WO 2006/070363 PCT/IL2005/001384
POSTIVE FLOW REBREATHER
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to U.S. Provisional Patent Application
60/639,296, filed December 28, 2004, whose disclosure is incorporated
herein in its entirety by reference.
FIELD OF THE INVENTION
The present invention relates to closed loop breathing devices that
adsorb CO2 from expired air and enrich the air with O2, thereby recycling
expired air for inspiration.
BACKGROUND OF THE INVENTION
Rebreathers supply recycled purified air to a user by adsorbing CO;
(carbon dioxide) from expired air and enriching the air with O2 (oxygen) in a
closed loop system. Rebreathers are lighter than open breathing systems that
require heavy tanks of air and/or O2.
Rebreathers provide a breathing environment that is isolated from the
external environment and are particularly useful in hostile environments, for
example in the presence of smoke from a burning fire; pollutants in at
industrial environment; and at high altitudes with insufficient O2
Additionally, rebreathers are used in underwater diving.
In a smoke-filled environment, a rebreather fits over the user face am
allows evacuation from the smoky environ.

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In the face of virtually any poisonous gas pollution, for example in an
industrial environment, rebreathers provide recycled air that allows workers
to find and repair the source of pollution. An alternative solution, a mask
filter, comprises a mask that includes one of a variety of filters; each filter
specific only for certain poisonous gases. To provide the same spectrum of
protection as a single rebreather, multiple masks and/or filters must be
maintained on site.
At high O2 deprived altitudes, a climber can continue to function by
periodically using a rebreather, eliminating the need to carry a heavy O2
tank. Divers can use size of O2 tank in conjunction with a rebreather for a
longer period than the O2 tank alone.
Rebreathers include a flexible bladder, herein a counter lung,
connected to an adsorption canister having a manifold that covers a user
mouth and/or nose. Expired air, while passing from the canister to the
counter lung, is recycled for inspiration by adsorbing CO2 and providing
enrichment with O2.
CO2, primarily in the form of carbonic acid dissolved in water vapor,
is adsorbed in the adsorption canister containing soda-lime. Soda-lime is a
mixture of 94% calcium hydroxide, 5% sodium hydroxide and 1%
potassium hydroxide. The canister additionally contains water for dissolving
the undissolved CO2 gas for adsorption; silica to preserve the granularity of
the soda-lime; and a pH sensitive dye that indicates exhaustion of the soda-
lime.
CO2 adsorption occurs through the following chemical reactions:


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Calcium hydroxide adsorbs the majority of the CO2 while sodium
hydroxide and potassium hydroxide accelerate the rate of CO2 adsorption.
The above noted chemical reaction is exothermic, with the temperature of
the soda-lime quickly reaching and maintaining a temperature of about 140
degrees Fahrenheit.
Following CO2 adsorption, O2 gas is introduced into the purified air
from a compressed O2 bottle and the air, purified of CO2 and enriched with
O2 is inspired by the user; thereby providing an efficient solution in a
difficult breathing environment.
While rebreathers have many advantages over bulky O2 tanks, air
tanks and filtered masks, rebreathers are not without drawbacks.
Rebreathers repeatedly recycle the user's expired air, rapidly
absorbing the heat of the user's body temperature, thereby raising the
temperature of the recycled air above the ambient temperature of the
environment.
More problematic the exothermic reaction required for CO2
adsorption, noted above, adds significant heat to the air in the closed' loop,
causing the air to become uncomfortably hot. Additionally, environmental
heat can raise the rebreather temperature even higher; for example when a
rebreather is administered in the presence of the searing heat of a raging fire.
In such applications, the overly heated air in the closed loop, may not only be

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uncomfortable, but hazardous; contributing to user panic that may result in
irreversible shock.
Rebreathers used by divers do not require a mechanism to cool the
inspired air as the low temperature of the surrounding water provides
adequate cooling; however in land-based use, diving rebreathers would
similarly provide the user with uncomfortably hot air.
Over heated recycled rebreather air accrues two additional problems;
the first problem being inadequate mixture of O2 with the inspired air. The
O2 gas, by virtue of expanding from the tank, is cooler and heavier than the
over-heated expired air in the counter lung. The heavier cool O2 sinks to the
bottom of the counter lung while the lighter hot non-enriched expired air
rises and covers the air intake at the top of the counter lung. With non-
enriched hot exhaled air primarily entering the air intake, the user is
deprived of necessary O2.
The second problem associated with overheated air is inefficient
adsorption of CO2. As the base granules become heated from the exothermic
reaction associated with CO2 adsorption, the efficiency of the granules is
reduced, resulting in less adsorption of CO2. Additionally as the air expands
due to the heat, the expired air is propelled out of the adsorption canister,
resulting in even less efficient adsorption of CO2.
Inefficient CO2 adsorption and poor mixing of O2 with the expired air,
both resulting from overly hot exhaled air, may result in user hypoxia and
associated sequela.
U.S. Patent 4,314,566 to Kiwak discloses a rebreather having an
externally located heat exchanger system; and U.S. Patent 5,269,293 to

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Loser et al. discloses an external zeolite adsorbent cooling system; both
systems provide a potential solution to overheating but add considerable
weight, bulk, size and/or expense to the rebreather.
In addition to all the problems associated with the exothermic
adsorption of CO2, there are three problems associated with the demand
valve on the O2 bottle that opens to release O2 gas during each rebreathing
cycle.
The first problem is that demand valves are complex and open and
close with each breathing cycle, making the valves prone to malfunction.
The second problem is that demand valves are heavy, adding unwanted
weight to a rebreather. The third problem is that the demand valve only
opens following expiration. If a user begins the first breathing cycle with an
inspiration, as opposed to an expiration, the user is provided with nothing to
inspire; likely resulting in a bout of choking that further deprives the user of
life-sustaining air.
US Patent 6,712,071 to Parker teaches an oxygen sensor and injector
system for ensuring proper oxygen content; and US Patent 6,003,513 to
Readey et al teaches a stepper-motor controlled variable flow rate system to
maintain O2 at a constant level; in addition to adding weight, bulk and
complexity, both systems add significant bulk to the rebreather and only
begin functioning following at least one exhalation, thereby failing to
prevent choking.
In summary, while providing an efficient breathing system, rebreathers
have failed to solve fundamental problems, including providing air:
at a comfortable temperature;
efficiently purified of CO2;

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properly mixed with O2;
upon a first inspiration; and
without the bulk, weight or complexity of an O2 demand valve.
SUMMARY OF THE INVENTION
The present invention successfully addresses at least some of the
shortcomings of the prior art with a rebreather having a simple, durable and
lightweight construction; providing air efficiently purified of CO2 and
properly enriched with O2, at a comfortable temperature from the very first
inspiration.
An aspect of an embodiment of the present invention comprises a
closed-loop rebreather, having a housing that includes a CO2 adsorbing
canister and a counter lung extending from the housing.
In an exemplary embodiment, the housing and counter lung are
assembled so that during operation expired air passes through the canister,
where a volume of CO2 from the expired air is adsorbed. The air then passes
into the counter lung and from the counter lung through a passage in the
housing.
Additionally, there is provided a bottle of compressed O2 operatively
associated with the housing and adapted to continuously release O2 gas into
the counter lung during said operation.
In an exemplary embodiment, the rebreather includes a valve on said
bottle that remains open during said operation and the O2 gas substantially
fills the counter lung in the beginning of said operation, and/or prior to the
first inspiration.

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In a further exemplary embodiment said continuous release is adapted
to cool said bottle and said cooled bottle includes a passage through which
the inspired air passes, thereby cooling the inspired air.
Additionally the inspired air retains said cooling in the closed-loop as
the expired air passes through the canister, thereby increasing said volume of
adsorbed CO2.
In still another exemplary embodiment, the rebreather includes an
elongate sleeve extending from the canister substantially into the counter
lung, the sleeve having an opening substantially distant to the canister. The
expired air passes through the canister, through said sleeve and into the
counter lung.
In a further exemplary embodiment, said sleeve is adapted to cause
the expired air to substantially mix with the released O2 gas in the counter
lung, ensuring that the O2 is substantially mixed with the air.
Additionally, said sleeve creates impedance as the expired air passes
through the sleeve, said impedance causing the expired air to pass more
slowly through said sleeve and the canister, thereby increasing said volume
of adsorbed CO2.
In an additional exemplary embodiment, said sleeve further includes
at least one restriction, said restriction causing the expired air to pass more
slowly through said sleeve and the canister, thereby increasing the volume of
adsorbed CO2.
An aspect of an embodiment of the present invention comprises a
method for cooling for air in a closed loop rebreather, comprising
continuously expanding O2 gas from a bottle of compressed O2 gas, cooling
said bottle with the expanding O2 gas, passing a volume of warm air

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proximate to said bottle, exchanging heat between said volume and said
bottle, and cooling said volume.
In an exemplary embodiment, the method further includes
continuously releasing the O2 from said bottle.
In still a further aspect of an embodiment of the present invention, a
closed-loop rebreather comprises a housing that includes a CO2 adsorbing
canister and a bottle of compressed O2 adapted to release O2 gas. The
rebreather further includes a counter lung extending from the housing, and
an elongate sleeve extending from the canister substantially into the counter
lung. The rebreather is assembled such that expired air passes through the
canister, where a volume of CO2 from the expired air is adsorbed, the air
continues into the counter lung and said bottle releases O2 gas into the
counter lung.
In a further exemplary embodiment, said sleeve is adapted to cause
the adsorbed air to substantially mix with the released O2 in the counter
lung. Additionally, said sleeve creates impedance as the expired air passes,
said impedance causing the expired air to pass more slowly through said
sleeve and the canister, thereby increasing the volume of CO2 adsorbed from
the expired air.
In still an additional exemplary embodiment, said sleeve further
includes at least one restriction, said restriction causing the expired air to „
pass more slowly through said sleeve and the canister, thereby increasing the
volume of CO2 adsorbed from the expired air.
In an additional exemplary embodiment, a valve is included on said
bottle that remains open during said operation and said bottle is adapted to
continuously release O2 gas into the counter lung during said operation.

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In a further exemplary embodiment, the O2 gas substantially fills the
counter lung in at least one of at the beginning of said operation and prior to
the first inspiration.
Optionally, said O2 bottle is adapted to release O2 gas in a manner that
cools said compressed O2 bottle. In a further exemplary embodiment, said
cooled bottle includes a passage through which the inspired air passes,
thereby cooling the inspired air.
In still a further exemplary embodiment, said inspired air retains said
cooling in the closed-loop as the expired air passes through the canister,
thereby increasing the volume of CO2 adsorbed.
An additional aspect of an embodiment of the present invention
comprises a method for substantially mixing expired air with O2 in a
rebreather. The method comprises passing O2 into a counter lung, extending
a sleeve substantially into a counter lung, passing expired air through the
sleeve into the counter lung and substantially mixing the air with the O2.
Unless otherwise defined, all technical and scientific terms used herein
have the same meaning as commonly understood by one of ordinary skill in
the art to which this invention belongs. Although methods and materials
similar or equivalent to those described herein can be used in the practice or
testing of the present invention, suitable methods and materials are described
below. In case of conflict, the patent specification, including definitions, will
control. In addition, the materials, methods, and examples are illustrative
only and not intended to be limiting.
BRIEF DESCRIPTION OF THE DRAWING
The invention is by way of example only, with reference to the
accompanying drawing. With specific reference now to the drawing in detail,

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it is stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of the preferred method of the present
invention only, and are presented in the cause of providing what is believed
to be the most useful and readily understood description of the principles and
conceptual aspects of the invention.
In this regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental understanding of
the invention, the description taken with the drawings making apparent to
those skilled in the art how the methods of the invention may be embodied in
practice.
Exemplary non-limiting embodiments of the invention described in
the following description, read with reference to the figure attached hereto.
Dimensions of components and features shown in the figure are chosen
primarily for convenience and clarity of presentation and are not necessarily
to scale.
The attached figure is:
A schematic diagram of a rebreather, in accordance with an
embodiment of the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
The present invention relates to a rebreather with simple, trouble-free
parts and operation; that efficiently adsorbs CO2 from expired air;
substantially continuously mixes O2 into the expired air; and supplies air for
inspiration to the user at a comfortable temperature.
As seen in the figure, rebreather 100 comprises a housing 120,
containing a CO2 adsorbing canister 121 having an air flow way there

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through, the flow way containing a CO2 adsorbent material 170 adapted to
adsorb CO2 from expired air 122.
CO2 laden exhaled air 122 passes forward from a mouthpiece 140
through canister 121, into a counter lung 160. Within canister 121, CO2
molecules, primarily in the form of carbonic acid, are substantially adsorbed
by adsorbent material comprising soda-lime granules 170 in an exothermic
reaction yielding purified air 132.
As used herein:
"CO2 adsorbing canister" refers to a canister having a flow way there
through and containing a CO2 adsorbent material;
"CO2 adsorbent material" refers to any material that substantially
adsorbs CO2, including, but not limited to soda lime;
"substantially adsorbs CO2" refers to adsorption of a substantial
percentage of CO2, such that, by way of example, if expired unpurified air
volume 122 contains 3% CO2, purified air volume 132 contains about 1%
CO2; and
"purified air" refers to air 132 from which CO2 has been substantially
adsorbed.
In an exemplary embodiment, a compressed volume of O2 168 in
bottle 110 is continually released during operation of rebreather 100 through
a simple continuous release nozzle 162 to enrich purified air 132 with O2 gas
164. Nozzle 162 typically has a simple, lightweight and robust design.
Nozzle 162 assumes an open position to begin the release of O2 168 and
remains open throughout operation of rebreather 100, without further
movement or adjustment, resulting in a negligible chance for
malfunctioning.

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In an exemplary embodiment, an elongate sleeve 144 extends from
canister 121 substantially into counter lung 160 and has an opening 148
substantially distant from canister 121. As sleeve 144 releases purified air
132 substantially distant from canister 121, purified air 132 passing from
sleeve opening 148 substantially mixes 124 with O2 164.
In and exemplary embodiment, at least a portion of sleeve 144
comprises a flexible material. Alternatively, at least a portion of sleeve is
semi-flexible, semi-rigid and/or rigid, for example comprising several rigid
sections that either telescope one into the other or are flexibly connected one
to the other.
In an exemplary embodiment, substantial mixing 124 resulting in
substantially homogenous air 180, purified of CO2 and enriched with O2.
Purified air 180 then returns to mouthpiece 140 by passing back from
counter lung 160, enriched with O2 164 ensuring that the user continually
receives a proper amount of O2 164 in each inspiration. Enriched air 180 for
inspiration passes back to mouthpiece through a return passage 112 that
directs air 180 from counter lung 160 to mouthpiece 140.
As used herein, "forward passing air" refers to exhaled air 122 passing
through mouthpiece 140, through housing 120 and canister 121 amd into
counter lung 160; and "back passing air" or "returning air" refers to air 180
passing from counter lung 160 through housing 120 and through mouthpiece
140, to be inspired by a user after which air 186 is recycled as forward
passing exhaled air 122.
As used herein, "recycling" refers to air 180 that is inspired by a user
from rebreather 100 and that is thereafter expired by the user as expired air
122 through mouthpiece 140, into rebreather 100.

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In an exemplary embodiment, as compressed O2 168 in bottle 110
expands, bottle 110 cools. As enriched O2 180 flows in passage 112 along
cooled bottle 110, enriched air 180 loses heat associated with the user body
temperature and the above-noted exothermic chemical reactions in
adsorption canister 121, and becomes cooled air 186. This arrangement,
whereby hot air 180 becomes cooled air 186 through contact with bottle 110,
ensures that the user receives a supply of returning air 186 at a comfortable
temperature, helping to prevent user panic and shock noted above.
When drawing air 180 in a heated environment, for example in a
burning building, cooled air 186 becomes all the more important, with bottle
110 cooling the searing heat of air 180 caused by the fire and aiding the user
to remain alert in spite of the heat from a nearby fire.
In an exemplary embodiment, expired air 122 retains a portion of the
cooling inherent in cooled air 186 as air 122 recycles following exhalation.
Retained cooling within expired air 122 thereby cools soda-lime granules
170 in canister 121 that become heated due to the exothermic adsorption of
granules 170. Cooling granules 170 increase the efficiency of the exothermic
CO2 adsorption process in canister 121, by reducing the heat of the
exothermic reaction. Cooled granules 170 thereby increase the percentage of
CO2 adsorbed from air 122 in each breathing cycle, yielding greater purity in
purified air 132.
In an exemplary embodiment, mouthpiece 140 includes a back pass
capillary valve 192 and a forward pass capillary regulator 194. As expired
air 122 is expired forward from mouthpiece into canister 121, back pass
capillary valve 192 closes to prevent back passing air 186 from parsing
through mouthpiece 140. Conversely, as cooled air 186 is inspired through

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mouthpiece, 140 forward pass capillary regulator 194 closes to prevent
forward passing expired air 122 from passing through mouthpiece 140.
In an exemplary embodiment, rebreather 100 is compact, lightweight
and easily dispensed to a user by emergency personnel. In providing
rebreather 100 to a victim, mouthpiece 140 is simply placed in the victim's
mouth, counter lung 160 is tucked under the victim's chin and rebreather 100
is activated to instantly supply O2 164 on the first inspiration. The instant
supply of O2 164 prevents user choking as would be the case were the user
to attempt to inspire from a deflated counter lung 160.
During the first expiration, air 122 enters canister 121 and during a
second expiration, air 132 enters sleeve 144. With a third expiration, purified
air 132 moves out of a sleeve opening 148 while sleeve 144 creates
impedance within air 132.
Impedance on air 132 slows the speed at which air 132 leaves sleeve
144, decreasing the speed of unpurified air 122, thereby increasing the
contact time of unpurified air 122 with soda-lime granules 170; accruing
greater efficiency in the adsorption of CO2 from expired air 122.
Optionally, sleeve 144 includes a restriction 145 that restricts sleeve
passage 146 and further decreases the speed of air 122, thereby further
increasing contact time with granules 170 and purification efficiency of
expired air 122.
Restriction 145 is shown as a single invagination of sleeve passage
146 but could take many forms, inter alia, multiple imaginations and/or
partial closure of opening 148. Alternatively, restriction of passage 132 may
constitute a complete closure of opening 148 and one or more openings may
be included in the wall of passage 146.

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In addition, as mentioned above, the cooler overall temperature of air
122 as a result of cooled air 186 allows the exothermic reaction to proceed at
lower temperatures, accruing greater efficiently in the removal of CO2 from
expired air 122.
Continuing with the initial function of rebreather 100; the user's third
expiration of air 122 results in the substantial mixing 124 in counter lung
160, mentioned above and, with user's fourth expiration, homogenous
enriched air 180 enters passage 112 to become cooled air 186. All this time,
the user has been able to inspire O2 164 due to the constant supply of O2164
from O2 bottle 110, preventing choking. With the user's fifth expiration, the
user begins to inspire cooled air 186 that passes through mouthpiece 140.
The efficient supply of life-sustaining O2 164 and/or air 186 at a
comfortable temperature, from the first inspiration and onward, allows the
user to immediately proceed toward safety without wasting time waiting for
air 186, or choking in the absence of air 186.
Additionally, emergency personnel need not waste time assisting a
choking user in acclimating to use of rebreather 100, or attempting to fix a
jammed demand valve; thereby allowing the emergency personnel to
immediately continue searching for other victims; potentially saving more
lives due to the advantageous construction of rebreather 100.
Perhaps more important, the light weight of rebreather 100 allows
each emergency personnel to carry multiple rebreathers 100 on search and
rescue missions. Emergency personnel can quickly snap rebreather 100 on a
victim, direct the victim to safety, for example a safety exit in a building,
and immediately continue searching for other victims, armed with additional
rebreathers 100.

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While the design of rebreather 100 may vary, it is postulated that
emergency personnel may carry multiple small and lightweight rebreathers
100, in holsters extending from a custom waste belt (not shown). In addition
to allowing efficient dispensing of multiple rebreathers 100 in an emergency,
such an arrangement frees up the hands of the emergency personnel for
better uses, for example opening a fire exit or operating a fire extinguisher to
provide fire-free access to an emergency exit.
Once a user reaches safety, use of rebreather 100 may continue until
emergency personnel outside the burning building determine that the threat
of hypoxia and shock has passed and remove rebreather 100. Alternatively,
as bottle 110 substantially empties of O2 164, the pressure of oxygen 164
falls below a predetermined threshold and causes an audio and/or visual
indicator 188 to indicate that rebreather 100 must be replaced by the
emergency personnel.
Many variations may be made in rebreather 100, for example
substituting a combination nose and mouthpiece manifold (not shown) for
mouthpiece 140. Additionally or alternatively, housing 120 and/or counter
lung 160 may be supplied in any one of alternative shapes or sizes, the many
variations being well known to those familiar with the art.
The present invention has been described with particular reference to
applications in the presence of fire. However, additional uses will be readily
apparent to those familiar with the art. Additional uses include, as noted
above, underwater diving, breathing in the presence of industrial pollutants
such as noxious gases, and at high altitude where the atmosphere itself is too
thin for sustaining respiration.

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Consequently, it should be understood that this description is provided
without prejudice to the generality of the invention or its range of
applications. Additional applications, objects, advantages, and novel features
of the present invention will become apparent to one ordinarily skilled in the
art upon examination of the above noted examples, which are not intended to
be limiting.
It is expected that during the life of this patent many relevant systems
will be developed and the scope of the terms of the rebreather unit and
method of application is intended to include all such new technologies a
priori; for example soda-lime has been cited as an adsorbent, however the
invention contemplates any CO2 adsorbent that potentially can be used, or
that will be used now or in the future."
It is appreciated that certain features of the invention that are, for
clarity, described in the context of separate embodiments, may also be
provided in combination in a single embodiment. Conversely, various
features of the invention, which are, for brevity, described in the context of a
single embodiment, may also be provided separately or in any suitable
subcombination.
Accordingly, the invention is intended to embrace all such alternatives,
modifications and variations that fall within the spirit and broad scope of the
appended claims. All publications, patents and patent applications mentioned
in this specification are herein incorporated in their entirety by reference into
the specification, to the same extent as if each individual publication, patent
or patent application was specifically and individually indicated to be
incorporated herein by reference. In addition, citation or identification of any
reference in this application shall not be construed as an admission that such
reference is available as prior art to the present invention.

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As used herein the term "about" refers to ± 10 %. The terms
"include", "comprise" and "have" and their conjugates as used herein mean
"including but not necessarily limited to."
It will be appreciated by a person skilled in the art that the present
invention is not limited by what has thus far been described. Rather, the
scope of the present invention is limited only by the following claims.

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CLAIMS
1. A closed-loop rebreather, comprising:
1) a housing adapted to allow forward and backward passage of
air during operation of the rebreather;
2) a CO2 adsorbing canister contained within the housing;
3) a counter lung extending from the housing, such that
during rebreather operation, a volume of air passes forward
through the housing and canister, into the counter lung and
from the counter lung back through the housing, after which the
volume of air is recycled as forward passing air;
the rebreather further including a bottle of compressed O2
operatively associated with the housing and adapted to
continuously release O2 gas into the counter lung during
at least a portion of the rebreather operation.
2. The rebreather according to claim 1 and including a valve on
said bottle that remains open during said at least one forward passing, back
passing and recycling of air during said operation.
3. The rebreather according to claim 1, wherein said continuously
releasing of O2 gas begins substantially at the beginning of said operation.
4. The rebreather according to claim 1, wherein at least one
portion of said bottle is adapted to cool during said continuous release.

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5. The rebreather according to claim 4, wherein said bottle
includes a passage through which at least one portion of said volume of back
passing air passes.
6. The rebreather according to claim 5, wherein said at least one
portion of said back passing air volume passes through said bottle passage,
contacts said at least one cooled portion of said bottle, such that said at least
one portion of air cools.
7. The rebreather according to claim 6, wherein said at least one
portion of said back passing air volume substantially retains at least one
portion of said cooling as the air volume is recycled as forward passing air.
8. The rebreather according to claim 7, wherein said retained
cooling of said at least one portion of said forward passing air volume, cools
at least a portion of the CO2 adsorbing canister.
9. The rebreather according to claim 1, further including an
elongate sleeve extending from the canister and having an opening into the
counter lung substantially distant from the canister, wherein at least a
portion of said forward passing air volume passes through said sleeve into
the counter lung.
10. The rebreather according to claim 9, wherein said sleeve is at
least one of:
flexible;
semi flexible

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rigid;
semi rigid; and
sectioned.
11. The rebreather according to claim 9, wherein said sleeve is
adapted to cause said at least one portion of forward passing air volume to
substantially mix with the released O2 in the counter lung.
12. The rebreather according to claim 9, wherein said sleeve creates
impedance as the at least one portion of said forward passing air volume
passes through said sleeve, said impedance causing the at least one: portion
of forward passing air volume to pass more slowly through said sleeve and
the canister.
13. The rebreather according to claim 9, wherein said sleeve further
includes at least one restriction.

14. The rebreather according to claim 13, wherein said restriction is
adapted to cause the at least one portion of forward passing air volume to
pass more slowly through said sleeve.
15. The rebreather according to claim 14, wherein said restriction is
adapted to cause the at least one portion of forward passing air volume to
pass more slowly through the canister.
16. A method for cooling for air in a closed loop rebreather,
comprising:

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1) continuously expanding O2 gas from a bottle of compressed O2 gas;
2) cooling said bottle with said expanding;
3) forward passing and backward passing a volume of warm air within
the rebreather;
4) passing said backward passing volume proximate to said bottle;

4) exchanging heat between said volume and said bottle; and
5) cooling said volume.

17. The method according to claim 16, further including:
recycling said cooled volume.
18. A closed-loop rebreather, comprising:

1) a housing having a passage adapted to allow forward and
backward passage of air during operation of the rebreather;
2) a CO2 adsorbing canister contained within the housing;
3) a counter lung extending from the housing;
4) a bottle of compressed O2 operatively associated with the
housing and adapted to release O2 gas into the counter lung;
5) an elongate sleeve extending from at least a portion of at
least one of:
the passage; and
the housing,
said sleeve having an opening substantially distant from
the housing, and the sleeve being positioned such that a
volume of forward passing air passes through the sleeve
and into the counter lung.

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19. The rebreather according to claim 18, wherein said sleeve is at
least one of:
flexible;
semi flexible
rigid;
semi rigid; and
sectioned.
20. The rebreather according to claim 18, wherein said sleeve is
adapted to cause at least a portion of the adsorbed air volume to substantially
mix with the released O2 gas in the counter lung.
21. The rebreather according to claim 18, wherein said sleeve
creates impedance as the forward passing air volume passes,' said impedance
causing the forward passing air volume to pass more slowly through said
sleeve and the canister.
22. The rebreather according to claim 18, wherein said sleeve
further includes at least one restriction.

23. The rebreather according to claim 22, wherein said restriction is
adapted to cause the forward passing air volume to pass more slowly
through said sleeve.
24. The rebreather according to claim 23, wherein said restriction is
adapted to cause the forward passing air volume to pass more slowly
through the canister.

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25. The rebreather according to claim 18, wherein the forward
passing air volume is adapted to pass backward from the counter lung
through the housing, and including a valve on said bottle that remains open
during at least the forward passing and backward passing of the volume of
said air volume.
26. The rebreather according to claim 18 wherein said valve on said
bottle continuously remains open during a substantial portion of said
operation.
27. The rebreather according to claim 25, wherein said
continuously releasing of O2 gas begins substantially at the beginning of said
operation.
28. The rebreather according to claim 18, wherein at least one
portion of said bottle is adapted to cool during said continuous release.
29. The rebreather according to claim 28, wherein:
the forward passing air volume is adapted to pass backward
from the counter lung through the housing; and
said bottle includes a passage through which at least one portion of a
back passing volume of air passes.
30. The rebreather according to claim 29, wherein said at least one
portion of said back passing air that passes through said bottle passage, and

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contacts said at least one cooled portion of said bottle, such that said air
cools.
31. The rebreather according to claim 30, wherein the rebreather is
adapted so that the at least one portion of said back passing air rebreather is
recycled as a volume of forward passing of air.
32. The rebreather according to claim 31, wherein said at least a
portion of said back passing air substantially retains at least one portion of
said cooling as the air is recycled as forward passing air.
33. The rebreather according to claim 32, wherein said retained
cooling of said at least a portion of said forward passing air, cools at least a
portion of the CO2 adsorbing canister.
34. A method for causing forward passing air to substantially mix
with O2 gas in a rebreather, the method comprising:

1) releasing O2 into a counter lung;
2) extending a sleeve substantially into the counter lung;
3) passing a volume of forward passing air through said sleeve into
the counter lung; and
4) substantially mixing the air and said O2.
35. The method according to claim 34, further including:
passing said forward passing volume through an adsorption
canister prior to passing through said sleeve;
impeding passage of said forward passing ah* volume; and

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slowing the passage of said forward volume through the
canister.

A closed-loop rebreather, comprising a housing adapted to allow forward and backward passage of air during operation of the rebreather, a CO2 adsorbing canister contained within the housing, a counter lung extending from the housing, such that during rebreather operation, the air passes forward through the canister, into the counter lung and back through the housing, after which the air is recycled as forward passing air. The rebreather further including a bottle of compressed O2 operatively associated with the housing and adapted to continuously release O2 gas into the counter lung during rebreather operation.