Patent Application
20070131684
The present invention relates to explosion containment, and more particularly to a container allowing safe transport of at least one small explosive device.
Millions of small explosive devices such as detonators, detonating cord, airbag inflators and fuses are made and shipped every year. Detonators, detonating cord, uncased explosives, and other devices containing small explosive charges are widely used by many security and military agencies, for example for the destruction of suspect explosive devices, disposal of unexploded munitions, and wall breaching during hostage rescue operations. These devices are also widely used in the petroleum industry, the entertainment industry, the construction industry, etc.
As a result, small explosive devices and charges often need to be carried in the presence of others, including the general public, usually in portable cases, such as when detonators and detonating cords are taken by security personnel to sites where operations require breaching walls and destruction of explosive materials.
Upon detonation, rapid combustion processes produced even by a small explosive device compress surrounding fluid media so quickly that shock waves are produced. Also, the physical expansion of the hot blast combustion products adds to pressure loading of objects in its path, as well as generates radiation. The hot blast combustion products are typically capable of igniting combustible materials nearby and inflicting burns on exposed humans. Humans may be killed by intense blast pressure alone, as this causes lung damage above threshold levels. Below threshold conditions for fatal injury, blast pressure may cause damage to ears and lungs, and sudden accelerations that lead to spinal injuries. Moreover, fragments from exploding cased explosive devices may lead to fatal internal damage.
Explosive effects dissipate rapidly in air as long as the blast is unconfined. Large obstructions such as buildings surrounding a street in which a blast occurs prolong pressure durations and lead to greater damaging capability. Complete or near-total confinement maximizes blast effect duration, as the blast pressure is prevented from being dissipated.
In order to provide safe handling of small explosive devices, it is often desired to prevent detonation of one explosive charge from causing detonation of others nearby, an event widely termed “sympathetic detonation”, as mass detonation of large quantities of small explosive charges generates blast parameters equivalent to single-charge detonations of similar weight. A number of prior art small explosive devices containers are designed to prevent sympathetic detonation, but not to confine either blast effect or fragments. As a result, such containers are usually destroyed when the elements contained therein explodes, and components are hurled at significant velocities. As such, these containers would be unsuitable for transportation of small explosive devices next to people, as the components projected by the explosion could cause serious injury.
For example, in U.S. Pat. No. 5,160,468, Halsey et al. disclose the use of a mitigating material, pumice, to surround hard plastic tubes to contain explosive devices. The hard plastic tube forms a barrier between the explosion and the mitigating material. If the plastic tube is omitted, the mitigating material attenuates the blast pressure but is not adapted to retain fragments produced by the blast.
Accordingly, there is a need for an improved container allowing safe transportation of small explosive devices.
It is therefore an aim of the present invention to provide an improved container allowing safe transportation of small explosive devices.
Therefore, in accordance with the present invention, there is provided a container for containing an explosive device, the container comprising a mitigating layer defining an enclosure openable to insert the explosive device therein and closable to surround the explosive device, the mitigating layer reducing a force of a blast caused by an explosion of the explosive device, and a fragment-retaining layer substantially surrounding the mitigating layer, the fragment-retaining layer being resistant to a remainder of the force of the blast passing through the mitigating layer and retaining fragments propagated by the explosion of the explosive device, such as to reduce potential injury to a person in proximity of the container.
Also in accordance with the present invention, there is provided a container for containing an explosive device, the container comprising an outer shell including a body and a cover relatively movable between an open position and a closed position, a fragment-retaining layer disposed against inner surfaces of the body and the cover such as to substantially define a first enclosure when the body and the cover are in the closed position, a mitigating layer disposed against inner surfaces of the fragment-retaining layer such as to define a second enclosure within the first enclosure when the body and cover are in the closed position, the second enclosure being adapted to receive the explosive device therein, wherein the mitigating layer reduces a force of a blast caused by an explosion of the explosive device, and the fragment-retaining layer resists a remainder of the force of the blast passing through the mitigating layer and retains fragments propagated by the explosion.
Further in accordance with the present invention, there is provided a method of containing an explosion of an explosive device, the method comprising reducing a force of the explosion using a mitigating layer surrounding the explosive device, and containing the reduced force of the explosion and fragments projected by the explosion using a fragment-retaining layer surrounding the mitigating layer.
Reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment of the present invention and in which:
Referring now to the drawings, a container or transport case 10 according to the present invention is shown. The case 10 comprises an outer shell 12 surrounding a fragment-retaining layer 14, which surrounds a mitigating layer 16.
The outer shell 12 preferably has a rectangular cross-section, and includes a body 18 and a cover 20 which together define an enclosure, also preferably of rectangular cross-section. In a particular embodiment, the outer shell 12 protects the internal components and materials being transported from weather and incidental damage, and as such is made of a shock resistant plastic, for example a polypropylene copolymer such as Coroplast™. Alternate materials for the outer shell include wood or any appropriate type of metal such as for example steel or aluminum.
In the embodiment shown, the cover 20 is pivotally retained on the body 18 through hinges 22. The body 18 and cover 20 also include locking means 24 retaining the cover 20 in the closed position when engaged. Alternatively, the hinged cover 20 can be replaced by a cover completely separate from the body 18, or by a guillotine-type door, a hatch-type door, a drawer, a plurality of doors, etc.
In a particular embodiment, the case 10 is designed to handle small explosive devices (e.g. less than 1 kg total of TNT-equivalent explosive), and as such the hinges 22 and locking means 24 allow some gas to escape between the closed cover 20 and the body 18, with the gas leakage and attendant shock waves mitigated to the extent required to prevent permanent injury to nearby people or prevent sympathetic detonation or burning of nearby energetic materials. In an alternate embodiment, the case 10 is used to contain explosive devices and other devices that may contain hazardous biological, radioactive, or chemical agents that could be dispersed under pressure, and as such the seal between the cover 20 and body 18 is adequate to prevent release of the hazardous material. The degree to which the seal is impervious to the transmission of gas can thus be varied through various closure modifications readily available to one in the art.
A handle 26, which may be fixed or extendable, is attached to the body 18 to facilitate transport of the case 10 either by hand or by a robotic device. It is also considered to provide the case 10 with more than one handle 26, or alternatively with no handle at all.
The fragment-retaining layer 14 is located within the enclosure defined by the outer shell 12 and is in contact therewith. The fragment-retaining layer 14 includes a bottom sheet 28 and four (4) side sheets 30 located in the body 18, and a top sheet 32 located in the cover 20. The bottom and side sheets 28, 30 preferably abut one another and the sheets 28, 30, 32 together define an enclosure within the enclosure of the outer shell 12.
The sheets 28, 30, 32 of the fragment-retaining layer 14 are made of a fragment-retaining material which minimize shock wave transmission as well as retains fragments propagated by an explosion of a size corresponding to the explosive device(s) to be transported in the case 10. In a particular embodiment, the sheets 28, 30, 32 are made of polycarbonate, such as Lexan®, as this material has been proven to deform plastically to a great extent under explosive loading without rupture. Polycarbonate also features low acoustic impedance, which is desirable for shock wave attenuation. Alternatively, the sheets 28, 30, 32 can be made of a metal of similar properties and/or can comprise ballistic armor in order to protect the encased explosive devices from impinging projectiles or ammunition fragments. As such, the fragment-retaining layer 14 resists to a remainder of the blast force passing through the mitigating layer 16.
The mitigating layer 16 is located within the enclosure defined by the fragment-retaining layer 14 and is in contact therewith. A bottom panel 34 is located against the bottom sheet 28, a side panel 36 is located against each of the side sheets 30, and a top panel 38 is located against the top sheet 32. The inner surfaces 56 of the panels 34, 36, 38 define an enclosure for the explosive device which will be contained in the case 10.
The panels 34, 36, 38 of the mitigating layer 16 are formed of a blast effect mitigating material which effectively reduces the strength of the blast of an explosive device in close proximity. Examples of such materials are disclosed by Gettle et al. in U.S. Pat. Nos. 5,225,622 and 5,394,786, which are both incorporated herein by reference. The mitigation mechanism of such materials is a combination of mechanical and chemical factors that stop the chemical reaction of the explosive before the entire explosive is consumed. A portion of the remainder of the explosive force is mitigated as it passes through the material. In a preferred embodiment, the panels 34, 36, 38 are made from lightweight honeycomb filled with attenuating filler material and sealed off on both sides with a thin relatively friable tissue. Other mitigating materials can also be used in the panels 34, 36, 38, such as pumice, foamed plastic beads, etc.
Although the mitigating layer 16 is shown as being formed of separate panels, it can also be integrally cast or otherwise molded to maintain an intended shape. Alternatively, the mitigating layer 16 can be tubular or in the form of amorphous bags of blast effect mitigating material so long as the bags are adequately secured to resist displacement when moved or disturbed.
The inner surfaces 56 of the panels 34, 36, 38, which define the enclosure where the explosive device will be contained, includes an interior lining that either provides negligible resistance to or delay in rupture, or permits transmission of the impinging blast wave into the blast effect mitigating material. In a preferred embodiment, the lining is perforated or otherwise permanently open to the unobstructed flow of gas between the space where explosive devices and materials are placed and the blast effect mitigating material.
Alternatively, the lining can be a fabric or metal foil that prevents penetration of moisture or spilled fluids into the blast effect mitigating material, a frangible material resistant to the transmission of gas in ambient conditions but otherwise readily ruptured by the impingement of a blast in the event of a detonation inside the case 10. Such a lining would be preferable when the blast effect mitigating material is a gel or fluid, or when powdered, liquid, or gaseous extinguishing agents are employed that assist in mitigating explosive effects or otherwise serve to suppress post-blast ignition of nearby flammable materials.
In the embodiment shown, the case 10 includes at least one blast effect mitigating divider 40, such that opposed exposed surfaces 58 of the divider 40 define together with the inner surfaces 56 of the panels 34, 36, 38 a plurality of separate compartments, in order to resist or inhibit the occurrence of sympathetic detonation when more sensitive explosive devices are carried. In
Each divider 40 includes a middle sheet 42 sandwiched between two divider panels 44. The middle sheet 42, like the bottom, side and top sheets 28, 30, 32 of the fragment-retaining layer 14, is composed of a fragment-retaining material such as for example polycarbonate. Like the sheets 28, 30, 32, the middle sheet 42 can also include ballistic armor to prevent fragments and projectiles such as bullets from impacting explosive devices inside the compartment. The divider panels 44 are composed of blast effect mitigation material similarly to the bottom, side and top panels 34, 36, 38 of the mitigating layer 16. The opposed exposed surfaces 58 of the divider panels 44 include an interior lining similar to the lining of the inner surfaces 56 of the panels 34, 36, 38.
In the embodiment shown, the case 10 also includes removable blast effect mitigating dividers 46, one of which is shown in
In a particular embodiment, the dividers 40 and removable dividers 46 are intended to prevent sympathetic detonation between explosive devices located in separate compartments. However, prevention of sympathetic detonation is not essential. The critical requirement is that in the event of a detonation of one or more explosive devices within the case 10, release of blast generated gas, from the case 10, is so slight that no permanent injury is inflicted on humans in close proximity to the case 10. Fragments from explosive device components, and components of the case 10, are preferably completely confined. Extremely rapid cooling of hot gaseous products is also preferable such as to prevent possible ignition of case materials and other items kept within the case 10.
Alternatively, it is considered to provide a case 10 without the dividers 40 and/or without the removable dividers 46. For example, the case 10 can provide a single compartment.
In the embodiment shown, the body 18 includes an inspection port 54, formed by aligned holes through the outer shell 12, fragment-retaining layer 14 and mitigating layer 16. The port 54 facilitates examination or characterization by various means so that inspection devices such as optical and other electromagnetic imaging devices, chemical sensors, and radiation detection probes may be installed in appropriate locations. Alternatively, the port 54 may be provided with an appropriate nozzle to inject various kinds of agents, such as aqueous foams for blast effect mitigation or neutralizing of chemical or biological agents, or cleaning material for scrubbing radioactive dusts. The port 54, when not in use, is closed by an appropriate cover (not shown). Alternately, the port 54 can be omitted.
In the embodiment shown, the body 18 also includes at least one vent 52, which is defined by an aperture cut in one wall of the outer shell 12, in order to release hot blast gases. Preferably, the vent 52 is located near explosive devices within the case 10 and is vented in a direction away from a person carrying the case 10. The vent 52 is covered by the portion of the wall of the outer shell 12 removed to form the aperture (not shown), re-attached over the aperture in such a manner that the vent cover is easily dislodged under internal pressure.
Alternately, the vent 52 could be located in other locations, for example in corners of the outer shell 12. Also, alternate covers for the vent 52 include an elastic or flexible bag that expands under pressurization caused by an internal explosion. This expandable member may be substantially comprised of a fabric or plurality of fabric layers capable of catching debris and fragments from the detonation of a stored explosive device. Alternatively, the expandable member may be substantially comprised of a mesh that allows gradual release of internal gas, thereby reducing the loads imparted by the blast to the hinges 22 and locking means 24. Any combination of such components for vent covers can be made by an individual skilled in the design of blast protection devices, such as bellows-type components combined with mesh and elastic “balloon” components.
Although not shown, mountings or other provisions for cylindrical vessels, or other shapes of explosive devices, may be provided in the compartments. Straps or other similar components can be provided for additional restraint to the explosive devices within the compartments.
In a particular embodiment, wheels (not shown) are attached to the outer shell 12 to facilitate movement of the case 10 by hand or robot. The wheels may be integral to the outer shell 12, or be provided by detachable means enabling the wheel assembly to be removed when not needed. Alternatively, skids may be provided that also serve to facilitate movement.
Moreover, explosive devices or other items may be placed in protective cartons or wraps within the compartments to provide additional levels of protection. Such wraps and cartons may be substantially comprised of high-strength materials that resist bullets and ammunition fragments from penetrating.
The case 10 (as well as detachable wheels, if provided) may be provided with a bag enclosure that seals the case 10 when it is shut, to prevent release of dangerous materials to the external environment, for instance if the device within contains radioactive materials or potentially lethal pathogens. The bag enclosure may be part of the detachable wheeled or skid device, attached to the outer shell 12, or incorporated with the internal compartments or linings of the case 10. This bag enclosure may be coated or otherwise substantially comprised of materials that serve to neutralize the anticipated hazard.
The case 10 can also include shielding against the transmission of electromagnetic radiation or interference (EMI), including the effects of electromagnetic pulse (generally designated as EMP) when the case 10 is closed. The case 10, acting as a protection system, thus protects explosive devices kept therewithin from unintentional detonation or neutralization from radio waves or other electromagnetic events present outside the closed case 10. Provisions for electrical grounding may also be placed in suitable locations of the case 10 in order to prevent the buildup of static electricity.
Part or all of the outer shell 12 may utilize materials that facilitate external examination of the case contents, such as those permitting transmission therethrough of a desired portion of the electromagnetic spectrum. The fragment-retaining layer 14 and the mitigating layer 16 may be made of materials that are correspondingly similar.
The outer surface of the outer shell 12, the inner surfaces 56, and the exposed surfaces 58, 60, either alone or in combination, may be coated with fire-resistant materials in order to avoid ignition upon detonation of an encased explosive device. This is preferable when the case 10 is destined to contain energetic materials that may be capable of sustained burning with or without access to ambient air.
Should vessels or containers storing radioactive, chemical, or biological agents be placed within cases where explosive devices are also kept, internal protective components that prevent piercing the agent container may be integrated within the second enclosure.
The case 10 of the present invention thus minimizes the release of potentially hazardous phenomena under pressure above ambient to the environment external to it. Thus shock waves and pressurized gas leakage are mitigated to the degree desired by those who may be come into close proximity to the case 10 when explosive devices are contained therewithin.
The mitigating layer 16 preferably provides substantial cushioning in order to protect explosive devices placed within the case 10 from shock and impact. Thus, the case 10 may be dropped, fall from a moving vehicle, stepped on, crushed by stacking with heavy objects, or struck by bullets with a reduced risk of explosion of the contained explosive devices or, in the case of an explosion, with limited risk of injury to people nearby. As it often is required to be carried by hand, the case 10 is preferably sized such as to be relatively light.
The case 10, sized accordingly, can safely contain a variety of small explosive devices, including, but not limited to, detonators, detonating cords, airbag inflators, fuses, small hand grenades, small anti-personnel mines, various recovered explosive devices, etc.
Although the case 10 has been described as a portable case, it is also considered to integrate the case in a rolling cart, in a vehicle, in a building, etc. Where the case 10 is integrated in an enclosure of an existing structure, the outer shell 12 can be omitted. The case integrated in a rolling cart could be used, for example, in an airplane, where the rolling cart would be of a serving-cart type, to be rolled in proximity of a potentially dangerous device found, so that the device could be place within the case 10 with minimal handling. The case integrated in a vehicle could be used, for example, in a the cabin of a law enforcement vehicle, to transport small explosive devices destined to explode suspect devices, or to transport the suspect devices themselves away from the public.
The embodiments of the invention described above are intended to be exemplary. Those skilled in the art will therefore appreciate that the foregoing description is illustrative only, and that various other alternatives and modifications can be devised without departing from the spirit of the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.
This application claims priority on U.S. provisional application Ser. No. 60/713,740 filed Sep. 6, 2005, the entire specification of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60713740 | Sep 2005 | US |
