U.S. patent application number 12/267630 was filed with the patent office on 2011-07-21 for blast mitigation.
Invention is credited to OMER CARMEL, NEIL KUCHINSKY, ADAM WAKS.
Application Number | 20110174144 12/267630 |
Document ID | / |
Family ID | 42335463 |
Filed Date | 2011-07-21 |
United States Patent
Application |
20110174144 |
Kind Code |
A1 |
KUCHINSKY; NEIL ; et
al. |
July 21, 2011 |
BLAST MITIGATION
Abstract
An apparatus and a method for mitigation of the effects
associated with both blast and shrapnel. The mitigating apparatus
is designed with alternating layers of blast mitigating substance,
preferably liquid or hydrophilic gel or other viscous fluid, and
anti-ballistic substance, preferably a textile, to treat both the
air shock wave and the bomb-generated fragmentation and shrapnel,
which originate from a detonation or explosion.
Inventors: |
KUCHINSKY; NEIL; (COLONIAL
HEIGHTS, VA) ; CARMEL; OMER; (TEL MOND, IL) ;
WAKS; ADAM; (KIRYAT ONO, IL) |
Family ID: |
42335463 |
Appl. No.: |
12/267630 |
Filed: |
November 10, 2008 |
Current U.S.
Class: |
89/36.02 |
Current CPC
Class: |
F42D 5/045 20130101 |
Class at
Publication: |
89/36.02 |
International
Class: |
F41H 5/04 20060101
F41H005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2007 |
IL |
187252 |
Claims
1. An apparatus for blast mitigation of an explosive charge, the
apparatus comprising: at least one layer of blast mitigating
substance contained by a frangible mantle, said blast mitigating
substance including a hydrophilic gel; at least one layer of
anti-ballistic substance disposed adjacent said mantle; said layers
of blast mitigating substance and of anti-ballistic substance being
adapted and constructed for placement in proximity to the explosive
charge so as to absorb both blast and shrapnel from said
charge.
2. The apparatus according to claim 1, wherein said layers of blast
mitigating substance and anti-ballistic substance are concentric
annular layers.
3. The apparatus according to claim 1, wherein said layer of blast
mitigating substance comprises at least one modular unit adapted
and configured for coupling to another modular unit, said
anti-ballistic substance being disposed adjacent at least part of
said at least one modular unit.
4. The apparatus according to claim 3, further comprising a
plurality of said modular units coupled to one another to form a
safety screen element.
5. The apparatus according to claim 1, wherein said layer of blast
mitigating substance includes a plurality of interconnected
compartments.
6. The apparatus according to claim 1, comprising at least two
layers of blast mitigating substance in a frangible mantle,
alternating with at least two layers of an anti-ballistic
substance.
7. The method of claim 6, wherein said at least two layers of
anti-ballistic substance have different anti-ballistic
characteristics.
8. The apparatus according to claim 1, further comprising a top
layer of blast mitigating substance in a frangible mantle.
9. The apparatus according to claim 8, further comprising at least
one top layer of anti-ballistic substance disposed on top of said
top layer of blast mitigating substance.
10. The apparatus according to claim 1, wherein gel powder is
disposed in said mantle for formation on site of hydrated gel by
the addition of water.
11. The apparatus according to claim 1, wherein said blast
mitigating substance is a viscous liquid.
12. The apparatus according to claim 1, further comprising at least
one filling element for each said layer of blast mitigating
substance.
13. The apparatus according to claim 1, wherein said anti-ballistic
substance is selected from the group consisting of Polyamide-type
material, Aramid-type material, High Performance Polyethylene
(HPPE) and Kevlar.RTM..
14. A method of forming an apparatus for blast mitigation of an
explosive charge, the method comprising: providing at least one
layer of blast mitigating substance contained by a frangible
mantle, said blast mitigating substance including a hydrophilic
gel; and disposing at least one layer of anti-ballistic substance
adjacent said mantle; said layers of blast mitigating substance and
of anti-ballistic substance being adapted and constructed for
placement in proximity to an explosive charge so as to absorb both
blast and shrapnel from said charge.
15. The method according to claim 14, further comprising the step
of adding said blast mitigating substance after placement.
16. The method according to claim 15, further comprising providing
said gel in powder form in said mantle for filling with liquid on
site to form a hydrated gel.
17. The method according to claim 14, further comprising arranging
alternating layers of blast mitigating fluid in a frangible mantle,
and anti-ballistic substance, for placement adjacent an explosive
charge so as to absorb both blast and shrapnel from said
charge.
18. The method according to claim 17, wherein said layers of the
anti-ballistic substance have different anti-ballistic
characteristics.
19. The method according to claim 14, wherein said anti-ballistic
substance is selected from the group consisting of Polyamide-type
material, Aramid-type material, High Performance Polyethylene
(HPPE) and Kevlar.RTM..
20. A method for mitigation of effects of a blast of a charge, the
method comprising: alternately disposing, adjacent the charge,
layers substantially for shock wave absorption and layers for
mitigation of shrapnel dispersion, wherein said layers
substantially for shock wave absorption include a hydrophilic gel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of
blast mitigation that results in a decrease of the damage
associated with explosives.
BACKGROUND OF THE INVENTION
[0002] Terrorist attacks which target civilians and public places
by using charges and bombs, as well as ordnance and explosives in
storage, etc., are common in today's world. When such a bomb or
charge explodes, it can damage nearby buildings and structures and
may result in injuries and even fatalities. The damage, which
originates from the blast, is caused by two main phenomena: the air
shock waves and the shrapnel, which propagate following the blast.
The air shock waves are short duration compressive waves, which
move radially outward through the air from the blast source. These
high pressure waves, which propagate immediately, create a shock
wave which causes devastation through their propagation. The shock
waves also heat the air to extremely high temperatures, a
phenomenon known as the fireball effect. The shrapnel, which is
spread following the blast, gains its high kinetic energy from the
blast's energy and, therefore, is another source of damage and
devastation.
[0003] Blast mitigation has been addressed in the past by a number
of methods and systems. In times past, sandbags were piled up to
absorb some of the blast energy. In most recent cases, liquid, and
especially water, was used for the blast mitigating device. The
water is used to suppress a large proportion of the energy of the
bomb blast. An example of this can be seen in Barrett, U.S. Pat.
No. 4,836,079, which describes a frangible container filled with
liquid positioned so as to cover a bomb. When the blast occurs, the
container is broken by the detonation and the released liquid
limits the shock wave propagation and the fireball effect.
[0004] Another approach involves a sensor-activated water
suppression system. This type of system has been designed to
suppress the blast and the incendiary effects from the blast by
means of the rapid combustion of liquid. Examples of such a system
can be found in Burky et al, U.S. Pat. No. 6,119,574.
[0005] Liquid foams were also suggested as means for blast
mitigation. An example of this approach is disclosed in Moxon et
al, U.S. Pat. No. 4,964,329.
[0006] In all these systems, a liquid substance is the main
material utilized for blast mitigation. However, liquids are
effective mainly for the suppression of the shock wave originating
from the blast and for the decrease of the high temperature. The
effect of the water is limited with regard to shrapnel which
originates from the charge and follows the shock wave. Thus, when
the shrapnel interacts with the mitigating material, such as water,
which is present in the prior art systems, this mitigating material
has already interacted with the shock waves and, therefore, the
effectiveness of the liquid with regard to stopping the energetic
shrapnel is significantly reduced.
[0007] The inability of existing devices to effectively mitigate
both the shock wave energy and the shrapnel energy is becoming more
and more of a liability, as terrorists' charges deliberately
contain metal nails and other sharp metal debris.
[0008] There is known, from U.S. patent application 2007/0089595,
armor for a missile launcher including three layers. The outer-most
layer includes a plurality of elongated, pressurized tubes
containing fire retardant and silicone gel. Silicone gel is also
interposed between the tubes. Silicone gel is a hydrophobic
material that is essentially a glue. It hardens quickly after
exposure to air and this hardening is irreversible. This invention
utilizes silicon gel as a solid elastic material which can slow
solid fragments. However, since silicone gel has no water, it does
not mitigate blast waves and cannot be washed away after use.
Furthermore, the device must be filled in advance and is extremely
heavy.
[0009] Accordingly, it is the purpose of this invention to provide
an apparatus and method, which will mitigate more effectively,
first the shock wave and the temperature increase caused by a blast
and, in addition, will entrap high-energy shrapnel which is
scattered following the air shock wave, while providing a flexible
method of placing the apparatus at the required location and ease
of disposal after use.
SUMMARY OF THE INVENTION
[0010] There is provided according to the present invention an
apparatus and a method for mitigation of the effects associated
with both blast and shrapnel. The mitigating apparatus is designed
with alternating layers of blast mitigating substance, preferably
liquid or hydrophilic gel or other viscous fluid, and
anti-ballistic substance, preferably a textile, to treat the two
main causes of damage originating from a detonation or explosion,
namely, the air shock wave, which is the first to propagate after
the explosion, and the bomb-generated fragmentation and shrapnel,
which propagate following the air shock wave. The fluid suppresses
the air shock wave, absorbing some of its energy, and the
anti-ballistic textile layers inhibit continued movement of the
shrapnel.
[0011] Preferably, the anti-ballistic textile layers covering the
apparatus' blast mitigating compartments are designed with varying
anti-ballistic performance and arranged such that they allow the
portion of the shock wave's energy not absorbed by the apparatus to
be released in a defined direction.
[0012] The blast mitigation substance of the apparatus is held in
at least one closed compartment, which surrounds the explosive
charge. The lower or inner wall of the compartment is placed on top
of or around the explosive and is made of a material which is
ruptured by the air shock wave created in the explosion. The upper
and/or external walls of the compartment are covered with or made
of anti-ballistic textile. In this way, the apparatus absorbs the
shock wave's energy without being completely dismantled, and is
still able to suppress the shrapnel's kinetic energy and decrease
the damage it can cause.
[0013] According to one embodiment of the invention, the apparatus
is made of several layers of blast mitigation compartments, where
an anti-ballistic textile layer covers each blast mitigation
compartment layer. The anti-ballistic layers are preferably
arranged such that the outer layers have better anti-ballistic
impact performance than the inner layers.
[0014] Preferably, a special section of the most external layer, or
certain sections of other layers, are specially designed to allow
the remainder of the shock wave's energy not absorbed by the
liquid, to be released in a defined direction. In one embodiment of
the invention, this design includes at least one layer of an
anti-ballistic textile sheet attached to the outer cover of the
apparatus only on one side thereof. This facilitates release of the
remainder of the high pressure shock wave along the other side of
the sheet, in a pre-selected upward direction.
[0015] In another embodiment of the invention, the layers of the
anti-ballistic substance are arranged such that they have higher
anti-ballistic performance in certain sections than in other
sections, both in the inner layers and in the outer layers. This
design routes the air shock wave through the sections having lower
anti-ballistic performance to release them to the environment. One
example includes providing a "window" in the anti-ballistic layer
directly above each liquid compartment layer.
[0016] The apparatus may be provided with the blast mitigating
substance already inside its compartments, or it may be provided
empty and be filled on site with the blast mitigating substance.
When the blast mitigating substance is a hydrophilic gel, powdered
gel may be provided inside the compartments, and the compartments
can be filled with water on site. Upon filling, the powdered gel
absorbs the water and expands to form an hydrated, protective gel,
while retaining the blast mitigating characteristics of the water.
The fact that the apparatus may be filled with the blast mitigating
substance on site enables it to provide protection also against
large size explosive charges. In such cases, the empty apparatus is
considerably lighter (and smaller) than the filled apparatus, and
can be carried by a single person. The apparatus is positioned on
top of or around the explosive charge, and following that, can be
filled with water or other fluid using a filling connection.
Furthermore, after use, the gel can be dissolved in additional
water and easily washed away.
[0017] There is thus provided, according to the present invention,
an apparatus for blast mitigation of an explosive charge, the
apparatus including at least one layer of blast mitigating
substance contained by a frangible mantle; at least one layer of
anti-ballistic substance disposed adjacent the mantle; the layers
of blast mitigation substance and of anti-ballistic substance being
adapted and constructed for placement in proximity to the explosive
charge so as to absorb both blast and shrapnel from the charge.
Preferably, the apparatus includes at least two layers of blast
mitigating substance in a frangible mantle, alternating with at
least two layers of an anti-ballistic substance.
[0018] According to one embodiment of the invention, the layers of
blast mitigating substance and anti-ballistic substance are
concentric annular layers.
[0019] According to an alternative embodiment of the invention, the
layer of blast mitigating substance includes at least one modular
unit adapted and configured for coupling to another modular unit,
the anti-ballistic substance being disposed adjacent at least part
of the modular unit.
[0020] There is also provided, according to the invention, a method
of forming an apparatus for blast mitigation of an explosive
charge, the method including providing at least one layer of blast
mitigating substance contained by a frangible mantle; and disposing
at least one layer of anti-ballistic substance adjacent the mantle;
the layers of blast mitigation substance and of anti-ballistic
substance being adapted and constructed for placement in proximity
to a explosive charge so as to absorb both blast and shrapnel from
the charge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The present invention will be further understood and
appreciated from the following detailed description taken in
conjunction with the drawings in which:
[0022] FIG. 1 depicts a cross section of one embodiment of the
proposed apparatus for suppressing the blast of a charge.
[0023] FIG. 2 is a schematic illustration of an arrangement of
anti-ballistic layers in an apparatus according to one embodiment
of the invention.
[0024] FIG. 3 is an exploded view of the apparatus of FIG. 1.
[0025] FIG. 4a is a top sectional view of an apparatus according to
an alternative embodiment of the invention, for suppressing blast
of a charge.
[0026] FIGS. 4b and 4c are cut-away perspective and side sectional
views, respectively of the apparatus of FIG. 4a.
[0027] FIG. 4c is a top sectional view of an apparatus according to
another alternative embodiment of the invention.
[0028] FIGS. 5a, 5b and 5c are top, perspective and side sectional
illustrations of a blast mitigating modular unit constructed and
operative according to an alternative embodiment of the
invention.
[0029] FIG. 5d is a schematic illustration of a number of modular
units fitted together to form a blast mitigating wall.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The present invention relates to a system and method for
mitigating the damage incurred by the blast of a charge. More
particularly, the invention deals with an apparatus and a method
for mitigation of the effects associated with blasts adjacent the
apparatus, both shock wave and shrapnel. This is accomplished by
providing an apparatus containing alternating layers of
anti-ballistic sheets and at least one compartment which contains a
blast mitigating substance, preferably a liquid or gel or other
viscous fluid, which is arranged to be disposed on or around the
charge. This particular architecture enables mitigation of damage
caused both by the shock wave and shrapnel associated with
exploding charges. It will be appreciated that the apparatus
chiefly provides protection against lateral propagation of the
shock wave and shrapnel, permitting channeling of excess energy of
the blast upwards, above the exploding charge.
[0031] In FIGS. 1 and 3, there are shown cross sectional and
exploded illustrations, respectively, of a blast mitigating
apparatus constructed and operative in accordance with one
embodiment of the invention. In this embodiment, the apparatus 10
includes a bottom cover 6, an upper cover 2, a side cover 2', and a
plurality of substantially cylindrical compartments 1. Each
cylindrical compartment 1 includes a frangible, water resistant
mantle 3 filled with an appropriate blast mitigating substance
(preferably water, gel or viscous fluid suited for absorbing
kinetic energy, although alternatively, sand or powdered material
or any other blast mitigating material can be utilized). Mantle 3
is preferably made of a thin layer of a material, such as
polyethylene, arranged to contain the blast mitigating substance.
The mantle is ruptured when the explosion occurs, causing the blast
mitigation substance to absorb a portion of the generated shock
wave and consequent high temperature wave.
[0032] Cylindrical compartments 1 are arranged in a plurality of
layers 40, 40', and 40''. The cylindrical compartments in each
layer are interconnected via tubes 4, 4' and 4'', permitting fluid
flow therebetween. The cylindrical compartments are filled with
blast mitigating substance, as via tubes 12. Interconnecting tubes
4, 4' and 4'' permit the rapid filling of the entire apparatus.
[0033] The apparatus further includes a plurality of anti-ballistic
material layers 13, 15, and 17 disposed between layers 40, 40' and
40'', and preferably extending from one side to another of side
cover 2'. Apparatus 10 may also include additional anti-ballistic
material layers 22, 24, 26 and 28, which are connected only to one
side of side cover 2'.
[0034] The apparatus 10 is designed so that, upon blast, the
alternating layers will mitigate both the shock wave and the
shrapnel. It will be appreciated that the shrapnel generated by a
blast often has such high kinetic energy that it can cut right
though a sheet of anti-ballistic fabric. The blast mitigating
substance and internal anti-ballistic layers of the apparatus of
the invention absorb some of this kinetic energy, so that high
energy fragments can be trapped in one of the outer layers of
anti-ballistic material.
[0035] Preferably, anti-ballistic layers 13, 15 and 17 are designed
with an increasing level of anti-ballistic properties. Thus, the
upper anti-ballistic substance layer 17 will have better
anti-ballistic impact performance than the next lower
anti-ballistic substance layer 15, which, itself, has better
anti-ballistic performance than anti-ballistic layer 13. This can
be implemented by using, for example, a Polyamide-type material as
the anti-ballistic substance layer 13, using an Aramid-type
material, which is known to provide better anti-ballistic
mitigation over Polyamides, in layer 15, and then integrating an
even stronger anti-ballistic substance in layer 17, such as High
Performance Polyethylene (HPPE). This design maximizes the
interception of flying shrapnel and still allows the shock wave to
propagate through the apparatus while mitigating its energy. Side
cover 2' is made of a high impact performance anti-ballistic
substance and is preferably an arcuate, woven anti-ballistic sheet,
impeding laterally flying shrapnel, and is coupled to the bottom
wall 6 and top cover 2. Top cover 2 preferably is made of a high
impact anti-ballistic material, such as HPPE.
[0036] Beyond the upper level 40'' of blast mitigating cells, there
are additional layers 28, 26, 24 and 22 of substance, preferably
anti-ballistic material, which serve to stop flying shrapnel while
still enabling the remainder of the shock wave to be released in a
defined direction, i.e., upwards over the charge. A schematic
illustration of an arrangement of anti-ballistic layers 22, 24, 26
and 28 in apparatus 10, according to one embodiment of the
invention, is shown in FIG. 2. These layers are connected to the
side cover 2' of the apparatus only along a single edge, so that
the remaining shock wave energy can be released along the opposite
edge. Thus, layer 28 is illustrated as being coupleable via edge 27
to one side of side cover 2' (not shown). Layer 26 is disposed for
coupling to the opposite side of side cover 2', via edge 25. Layer
24 is disposed to be coupled to another side of side cover 2', via
edge 23, in 90.degree. rotation relative to edge 27. Layer 22 can
be coupled to side cover 2' via edge 21, opposite edge 23. This
architecture of anti-ballistic layers allows the shock wave to
propagate in the vertical direction, while forcing it to pass along
the longest possible route through the blast mitigating apparatus,
thus substantially reducing its energy.
[0037] In an alternative embodiment of the invention, at least one
of layers 13, 15 and 17 includes at least one portion coupled to
the rest of the layer along only one edge, creating an area with an
effective lower anti-ballistic performance and thus functioning as
a window for releasing the remainder of the shock wave created in
the blast. Preferably, this portion is located above at least one
liquid compartment.
[0038] The apparatus of the embodiment of FIG. 1 is utilized by
placing it on the explosive charge 50. When the charge explodes,
the special design of the apparatus mitigates damage caused by the
explosion in the following manner: First, the bottom wall 6 of the
apparatus, made of a low anti-ballistic performance material, is
dismantled by the first high pressure air shock wave. The mantle 3
of the bottom blast mitigating compartments layer 40 then is
ruptured by the air shock wave and the following high temperature
gases generated by the explosion, causing a release of the blast
mitigating substance, which interacts with the high temperature and
pressure gases. Then, the first anti-ballistic substance layer 13
interacts with the somewhat quenched shock wave, by absorbing some
of its remaining energy, and trapping some of the shrapnel which
are spread following the shock wave, whose kinetic energy has been
reduced by the blast mitigating fluid. Layer 13 is preferably
chosen such that it absorbs part of the energy while being
dismantled, so that the high-pressure wave can propagate through it
to the upper layers of the apparatus. The upper layers 40', 40''
function in the same manner as the first liquid compartment layer
40, but they interact with a lower energy shock wave and with gases
which were partially suppressed already by the bottom layers of the
apparatus. Layers 15 and 17 preferably are also chosen such that
they will absorb the explosion energy while being torn, leaving the
pressure wave to continue propagating in the upwards direction by
shifting layers 28, 26, 24 and 22 upwards, while their edges remain
coupled to the apparatus' external side cover 2'. The shock wave
energy is released from the upper external cover 2 of the
apparatus, while the anti-ballistic layers 28, 26, 24 and 22, as
well as the side external cover 2' absorb the laterally propagating
shrapnel, while leaving its remaining energy to disperse mainly in
the vertical direction. The side cover 2' of the apparatus, which
is made of a strong anti-ballistic sheet, blocks the pressure wave
from expanding laterally and, therefore, forces the remaining
energy of the explosion to propagate mainly in the vertical
direction.
[0039] Thus, the apparatus is able to alternately absorb and quench
the blast energy, which becomes smaller while passing through each
layer, and to direct the remaining energy for release in a
preferred direction while blocking most of the blast energy in
other directions and stopping the flying shrapnel. While a device
having a plurality of alternating layers, as described above, is
preferred for larger charges, it will be appreciated that the
apparatus of the invention may, alternatively, have only one layer
of blast mitigating material and one layer of anti-ballistic
material.
[0040] With reference to FIGS. 4a, 4b and 4c, there is shown an
apparatus 60, according to an alternative embodiment of the
invention, for mitigating the blast of a charge 62. Apparatus 60
includes an internal, annular or elliptical layer 64 of
anti-ballistic substance, preferably Kevlar.RTM., surrounded by an
external annular or elliptical layer 66 of blast mitigating
substance (e.g., water, gel, highly viscous energy absorbing
fluids, sand, powder, etc). In this embodiment, layer 66 consists
of a single closed compartment having a frangible mantle 68 formed,
for example, of polyethylene. A second layer 70 of anti-ballistic
substance is preferably provided outside the blast mitigating
substance layer 66, for entrapping fragments that were not
entrapped by internal layer 64, whose kinetic energy has been
somewhat dissipated by the fluids in blast mitigating substance
layer 66. It will be appreciated that layers 64, 66 and 70 are
preferably concentric. A top cover layer 72 of blast mitigating
substance 71 held in a frangible mantle is provided covering layers
64, 66 and 70. In addition, additional outer layers of blast
mitigating substance 74 and anti-ballistic material 76 may be
provided around layer 70, for providing protection against larger
charges, as shown in FIG. 4c. Top cover 72 is generally only a
blast mitigating layer to facilitate release of the unabsorbed
energy of the explosion in a preferred direction, i.e., in an
upwards direction over the charge, although a layer of
anti-ballistic material (not shown) may be provided on or under
cover layer 72. It will be appreciated that the apparatus
preferably is filled with the blast mitigating substance in situ,
for ease of transportation and assembly.
[0041] Operation of the apparatus of this embodiment is as follows.
The apparatus is disposed around charge 62, which is contained in
the cavity formed inside internal layer 64. Apparatus 60 is
designed to be placed over or around the charge, with inner layer
64 being closest to the charge. Internal layer 64 is made of an
anti-ballistic material that breaks upon interaction with a
propagating shock wave and shrapnel, absorbing some of their energy
in the process and entrapping the lower energy fragments. According
to a preferred embodiment of the invention, internal layer 64 is
formed of at least one full circle of Kevlar.RTM. sheet wrapped
around itself. The mantle 68 of the blast mitigation substance in
layer 66 breaks upon interaction with the propagating shock wave,
releasing the blast mitigating substance and absorbing more of the
shock wave's energy. Anti-ballistic layer 70 is designed to
intercept flying shrapnel not trapped by internal layer 64. If
additional mitigation is required, as in FIG. 4c, the apparatus may
include one or more additional alternating layers of blast
mitigating substance surrounded by anti-ballistic fabric. In this
case, the blast and shrapnel mitigation process, as described
above, is repeated.
[0042] The apparatus of the present invention can be used as a
screen, to protect people and objects (buildings, cars, etc.) from
a charge which explodes in their vicinity. Thus, the apparatus can
be erected in advance, for example, to form a protecting screen
adjacent an entrance to a building, such as a hotel entrance, or
erected as needed to cover a charge or to form, for example, an
evacuation screen or safety corridor for safe passage in dangerous
surroundings, check points, and so on.
[0043] With reference to FIGS. 5a, 5b and 5c, there is shown a
schematic illustration of a modular blast mitigating unit 80,
constructed and operative according to an alternative embodiment of
the invention. Modular unit 80 includes a top wall 86, a bottom
wall 88 and a side wall 82, defining a compartment 90 for holding a
blast mitigating substance. Modular unit 80 is shaped to enable
fitting of a number of units closely together in an interlocking
relationship. A sheet 83 of anti-ballistic material may be affixed
to any or all of the outer walls of the modular units. Modular unit
80 further includes filling elements 84, that may be closed using
an appropriate cap, for filling space 90 with a blast mitigating
substance. Preferably, filling elements 84 protrude from top wall
86 for use also as coupling elements, for coupling to additional
modular units 80' seated on top. Complementary recesses 89 are
preferably provided in the bottom wall 88' of modular units 80, 80'
for coupling the modular units like Lego.RTM. blocks.
[0044] An advantage of the irregular shape of the modular unit 80
of this embodiment is that it eliminates line-of-sight gaps between
adjacent units. Such gaps, if they exist, could serve to permit the
unwanted passage of blast radiation.
[0045] In FIG. 5d, there is shown a schematic illustration of a
blast mitigating wall formed by a number of modular units 80,
fitted together. The fitted modular units 80 preferably are
separated from one another by anti-ballistic sheets 83 (e.g.,
Kevlar.RTM. sheets) that line the outside walls of the modular
units. The outer walls of the constructed screen or apparatus may
be lined with anti-ballistic sheets, so to further improve shrapnel
interception.
[0046] It will be appreciated that a plurality of such safety
screen elements can be combined with others, so as to form a V or U
shaped apparatus for use in protecting against the effects of an
explosive charge.
[0047] The modular units may be filled with the blast mitigating
substance just before or after assembly, providing maximum mobility
and ease of assembly. It will be appreciated that water or other
easily disposable liquid, is the preferred blast mitigation
substance for one-time use. However, hydrophilic gel is preferred
in cases where the protective screen is expected to be in use as a
protective screen for a relatively long time. This is due to the
fact that, even if a small hole develops in the mantle, the
semi-solid gel will not leak out, so the protective barrier will
remain intact. According to a preferred embodiment of the
invention, the gel is a polymeric gel, particularly a
polyacrymalide. More preferably, the gel is a non-toxic,
biodegradable polyacrymalide. Most preferably, the gel is a
non-toxic polyacrymalide that biodegrades to CO.sub.2, nitrogen and
water. Alternatively, any other suitable hydrophilic gel can be
utilized. It is a particular feature of this embodiment that, after
use, the gel can be dissolved in additional water and easily washed
away. Thus, no special equipment is required for disassembly and
removal of the protective barrier.
[0048] When water or a suitable hydrophilic gel is the blast
mitigating substance, it may be desirable to add bleach or other
antimicrobial material to the water to prevent the growth of mold,
mildew, algae, and microbes in the water when the water is left in
the blast mitigating apparatus for extended periods of time. In
addition, it will be appreciated that sometimes terrorists put
biological substances in with their explosives, e.g., HCV or HIV
infected blood. If desired, the blast mitigating substance
(particularly when in liquid form) may include biological
warfare-mitigating substances, which mist the entire area of the
blast with the chosen anti-biological substance upon detonation.
Bleach also serves as such a biological warfare mitigating
substance. Alternatively, or in addition, the internal compartments
of the blast mitigating apparatus may be provided with substances
which provide radiological weapon mitigating protection. Such
substances are those which reduce or eliminate alpha, beta and
gamma rays prior to explosion of the charge.
[0049] According to another embodiment of the invention, the
innermost layer of the device can be fitted with a light source,
such as light-emitting film, and mirrors and/or remotely operated
robotic tools (not shown). These devices would permit examination
and/or dismantling of the explosive charge while it is inside the
blast mitigating apparatus, without endangering an operator.
[0050] While the invention has been described with respect to a
limited number of embodiments, it will be appreciated that many
variations, modifications and other applications of the invention
may be made. It will further be appreciated that the invention is
not limited to what has been described hereinabove merely by way of
example. Rather, the invention is limited solely by the claims
which follow.
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