.  4 J 1 . Within this gap  413 , the fabric trilayer  407  is visible. The gap  413  may have a width dimension of between about 0.10 of an inch to about 3.00 inches. However, other widths are possible and are within the scope of this disclosure. 
     Referring now to FIG.  4 J 3 , this figure is a side view of an intermediate self-sealing volume  200  illustrating a rectangular breather fabric  407 R applied over the gap  413  (illustrated in FIG.  4 J 2 ). This rectangular breather fabric  407 R may have a length dimension (L 1 ) of between about 0.5 of an inch to about 4.00 inches that extends beyond gap  413  on either side of gap  413  (about 0.25 to about 1.00 inch on either side of sealant patch  106 P) which usually is less than the overall length of the volume  200 . 
     Next, FIG.  4 J 4  is a side view of an intermediate self-sealing volume  200  illustrating a sealant patch  106 P applied over the gap  413  and rectangular breather fabric  407 R of FIG.  4 J 3 . The sealant patch  106 P may have a length dimension (L 2 ) of approximately between about 0.25 of an inch to about 1.00 incheinch that extends beyond gap  413  but less than fabric  407 R on either side of fabric  407 R (about 0.25 to about 1.00 inch less on either side of fabric  407 R) which usually is less than the overall length of the volume  200 ] And FIG.  4 J 5  is a side view of an intermediate self-sealing volume  200  illustrating an outer, second trilayer fabric  407  applied over the sealant patch  106 P and sealant  106  of FIG.  4 J 4 . 
     FIGS.  4 K 1 - 4 K 7  are views of the formation of a self-sealing volume  200  using a calendared sealant patch technique. Specifically, FIG.  4 K 1  is a side view of an intermediate self-sealing volume  200  illustrating an inner, first fabric trilayer  407  positioned over a liner layer  202  (not visible in this FIG.  4 K 1  but see FIG.  4 F 1 ). 
     FIG.  4 K 2  is a side view of an intermediate self-sealing volume  200  illustrating the sealant layer  106 A or a calendared sealant  106 A applied with a gap  413  over the fabric trilayer  407  of FIG.  4 K 1 . For forming a calendared sealant  106 A, the sealant  106  is previously laminated directly to a fabric  407  by passing the sealant  106  and fabric  407 , stacked together, between solid metal rolls under pressure. 
     The gap  413  of FIG.  4 K 2  may have the same dimensions described above with respect to the exemplary embodiment illustrated in  FIG. 4J . Similar to FIG.  4 J 2  described above, within this gap  413 , the fabric trilayer  407  is visible. Next, FIG.  4 K 3  is a side view of an intermediate self-sealing volume  200  illustrating a calendared sealant patch  106 CP applied over the gap  413  and sealant  106 A of FIG.  4 K 2 . Usually, calendered sealant patch  106 CP is applied so that fabric side is positioned on sealant layer  106 A. The calendared sealant patch  106 CP may have a length dimension (L 3 ) of approximately between about 0.5 of an inch to about 4.00 inches that extends beyond gap  413  on either side of gap  413  (about 0.25 to about 1.00 inch on either side of gap  413 )] Next, FIG.  4 K 4  is a side view of an intermediate self-sealing volume  200  illustrating an outer, second trilayer fabric  407  applied over the calendared sealant patch  106 CP and sealant layers  106 A of FIG.  4 K 3 . 
     FIG.  4 K 5  is a cross-sectional, top view of the calendared sealant patch embodiment of FIG.  4 K 4 . In this exemplary embodiment illustrated in FIG.  4 K 5 , the gap or absence of material  413  between sealant layers  106 A is more visible. The inner most trilayer  407 A faces the inside of the volume  200  while the outermost trilayer  407 B faces an outside or exterior of the volume  200 . As noted previously, the gap  413  allows a manufacturing fluid, such as air, to permeate through the first trilayer  407 A, through the gap  413  between the sealant layers  106  and through the calendared patch layer  106 CP and outermost trilayer  407 B corresponding to directional arrow A in this FIG.  4 K 5 . 
     FIG.  4 K 6  is a side view of the calendared sealant patch  106 CP of FIGS.  4 K 3  and  4 K 5  alone. FIG.  4 K 7  is a cross-sectional view of the calendared sealant patch  106 CP illustrated in FIG.  4 K 6 . Like the sealant layer  106  described above, the calendared sealant patch  106 CP may have a thickness of between about 0.02 of an inch to about 0.3 of an inch. The calendared sealant patch  106 CP may comprise a fabric  417  made of nylon, polyester, polypropylene, and an aramid having exemplary weights between about 1.0 ounces to about 32.0 ounces. The fabric can be woven, nonwoven, or knit. The sealant layer or side  106  is pressed on or calendared onto the fabric  107 . Lower weight fabric may be employed such as nylon fabric having exemplary weights between about 1.0 ounce to about 12.0 ounces, and preferably, about 2.0 ounces. 
     FIGS.  4 L 1 - 4 L 5  are side views of the formation of a self-sealing volume  200  using a breather fabric strips or cords technique. FIG.  4 L 1  is a side view of an intermediate self-sealing volume  200  illustrating an inner, first fabric trilayer  407  positioned over a liner layer  202  (not visible in this FIG.  4 J 1  but see FIG.  4 F 1 ). Next, FIG.  4 L 2  is a side view of an intermediate self-sealing volume  200  illustrating the sealant applied with a gap  413  over the fabric trilayer  407  of FIG.  4 L 1 . This gap  413  of FIG.  4 L 2  may have the same dimensions described above with respect to the exemplary embodiment illustrated in  FIG. 4J . Similar to FIG.  4 J 2  described above, within this gap  413 , the fabric trilayer  407  is visible. 
     FIG.  4 L 3  is a side view of an intermediate self-sealing volume  200  illustrating breather fabric strips  407 S applied over the gap  413  illustrated in FIG.  4 L 2 . These strips  407 S may have a length dimension of approximately between about 0.25 of an inch to about 4.00 inches and a width dimension of approximately between about 0.25 of an inch to about—2.0 inches. The number of strips  407 S is usually between about 4 and about 20, depending upon size. 
     FIG.  4 L 4  is a side view of an intermediate self-sealing volume  200  illustrating a sealant patch  106 P applied over the gap  413  and breather fabric strips  407 S, as well as portions of the sealant layer  106 A of FIG.  4 L 3 . Similar to FIG.  4 J 4 , the sealant patch  106 P may have dimensions similar to the sealant patch  106 P described above in connection with FIG.  4 J 4 . FIG.  4 L 5  is a side view of an intermediate self-sealing volume  200  illustrating an outer layer of the trilayer fabric  407  applied over the sealant patch  106 P and sealant  106 A of FIG.  4 J 4 . 
     These  FIGS. 4J, 4K, and 4L  illustrate exemplary sequences of steps that may be taken in order to produce the breather structures  409  as illustrated in FIGS.  4 F 1 ,  4 G, and  4 I. However, one of ordinary skill the art will appreciate that other steps may be taken and other sequences of steps may be made while still creating the breather structures  409  as illustrated in FIGS.  4 F 1 ,  4 G, and  4 I. 
     Referring now to  FIG. 5A , this figure is a flowchart illustrating a method  500  for forming a self-sealing volume  200  according to an exemplary embodiment. Routine block  502  is the first block of method  500 . In routine or sub-method block  502 , a preform  304  as illustrated in FIG.  4 A and further illustrated in  FIGS. 7A-7B  may be generated. A preform  304  typically has a three dimensional shape as illustrated in  FIGS. 4C, and 7A-7B . Further details of routine block  502  will be described below in connection with  FIGS. 7A-7B , and  FIGS. 8-9 . The preform  304  may or may not have a symmetrical shape. At the end of block  502 , a metal fixture  507  is mounted within the opening  405  of the preform mold. 
     Next, in block  505 , the preform  304  may be coated with an elastomeric mold release material  302  as illustrated in  FIG. 4A . As noted previously, this elastomeric mold release material may comprise silicone, elastomeric silicone, polyvinyl alcohol (PVA) or polyolefin mold release agents. Specifically, an elastomeric release material  302 , such as SMOOTH-ON-EZ-SPRAY™ SILICONE® 20 silicone (which is a 20 Shore A silicone elastomer) may be sprayed or otherwise coated over the surface of the preform  304 . 
     In block  510 , the elastomeric mold release material  302  may be coated with a volume liner  202 . Liner  202  may comprise may comprise any elastomeric material that will have a greater resistance to hydrocarbon fuel  204  than a polyurethane elastomer. Exemplary materials for the liner material  202  include, but are not limited to, polyurethane, polyurea, nitrile rubber, polysulfide, polyvinylalchohol (PVA), Hydrogenated Nitrile Butadiene Rubber (HNBR), Epichlorohydrin rubber (ECO), and polyvinylidene fluoride. The inner liner  202  may comprise a polysulfide, such as PRC RAPID SEAL 655™ aliphatic polysulfide sold by PRC-DeSoto International, Inc. Or the liner  202  may comprise another fuel resistant elastomeric material. It can be sprayed in or on, coated or laid in as a sheet. 
     In block  510 , a nut ring  509  may be mounted into the opening  405  of the preform mold containing the metal fixture  507  as understood by one of ordinary skill in the art. Each nut ring  509  is fitted with cords or fabric flanges that extend radially into the elastomeric composite  100  to provide secure attachment of the metal nut ring  509  to the self-sealing volume  100 . These cords or fabric flanges are typically fitted on each nut ring  509  prior to starting method  500 . 
     Alternatively, the volume  300 A can be fabricated without the volume liner  202  which can be added in a subsequent step after the volume  300 A is cured and the preform  304  and the elastomeric mold release layer  302  have been removed. 
     In an alternate exemplary embodiment, a path  522  is illustrated with a dashed line to convey that it&#39;s optional. It may be followed if the inner liner layer  202  is applied by spraying. Next, in optional block  515  (illustrated with dashed lines), the fabric or fiber layer  104  may be formed by coating the layer  104  with a solvated polyurethane. Alternatively, fabric or fiber layer  104  may be coated with a resorcinol formaldehyde resin or a solvated isocyanate. 
     Usually, this coating of the fiber layer  104  is completed as a separate step during manufacture of the fabric and it may not be part of the construction of the self-sealing container. Subsequently, in routine or submethod  520 , the elastomeric material layer  102  may be created. Further details of routine or submethod  520  are described below in connection with  FIG. 6 . 
     Next, in block  525 , a first layer of the elastomeric material  102 D as illustrated in  FIG. 4B  of the intermediate product  300  is applied to the liner  202 . The elastomeric material  102 D is also applied to fabric layer  104 B. When applying the elastomeric material  102 D, the elastomeric material  102 D is generally applied to be as thin (but not viscous) as possible. The method  500 A then continues to block  535  of  FIG. 5B . 
       FIG. 5B  is a continuation flowchart of  FIG. 5A  illustrating the method  500 B for forming a self-sealing volume  200  according to an exemplary embodiment. In block  535 , a first coated fabric or fiber layer  104 B is applied to the first layer  102 D of the elastomeric material  102 D as illustrated in  FIG. 4B . In an alternative exemplary embodiment, the elastomeric material  102 D may be applied to the coated fabric  104 B and then these two layers  102 D,  104 B may be applied to the liner layer  202  in which the elastomeric material  102 D is sandwiched between the fabric layer  104 B and the liner layer  202 . 
     In block  540 , a second layer of the elastomeric material  102 C is applied to the first coated fabric or fiber layer  104 B of  FIG. 4B . In block  545 , sealant layer  106  may have a primer or adhesion activator coated on prior to application. Then, the sealant layer  106  is applied to the second layer of the elastomeric material  102 C as illustrated in  FIG. 4B . As noted previously, the sealant layer  106  may comprise natural rubber or partially vulcanized natural rubber (NR) (having less than about 1% sulfur). Other materials that may be used include polyisoprene (IR), styrene butadiene (SBR), blends of SBR with NR or IR, and low durometer polyurethanes (approximately Shore A less than 70). In block  550 , a third layer of the elastomeric material  102 B is applied to the sealant layer  106 . 
     In block  555 , a second coated fabric or fiber layer  104 A is applied to the third layer of the elastomeric material  102 B as illustrated in  FIG. 4B . In block  560 , a fourth layer of the elastomeric material  102 A is applied to the second coated fabric or fiber layer  104 A as illustrated in  FIG. 4B . The method  500 B then continues to block  575  of  FIG. 5C . 
       FIG. 5C  is a continuation flowchart of  FIG. 5B  illustrating the method  500 C for forming a self-sealing volume according to an exemplary embodiment. In block  575 , the coated preform  304  having the wall structure illustrated in  FIG. 4B  is rotated so that the elastomeric material remains uniform throughout the fabric and over the preform  304  until the elastomeric material layers  102  cool and become stiff. Next, in block  580 , the coated preform  304  comprising the intermediate products  300 A as illustrated in  FIG. 4C  is placed into a mold  400 . 
     Subsequently, in block  585 , the perform  304  forming the intermediate products  300 A is closed within the mold  400  as illustrated in  FIG. 4C . In block  590 , heat and pressure may be applied to the mold  400  from heat source  410  and gas pressure source  403  in order to cure the preform  304  or intermediate product  300 A to form the cured, single intermediate product  300 C as illustrated in  FIG. 4D . The gas pressure source  403  may fill the preform  304  and exit it while to expand the mold release layer  302  such that layer  302  pushes the composite wall structure/system  100  against the heated mold  400  during curing. Specifically, the gas pressure source  403  may inflate the elastomeric mold release layer  302  that is on the outside of the gas-permeable preform  304  so that the wall structure  100  ( FIG. 1B ) is pressed against the heated mold  400 . Once the structure  300 A of  FIG. 4C  cures into structure  300 C of  FIG. 4D , the fixture  507  may be removed from the nut ring  509 . 
     In block  592 , the inlet  503 , metal fixture  507 , preform  304  and corresponding elastomeric mold release layer  302  attached thereto may then be removed from the resultant cured volume  300 C as illustrated in  FIG. 4E  to form the completed wall system or self-sealing volume  200  as illustrated in  FIG. 4E . Specifically, the preform  304  and corresponding elastomeric mold release layer  302  may be broken into small pieces relative to the entire cured volume or wall system  200  and removed through nut ring  509  that penetrates through the volume formed by the wall system  200  as illustrated in  FIG. 4E . 
     Next in block  593 , if a volume liner  202  was not added in block  510 , a volume liner  202  can be sprayed into the completed volume  300 C so that a liquid impermeable coating completely covers the inside of the volume  300 C. Liner  202  may comprise any elastomeric material that will have a greater resistance to hydrocarbon fuel  204  than a polyurethane elastomer. Exemplary materials for the liner material  202  include, but are not limited to, polyurethane, nitrile rubber, polysulfide, polyurea, polyvinylalchohol (PVA), Hydrogenated Nitrile Butadiene Rubber (HNBR), Epichlorohydrin rubber (ECO) and polyvinylidene fluoride. 
     Next, in block  594 , the volume formed by the wall system  200  may be filled with a fluid For example, the fluid may comprise a hydrocarbon fuel, such as gasoline or diesel. The method  500  then ends after block  594 . 
       FIG. 6  is a flowchart illustrating a routine or submethod  520  for creating a elastomeric material layer  102  according to an exemplary embodiment. Block  605  is the first step of submethod or routine  520 . 
     In block  605 , an organic diisocyanate or diisocyanate prepolymer having a predetermined molecular weight is prepared. Normally, any of the well-known organic polyisocyanates useful for making castings may be utilized for the elastomeric material layer  102 . Toluene diisocyanate and methylene diphenyldiisocyanate are suitable exemplary materials as they are frequently used for making castings. 
     The amount of polyisocyanate used is about 0.9 to about 1.5 mole equivalents. The molecular weight that may be used for the organic diisocyanate may comprise a magnitude of approximately 250 g/mole. For a diisocyanate prepolymer, the magnitude may comprise approximately 624 g/mode or a free isocyanate percentage of between about 6.45 to about 6.74 percent. 
     Then, in block  610 , the diisocyanate or diisocyanate prepolymer is mixed with a reactive hydrogen containing material having a predetermined molecular weight. Specifically, a reactive hydrogen-containing material having a molecular weight of about 700 to about 4000 may be used. Representative of the reactive hydrogen-containing materials are the broad classes of polyester polyols, polyether polyols, hydrocarbon-polyols. The polyester polyols that are preferred are the esters of adipic acid with the lower glycols such as ethylene glycol, propylene glycol, and butylene glycol, and mixtures of these. The polyether polyols that are preferred are propylene ether glycol, polypropylene ether polyol, and polytetramethylene ether polyol. 
     In conjunction with the polyol a short chain glycol, organic diamine, polyetheramine or alkylanolamine may be used to increase molecular weight of the polyurethane reaction mixture layer  102 . Representative members of these classes of materials include, but are not limited to, ethylene glycols, propylene glycols, butane diols, methylene bis-chloroaniline, methylene dianiline, bis-amino phenyl sulfone and amino methyl propanol. If organic amines are used, then urea linkages will be created rather than urethane linkages, resulting in a mixed polyurethane urea. 
     Then, in block  615 , the reaction product/layer  102  at this stage is not allowed to cure completely but it is allowed to cool after casting thereby stiffening. This is accomplished by keeping the polyurethane reaction mixture below the temperature at which curing will occur, typically below about 90° C. to about 150° C., and preferably below about 90° C. The polyurethane reaction mixture in block  615  may be applied to the preform at a temperature of between about 40.0° C. to about 75.0° C. As it cools, the reaction product will stiffen and become gel-like in a time period of between about 20.0 minutes to about 60.0 minutes, and preferably in about 20.0 minutes. The submethod then returns to block  525  of  FIG. 5A . 
     Referring now to FIG.  7 A 1 , this figure illustrates a cross-sectional view of a device  400 C,  400 D for forming flexible molds  400 E,  400 F according to an exemplary embodiment. The device  400 C,  400 D may comprise two flexible molds shells that are used to create flexible molds  400 E,  400 F. In the exemplary embodiment illustrated in FIG.  7 A 1 , the two mold shells have the cross-sectional shape of one half of geometric hexagon. As noted previously, inventive method and system are not limited to the shapes described or illustrated in this disclosure. Other shapes are possible as understood by one of ordinary skill in the art. 
     The two rigidmolds shells  400 C,  400 D may comprise materials such as, but not limited to plaster, wood, molded plastic, clay, fiberglass composite, etc. One of the mold shells  400 C,  400 D may comprise an aperture or opening  405  such as mold shell  400 D. This opening  405  will be used for a fixture  507  as will be described in further detail below. 
     As mentioned previously,  FIGS. 7A and 7B  illustrate one of several options for producing a preform. Other options/embodiments covered by this disclosure, but not illustrated, include three dimensional preform molds cut from a block of polyethylene, polystyrene foam or other similar material. In these other, alternative embodiments, the preform molds may be rigid (not flexible) as understood by one of ordinary skill in the art. 
     As illustrated in FIG.  7 A 1 , the flexible molds  400 E,  400 F will generally have a shape that corresponds to the shape of the two rigid mold shells  400 C,  400 D. The flexible molds  400 E,  400 F previously made of a material such as, but not limited to, silicone, polyethylene, or polypropylene. 
     FIG.  7 A 2  is a cross-sectional view of the flexible molds  400 E,  400 F formed from the device  400 C,  400 D of FIG.  7 A 1  according to an exemplary embodiment. According to this exemplary embodiment, the two rigidmolds shells  400 C,  400 D have been removed so that only the flexible molds  400 E,  400 F each having one half of a hexagonal cross-sectional shape remain. As noted previously, one of the flexible molds  400 F has an opening  405 . 
     FIG.  7 A 3  is a cross-sectional view of preform material  304 A,  304 B positioned within the flexible molds  400 E,  400 F of FIG.  7 A 2  according to an exemplary embodiment. According to this exemplary embodiment, the preform material  304 A,  304 B will form a gas-permeable, solid structure. The preform material  304 A,  304 B may be generated by mixing equal parts of a diisocyanate such as sold under the tradename SMARTFOAM A and a polyol such as SMARTFOAM B. These mixtures are poured into the fabricated two piece molds  400 E,  400 F that usually have inside dimensions which correspond to the required outside dimensions of the preform  304 . Once the preform material  304 B of the mold  400 F cures slightly (or prior to pouring of the preform material  304 B) the mold  400 F may be fitted with a metal fixture  507 . 
     The metal fixture  507  of FIG.  7 A 3  will provide ingress for air and will serve as a mounting for the preform  304  during layup. The location of the metal fixture  507  is selected to coincide with the location of a nut ring  509  in the finished self-sealing volume  100 . 
     FIG.  7 A 4  is a cross-sectional view of the two halves of a gas-permeable, solid preform  304 A,  304 B generated from the flexible molds  400 E,  400 F of FIG.  7 A 3  according to an exemplary embodiment. In this exemplary embodiment, the flexible molds  400 E,  400 F have been removed such that the gas-permeable, solid preform halves  304 A,  304 B remain. The second half  304 B has the metal fixture  507  as described above. These halves  304 A,  304 B may be rotated as indicated by the directional arrows until completely cured. Rotation may or may not be used. In other embodiments, the halves  304 A,  304 B are not rotated. The material described above for the performs  304 A,  304 B generally cure at standard room temperature and pressure as understood by one of ordinary skill in the art. 
     FIG.  7 A 5  is a cross-sectional view of the two halves of the gas-permeable, solid preform  304 A,  304 B put/mated together according to an exemplary embodiment. The fully cured, two halves  304 A,  304 B are mated together by adhesives. Usually, adhesives that do not contain solvent or water may be employed. Such adhesives include, but are not limited to, epoxies or two part urethanes. 
     The resultant gas-permeable solid preform  304 D may be characterized as a urethane preform  304 D. This FIG.  7 A 5  also illustrates a coating  707  that may be applied to the preform surface to provide a smooth, rigid surface for build-up. Materials used for the coating  707  may include, but are not limited to, a rigid polyurethane such as FEATHERLITE® brand low-density urethane casting resin. 
     FIG.  7 A 6  is a cross-sectional view of the gas-permeable, solid preform  304 D after apertures or holes  701  have been created within the preform  304 D according to an exemplary embodiment. Any number of holes  701  may be created within the solid preform  304 D. The holes  701  may be created with machines such as, but not limited to, drills or lasers. The holes  701  may be randomly positioned or positioned at evenly spaced intervals as understood by one of ordinary skill in the art. The holes  701  will help a fluid originating from the gaseous pressure source  403  to exit the preform  304 D in order to properly inflate the release layer  302  as described above. Holes  701  are usually only needed if an impermeable skin (i.e. like FEATHERLITE® brand low-density urethane casting resin) is applied to the outside of the foam/solid preform  304 D but can be used in any foam/solid preform  304 D. Holes  701  are also usually needed in closed-cell foams forming the preform  304 D which generally do not require the use of an outer shell (i.e like FEATHERLITE® brand low-density urethane casting resin). The depth of the holes  701  only need to penetrate the FEATHERLITE® brand low-density urethane casting resin, or close-cell foam skin but can penetrate further into the foam. The foam has pores which may connect to the holes  701 . An open cell foam used for the solid preform  304 D may not require any holes  701  in some instances. 
     The outer surface of the solid preform  304 D may be sanded and finished to the desired internal dimension that may be used for the self sealing volume  100  once formed, as understood by one of ordinary skill in the art. “Finished,” as described herein, means to sand and smooth so as to remove cracks, seams and imperfections as understood by one of ordinary skill in the art. 
     Referring now to FIG.  7 B 1 , this figure illustrates a cross-sectional view of a solid mold  400 G,  400 H for forming a gas-impermeable, hollow preform  304 C according to an exemplary embodiment. This solid mold  400 G,  400 H is “solid” in the sense that its walls may comprise a solid material. However, the solid mold  400 G,  400 H may comprise a hollow interior  400 Z so that a hollow type preform  304 C (SEE FIG.  7 B 5 ) may be generated. The solid molds  400 G and  400 H are part of the submethod  502 B described below in  FIG. 9 . Submethod  502 B may comprise a form of roto casting (also known as rotacasting) as understood by one of ordinary skill in the art. Such rotacasting may use self-curing resins in unheated molds, and may share slow rotational speeds that are in common with rotational molding. 
     Similar to the exemplary embodiment illustrated in  FIG. 7A , a portion, such as one half, of the solid mold  400 G,  400 H may comprise an opening  405  for receiving the fixture  507  (described above). The solid mold  400 G,  400 H may be made from materials such as metal, composites, etc. which can withstand curing temperatures for the hollow preform  304 C (illustrated in FIGS.  7 B 5 ,  7 B 6 ). 
     FIG.  7 B 2  is a cross-sectional view of the solid mold  400 G,  400 H of B 1  with a fixture  507  attached to a side  400 G of the solid mold having an opening  405  according to an exemplary embodiment. The fixture  507  illustrated in FIG.  7 B 2  is similar to the one illustrated in  FIG. 7A . 
     FIG.  7 B 3  is a cross-sectional view of the solid mold  400 G,  400 H in which a liquid state of preform material  304 C is poured into the solid mold  400 G,  400 H via the fixture  507  according to an exemplary embodiment. The fixture  507  may receive a nozzle  503 . The nozzle  503  may dispense the liquid state of the preform material  304 C. The liquid state of the preform material  304 C may comprise a material similar to the embodiment described in  FIG. 7A . Specifically, the liquid state of the preform material  304 C may comprise equal parts of a diisocyanate such as sold under the tradename FEATHERLITE Part A and a polyol such as FEATHERLITE Part B. The amount of diisocyante used generally comprises enough to coat the mold and provide a uniform preform thickness of between about 1.0 mm to about 10.0 mm. 
     FIG.  7 B 4  is a cross-sectional view of the solid mold  400 G,  400 H containing the preform liquid material  304 C while the solid mold  400 G,  400 H is being rotated according to an exemplary embodiment. Specifically, after a requisite amount of liquid preform material  304 C is deposited in the solid mold  400 G,  400 H, the fixture  505  is sealed and the solid mold  400 G,  400 H is rotated such that the preform material  304 C cures in attaches to the inner volume of the solid mold  400 G,  400 H in order to generate a gas-impermeable, hollow type preform  304 C. The material described above for the perform  304 C generally cures at standard room temperature and pressure as understood by one of ordinary skill in the art. 
     FIG.  7 B 5  is a cross-sectional view of the solid mold  400 G,  400 H being opened after curing of the preform liquid material  304 C into a gas-impermeable, hollow preform  304 C according to an exemplary embodiment. The hollow preform  304 C retains the fixture  507  after curing. The hollow preform  304 C may have thickness which ranges between about 1.0 mm and about 10.0 mm. 
     FIG.  7 B 6  is a cross-sectional view of the gas-impermeable, hollow preform  304 C after apertures or holes  701  have been created within the preform according to an exemplary embodiment. Any number of holes  701  may be created within the hollow preform  304 C. The holes  701  may be created with machines such as, but not limited to, drills or lasers. The holes  701  may be randomly positioned or positioned at evenly spaced intervals as understood by one of ordinary skill in the art. The holes  701  will help a fluid originating from the gaseous pressure source  403  to exit the preform  304 D in order to properly inflate the release layer  302  as described above. 
     The outer surface of the hollow preform  304 C may be sanded and finished to the desired internal dimension that may be used for the self sealing volume  100  once formed, as understood by one of ordinary skill in the art. “Finished,” as described herein, means to sand and smooth so as to remove cracks, seams and imperfections as understood by one of ordinary skill in the art. 
       FIG. 7C  is a cross-sectional view of a device for forming flexible molds according to another exemplary embodiment. 
     Referring now to  FIG. 7C , this figure illustrates a cross-sectional view of a device  400 C,  400 D for forming flexible molds  400 E,  400 F according to an exemplary embodiment. This figure is similar to FIG.  7 A 1  described above. 
     The device  400 C,  400 D may comprise two flexible molds shells that are used to create flexible molds  400 E,  400 F. The flexible mold shells  400 C,  400 D may comprise a combination of convex and concave geometries. For example, see convex regions  802 A,B and concave regions  804 A,B. Additional and/or fewer convex regions  802 A,B and concave regions  804 A,B may be provided without departing from the scope of this disclosure. Further, these convex regions  802 A,B and concave regions  804 A,B may be added to all molds described in this disclosure, such as those illustrated in  FIG. 7B . 
     With the inventive wall system resulting from the molds described above, a complex three dimensional volume  200  may be generated which may or may not contain concave geometries  802 ,  804 . Meanwhile, as understood by one of ordinary skill in the art, conventional and prior art mold systems may only produce convex geometries and not concave geometries as described above and illustrated in  FIG. 7C . Conventional and prior art mold systems usually cannot produce concave geometries and/or a combination of convex and concave geometries in a final product, such as a self-sealing volume. 
       FIG. 8  is a flowchart  502 A illustrating a routine or submethod  502 A for generating the solid preform  304 D of  FIG. 7A  according to an exemplary embodiment. Block  702  is the first step of routine  502 A. This routine  502 A corresponds with routine  502  described above in connection with  FIG. 5A . As mentioned previously, routine  502  of  FIG. 5A  may have at least two different paths or methods, such as illustrated in  FIG. 8  and  FIG. 9 . 
     In block  702  of  FIG. 8 , a flexible, reusable mold  400 E,  400 F as illustrated in FIGS.  7 A 1 -A 3  is created. The flexible, reusable mold  400 E,  400 F may be created with the use of supports or mold forms  400 C,  400 D as set forth in FIG.  7 A 1 . The flexible, reusable mold  400 E,  400 F, once created, may be used to generate a preform  304 . 
     In block  704 , the flexible, reusable mold  400 E,  400 F is removed from supports  400 C,  400 D as illustrated in FIG.  7 A 2 . In block  706 , a fixture  507  may be positioned within an aperture  405  of a portion of the flexible, reusable mold  400 E,  400 F, such as in flexible mold  400 F as illustrated in FIG.  7 A 3 . The fixture  507  is positioned before the material for the preform  304 B hardens. 
     In block  708 , the material for the preform  304  is cast into the flexible, reusable mold  400 E,  400 F such as illustrated in FIG.  7 A 3 . In block  710 , the hardened preform materials forming preform sections  304 A,  304 B may be removed from the flexible and reusable mold  400 E,  400 F as illustrated in FIG.  7 A 4 . Next, in block  712 , the preform sections  304 A,  304 B may be fitted together and coupled permanently with the use of adhesives as illustrated in FIG.  7 A 5 . 
     In optional block  714 , the outside of or external layer of the preform  304 D may be coated with a thermoset layer as illustrated in FIG.  7 A 5  with the nozzle  707  dispersing a coating. Next, in block  716 , the preform  304 D may be adjusted to precise dimensions that will correspond to the self-contained volume  100  described above. Specifically, in this block  716 , adjusting may include sanding, buffing, cutting, shaving, and the like, to the preform  304 D. Subsequently, in block  716 , apertures/holes  701  may be created within the solid, gas-permeable preform  304 D. The process then returns to block  505  of  FIG. 5A . 
       FIG. 9  is a flowchart illustrating a routine or submethod for generating the hollow preform  304 C of  FIG. 7B  according to an exemplary embodiment. Block  703  is the first step of routine  502 B. This routine  502 B corresponds with routine  502  described above in connection with  FIG. 5A . As mentioned previously, routine  502  of  FIG. 5A  may have at least two different paths or methods, such as illustrated in  FIG. 8  and  FIG. 9 . 
     In block  703  of  FIG. 9 , the reusable mold  400 G,  400 H such as illustrated in FIG.  7 B 1  may be assembled/prepared. This reusable mold  400 G,  400 H may produce hollow performs  304 C as described above. 
     In block  705 , a fixture  507  may be positioned within the reusable mold  400 G,  400 H. Specifically, one section  400 G of the reusable mold  400 G,  400 H may have an aperture for receiving a fixture  507 . 
     In block  707 , preform material  304 C may be poured in a liquid state from a nozzle  509  to the inside of the reusable mold  400 G,  400 H such as illustrated in FIG.  7 B 3 . Next, in block  709 , the reusable mold  400 G,  400 H may be sealed and then rotated in three dimensions while the liquid preform material  304 C cures against the inside or internal wall of the reusable mold  400 G,  400 H. 
     In block  711 , the hollow, gas-permeable preform  304 C may be removed from the reusable mold  400 G,  400 H. The hollow gas-impermeable preform  304 C may be adjusted to precise dimensions corresponding to the self-contained volume  100 . Specifically, in this block  711 , adjusting may include sanding, buffing, cutting, shaving, and the like, to the preform  304 C. Subsequently, in block  713 , apertures/holes  701  may be created within the hollow, gas-impermeable preform  304 D. The process then returns to block  505  of  FIG. 5A . 
     Elastomeric Material  102 —Example 1 
     39 parts of a polyester polyol such as Baytec GSV 85A (which is a 2,000-molecular-weight polyethylene/polybutylene adipate diol) having a hydroxyl number of 55 were premixed with a 5 parts of butane diol at a temperature of about 50° C. To this polyol mixture, 100 parts of a polyester pre-polymer such as Baytec  242  (which is a modified diphenylmethane diisocyanate (MDI)-terminated polyester prepolymer), was added at a temperature of about 50° C. and mixed. The resulting polyurethane reaction mixture  102 D was spread onto a foam polyurethane preform  304  that had been previously coated with a layer  302  of Smooth On EZ Spray SILICONE® 20 silicone (which is a 20 Shore A silicone elastomer) and a layer of inner liner  202  made from a polysulfide such as PRC Rapid Seal 655 aliphatic polysulfide sold by PRC-DeSoto International, Inc. 
     Next about a 24 oz NYLON fabric  104 B that had been previously coated and dried with a solvated polyurethane, namely Estane  5714 , an aliphatic polyurethane, or a polyether type thermoplastic polyurethane, was placed on the preform  304 . This was followed by another layer of the same polyurethane reaction mixture  102 C. Next, a layer of partially vulcanized natural rubber having less than about 1% sulfur, forming the sealant layer  106  was applied followed by adding another layer of the same polyurethane reaction mixture  102 B. Subsequently, a layer of polyurethane coated 24 oz NYLON fabric  104 A and a final layer of the same polyurethane reaction mixture  102 A were applied. 
     The resulting “wet” composite of intermediate fuel tank  300  was rotated and turned until the polyurethane reaction mixture layers  102  cooled to yield a tacky but intractable coating. At this stage, the fuel tank was placed in one half of a three dimensional mold  400 . The second half  400 A of the mold was closed onto the first half  400 B and the fuel tank  300 A,  300 B was cured for at least about 90.0 minutes at a temperature of about 120° C. and an air pressure of about 20 psi from the gaseous pressure source  403 . 
     Elastomeric Material  102 —Example 2 
     39 parts of a polyester polyol such as Baytec GSV 85A (which is a 2,000-molecular-weight polyethylene/polybutylene adipate diol) having a hydroxyl number of 55 were premixed with a 4 parts of propane diol at a temperature of about 50° C. To this polyol mixture, 100 parts of a polyester pre-polymer such as Baytec  242  (which is a modified diphenylmethane diisocyanate (MDI)-terminated polyester prepolymer) were added at a temperature of about 50° C. and mixed. The resulting polyurethane reaction mixture  102 D was spread onto a foam polyurethane preform  304  that had been previously coated with a layer  302  of Smooth On EZ Spray SILICONE® 20 silicone (which is a 20 Shore A silicone elastomer) and a layer of inner liner  202  made from a polysulfide, such as PRC Rapid Seal 655 aliphatic polysulfide sold by PRC-DeSoto International, Inc. 
     Next, about a 24 oz NYLON fabric  104 B that had been previously dried and coated with a solvated polyurethane, namely Estane  5714 , an aliphatic polyurethane, or a polyether type thermoplastic polyurethane, was placed on the preform  304 . This was followed by adding another layer of the same polyurethane reaction mixture  102 C. Subsequently, a layer of partially vulcanized natural rubber having less than about 1% sulfur, forming sealant layer  106  was applied followed by another layer of the same polyurethane reaction mixture  102 B. Subsequently, a layer of polyurethane coated 24 oz NYLON fabric  104 A and a final layer of the same polyurethane reaction mixture  102 A were applied. 
     The resulting “wet” composite of intermediate fuel tank  300  was rotated and turned until the polyurethane reaction mixture layers  102  cooled to yield a tacky but intractable coating. At this stage, the fuel tank was placed in one half of a three dimensional mold  400 . The second half  400 A of the mold was closed onto the first half  400 B and the fuel tank  300 A,  300 B was cured for at least about 90.0 minutes at a temperature of about 120° C. and an air pressure of about 20 psi from the gaseous pressure source  403 . 
     Elastomeric Material  102 —Example 3 
     15 parts of a polyester polyol such as Baytec GSV 85A (which is a 2,000-molecular-weight polyethylene/polybutylene adipate diol) having a hydroxyl number of 55 were premixed with a 6 parts of butane diol at a temperature of about 50° C. To this polyol mixture, 100 parts of a polyester pre-polymer such as Baytec  242  (which is a modified diphenylmethane diisocyanate (MDI)-terminated polyester prepolymer) was added at a temperature of about 50° C. and mixed. The resulting polyurethane reaction mixture  102 D was spread onto a foam polyurethane preform  304  that had been previously coated with a layer  302  of Smooth On EZ Spray SILICONE® 20 silicone (which is a 20 Shore A silicone elastomer) and a layer of inner liner  202  made from a polysulfide, such as PRC Rapid Seal 655 aliphatic polysulfide sold by PRC-DeSoto International, Inc. Next, about a 24 oz NYLON fabric  104 B that had been previously dried and coated with a solvated polyurethane, namely Estane  5714 , an aliphatic polyurethane, or a polyether type thermoplastic polyurethane, was placed on the preform  304 . 
     This was followed by adding another layer of the same polyurethane reaction mixture  102 C. Next, a layer of partially vulcanized natural rubber having less than about 1% sulfur, forming sealant layer  106  was applied followed by another layer of the same polyurethane reaction mixture  102 B. Subsequently, a layer of polyurethane coated 24 oz NYLON fabric  104 A and a final layer of the same polyurethane reaction mixture  102 A were applied. 
     The resulting “wet” composite of intermediate fuel tank  300  was rotated and turned until the polyurethane reaction mixture layers  102  cooled to yield a tacky but intractable coating. At this stage, the fuel tank was placed in one half of a three dimensional mold  400 . The second half  400 A of the mold was closed onto the first half  400 B and the fuel tank  300 A,  300 B was cured for at least about 90.0 minutes at a temperature of about 120° C. and an air pressure of about 20 psi from the gaseous pressure source  403 . 
     Elastomeric Material  102 —Example 4 
     39 parts of a polyester polyol such as Baytec GSV 85A (which is a 2,000-molecular-weight polyethylene/polybutylene adipate diol) having a hydroxyl number of 55 were premixed with a 4 parts of butane diol and 1.4 parts of an Alkoxylated trimethylolpropanesuch as Curene 93 (which is an ethoxylated trimethylol propane with a hydroxyl number of 610) at a temperature of about 50° C. To this polyol mixture, 100 parts of a polyester pre-polymer such as Baytec  242  (which is a modified diphenylmethane diisocyanate (MDI)-terminated polyester prepolymer) were added at a temperature of about 50° C. and mixed. 
     The resulting polyurethane reaction mixture  102 D was spread onto a foam polyurethane preform  304  that had been previously coated with a layer  302  of Smooth On EZ Spray SILICONE® 20 silicone (which is a 20 Shore A silicone elastomer) and a layer of inner liner  202  made from a polysulfide such as PRC Rapid Seal 655 aliphatic polysulfide sold by PRC-DeSoto International, Inc. Next, about a 24 oz NYLON fabric  104 B that had been previously dried and coated with a solvated polyurethane, namely Estane  5714 , an aliphatic polyurethane, or a polyether type thermoplastic polyurethane, was placed on the preform  304 . 
     This was followed by adding another layer of the same polyurethane reaction mixture  102 C. Next, a layer of partially vulcanized natural rubber having about forming sealant layer  106  was applied followed by another layer of the same polyurethane reaction mixture  102 B. Subsequently, a layer of polyurethane coated 24 oz NYLON fabric  104 A and a final layer of the same polyurethane reaction mixture  102 A were applied. 
     The resulting “wet” composite of intermediate fuel tank  300  was rotated and turned until the polyurethane reaction mixture layers  102  cooled to yield a tacky but intractable coating. At this stage, the fuel tank was placed in one half of a three dimensional clam shell mold  400 . The second half  400 A of the mold was closed onto the first half  400 B and the fuel tank  300 A,  300 B was cured for at least about 90.0 minutes at a temperature of about 120° C. and an air pressure of about 20 psi from the gaseous pressure source  403 . 
     Elastomeric Material  102 —Example 5 
     39 parts of a polyester polyol such as Baytec GSV 85A (which is a 2,000-molecular-weight polyethylene/polybutylene adipate diol) having a hydroxyl number of 55 were premixed with a 4 parts of butane diol, 1.4 parts of an ethoxylated trimethylol propane with a hydroxyl number of 610 (available under the tradename Curene 93 by Anderson Development Company of Adrian, Mich.) and 1.3 parts of trimethylolpropane monoallyl ether with a hydroxyl number of 640 at a temperature of about 50° C. To this polyol mixture, 100 parts of a polyester pre-polymer such as Baytec  242  (which is a modified diphenylmethane diisocyanate (MDI)-terminated polyester prepolymer) was added at a temperature of about 50° C. and mixed. 
     The resulting polyurethane reaction mixture  102 D was spread onto a foam polyurethane preform  304  that had been previously coated with a layer  302  of Smooth On EZ Spray SILICONE® 20 silicone (which is a 20 Shore A silicone elastomer) and a layer of inner liner  202  made from a polysulfide, such as PRC Rapid Seal 655 aliphatic polysulfide sold by PRC-DeSoto International, Inc. Next, about a 24 oz NYLON fabric  104 B that had been previously dried and coated with a solvated polyurethane, namely Estane  5714 , an aliphatic polyurethane, or a polyether type thermoplastic polyurethane, was placed on the preform  304 . 
     This was followed by adding another layer of the same polyurethane reaction mixture  102 C. Next, a layer of partially vulcanized natural rubber having about less than 1% sulfur, forming sealant layer  106  was applied followed by another layer of the same polyurethane reaction mixture  102 B. Subsequently, a layer of polyurethane coated 24 oz NYLON fabric  104 A and a final layer of the same polyurethane reaction mixture  102 A were applied. 
     The resulting “wet” composite of intermediate fuel tank  300  was rotated and turned until the polyurethane reaction mixture layers  102  cooled to yield a tacky but intractable coating. At this stage, the fuel tank was placed in one half of a three dimensional mold  400 . The second half  400 A of the mold was closed onto the first half  400 B and the fuel tank  300 A,  300 B was cured for at least about 90.0 minutes at a temperature of about 120° C. and an air pressure of about 20 psi from the gaseous pressure source  403 . 
     The measurements below Table 1 listed below show the difference between the system  200 /method  500  and a conventional method for forming self-sealing volumes. While the self-sealing volumes formed by the inventive system/method and the conventional method had different shapes relative to each other, their dimensions demonstrate some significant advantages with the inventive system  200  and method  500 . The outer dimensions of each volume have been compared. What this data shows is that there is more dimensional variability in the conventional method for forming a self-sealing volume compared to the inventive system  200  and method  500 . 
     The coefficient of variation (CV), a measure of the extent of variability in relation to mean of the population, is between about 0.35% and about 0.49% for the conventional method. Meanwhile, it&#39;s between about 0.072% and about 0.080% for the inventive method  500  and system  200 . Comparing this data, this is an improvement of between at least five to about six times (500-600%) with the invention. It is believed that the inflation of the wall system  200  via inflation of the mold release layer  302  against the mold  400  is at least one element which contributes to this improvement dimensional stability over the conventional art. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 CONVENTIONAL SELF SEALING VOLUME VS. INVENTIVE SELF-SEALING VOLUME 
               
             
          
           
               
                   
                   
                 CONVENTIONAL 
                   
                 SELF-SEALING  
               
               
                   
                   
                 SELF-SEALING VOLUME 
                   
                 VOLUME OF INVENTIVE SYSTEM  
               
             
          
           
               
                   
                   
                   
                 Measure- 
                 Measure- 
                   
                 200 AND METHOD 500 
               
             
          
           
               
                   
                   
                   
                 ment 1 
                 ment 2 
                   
                   
                 Measurement 1 
                 Measurement 2 
               
               
                 Meas- 
                 Date 
                 VOLUME 
                 Width 2″ 
                 Width 5″ 
                 Date 
                 VOLUME 
                 Width 2″ 
                 Width 5″ 
               
               
                 urement 
                 Measured 
                 ID 
                 from end 
                 from end 
                 Measured 
                 ID 
                 from end 
                 from end 
               
               
                   
               
             
          
           
               
                 1 
                 Sept. 10, 2012 
                 1. 
                 17.59 
                 17.48 
                 Sept. 19, 2012 
                 23. 
                 19.76 
                 19.78 
               
               
                 2 
                 Sept. 10, 2012 
                 2. 
                 17.59 
                 17.53 
                 Sept. 19, 2012 
                 24. 
                 19.8 
                 19.82 
               
               
                 3 
                 Sept. 10, 2012 
                 3. 
                 17.57 
                 17.6 
                 Sept. 19, 2012 
                 25. 
                 19.8 
                 19.81 
               
               
                 4 
                 Sept. 10, 2012 
                 4. 
                 17.52 
                 17.58 
                 Sept. 19, 2012 
                 26. 
                 19.79 
                 19.78 
               
               
                 5 
                 Sept. 10, 2012 
                 5. 
                 17.58 
                 17.5 
                 Sept. 19, 2012 
                 27. 
                 19.77 
                 19.79 
               
               
                 6 
                 Sept. 10, 2012 
                 6. 
                 17.61 
                 17.6 
                 Sept. 19, 2012 
                 28. 
                 19.8 
                 19.8 
               
               
                 7 
                 Sept. 19, 2012 
                 7. 
                 17.67 
                 17.54 
                 Sept. 19, 2012 
                 29. 
                 19.78 
                 19.79 
               
               
                 8 
                 Sept. 19, 2012 
                 8. 
                 17.65 
                 17.38 
                 Sept. 19, 2012 
                 30. 
                 19.78 
                 19.75 
               
               
                 9 
                 Sept. 19, 2012 
                 9. 
                 17.59 
                 17.4 
                 Sept. 19, 2012 
                 31. 
                 19.79 
                 19.8 
               
               
                 10 
                 Sept. 19, 2012 
                 10. 
                 17.57 
                 17.41 
                 Sept. 19, 2012 
                 32. 
                 19.8 
                 19.81 
               
               
                 11 
                 Sept. 19, 2012 
                 11. 
                 17.58 
                 17.6 
                 Sept. 19, 2012 
                 33. 
                 19.8 
                 19.79 
               
               
                 12 
                 Sept. 19, 2012 
                 12. 
                 17.62 
                 17.49 
                 Sept. 19, 2012 
                 34. 
                 19.78 
                 19.8 
               
               
                 13 
                 Sept. 20, 2012 
                 13. 
                 17.59 
                 17.46 
                 Sept. 19, 2012 
                 35. 
                 19.81 
                 19.8 
               
               
                 14 
                 Sept. 20, 2012 
                 14. 
                 17.7 
                 17.5 
                 Sept. 19, 2012 
                 36. 
                 19.8 
                 19.79 
               
               
                 15 
                 Sept. 20, 2012 
                 15. 
                 17.61 
                 17.49 
                 Sept. 19, 2012 
                 37. 
                 19.8 
                 19.8 
               
               
                 16 
                 Sept. 20, 2012 
                 16. 
                 17.67 
                 17.61 
                 Sept. 19, 2012 
                 38. 
                 19.81 
                 19.8 
               
               
                 17 
                 Sept. 20, 2012 
                 17. 
                 17.51 
                 17.59 
                   
                   
                   
                   
               
               
                 18 
                 Sept. 20, 2012 
                 18. 
                 17.45 
                 17.39 
                   
                   
                   
                   
               
               
                 19 
                 Sept. 20, 2012 
                 19. 
                 17.66 
                 17.48 
                   
                   
                   
                   
               
               
                 20 
                 Sept. 20, 2012 
                 20. 
                 17.55 
                 17.37 
                   
                   
                   
                   
               
               
                 21 
                 Sept. 20, 2012 
                 21. 
                 17.66 
                 17.39 
                   
                   
                   
                   
               
               
                 22 
                 Sept. 20, 2012 
                 22. 
                 17.68 
                 17.35 
                   
                   
                   
                   
               
               
                 Average 
                   
                   
                 17.60 
                 17.49 
                   
                   
                 19.79 
                 19.79 
               
               
                 Std Dev 
                   
                   
                 0.061 
                 0.086 
                   
                   
                 0.014 
                 0.016 
               
               
                 % CV 
                   
                   
                 0.35% 
                 0.49% 
                   
                   
                 0.072% 
                 0.080% 
               
               
                   
               
             
          
         
       
     
     Certain steps in the processes or process flows described in this specification naturally precede others for the invention to function as described. However, the invention is not limited to the order of the steps described if such order or sequence does not alter the functionality of the invention. That is, it is recognized that some steps may preformed before, after, or parallel (substantially simultaneously with) other steps without departing from the scope and spirit of the invention. 
     For example, in an alternative exemplary embodiment, the urethane reaction mixture  102  may be applied according to the following sequence: to the inner liner  202 , similar to step  525 ; then, the reaction mixture  102  may be applied to the fabric layer  104 ; then the fabric layer  104  may then be applied to the inner liner  202 , similar to step  525 ; then the reaction mixture  102  may be applied to the fabric layer  104  again; then, the sealant layer  106  may be applied, similar to step  545 ; and then, the reaction mixture  102  may be applied to a second fabric layer  104 . 
     In some instances, certain steps may be omitted or not preformed without departing from the invention. Further, words such as “thereafter”, “then”, “next”, etc. are not intended to limit the order of the steps. These words are simply used to guide the reader through the description of the exemplary method. 
     As noted previously, at least one inventive aspect of the inventive system and method is that the preform  304  is inflated during cure of the elastomeric material included in layer  100 . With this inflation of the preform  304 , the wall system  200  conforms to the exact dimensions of the mold  400  which holds the preform  304  and the wall system  200  sandwiched there between. This process yields a dimensionally correct/precisely built self-sealing volume  200 . 
     According to an additional exemplary embodiment, a first barrier layer (not illustrated) may be provided between the liner  202  and the sealant  106 . The purpose of the barrier layer is to limit the permeation of fuel  204  over time through the inner liner layer  202 , the elastomeric material layer  102 D, the fabric layer  104 B, and the elastomeric material layer  102 C. A second barrier layer, like the first barrier layer (both not illustrated) may also be provided on the exterior of the self-sealing volume  200  to also limit fuel permeation from fuel  204  that may come in contact with the volume  200 , such as through a spill or leak from another volume or source. 
     Although selected aspects have been illustrated and described in detail, it will be understood that various substitutions and alterations may be made therein without departing from the spirit and scope of the present invention, as defined by the following claims.