Note: Descriptions are shown in the official language in which they were submitted.
CA 02545303 2006-04-28
CASE FOR SMALL EXPLOSIVE DEVICE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to explosion containment,
s and more particularly to a container allowing safe transport
of at least one small explosive device.
Background Art
Millions of small explosive devices such as detonators,
detonating cord, airbag inflators and fuses are made and
to 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
15 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
ao 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
2s 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
-1-
CA 02545303 2006-04-28
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
to 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
i5 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
2o 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
2s 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
3o people, as the components projected by the explosion could
cause serious injury.
-2-
CA 02545303 2006-04-28
For example, in U.S. 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
s 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.
SUMMARY OF INVENTION
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 a small
explosive device, the container comprising a first rigid
enclosure, a second enclosure within the first enclosure,
the second enclosure being formed of a first material
retaining fragments propagated by an explosion of the small
2o explosive device, a third enclosure within the second
enclosure, the third enclosure being formed of a second
material reducing the force of a blast caused by the
explosion of the small explosive device, and the container
being openable to insert the small explosive device within
the third enclosure, and closable to contain the small
explosive device, the second and third enclosures containing
the explosion such as to reduce potential injury to a person
in proximity of the case.
-3-
CA 02545303 2006-04-28
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to the accompanying
drawings, showing by way of illustration a preferred
embodiment of the present invention and in which:
s Fig. 1 is a perspective view of a container according
to a preferred embodiment of the present invention; and
Fig.2 is a cross-sectional view of the container of
Fig. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
to Referring now to the drawings, a 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-
i5 section, and includes a body 18 and a cover 20, which
together define a first enclosure, also preferably of
rectangular cross-section. The outer shell 12 protects the
internal components and materials being transported from
weather and incidental damage, and as such is preferably
2o made of a shock resistant plastic, for example a
polypropylene copolymer such as CoroplastTM.
The cover 20 is preferably pivotably 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
2s closed position when engaged. Alternatively, the hinged
cover 20 could 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.
-4-
CA 02545303 2006-04-28
The case 10 is preferably designed to handle small
explosive devices (e. g. less than lkg total of TNT-
equivalent explosive), and as such the hinges 22 and locking
means 24 allow some gas to escape between the closed cover
s 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
io 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
15 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
either by hand or by a robotic device. It is also
2o considered to provide the case 10 with more than one handle
26, or alternatively with no handle at all.
The fragment-retaining layer 16 is located within the
first enclosure, against the outer shell 12. The fragment-
retaining layer 16 includes a bottom sheet 28 at the bottom
2s of the first enclosure, four (4) side sheets 30, one per
side of the first enclosure, 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 define a second
enclosure within the first enclosure. The sheets 28,30,32
3o minimize shock wave transmission as well as retain fragments
propagated by an explosion, and as such are preferably made
of polycarbonate, such as Lexan~, as this material has been
proven to deform plastically to a very great extent under
-5-
CA 02545303 2006-04-28
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, or can
comprise ballistic armor in order to protect the encased
explosive devices from impinging projectiles or ammunition
fragments.
The mitigating layer 16 is located within the second
enclosure, against the fragment-retaining layer 16. A bottom
io 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 a third
enclosure for the explosive device which will be contained
in the case 10. The panels 34,36,38 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. patents Nos. 5,225,622 and 5,394,786,
2o 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
2s 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
3o 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
-6-
CA 02545303 2006-04-28
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
s resist displacement when moved or disturbed.
The inner surfaces 56 of the panels 34,36,38, which
define the third enclosure where the explosive device will
be contained, includes an interior lining that either
provides negligible resistance to or delay in rupture, or
io 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
15 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
2o 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
z5 mitigating explosive effects or otherwise serve to suppress
post-blast ignition of nearby flammable materials.
To resist or inhibit the occurrence of sympathetic
detonation when more sensitive explosive devices are
carried, the case 10 preferably includes at least one blast
3o 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
-7-
CA 02545303 2006-04-28
compartments. In Fig.l, two such dividers 40 are
illustrated, extending throughout the second enclosure in a
perpendicular manner.
Each divider 40 includes a middle sheet 42 sandwiched
s between two divider panels 44. The middle sheet 42, like the
bottom, side and top sheets 28,30,32, is preferably composed
of 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
io inside the compartment. The divider panels 44 are composed
of material similar to the material of the bottom, side and
top panels 34,36,38. The opposed exposed surfaces 58 include
an interior lining similar to the lining of the inner
surfaces 56.
i5 The case 10 also preferably includes removable blast
effect mitigating dividers 46, one of which is shown in
Fig. 1. The removable dividers 46 each include a middle sheet
48 similar to the middle sheet 42 of the divider 40,
sandwiched between two divider panels 50 similar to the
2o divider panels 44 of the divider 40. The removable dividers
46 also includes opposed exposed surfaces 60 including a
lining similar to the lining of the exposed surfaces 56 of
the divider 40. The removable dividers 46 are sized such as
to be snuggly slidable within a compartment of the second
2s enclosure.
In a preferred 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
3o 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
_g_
CA 02545303 2006-04-28
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
s 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 removable dividers 46 such that
to the case 10 provides a single compartment.
The body 18 also preferably 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
15 various means .so that inspection devices such as optical and
other electromagnetic imaging, 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,
2o 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):
The body 18 also preferably includes at least one vent
2s 52, which is preferably defined by an aperture cut in one
wall of the outer shell 12, in order to release hot blast
gases. Preferably, the vent 52 would be located near
explosive devices within the case 10 and may be vented in a
direction away from a person carrying the case 10. The vent
30 52 is covered by the portion of the wall of the outer shell
12 that was cut to form the aperture (not shown), re-
_g_
CA 02545303 2006-04-28
attached over the aperture in such a manner that the vent
cover is easily dislodged under internal pressure.
The vent 52 could be located in alternate locations,
for example in corners of the outer shell 12. 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
to 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
i5 made by an individual skilled in the design of blast
protection devices, such as bellows-type components combined
with mesh and elastic "balloon" components.
Mountings or other provisions for cylindrical vessels,
or other shapes of explosive devices, may be provided in the
2o compartments. Straps or other similar components can be
provided for additional restraint to the explosive devices
within the compartments.
Also, wheels can be attached to the outer shell 12 to
facilitate movement of the case 10 by hand or robot. The
25 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
3o placed in protective cartons or wraps within the
compartments to provide additional levels of protection.
Such wraps and cartons may be substantially comprised of
-10-
CA 02545303 2006-04-28
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
s 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
to 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
i5 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, would thus
protect explosive devices kept within from unintentional
2o 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.
2s Part or all of the outer shell 12 may utilize materials
that facilitate external examination of the case contents,
such as those transparent in the desired portion of the
electromagnetic spectrum. The fragment retaining layer 14
and the mitigating layer 16 may be made of materials that
3o are correspondingly similar.
The outer surface of the outer shell 12, the inner
surfaces 56, and the exposed surfaces 58,60, either alone or
-11-
CA 02545303 2006-04-28
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
s 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
1o integrated within the second enclosure.
The case 10 can thus minimize the release of
potentially hazardous phenomena under pressure above ambient
to the environment external to it. Thus shock waves and
pressurized gas leakage will be mitigated to the degree
15 desired by those who may be come into close proximity to the
invention 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
2o 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
2s 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,
3o fuses, small hand grenades, small anti-personnel mines,
various recovered explosive devices, etc.
-12-
CA 02545303 2006-04-28
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
s 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
1o 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
i5 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
2o 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.
-13-
