Patent Publication Number: US-2019168961-A1

Title: Containers for transporting and disposing of recalled airbag inflators

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This nonprovisional patent application is a continuation of U.S. patent application Ser. No. 15/360,910, entitled (“Transporting and Disposing Recalled Airbag Inflators”) and filed on Nov. 23, 2016. This application claims priority to U.S. patent application Ser. No. 15,360,910, which claims priority to U.S. provisional patent application No. 62/336,558 (“Process and Apparatus for Transportation and Disposal of Recalled Airbag Inflators”), filed May 13, 2016, and further claims priority to U.S. provisional application No. 62/401,142, filed Sep. 28, 2016, all of which are incorporated by reference in their entireties. 
    
    
     FIELD OF THE EMBODIMENTS 
     The embodiments described herein related to transporting and disposing of recalled airbag inflators using ammonium nitrate propellant, and specifically barrels constructed and used for doing so. 
     BACKGROUND 
     Airbags for passenger vehicles commonly use an “inflator” to inflate the airbag in case of an emergency. A typical inflator includes an ignitor and a propellant that inflates an airbag in the event of a vehicle crash. One of the world&#39;s largest airbag suppliers—Takata®—has produced a large number of defective airbag inflators. As of November 2016, over 100 million Takata® inflators have been recalled worldwide. The scale of this recall has introduced safety, logistical, and environmental challenges involved with transporting and disposing of explosive and unstable airbag inflators. 
     The defective inflators use ammonium nitrate (“AN”) propellant. While designed to deploy upon receiving an electrical current at the inflator&#39;s initiator pins, the defective inflators can also deploy with exposure to an external heat source such as fire. According to news sources, the current, unregulated process of transporting recalled Takata® airbags has already caused at least 16 deaths. As a result, a comprehensive protocol for ensuring safe transport and disposal of recalled inflators is needed. 
     To gain approval for shipping on U.S. roads, all production automotive airbag inflators and energetic assemblies, such as seat belt pre-tensioners, are subjected to a Department of Transportation (“DOT”) “bonfire” test. Europe&#39;s DOT equivalent, BAM, requires a similar “gas burner” test. Both the DOT and BAM tests involve exposing airbag inflators to an open-flame heat source sufficient to cause auto ignition of the inflator&#39;s main generant bed. To pass the test and be approved for shipping, an inflator must function without fragmenting due to the external heat source. Bonfire testing is the most rigorous structural test of an AN-based inflator design because ammonium nitrate propellant can melt before it burns, resulting in conditions inside the inflator that amplify challenges of ensuring the design does not fail structurally during the open flame deployment scenario. 
     The U.S. government, and other governments around the world, will likely classify AN-based airbag inflators as explosives or change the existing classification for recalled inflators. That new classification (or reclassification) would prevent traditional shipping methods from being used to transport these inflators. AN-based airbag inflators that are known to fragment due to over pressurization of the inflator&#39;s pressure vessel housing during normal deployment conditions at ambient outside temperature are generally expected to fail at a higher rate (or are more likely to fail) when exposed to an external heat source such as DOT Bonfire testing. An inflator sample population that exhibits any structural failures when deployed at ambient temperature is likely to exhibit a significantly higher rate of structural failure when an external heat source causes the inflator to deploy. This is because operating pressure of the inflator&#39;s internal combustion chamber tends to increase with temperature, while the steel pressure vessel strength decreases with temperature. This problem can become significantly worse if propellant melts. 
     Common auto-ignition materials ignite at temperatures above 130° C., which is significantly higher than any upper temperature limit the inflator design was intended to operate at during normal deployment conditions. Hence, an inflator suspected of structural failure when functioning at ambient temperature has an increasing likelihood of structural failure as temperature increases. Defective AN-based Takata® inflators can fragment even at ambient outside temperatures. Thus, they are expected to fragment more frequently if exposed to an external fire such as the DOT Bonfire test. These defective inflators are therefore not fit to be shipped using traditional methods used for non-defective inflators. 
     Currently, these recalled inflators are being shipped in steel drums with lids secured with tape, or in cardboard boxes, depending on the relevant state laws. These state laws have proven ineffective, as illustrated by a fatal explosion of a truck transporting recalled Takata® inflators in August 2016, in Texas. In some cases, specially designed thick-walled metal containers are being used to transport recalled inflators. However, these containers are expensive to build and are not suitable for mass production on the scale required for the current recalls. Lack of a common protocol at the national and global levels for the handling, packaging, storage, and shipment of inflators containing unstable ammonium-nitrate-based propellant may result in further human injury as well as economic and environmental damage. 
     As a result, a need exists for a nationally implementable, low-cost method for transporting recalled inflators. Safety concerns can be addressed with a process of modifying common containers or entire vehicles to achieve a structure and method suitable for the safe, bulk transport of recalled inflators using materials that are common across the continent, nation, or state. A method of construction and validation of the proposed shipping container designs is described for both large and small scales below. 
     SUMMARY 
     Layered mesh containers and methods of using the containers are described herein for safely transporting and disposing of recalled ammonium-nitrate-based airbag inflators. In one example, a method is provided for loading the inflators into a container having mesh layers and transporting the container to a disposal site. The method can include, for example, placing multiple airbag inflators in the container. The container can withstand a deployment of an airbag inflator that releases up to 4 moles of gas. The layers of mesh can contain the detonated airbag inflator and shrapnel associated therewith and allow gas associated with the detonation to exit the barrel. In one example, the method can include shipping the container to a deployment site, where the inflators are heated up to allow a controlled deployment. 
     The words “detonate,” “explode,” and “deploy” are used interchangeably herein, and can refer to any condition where the metal housing fragments or fails, and/or propellant exits the body of the inflator, either intentionally or unintentionally. The propellant, along with any other chemicals or substances within the housing of an airbag inflate, can be collectively referred to as “energetics” or “energetic material.” 
     The method can further include positioning the container in or on a transport vehicle. For example, the method can include using a forklift to lift the container from a first location and place the container in the bed of a truck. In some examples, the container can be placed in a construction-grade vehicle such as a dump truck. This portion of the method can also apply to vehicles other than road-going vehicles, such as ships or planes. In one example, the method includes placing the container in an intermodal shipping container which is then place on a truck or ship. 
     The method can also include measuring a first weight of the container including the live airbag inflator. The method can further include applying heat to the container sufficient to deploy the live airbag inflator. In some examples, this includes heating the container such that the inflators reach a core temperature of at least 130 degrees Celsius. In some examples, the container is heated such that the inflators reach a core temperatures of at least 180 degrees Celsius. This can include, for example, heating the container via convection, conduction, or radiation. In order to ensure complete disposal of an inflator, the inflator must reach auto-ignition temperature. The main generate bed of an inflator will typically automatically ignite at temperatures between 130 and 185 degrees Celsius. Therefore, in some examples, the inflators are heated to a temperature of about 200 degrees Celsius to ensure ignition. 
     A second weight of the container can be measured after applying the heat. Based on initial information such as the weight of the container and the number of inflators in the container, the difference between the weights can inform whether the inflators deploy, and if so, how many deployed. Based on the difference being above a threshold value, the deployed inflator(s) can be removed from the container. 
     In one example, a temperature sensor can be used to measure the temperature of an inflator in the container. In another example, the container is placed inside a disposal container prior to heating the container. The disposal container can be heated in addition to heating the container. 
     The container can take a variety of different forms. In one example, the container includes multiple lattices coupled to one another to form an enclosure. The enclosure can be shaped to contain multiple airbag inflators. At least one of the lattices can be coupled to another lattice via a rotatable coupling that allows a user to open and close the container. Each lattice can be strong enough to withstand deployment of one or more airbag inflators without substantial deformation of the lattice. Substantial deformation can include, for example, deformation sufficient to compromise the structural integrity of the lattice or otherwise allow any solid portion of the airbag inflators to exit the enclosure upon deployment. The lattices can be made from metal strands having sufficient thickness to provide the desired strength. For example, each strand can have a thickness of between about 0.04 inches and 1 inch. 
     Continuing the example, the container can include a mesh layer positioned on an inner surface of at least one of the lattices. In some examples, the mesh layer can be positioned on inner surfaces of all the lattices making up the enclosure. The term “surface” is used broadly, as the lattices can be constructed from metal strands and therefore not have a continuous inner or outer surface. However, the inner and outer sides of the plane formed by the lattice can be considered surfaces for the purposes of this disclosure. 
     The mesh layer can include apertures or perforations sized to allow passage of gas while preventing passage of shrapnel from a deployed airbag inflator. For example, the apertures can be sized to prevent a sphere having a diameter of at least 0.9 inches from passing through the mesh layer. The container can also include an environmental barrier layer positioned on an outer surface of at least one of the lattices. The environmental barrier layer can include a material, such as plastic or a high-temperature, fire-retardant silicone foam, that prevents moisture from passing through that lattice. In some examples, the environmental barrier can be attached in such a way that it rips or detaches from the container to allow sufficient venting in the event of an inflator deploying. 
     In another example, a container can include a cylindrical sidewall and a solid cap coupled to a first end of the cylindrical sidewall. For example, the container can include a metal barrel with one end welded closed. The container can also include a vented cap removably coupled to a second end of the cylindrical sidewall. The vented cap can be shaped to allow passage of gas through the vented cap while preventing passage of shrapnel from a deployed airbag inflator. For example, the vented cap can include apertures sized to allow passage of gas but not shrapnel. 
     Continuing the example, the container can include a baffle positioned to redirect shrapnel from a deployed inflator away from the vented cap. The baffle can include, for example, one or more metal plates positioned near the vented cap. The baffle can be coupled to the cylindrical sidewall or to the vented cap. An environmental barrier can be coupled to the vented cap to prevent moisture from penetrating the container. 
     In yet another example, a container can include multiple solid metal sidewalls coupled to one another. In that example, at least one side of the container can include a lattice or grate that allows passage of gas but retains the inflators and any shrapnel associated with a deployed inflator. At least one of the solid metal sidewalls can be rotatably coupled to another sidewall such that a user can open and close the container. 
     A detailed description of these examples, and other examples, is provided below. Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to restrict the scope of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate various embodiments and aspects of the present invention. In the drawings: 
         FIG. 1  is an illustration of an example container for safely transporting and/or disposing of airbag inflators. 
         FIG. 2  is an illustration of an example container lid that includes a baffle built into the lid. 
         FIG. 2A  is a cross-sectional view of the example container lid of  FIG. 2 . 
         FIG. 3  is a diagram of an example container including a baffle and showing example travel paths of shrapnel and gas from a deployed inflator. 
         FIG. 4  is an illustration of an example container including an outer structural lattice and example inner mesh layers. 
         FIG. 4A  is an expanded view of an example inner mesh layer of  FIG. 4 . 
         FIG. 4B  is an expanded view of an example inner mesh layer of  FIG. 4 . 
         FIG. 4C  is an expanded view of an example inner mesh layer of  FIG. 4 . 
         FIG. 5  is an illustration of an example container with multiple solid sides and a grate that allows gas to escape the container. 
         FIG. 6  is an illustration of an example container inside a disposal container, showing the path for gases to escape both containers. 
         FIG. 7  is a diagram of an example system for disposing of airbag inflators and extracting power from the gases expelled from the inflators. 
         FIG. 8  is a flowchart of an example method for handling airbag inflators. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present exemplary embodiments, including examples illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     This disclosure describes a variety of containers that can be used to safely transport or dispose of airbag inflators. While these containers, and the methods of using them, can be applied to any type of airbag inflators, they are also intended to safely handle recalled airbag inflators produced by Takata®. Due to manufacturing defects, these recalled inflators have an increased likelihood of exploding when subjected to heat. References to “inflators” or “airbag inflators” herein are also assumed to encompass the recalled defective inflators from Takata®. 
     The containers described herein can be used for transporting inflators, disposing of inflators, or both. During the transportation stage, a container should provide safety from explosions while also aiding a user in filling the container, locking the container, and loading or unloading the container on or off a vehicle. Of course, the container must also be able to withstand forces generated from structural failure of inflator housings inside the container while venting gases appropriately. 
     At the disposal stage, a container can be used to intentionally deploy inflators by applying heat, such as fire, to the container. In the disposal process, the container might experience high temperatures and/or come in direct contact with an open flame. The container should be able to withstand these temperatures while still retaining all shrapnel related to inflator deployment and venting gases appropriately. Ideally, the container should be reusable. In some examples, the container can be used both for transportation and disposal, improving efficiency of the overall recall process. 
     Containers can come in a wide range of sizes. On the small end of the spectrum, a container can be sized to hold a single inflator. On the other hand, a container can be sized to occupy the bed of a dump truck or a large, intermodal shipping container. In some examples, a container can be sized between these two extremes, such that the containers can be easily moved while also holding a moderate number of inflators. For example, a container can be sized to accommodate a forklift, allowing a forklift operator to handle the containers without getting closer than necessary. 
     Due to the extent of the Takata® recall, many containers may need to be constructed. To keep costs low, these containers can be constructed from readily available materials. For example,  FIG. 1  shows a container  100  that is based on a commonly available steel drum. That drum, denoted cylinder  110  in  FIG. 1 , can include a cylindrical sidewall as well as a solid cap coupled to the bottom end of the cylinder  110 . As shown in the drawing, the cylindrical sidewall need not be a perfectly shaped cylinder. Instead, it can include structural ridges, a lip at the top and bottom, and other variations. Although cylinders provide more strength per volume, other shapes can be used as well, such as a rectangle. The cylinder  110  can be made from a heavy gauge steel, such as 16-Ga or thicker. 
     The container  100  of  FIG. 1  also includes a shrapnel barrier  120 . The shrapnel barrier  120  can be constructed such that shrapnel from a deployed inflator cannot pass through the barrier, while gases emitted from the deployed inflator can pass through. For example, the shrapnel barrier  120  can include a mesh, screen, grate, fencing, or lattice sized to accomplish these goals. In another example, the shrapnel barrier  120  can be a solid plate with apertures that accomplish the same goals. In either case, the shrapnel barrier  120  can include openings—such as an aperture or a space between four strands of a mesh—that are one square in or smaller. In some examples, shrapnel barrier  120  includes openings that are 0.5 square inches or smaller. In other examples, shrapnel barrier  120  includes openings that are 0.25 square inches or smaller. 
     Shrapnel barrier  120  can be made from a resilient material, such as steel, to ensure that deployed inflators and the resulting shrapnel does not damage the shrapnel barrier  120  and form larger openings that can allow shrapnel to pass through. The shrapnel barrier  120  can be a removable component, as shown in  FIG. 1 , or can be part of the cylinder  110  or the lid  130 . For example, the shrapnel barrier  120  can be welded to the top of the cylinder  110 . In that case, the cylinder  110  can include a door on the side for loading and unloading the container. 
       FIG. 1  also shows a lid  130  that can be removably or rotatably coupled to the cylinder  110  and/or shrapnel barrier  120 . For example, the lid  130  can be secured to the cylinder  110  via a hinge joint  132  and a latching mechanism. The hinge joint  132  can be coupled to the cylinder  110 , such as by welding, to ensure that the lid  130  stays attached to the cylinder  110 . The latching mechanism can include a component attached to the cylinder  110  and an associated component attached to the lid  130 . These two components can interact to form a latching mechanism. Alternatively, those components can be integrally formed into the cylinder  110  and lid  130 , respectively. 
     The lid  130  can include openings  134  to allow gases to vent from the cylinder  110 . For example, the lid  130  can be made from one or more solid pieces of steel with multiple apertures formed in the lid  130 . In one example, the lid  130  includes apertures formed by drilling. In another example, the lid  130  includes apertures punched through the lid  130 . In yet another example, the lid  130  includes a mesh portion that allows gas to vent. The mesh portion can include, for example, a section of a chain-link fence. 
     When used with a shrapnel barrier  120 , the openings  134  in the lid  130  can be larger than the openings in the shrapnel barrier  120 . For example, the openings  134  in the lid  130  can be between about 0.5 to about 8 square inches. The total surface area of the openings  134  in the lid  130  should be sufficient to allow gas to flow through at a rate that prevents unwanted pressure build-up in the container  100 . In some examples, the total surface area of the openings  134  in the lid  130  is equal to, or greater than, the total surface area of the openings  134  in the shrapnel barrier  120 . 
     The container  110  can also include an environmental barrier  140 . The environmental barrier  140  can be made from a moisture-impermeable material, such as a plastic sheet. The environmental barrier  140  can be sized to cover the lid  130  and/or shrapnel barrier  120 , preventing moisture from entering the openings in the lid  130  and/or shrapnel barrier  120 . The environmental barrier  140  can be secured to the container  100  using, for example, a band  150  as shown in  FIG. 1 . The band  150  can be sized such that it stretches to fit around the cylinder  110 , with the environmental barrier  140  under the band  150 . The tension in the band  150  can keep the environmental barrier  140  in place. Other mechanisms can hold the environmental barrier  140  in place, such as attaching the barrier  140  to a hook attached to the cylinder  110 . 
     The environmental barrier  140  can be designed and attached such that it prevents moisture from entering the container  100  when attached, but also allows gas to vent from the container  100  in the event of a deployment. In one example, the band  150  maintains tension sufficient to hold the environmental barrier  140  in place under normal circumstances, but allows the environmental barrier  140  to release when subjected to a high-pressure event such as an airbag inflator deployment. For example, when an airbag deflator explodes, the resulting pressure can force at least a portion of the environmental barrier  140  to release from under the band  150 , allowing the gas to escape. In another example, the pressure due to a deployment can cause the environmental barrier  140  to rip. This can provide a visual cue to determine whether any inflators in a container  100  have deployed. 
       FIG. 2  provides an illustration of an example lid  200  that includes a baffle built into the lid  200 . The lid  200  of  FIG. 2  can be used with the container  100  of  FIG. 1 , or any other cylindrical-shaped container. The lid  200  can be secured to a container using the mounts  240 . In one example, the mounts  240  can include removable pins that can interface with both the container and the lid  200 . In another example, one mount  240  is a hinge mount coupled to both the container and the lid  200 , allowing the lid  200  to rotate about the hinge for opening and closing the container. In that example, the other mount  240  can include a locking mechanism. 
     The lid  200  can also include an upper baffle plate  220  and a lower baffle plate  230 . The baffle plates  220 ,  230  can be oriented such that shrapnel from a deployment within the container is unlikely to escape. As shown in  FIG. 2A , the lower baffle plate  230  can be oriented such that it is perpendicular to a longitudinal axis of the container (not shown). Shrapnel traveling in a direction parallel to the longitudinal axis of the container would likely contact the lower baffle plate  230  and be redirected back down. Some shrapnel traveling parallel to the longitudinal axis can miss the lower baffle plate  230  and instead contact the upper baffle plate  220 . However, the upper baffle plate  220  is also oriented perpendicular to the longitudinal axis, which would therefore redirect shrapnel back down into the container. 
     If shrapnel enters the space between the upper and lower baffle plates  220 ,  230  traveling in a trajectory that is not parallel with the longitudinal axis of the container, a grate  250  oriented between the baffle plates  220 ,  230  can block the shrapnel from passing through the lid  200 . The grate  250  can be any type of material that blocks shrapnel but allows gas to pass through. For example, the grate  250  can be a wire mesh, a metal plate with openings in it, parallel slats, chain-link fencing, or any other suitable material. The openings in the grate  250  can be less one square inch in one example. In another example, the openings in the grate  250  can be greater than one square inch, but less than half an inch wide at any point. 
       FIG. 3  provides a diagram of a container  300  experiencing an airbag-inflator deployment. The container  300  can be a cylinder, rectangle, or any other shape. In this example, the container  300  includes an upper baffle  310  and a lower baffle  320  built into the container  300  itself. Because the baffles  310 ,  320  are integrated with the container  300 , the container  300  includes a door  330  that provides access to the interior of the container  300 . To load or unload the container, a user can open the door  330  via the handle  335  and access the interior of the container  300 . 
     In the example of  FIG. 3 , the container  300  includes five inflators  340 . A container  300  can be sized to hold more than five inflators  340 , however, and this quantity is merely chosen as one example. In practice, a particular container design can be tested to establish a “containable load” for the container. For example, the container can be subjected to the “DOT Bonfire” test (also known as the “UN6(c) Bonfire Test”) with a single inflator, then two inflators, and so on, until the container is unable to perform suitably. After establishing the maximum inflator load that a container can handle, a safety factor can be applied to establish a containable load. For example, 80% of the maximum can be used to establish a containable load. In that example, a container design that can contain up to 20 inflators in a DOT Bonfire test would have a containable load of 16 inflators. 
     In the example of  FIG. 3 , one of the five inflators  340  has deployed. The deployment has ejected several pieces of shrapnel  345  from the inflator  340 . In practice, the size, number, and makeup of the shrapnel  345  can vary greatly from one deployment to the next. In some cases, the inflator  340  itself may propel itself in various directions as the propellant escapes the body of the inflator  340 . As shown in  FIG. 3 , the shrapnel  345  impacts the sidewalls of the container  300  as well as the upper and lower baffles  310 ,  320  of the container  300 . In each case, the shrapnel is redirected from the wall or baffle back into the container  300 . 
     Meanwhile, gases  350  expelled from the deployed inflator  340  can travel between the upper and lower baffles  310 ,  320  of the container and escape into the atmosphere. The distance between the upper and lower baffles  310 ,  320  can be optimized to provide the smallest opening without unduly restricting the flow of gas  350 . This size can depend on the containable load for the container  300 , as a larger containable load will require a larger exit port for gases  350 . In practice, the baffles  310 ,  320  can be oriented such that they allow sufficient venting for a deployed containable load while maintaining the smallest opening possible. Additionally, the lengths of the baffles  310 ,  320  can be optimized to reduce the chance of shrapnel  345  exiting the container  300  while still allowing gas  350  flow. For example, the overlapping portions of the upper and lower baffles  310 ,  320  can be increased or decreased relative to the overlap shown in  FIG. 3 . 
       FIG. 4  provides an illustration of an example container  400 . The container  400  of  FIG. 4  includes a lattice structure forming a rectangular box. For example, the container  400  includes multiple sidewall lattices  410 , a rotatable top lattice  430 , and a rotatable front lattice  420 . While this example depicts both the top and front lattices  430 ,  420  as rotatable, the container  400  can also have only one of those lattices rotatable while the other is fixed. However, having both lattices  430 ,  420  rotatable provides a larger opening for loading and unloading the container  400 . The top and front lattices  430 ,  420  can include a locking mechanism that locks the lattice structure  410 ,  420 ,  430  together. 
     The lattices can be constructed from wire mesh, such as a metal wire or fencing. The thickness of the wire can be between about 0.09 inches and 0.6 inches, in one example. The openings in the lattice structure can be sized such that a sphere having a diameter greater than 0.5 inches would not fit through the openings. Other sizes can be used as well. If the lattice structure has openings that are small enough, then an inner mesh layer is not necessary. 
     In the example of  FIG. 4 , however, various inner mesh layers  440 ,  450 , and  460  are shown. Mesh layer  440  is shown in greater detail in  FIG. 4C , mesh layer  450  is shown in greater detail in  FIG. 4B , and mesh layer  460  is shown in greater detail in  FIG. 4C . Although they take different shapes, each mesh layer  440 ,  450 ,  460  includes openings  442 ,  452 , and  462 , respectively, that are sized to prevent shrapnel from passing through the mesh layer while allowing gases to vent through. These openings  442 ,  452 ,  462  can be sized such that a sphere having a diameter of 0.25 inches or greater cannot pass through the mesh layer. Larger or smaller openings  442 ,  452 ,  462  can be used. Although the mesh layers  440 ,  450 ,  460  are shown as covering only a small portion of a lattice  410 , in practice a mesh layer can cover an entire lattice. In some examples, each lattice component of the container  440  includes an interior mesh layer. 
     In some examples, an environmental barrier can be used with the container  400  to prevent rain or other moisture from entering the container  400 . For example, a plastic sheet can be secured to the top of the container to prevent fluid from dropping down into the container  400  while also allowing the sides of the container  400  to vent gases. In some examples, the environmental barrier can cover multiple sides of the container  400 . The environmental barrier can be configured such that it releases from the container  400  or rips apart when deployment occurs. 
       FIG. 5  is an illustration of an example container  500  constructed from readily available materials such as steel plates and a grate. In this example, the container  500  includes four sidewalls  510  joined together via 90-degree brackets  540  and fasteners  545 . Although fasteners  545  are shown here, other methods, such as welding, could be used instead. The sidewalls  510  can be made from a strong, solid material such as a steel. Other materials can be used as well, with varying thickness based on the strength of the material. Regarding steel, an example type of steel plate that can be used for a sidewall  510  is 0.25-inch-thick 4130 steel. These types of steel plates can be purchased off the shelf in a 2-foot by 2-foot configuration, for example. 
     An example bracket  540  that can be purchased off the shelf is 90-degree-angle steel, 0.25-inch-thick, 2 feet long, and 2 inches wide and deep. The brackets  540  can be positioned such that they extend beyond the base of the sidewalls  510 , as shown in  FIG. 5 , such that the brackets  540  are the only components of the container  500  touching supporting the container  500  when positioned on flat ground. 
     A top plate  520  can be used to seal the top portion of the container  500 . The top plate  520  can be made from a similar steel plate as used for the sidewalls  510 . The top plate  520  can be coupled to one of the sidewalls  510  via a hinge joint  530 . In this example, the hinge joint  530  spans one edge of the top plate  520 , although in other examples the hinge joint  530  can be smaller, such as an embodiment using two or three hinge joints  530 . The top plate  520  can include a locking mechanism that locks the top plate to one of the sidewalls  510  when closed. 
     A grate  550  can be coupled to the sidewalls  510  via one or more brackets  540 . The grate  550  can be an off-the-shelf item, such as a 2-foot by 2-foot grate with slats having a height of 1 to 1.5 inches, width of 0.25 inches, and about 1 inch between slats. These types of grates are commonly used for roads and sidewalks, for example. Other types of grates or mesh can be used as well, such as a metal-wire mesh, chain-link fencing, or other suitable types. An additional steel plate can optionally be attached to the base of the brackets  540 , such that the container  500  is fixed on the optional steel plate and includes a gap between the optional steel plate and the grate  550 . Fixing the container  500  to the steel plate improves safety in the event of a tip-over, due to fire, explosions, or an accident involving the transport vehicle. 
     When deployment occurs within the container  500  of  FIG. 5 , gas can escape through the grate  550  of the container  500 . In some examples, the grate  550  can be sized such that no shrapnel can pass through the grate  550 . In other examples, the grate  550  can be sized to allow small shrapnel pieces to pass through the grate  550 . However, because the grate  550  is at the bottom of the container  500 , the shrapnel would do minimal damage, especially when the container  500  is placed on the ground or on top of a solid surface, or when the steel plate is fixed to the legs of the container below the grate. 
     In some examples, wheels can be affixed to the container  500  to allow the container  500  to be more easily moved from one location to another. For example, commonly available caster wheels can be mounted to the container  500 . In one example, metal fasteners are used to fasten the caster wheels to the container  500 . Similar wheels can be attached to any of the containers disclosed herein. 
     Although  FIG. 5  shows a container with solid sides, a solid top, and a grate on the bottom, other configuration are also possible. For example, the grate can be placed on any side of the container, or on the top of the container. In some examples, only one grate is used and the remaining surfaces are solid. In other examples, multiple grates are used and the remaining surfaces are solid. In yet other examples, all of the surfaces are solid and no grates are used. Any combination can be used based on the intended use of the container. 
       FIG. 6  provides an illustration of an example embodiment of a disposal container  600  within which the container  500  from  FIG. 5  is place. In some examples, the container  500  of  FIG. 5  can be used directly as a disposal container, for example by applying heat to the container  500  sufficient to trigger inflator deployment within the container  500 . In other examples, the container  500  can be placed within a larger disposal container  600  that can capture any shrapnel exiting the smaller container  500 . 
     As shown in  FIG. 6 , for example, the disposal container  600  can include solid walls  610 , including a base  610 , that can capture any shrapnel ejected through the grate  550  of the container  500  inside the disposal container  600 . The disposal container  600  can include a vented lid  620  that allows gases  630  from deployed inflators to exit the disposal container  600 . In some examples, the disposal container  600  can work without any lid at all, especially in cases where the container  500  inside the disposal container  600  is expected to retain shrapnel. 
     Although  FIG. 6  shows the container  500  of  FIG. 5  within the disposal container  600 , any type of container can be placed inside the disposal container  600 . For example, the containers of  FIG. 1, 3 , or  4  can be placed inside the disposal container  600 . In some examples, the disposal container  600  is sized to accommodate multiple transport containers. In that example, a single disposal container  600  can be used to “cook off” inflators within multiple transport containers. This can make the process more efficient depending on the facilities used to heat the disposal container  600 . The transport containers may also be exposed to an open, uncontained heat such as a flame for the purpose of disposing of the inflators. 
     During the disposal process, large amounts of energy can be released from inflators by the combustion of inflator propellant. A single passenger-side airbag inflator can release 4 moles of matter, in the form of gas, at temperatures in excess of 400 degrees Celsius.  FIG. 7  provides an illustration of an energy recovery system  700  that can be used to recover energy produced by inflator propellant combustion. The example of  FIG. 7  shows three of the containers  300  described with respect to  FIG. 3 . The containers  300  are placed on a heating surface  710  that can accommodate several containers  300 . Heat  720  can be applied to the heating surface  710 , or applied directly to the containers  300  in some examples. In one example the heating surface  710  can be a large grate that allows flames  720  to pass through and contact the containers  300 . In another example, the heating surface  710  is a solid surface that is heated via flames  720  and then transfers heat to the containers  300  via conduction. Any type of heat transfer mechanism can be used, including conduction, convection, induction, or radiation. 
     As shown in  FIG. 7 , a hood  730  can be attached to each container  300 . The hood  730  can be configured to seal around the top of the container  300 , forcing any gas produced via deployment to enter the hood  730 . The hood  730  can connect to piping  740  that routes the high-energy gas away from the container  300 . In the example of  FIG. 7 , several hoods  730  connect to piping  740  that joins together and routes toward a filter  750 . 
     The filter  750  can prepare the gas flow for entering a turbine  760 . Based on the needs of the turbine  760 , the filter  750  can be designed to provide an appropriate level of filtering. For example, the filter  750  can be a simple grate or mesh that prevents solid shrapnel particles from entering the turbine  760 . In another example, the filter  750  can include a filter medium, such as paper or charcoal, that removes certain particulates from the gas flowing through the piping  740 . The filtered gas then enters the turbine  760  and causes the turbine  760  to produce power that can be harnessed and reused. For example, the turbine  760  can be used to power a heating mechanism that produces and applies heat to the heating surface  710 . Other energy-recovery mechanisms can be used in place of a turbine. For example, the expelled gases can be used to heat a boiler. 
     In one example, the containers are heated using excess heat created from a process unrelated to the inflators. For example, the containers can be heated using excess heat from a power generation process at a coal plant or nuclear plant. In that example, the containers can be made to interface with a heat source that provides rejected heat from the power generation process. For example, if the heat is rejected from the power generation process via air, the exhaust manifold that exhausts the heated air can be attached to a container. The container can include an a manifold that mates with the exhaust manifold to direct the heated air toward the inflators in the container. In an example where the heat is rejected from the power generation process via a liquid, the container can include a heat exchanger that can intercept the heated liquid, extract heat from the liquid, and direct the liquid back to its original path. The shape and size of the container can be modified to fit any type of heat source. Using heat waste from an industrial process can lower the costs for disposing of the recalled inflators. 
       FIG. 8  is a flowchart of an example method for handling airbag inflators. Stage  810  of the method can include placing a live airbag inflator in a vented container, such as one of the containers disclosed above with respect to  FIGS. 1-7 . The container can be shaped to hold multiple live airbag inflators, and can withstand a deployment of an airbag inflator by retaining the deployed airbag inflator and shrapnel associated therewith while allowing gas associated with the deployment to exit the container. 
     Stage  820  of the method can include positioning the container in or on a transport vehicle. This can include, for example, lifting the container by hand and placing it in a truck bed. In another example, a forklift, crane, or other lifting mechanism can be used to lift the container and move it. The transport vehicle can be any type of vehicle, including a car, truck, ship, train, or airplane. In some examples, the container is already positioned on a transport vehicle before stage  810  takes place. For example, a container can be constructed using a standard inter-modal shipping container. The shipping container can include a lattice structure similar to that described with respect to  FIG. 4 . In that example, the shipping container can be positioned on the trailer of a truck before the airbag inflators are positioned in the container. 
     Stage  830  can include measuring a first weight of the container including the live airbag inflator. For example, the container can be placed on a large scale to determine a total weight. In another example, a lifting mechanism can measure the weight of the container as the container is positioned on a transport vehicle at stage  820 . This stage can also include noting the total number of inflators in the container, as well as the number of driver-side inflators, passenger-side inflators, side-impact inflators, and curtain inflators. 
     Stage  840  includes applying heat to the container sufficient to deploy a live airbag inflator. This can include, for example, applying a flame directly to the container. In another example, heated air can be directed toward the container. In yet another example, a heating surface can conduct heat into the container. In one example, the container is heated such that the inflators reach a minimum internal temperature of 130 degrees Celsius. In another example, the container is heated such that the inflators reach a minimum temperature of 180 degrees Celsius. 
     In yet another example, the container is heated such that the inflators reach a minimum temperature of 200 degrees Celsius. 
     Stage  850  can include measure a second weight of the container including the inflator. For example, at the conclusion of the heating process, the container can be placed on a scale. A single passenger-side inflator typically loses approximately 80-140 grams of mass due to a deployment. A single driver-side inflator typically loses approximately 20-50 grams of mass due to a deployment. A single side-impact inflator typically loses approximately 20-40 grams of mass due to a deployment. 
     Stage  860  can include calculating a difference between the first weight and the second weight. The difference between these two weights can indicate whether any inflators within the container have deployed, and if so, how many. The difference between the first and second weights can also be divided by the number of inflators in the container to determine an average weight difference per inflator. 
     Based on the difference between the first and second weight being above a threshold value, at stage  870 , the exploded inflator can be removed from the container. The threshold value can be based on the number of inflators in the container. As an illustration, an example container can hold 10 driver-side inflators and 10 passenger-side inflators. An estimation can predict that the driver-side inflators will lose 300 grams (30 grams each) if all inflators deploy, while the passenger-side inflators will lose 1000 grams (100 grams each) if they all deploy. In that example, the difference between the first and second weight should be above a threshold that is close, or equal to, 1300 grams. If the difference is substantially less than 1300 grams in that example, then the container can undergo further heating, including being heated at a higher temperature than previously. After the additional heating, a replacement second weight can be obtained and used to calculate a weight difference from the first weight. 
     In one example, a large-scale shipping container can be used for transporting airbag inflators. For example, a commonly used 30-yard dumpster or dump truck bed rated for 20-ton gravel loads can be used. A smaller metal shipping container could also be nested inside a larger one to achieve sufficient container integrity, such as small dumpster housed inside a larger dumpster. The purpose of the shipping container can be to prevent inflator metal fragments from exiting the sidewall of the container and directing all energy that results from inflator deployments up toward the top of the container. 
     Another purpose of the shipping container can be to prevent propagation of an explosion. In some examples, recalled inflators can have characteristics that create a risk of an explosion propagating to nearby inflators. This can be specified in the new classification, or reclassification, that applies to recalled inflators. The risk of propagation can be lessened by controlling the size of the “containable load” used with each container. However, the containers can be designed to withstand propagation and prevent explosions from propagating across containers. 
     Continuing the large-scale shipping container example, a containment blanket can be used to prevent shrapnel from escaping the container. The containment blanket can include a net or mesh structure that prevents shrapnel from passing through the containment blanket. The blanketing structure on top of the inflator load can prevent over-pressurization of the shipping container if inflators deploy inside the container, allowing inflator combustion gases to vent while preventing metal inflator fragments of critical mass from exiting the top of the container. Examples of suitable material for the containment blanket are expanded steel mesh or grates with properly sized openings. Another example of a suitable material is a chain-link fencing material. 
     The large-scale shipping container can also be implemented in a similar manner with respect to rail cars or barges, such that the inflators can be shipped via rail or water. 
     Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.