Note: Descriptions are shown in the official language in which they were submitted.
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INFLATABLE DECONTAMINATION SYSTEM
BACKGROUND
[00011 The present invention relates to the field of environmental
decontamination. It
finds particular application in conjunction with a portable enclosure for
microbial,
biological or chemical decontamination of large pieces of equipment, and will
be described
with particular reference thereto. It should be appreciated, however, that the
-invention is
also applicable to the decontamination, treatment, or isolation of other
items, both large and
small.
[0002] Small pieces of equipment used in medical, pharmaceutical, food, and
other
applications are frequently sterilized or otherwise microbially decontaminated
prior to use
or reuse. Concerns arise, however, when larger pieces of equipment, such as
vehicles, food
and pharmaceutical processing equipment, mail handling equipment, and the like
become
contaminated with chemical or biological contaminants, such as harmful
organisms or other
species. Such equipment is often too large or is unsuited to being transported
to a
decontamination system, such _as a sterilizer. Further, there is often concern
that
transporting the contaminated equipment around a facility or to an offsite
decontamination
system may pose hazards to those transporting the equipment or may spread the
contamination around the facility or to transportation equipment.
[00031 US Published Application No. 2003/0133834 to Karle discloses an
enclosure
assembly includes a framework formed from structural members and a flexible
transparent
enclosure which provides an enclosed space for isolation and or treatment of
patients,
equipment, and the like. A treatment material, such as hydrogen peroxide or
other gaseous
.or vapor sterilant, may be fed to the enclosure to microbially decontaminate
or otherwise
treat the equipment. The enclosure is quickly assembled and disassembled after
use,
making it suitable for treatment of large pieces of equipment which are not
readily moved
or which are too large to be accommodated conventional sterilization
equipment.
[00041 The system of Karle is suited to smaller enclosures where the height of
the
framework makes assembly feasible. Due to the large number of components,
there is a
risk that an important part of the frame may be lost if the assembly has been
used previously
and repacked without care.
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[0005] The present invention provides a new and improved portable
environmental
enclosure and method of use which overcome the above-referenced problems and
others.
BRIEF DESCRIPTION
[0006] In accordance with one aspect of the present exemplary embodiment, a
decontamination system for decontaminating an item includes an enclosure
comprising an
inflatable structure which, when inflated, defines an interior space for
receiving the item to
be decontaminated. A source of a decontaminant is fluidly connected with the
interior
space. The source supplies the decontaminant to the interior space for
decontaminating the
item.
[0007] In accordance with another aspect of the present exemplary embodiment.
a
method of decontaminating an item is provided. The method includes inflating
inflatable
structural elements to form an enclosure with an interior space to hold the
enclosure erect
and transporting an item into the interior space. The item is sealed in the
enclosure and a
gaseous decontaminant is introduced to the interior space to decontaminate the
item.
[0008] One advantage of at least one embodiment is that the decontamiriation
system is
readily transported to a site at or close to the location at which
contamination has occurred
or is recognized.
[0009] Another advantage of at least one embodiment is that the system is
employed
operational in a short period of time.
[0010] Another advantage of at least one embodiment is that the system can be
stored,
when not in use, in a small volume.
[0011] Another advantage of at least one embodiment is that the passages which
form
the enclosure are heated by inflation air, reducing condensation of the
decontaminant
between the decontaminant source and the enclosure interior.
[0012] Another advantage of at least one embodiment is that the enclosure is
temperature controlled on all sides.
[0013] Still further advantages will be apparent from a reading of the
following
description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The drawings illustrate embodiments of the invention and are not
intended to
limit it. Further embodiments will occur to those of ordinary skill in the art
on reading and
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following Detailed Description. The invention is to be construed as including
all such
further embodiments which come within the scope of the depended claims or
their
equivalents.
[0015] FIGURE 1 is a perspective view of a decontamination system according to
the
present invention;
[0016] FIGURE 2 is a top plan view of the decontamination system of FIGURE 1;
[0017] FIGURE 3 is a perspective view of the decontamination system of FIGURE
1
with the front doors open;
[0018] FIGURE 4 is a cross sectional view of the enclosure; and
[0019] FIGURE 5. is an enlarged perspective view of a portion of a side wall
of the
enclosure of FIGURE 1.
DETAILED DESCRIPTION
[0020] With reference to FIGURE 1, a portable decontamination system A
includes a
portable enclosure 10 which is suitable for temporarily isolating and
decontaminating large
items. The enclosure 10 is readily erected when needed for isolation of a
contaminated or
potentially contaminated item from the surrounding environment and for
subsequently
decontaminating the item with a gaseous or liquid decontaminant. The gaseous
decontaminant may be in the form of a gas, vapor, mist, aerosol, or fog.
Suitable gaseous
decontaminants include oxidizing agents, in particular, peroxides, such as
hydrogen
peroxide, ozone, or a combination of hydrogen peroxide with a co-agent, such
as ammonia
or UV radiation. Other suitable gaseous decontaminants include high
temperature air and
other gaseous decontaminants which are capable of destroying, inactivating, or
otherwise
rendering the contaminant less harmful. While particular reference is made to
vapor
hydrogen peroxide, it will be appreciated that other gaseous decontaminants
and
combinations of decontaminants are also contemplated.
[0021] The term "decontamination," as used herein, encompasses microbial
decontamination-the destruction or inactivation of biological contaminants,
including
living microorganisms and harmful replicating biological substances, such as
prions. The
term also encompasses chemical decontamination-the destruction or inactivation
of
chemical agents which are harmful to humans at low levels (e.g., below about
10 ppm.),
such as chemical warfare agents. It is not intended to encompass solely the
physical
removal of such contaminants, without destruction or inactivation, as in a
cleaning process,
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although a decontamination process may also effect cleaning. A
"decontaminant," as used
herein, is a substance which is capable of effecting decontamination. The
enclosure 10 is
configured for performing decontamination processes, particularly chemical and
microbial
decontamination processes, such as sterilization or lesser forms of
decontamination,
including disinfection and sanitization.
[0022] Items which can be isolated and decontaminated in the enclosure 10
include
motorized passenger and goods transport vehicles, such as ambulances, cars,
trucks, buses,
and other road vehicles, military vehicles, such as tanks and personnel and
munitions
carriers, aircraft, food and beverage processing equipment, such as cooking,
processing,
chilling, slicing, packaging and bottling equipment, and pharmaceutical
equipment. Other
equipment can also be treated, such as medical and veterinary equipment
contaminated with
body fluids or other sources of microorganisms, including beds, chairs,
washing facilities,
and the like. Pharmaceutical processing equipment, mail-handling equipment,
and other
equipment may be isolated and treated. The item is typically one which is
known or
suspected of being contaminated with a chemical or biological contaminant
which is
harmful to humans, such as chemical warfare agents, biological warfare agents,
and
naturally occurring chemical and biological contaminants. The item is readily
isolated and
treated without moving the item to a permanent, purpose-built isolation unit,
reducing the
chance that harmful microorganisms or other contaminants will be spread around
a facility.
Additionally, some equipment which is too heavy or too large for convenient
movement can
be cleaned in place.
[0023] The enclosure 10 includes a flexible inflatable structure 12. When
inflated with
an inflation fluid, such as air, as shown in FIGURE 1, the inflated structure
12 provides a
rigid freestanding walled enclosure. The structure 12 is self-supporting,
without the need
for a framework of support members formed from a rigid material, although such
a
framework may be employed if desired. With reference also to FIGURE 2, the
inflatable
structure 12 includes a plurality of inflatable walls 14, 16, 18. While the
enclosure 10 is
illustrated with an inflatable rear wall 14 and inflatable sidewalls 16, 18
which extend and
arch upwardly to form a roof 20 of the structure 12 (FIGURE 1), it will be
understood that
any number of walls may be employed as long as the enclosure is inflatable for
its desired
purpose. One or more of the walls 14, 16, 18 or potions of the walls may
include non-
inflatable portions. For example, the rear wall- 14 may alternatively be
formed of a single or
double layer. The walls 14, 16, 18 define an inflatable support structure
formed by a set of
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tubular members or other suitably shaped structural elements 21 which define
interconnected inflation passages 22. Once inflated, and tied or otherwise
anchored down,
as necessary, the enclosure is capable of withstanding wind speeds of up to
about 100
miles/hr. The enclosure 10 optionally includes a floor 24, suitable for
positioning on a
support surface 26. In one embodiment, the floor is thermally insulated to
facilitate
accurate temperature control. Alternatively, the support structure 12 is taped
or otherwise
sealed to the support surface 26 and has cross structures, as necessary to
help maintain the
base. of the walls in the proper location. The enclosure 10 is light weight
and, prior to
inflation, can be stored in a valise 28 of suitable size.
[0024] As shown in FIGURE 2, an interior space 30 within the enclosure 10 can
be
sealed from the surrounding atmosphere to create a substantially airtight
isolation chamber
for carrying out a decontamination process. Specifically, the floor 24 of the
enclosure is
sealed to the walls adjacent a lower end thereof. The rear wall 14 is sealed,
around its
perimeter, to the adjacent side walls 16, 18. An access opening 32, at an end
of the
enclosure opposite the rear wall 14 is sealed, during decontamination, by a
closure
comprising an interior door 34 and an exterior door 36 which define an
antechamber 38
therebetween. The doors 34, 36 each comprise a set of closure members in the
form of
flexible panels 40, 42, 44 (FIGURE 1), which may be formed from the same
material as the
inflatable structure 12. The panels are folded, rolled, or otherwise drawn
aside as shown in
FIGURE 3, to provide access to the enclosed space 30. Fastening members 46,
along edges
of the panels 40, 42, 44 allow the panels to be sealed to each other and to
the floor when in
the closed position. Suitable fastening members 46 include hook and loop tape
(e.g.,
ChicoTM hook and loop tape, available from Stretchline (Textiles) Ltd,
Tetbury, Gos., UK,
or VelcroTM tape). Other suitable -fastening members include zippers, and
Ziploc types of
closure. ChicoTM hook and loop tape, for example, is a fire retardant tape
formed from
100% nylon. It has a cushioning effect which both insulates and reduces
vibrations and,
when firmly closed, acts as an effective dust filter and, in one embodiment,
is snow and
sand proof.
[0025] In FIGURE 1, the exterior door has a center panel 40, which includes a
transparent portion 48 for providing a window to the interior space 30. The
center panel 40
may be rolled upward, from the floor, and held by tapes or ties 50 attached to
a fixed panel
52 (FIGURE 3) for access to the interior 30. Two side panels 42, 44, are also
drawn aside
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and held by suitably positioned tapes or straps 54 attached to the inflatable
structure 12.
The interior door 34 can be similarly constructed.
[0026] With continued reference to FIGURES 1 and 2, an inflation system 60 is
connected with the interconnected inflation passages 22 prior to inflation.
The inflation
system 60 includes a compressor 62 or other suitable air blower which
pressurizes
atmospheric air. Suitable blowers are electrically operated pumps, although a
manually
operated pump is alternatively used. The inflation system optionally also
includes heating
and/or cooling equipment 64 for heating/cooling the air prior to entering the
passages 22.
The compressor 62 may have two or more operating speeds to provide low and
high air
flow rates. The high flow rate is used for initially inflating the structure
12 and a lower rate
is used for sustaining the inflation structure.
[0027] The temperature controlled air enters the passages 22 and provides a
temperature
adjustable air blanket around the interior space 30, which enables the
appropriate
temperature for effective decontamination to be maintained within the interior
space. In the
case of hydrogen peroxide vapor, a suitable temperature is one which
eliminates or
minimizes condensation of the hydrogen peroxide vapor on the walls of the
enclosure or on
items to be decontaminated and is generally above that of the surrounding
exterior.
environment. A switch (not shown) or the like is optionally provided on the
pump 62,
which enables a user to change the pump from an inflation mode to a deflation
mode. The
inflation system 60 typically operates at about 1=300 m3/min. Depending on the
size of the
blower and the size of the inflatable structure, the enclosure can be erected
in a relatively
short period of time, typically in under about an hour. For larger enclosures,
a plurality of
blowers can be employed to increase the rate of inflation.
[0028] The inflationlsystem 60 is connected with the interior 30 via an inlet
port 70 of
the inflatable enclosure. As shown, a thermally insulated air conduit 72
extends between
the inflation system and the wall 18 of the enclosure. In one embodiment, the
end of the air
conduit is fitted with a suitable coupling member 74 for quickly coupling with
a
corresponding coupling member 76 extending from the inlet port 70.
Alternatively, a
permanent connection may be provided between the conduit 72 and the wall inlet
port 70.
The inflation system 60 optionally also supplies fresh air to the antechamber
38 via an inlet
or inlets 78. The air may be heated or cooled as for the air in the passages,
thus ensuring a
temperature controlled environment on all sides of the enclosure 10.
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[00291 As illustrated in FIGURE 2, the walls 14, 16, 18 and roof 20 of the
enclosure are
formed from inner and outer panels 80, 82 of flexible material, which are
arranged generally
parallel to one another. The panels 80, 82 are connected to each other by
vertically
extending connecting members 84, which may be formed from the same material.
Together, the inner and outer layers and connecting members form the tubular
members
which define the through passages 22. The walls 14, 16, 18 may be vertical or
slope
generally inward, towards their upper ends, adjacent the roof portion 20, as
illustrated in
FIGUREI. The passages 22 which define the side walls 16, 18 and roof portion
20 thus
extend generally vertically from the floor 24 to form the first side wall 16,
span the roof
portion 20, and continue down the other wall 18 to the floor. The connecting
members 84
define apertures 86, which enable the air to flow throughout the passages and
equalize the
pressure. An outlet check valve 88 in the outer panel 82 of the wall 16
opposite to the inlet
allows the release of excess pressure above a preselected maximum pressure and
allows the
passages to be continuously or intermittently replenished with heated or
cooled air, if
desired.
[0030] The panels 40, 42, 44, 80, 82 are sealed together at their edges to
provide an
airtight, or substantially airtight interior space 30. It will be appreciated
that each panel
may be formed from two or more separate panels which are sealed together at
their
respective edges. 'By substantially airtight it is meant that if air at a
pressure equivalent to
about 3.8 cm of water is supplied to the enclosure and allowed to equilibrate
for 2 minutes,
and then the air pressure supply is disconnected, the pressure within the
enclosure after a
further 5 minutes is at least about 2 cm of water, in one embodiment, at least
about 2.5 cm
of water. The enclosure may be leak tested, prior to use, to check that the
enclosure is
substantially airtight, for example, by pressurizing the enclosure to about
1.5 cm water,
equilibrating for 1 minute, and testing to ensure that an acceptable pressure
level is
maintained, such as a pressure of 1.0 cm water after 2 minutes.
[0031] The floor 24 of the enclosure is optionally heated for heating the
interior space
30. For example, as shown in FIGURE 4, the floor comprises lower and upper
layers of
flexible material 90, 92. A flexible resistance heating element 94 or other
heat source is
located in a gap 96 between the two layers. In one embodiment, the floor 24
comprises
sections, each section having its own associated heat source.
[0032] A mobile source 100 of gaseous decontaminant supplies a gaseous
decontaminant to the interior space 30. As shown in FIGURE 2, the source 100
is located
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exterior to the enclosure, although it is contemplated that the source is
alternatively
transported into the interior, prior to decontamination. A suitable source 100
for supplying
vapor hydrogen peroxide includes a source 102 of liquid hydrogen peroxide in
solution,
such as a reservoir of aqueous hydrogen peroxide at a concentration of about
20-40% by
weight hydrogen peroxide. The hydrogen peroxide liquid is fed by a pump 104 to
a
vaporizer 106, where the hydrogen peroxide and water components are vaporized
on a
heated surface (not shown). The vapor is carried in a carrier gas, such as air
or other flow
medium, supplied by a source of carrier gas 108, such as a blower or
pressurized reservoir.
The blower 108 may operate at about 1-300 m3/min. For larger enclosures, a
plurality of
mobile sources 100 may be employed. The air is optionally dehumidified in a
dehumidifier
110 and heated by a heater 112 prior to combining with the hydrogen peroxide
vapor.
[0033] One suitable mobile'source 100 of sterilant is a STERIS VHP 1000TM
hydrogen
peroxide vapor generator. Other suitable vaporizers are disclosed in U.S.
Patent No.
6,734,405 to Centanni, et al., and U.S. Published Application No. 2002/0159915
to Zelina,
et al. Other suitable misting, fogging, or aerosol generating equipment for.
generating the
gaseous decontaminant is also contemplated. Alternatively, the gaseous
decontaminant is
generated in situ, within the enclosure or is supplied from a pressurized
container (as in the
case, for example, of ozone).
[0034] The vaporizer 106 -is connected by one or more thermally insulated
supply
conduits 114 which pass through corresponding access ports 116 in the
enclosure wall 16,
18 and are carried within or through the passages 22 to the interior 30.
Within the interior,
the conduits 114 may branch to provide a gaseous decontamination distribution
network
118. The ports 116 are sealed around the conduits to reduce leakage.
Alternatively the
conduit(s) 114 and network 118 may be selectively connectable by releasable
connection
members, as for the air supply conduit 72.
[0035] The distribution network 118 includes a plurality of flexible conduits
120, which
can be collapsible. The conduits 120 transport the gaseous decontaminant to a
plurality of
decontaminant supply inlets 122 in the form of vents or nozzles spaced around
the interior
30. The heated air within the passages 22 assists in preventing or limiting
condensation of
hydrogen peroxide or other vapor decontaminant between the source 190 and the
nozzles
122. The nozzles 122 feed the gaseous decontaminant into the interior space
30. The
nozzles may be directional to assist in circulating the decontaminant. One or
more fans 124
or other circulation devices optionally assist in distributing the gaseous
decontaminant
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throughout the interior. The conduits 120 can be built into the passages 22,
in which case
they may fold flat, or be held in place, within the interior, by suitably
positioned clips or ties
126.
[0036] To ensure that the decontaminant contacts portions of an item that are
poorly
accessible to the decontaminant, flexible hoses 128 communicate between the
vaporizer and
the interior 30 through selectively operable ports 130 formed in the interior
and exterior
panels 80, 82 as best shown in FIGURE 5. The flexible hoses 128, which can be
routed into
the poorly accessible areas, for example, through windows of a vehicle to be
decontaminated. In the illustrated embodiment, the ports 130 are covered, when
not in use
by closures 132 such as flexible flaps formed from ChicoTM or VelcroTM hook
and loop tape
or other suitable sealing members. The flexible hoses 128 are fed through the
sidewall 16,
18, when needed, so that they extend between the interior and exterior. The
ports 130 are
configured to grip the hoses tightly, minimizing leakage from the interior 30.
Additional
sealing material, such as duct tape is optionally used to assist in sealing
around the hoses
128 at the ports 130. Alternatively, distribution tubes built into passages 22
terminate at
operable/sealable connection ports along the interior.
[0037] With reference to FIGURE 4, sensors 140 within the enclosure detect one
or
more parameters of the interior space 30, such as temperature, humidity,
concentration of
decontaminant (e.g., hydrogen peroxide concentration), concentration of a
contaminant
(e.g., anthrax spores or a chemical warfare agent), concentration of a product
of a reaction
of a contaminant with the decontaminant (such as the product of a reaction of
a chemical
warfare agent with hydrogen peroxide), and the like. In one embodiment,
several sensors
140 of each type are located around the interior space 30. The sensors are
hung from
suitably positioned hangars or straps 142 mounted to the interior panels 80
and
communicate with a monitoring and control system 144, such as a
microprocessor, located
exterior to the enclosure 10 by suitable optical or electrical connectors 146.
Biological
and/or chemical indicators 148 are optionally located within the enclosure and
examined,
after, the decontamination process. Suitable biological indicators include a
population of
spores or other hard to kill microorganisms. The presence of residual live
spores, after
decontamination, is an indication that the decontamination process was
inadequate.
Suitable chemical indicators exhibit a visual or otherwise detectable change
in response to a
preselected minimum concentration of the decontaminant.
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The monitoring and control system 144 includes a monitoring function 150
[0038]
which records inputs from the sensors and determines/stores values of the
sensed
parameters. The system 144 also includes a control function 152 which provides
feedback
control to the source 100 of decontaminant in response to the sensed
parameters. The
control function 152 uses the information provided by the monitoring function
150 to
control variables, such as the rate of hydrogen peroxide vaporization, the
carrier gas flow
rate, the carrier gas temperature, the inflation gas temperature and flow
rate, power to the
heater 94, and other operating parameters in order to maintain desired
conditions for
decontamination within the enclosure.
[0039] For example, where the hydrogen peroxide concentration detected in the
interior
30 is outside a preselected range, the control function 152 instructs the
source 100 of
decontaminant to increase or lower the rate of production of hydrogen
peroxide.
Alternatively or additionally, the control function 152 provides feedback
control to other
components of the system. For example if the temperature within the enclosure
is outside a
preselected range, the control function 152 instructs the heater 64 to adjust
the temperature
of air entering the passages, its introduction rate, or instructs the floor
heater 94 to adjust the
temperature of the floor to bring the temperature to within the preselected
range. In this
way, the system components can be adjusted to maintain a hydrogen peroxide
concentration
within the interior space 30 within a preselected range, such as from about
0.1-5 mg/L (72-
3600ppm), e.g., from 0.1-2.0 mg/L and avoid saturation concentrations being
reached. In
one embodiment, the hydrogen peroxide concentration is at least about 0.7 mg/L
(400+ppm). A temperature in the interior space 30 of about 15-120 C may be
used, e.g., at
least 25 C. The vapor hydrogen peroxide concentration is selected to be below
the
saturation point, which is a function of the temperature in the interior space
30.
[0040] As shown in FIGURE 2, the spent vapor, mixed with air from the interior
30,
optionally exits the enclosure 10 through an outlet conduit 154 connected with
an outlet port
156 and is advantageously transported to a catalytic converter 158 or other
destroyer before
being released to the atmosphere. A filter system 160 in the outlet conduit
removes traces
of residual contaminants in the exiting air. For example, the filter system
160 includes a
HEPA filter which traps microorganisms. A chemical filter is optionally
included which
removes certain harmful chemical agents. A pump 162 is used, in the
illustrated
embodiment, = to actively withdrawn the spent vapor. One or more outlet vents
164 are
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located in the wall of the antechamber 38 and are connected with the outlet
conduit 154 by
suitable flexible hoses 165 for withdrawing air from the antechamber.
[0041] Alternatively or additionally, all or a portion of the vapor is
recirculated through
the vaporizer via a return line 166, optionally after passing through a
catalytic converter
168, the dehumidifier I10 and heater 112 (FIGURE 2).
[0042] Hydrogen peroxide is a particularly effective decontaminant for many
airborne
microorganisms and other toxic materials including chemical and biological
warfare agents.
It shows effectivity against a wide range of vegetative and endospore forming
bacteria (e.g.,
anthrax); fungi; viruses; yeasts, and prions. It is also effective against
many chemical
warfare agents, including organosulfur agents, such as mustard gas (H, HD,
HS); G-series
nerve agents (organophosphate nerve agents), such as tabun (GA), sarin (GB),
soman (GD),
and cyclosarin (GF); V-series nerve agents, such as VX, VE, VG, VM and V-gas,
particularly when used in combination with ammonia in a ratio of hydrogen
peroxide:
ammonia of between 1:1 and 1:0.0001. The spores responsible for Anthrax and
other
microbial contamination, for example, are readily destroyed using a short
exposure period
to hydrogen peroxide of a few minutes. Destruction of chemical warfare agents
may take
several hours. In one embodiment, the decontaminant reduces the population of
live
microorganisms or concentration by weight of the harmful chemical agent to
less than 1%
of the original value and in one embodiment, reduces the contaminant to
undetectable
levels.
[0043] Ozone has also been found to neutralize most known biological and
chemical
contaminants. Chemical and biological contaminants may also be treated with
another
decontaminant, such as UV radiation, or the like.
[0044] Prior to introducing the vapor, a slight negative pressure can be
applied to the
interior 30 of the enclosure to speed up the introduction and dispersal of the
vapor.
[0045] The enclosure 10 is capable of maintaining an interior pressure which
is slightly
above atmospheric pressure or slightly below atmospheric pressure. Below
atmospheric
pressures are preferred when it is desirable to minimize any leakage of
airborne
contaminants from the enclosure. In one embodiment, for vapor hydrogen
peroxide
decontamination, the enclosure is able to withstand approximately three times
a normal
operating pressure of 2-5 cm of water to provide a margin of safety.
[0046] In one embodiment, the enclosure 10 is formed from a flexible sheet
material,
which is airtight and water resistant, such as vinyl or polyvinyl chloride
(PVC). It is also
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resistant to chemical decontaminants, such as hydrogen peroxide. One suitable
material is
sold under the tradename V3F Polytarp, and is a woven polyester fabric of
77g/m2 weight
which is laminated on both sides with flexible PVC, yielding a material of
about 580 g/m2.
This material is resistant to cracking to temperatures of about -25 C and
above. The
enclosure can thus be used for decontamination in indoor or outdoor variable
temperatures
between about -50 and +50 C.
[0047] As illustrated in FIGURES 1 and 5, in one embodiment, portions of the
walls 14,
16, 18 are transparent to provide operators outside the enclosure with a view
of what is
taking place inside. For example, windows 170 are formed in the walls by
forming
midportions 172, 174, 176 of the inner and outer panels 80, 82 and connecting
members 84
from panels of a transparent material, such as a clear PVC sheeting. One
suitable PVC
sheet material has a thickness of 0.5 mm and a weight of 646 g/m2 is sold
under the
traderiame VelbexTM by Wardle Storeys Ltd., Earby, Colne, Lancashire, UK.
Seams
between the various sheeting panels can be double lapped and sewn, adhesively
joined,
thermally fused together, or the like. The interior panels 80 of the walls may
be coated with
an antifungal, UV stabilized, water repellant coating. The water repellant
ingredients resist
condensation of the vapor on the walls of the enclosure, while the antifungal
components
inhibit the growth of fungus on the enclosure during storage.
[0048] The size of the enclosure 10 is variable, depending on the size of the
item to be
decontaminated. Typically, the interior volume can be from about 20m3 to about
1 0,000m3.
For example, for decointaminating vehicles, such as ambulances, the interior
may define a
volume of about l Om x 8m x 4m. For larger vehicles, such as aircraft, the
enclosure may be
significantly larger. For larger enclosures, e.g., above about 500-1000m3, the
structure 12
may not be fully self supporting, in which case, an interior or exterior frame
(not shown) of
metal poles or the like is constructed a.nd the enclosure supported thereon.
[0049] Additionally or alternatively to enabling supply of gaseous
decontaminant to the
interior, the enclosure 10 is optionally adapted to facilitate treatment of an
item in other
ways. For example, as shown in FIGURE 4, a liquid conduit 180 is optionally
connected
with one or more spray nozzles 182 within the interior space 30 for washing or
otherwise
treating the item to remove solid contaminants which are removable with water,
detergents,
liquid decontaminants, or combinations thereof. A drain 184 is formed in the
floor and the
enclosure positioned to allow the used liquid and associated dirt and
contaminants to flow
into a sump 186 formed in the support surface. The fluids collected in the
sump are
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ooptionally bagged and disposed of by a hazardous waste treatment facility or
otherwise
treated appropriately to remove contaminants.
[0050] The enclosure 10 is particularly suited to treatment of vehicles and
items which
can be transported on a vehicle, for example on a wheeled cart or conveyor,
into the
enclosure.
[0051] A typical decontamination proceeds as follows. A contaminating event,
such as
a release of chemical or biological warfare agents, occurs and is communicated
to an
operator who transports the deflated enclosure 10 and all or a portion of the
associated
equipment 60, 100, 158, 160, etc. to a site at which decontamination of
contaminated or
potentially contaminated items which were exposed to the contaminating event
is to take
place. For example, the enclosure 10, vapor generator 100, blower 60, and the
like are
loaded onto a truck and transported to an indoor or outdoor site or facility
at or close to the
location of the contaminating event. This minimizes the risk of spreading of
contamination.
[0052] The enclosure 10. is removed from its valise 28 and spread out, ready
for
inflation. The blower 60 is connected to the port 70 and inflation is
commenced, optionally
also with heating/cooling of the air and/or floor. As soon as the enclosure
has reached a
sufficiently stable inflated state, the vehicle, or other item(s) to be
decontaminated, is
transported into the enclosure by personnel dressed in hazard material
protective clothing.
Doors, windows, etc. of the vehicle are opened to allow access to the
decontaminant.
Sensors 140 and chemical /biological indications 148 are suspended from the
enclosure or
otherwise located within the interior space 30. Ends of the flexible tubes
120, 128 are
pushed through their respective ports, for example, from the interior to the
exterior, and
connected with the decontaminant source 100. The flexible tubes 128 are
positioned so that
their outlets are located in less accessible parts of the vehicle while tubes
120 are suspended
from clips 126. The inner and outer doors 34, 36 of the enclosure are closed
and the hook
and loop tapes 46 sealed together, prior to beginning introduction of the
gaseous
decontaminant. The pressure in the interior space 30 may be reduced to
slightly below
atmospheric pressure, to minimize leakage of contaminants and to speed
introduction of the
decontaminant.
[0053] If a washing operation or liquid decontamination is to be performed,
this is
optionally carried out prior to the gaseous decontamination, although it could
alternatively
be performed after or in place of the gaseous decontamination.
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[0054] The gaseous decontaminant is introduced to the interior space 30 to
achieve a
concentration which is sufficient to ensure decontamination of the item to an
acceptable
level within a preselected period of time, such as from a few minutes to
several days. In the
case of hydrogen peroxide, for example, a concentration of about 400-1000 ppm
at a
temperature of 20-50 C is generally sufficient to reduce microbial
contamination by a 6 log
reduction (i.e., a population of 106 spores is reduced to 1 or less) in under
about two hours,
and generally in about 30 minutes or less. Similar concentrations,. and
temperatures may be
used for destroying chemical agents or reducing their activity, to a level at
which they are
not considered hazardous. Longer times may be needed, however. Once the
decontamination period is complete, the interior space 30 is aerated, for
example, by
switching off the vaporizer 106 and introducing dehumidified, exterior air
with the blower
108 while withdrawing air from one or more vents 156.
[0055] Alternatively or additionally, vents 188 in the inflation passages 22
release air
into the enclosure. The vents 188 may be closed, when not in use, by flaps
covered with
ChicoTM or VelcroTM hook and loop tape, in a similar manner to the vents 132.
To hold the
flaps open, the hook and loop tape may be temporarily attached by hook and
loop tape to
corresponding hook and loop fabric attached to the inner wall 80. A mesh
screen 190 covers
the vent and allows air to pass freely through. The aeration is. continued
until the
decontaminant concentration within the enclosure is low enough for operators
to reenter. In
the case of hydrogen peroxide, a safe level is considered to be about lppm, or
less. ,The
aeration phase may last several hours, or longer. The vehicle or other
decontaminated item
may be subjected to tests for residual contaminant before it is returned to
service. Or, if
appropriate, the item may be disposed of.
[0056] After use, the inflatable enclosure 10 may be deflated and repackaged
in a
carrying bag 28 for a subsequent reuse. Prior to repackaging, the enclosure is
optionally
subjected to a suitable decontamination process, such as a gaseous
decontamination process,
for example with hydrogen peroxide vapor. Such a decontamination process may
be used
to decontaminate both outer and interior surfaces of the enclosure.
Alternatively, the
enclosure is used one time and then disposed of, using an appropriate safe
disposal method.
[0057] It will be appreciated that, depending on the size of the item and the
size of the
enclosure, a plurality of items may be decontaminated simultaneously within
the enclosure.
