Oxygen Generators
This'll give you something to think
about while you're drowning, choking, being strangled, hung,
water-boarded or otherwise suffocating (e.g., auto-erotic
asphyxiation while trapped in a burning disco in a sunken
submarine ), &c...
US7171964
Instant chemical based flexible oxygen in a
non-pressurized flexible or rigid containment system
The invention is a portable, non-pressurized oxygen generation
device. A first chamber holds an oxygen liberating chemical, and a
catalyst from a second chamber begins the oxygen liberating
reaction when the two chemicals mix. The chemicals are
pre-measured, and oxygen generation can begin within seconds of
activation.
A number of materials can be used to generate oxygen, but the
preferred mix is an aqueous solution of 7 to 10% hydrogen
peroxide as first reaction material and reagent grade manganese
as the second reaction material.
US3574561
Oxygen generator system utilizing alkali metal
peroxides and superoxides
US3615252
Oxygen-generating device
Oxygen-generating material 24, preferably of peroxide
composition, is placed in the bottom end of canister 10, as shown.
The oxygen-generating material may be in either solid or liquid
form, and preferably may be sodium peroxide in powder or granular
form.
If the reacting agent is water and the oxygen-generating
material 24 is sodium peroxide, the generation of oxygen will be
in accordance with the formula...
US3868225
Sodium chlorate oxygen producing apparatus
A sodium chlorate oxygen producing apparatus in which sodium
chlorate candle is mounted in a sodium chlorate candle container
and is supported therein by gas permeable thermally insulating
material disposed around the candle, an ignition device is
attached to the candle container and is adapted upon operation to
ignite the sodium chlorate candle to produce oxygen for exit
through an outlet passage, and a catalytic means is disposed in
the path of oxygen to eliminate substantially all carbon monoxide
and carbon dioxide from that oxygen, the sodium chlorate candle
having first, second and third zones of different compositions in
order from the point of ignition by the ignition device, the first
zone being a rapidly burning flash composition comprising
sodium chlorate, iron, barium peroxide and boron, said second
zone being a more slowly burning cone composition comprising
sodium chlorate, iron, barium peroxide, asbestos and a
quantity of said flash composition, and said third zone being the
slowest burning composition of the three zones, forming the main
body of the candle and comprising sodium chlorate, iron, barium
peroxide and glass powder, said sodium chlorate candle also
having a booster compositoin layer disposed between an adjacent
pair of said zones, said booster composition comprising at least
iron and barium peroxide and having a rate of burning intermediate
the rates of burning of said adjacent layers thereby to ensure an
adequate transition of combustion from the faster burning to the
slower burning of said adjacent zones.
US3955931
Oxygen generator
Exothermic reacting chemical oxygen generators are heat insulated
with a hydrate to protect the user. The hydrate, when heated by
the generator releases water which is vaporized and allowed to
escape to a zone which will not be grasped by the user or is
absorbed in a surrounding inert insulation layer where it can
condense and revaporize as the heat wave passes through the
surrounding inert insulation. The generator is preferably in the
form of a disposable canister such as a tin can containing an
oxygen generating chlorate candle and means for igniting the
candle. A mask or cannula carrying cap is snapped on the can and
has mechanism for piercing the can and activating the ignition
means to flow oxygen to the mask or cannula.
1. Field of the Invention
This invention relates to the art of protecting the users of
exothermic reacting chemical oxygen generators from heat released
by the generators and specifically deals with a disposable tin can
type chlorate candle oxygen generator with a snap-on cap having
mechanism for activating the candle and delivering the oxygen to a
cap carried face mask where the body of the can is insulated with
a hydrate salt layer sandwiched between refractory fiber
insulation layers so that the can can be handled without
discomfort from heat released during the oxygen generating
decomposition of the chlorate candle.
In my prior U.S. Pat. Nos. 3,702,305 and 3,725,156 there are
disclosed and claimed chemical formulations and ignition cone
compositions adapted for oxygen generator cells disclosed and
claimed in the Churchill and Thompson U.S. Pat. No. 3,736,104.
These compositions and generator cells can be used with the
present invention to avoid heretofore required oxygen dispensing
and cell carrying cases described and claimed in the Churchill,
Thompson, and McBride U.S. Pat. No. 3,733,008.
2. Prior Art
The Jackson and Bovard U.S. Pat. No. 2,558,756 seeks to insulate
an oxygen generating composition in a canister with an envelope of
potassium perchlorate between the composition and canister which
is alleged to decompose endothermically with evolution of oxygen
under the heat of reaction of the composition in the canister. The
patentees contend that such an envelope of potassium perchlorate
plus glass wool surrounding the envelope in the canister will hold
the external temperature of the canister to a maximum of about 200
DEG C. (392 DEG F.). Such high temperatures do not permit the
canister to be grasped by the user and, therefore, Jackson and
Bovard were forced to mount the canister in an envelope providing
an air space around the canister and formed of a relatively
non-heat-conducting material such as a laminated fabric resin
equipped with perforations for radiating heat. Since potassium
perchlorate has a low heat conductivity and a very low heat of
decomposition into the chloride and oxygen, it would appear that
these characteristics of the perchlorate are the reason for the
insulating action and not, as stated in the patent, by an
endothermic decomposition.
SUMMARY OF THIS INVENTION
This invention now provides chemical oxygen generator canisters
housing a combustible material which upon ignition undergoes
exothermic reaction to evolve oxygen which are insulated so
efficiently that they may be grasped without discomfort even when
the composition reaches its highest temperature in generating the
oxygen. The canisters of this invention are insulated with a
hydrate salt that releases its water when heated by temperatures
developed during the exothermic decomposition of the oxygen
generating material in the canister. The released water is
vaporized thereby converting sensible heat into heat of
vaporization and the vapor is allowed to escape to a zone of the
canister which is not grasped by the user or is condensed in a
surrounding insulating layer and then reevaporated as the heat
wave passes through this outer insulating layer. Useful hydrate
salts are inexpensive and are preferably sandwiched between
aluminum foil backed layers of inert refractory fibers. Surface
temperatures of about 160 DEG F. can be maintained.
The preferred hydrate salts contain a large percentage of hydrated
water and break down at a reasonably low temperatures, for
example, less than 200 DEG C.
Epsom salt (MgSO4 . 7H2 O), trisodium phosphate (Na3 PO4 . 12H2
O), and glauber's salt (Na2 SO4 . 10H2 O) are preferred insulating
hydrate salts but the following hydrate salts are also useful.
Al2 (SO4)3 . 18H2 O
Na2 SO3 . 7H2 O
NH4 Al(SO4)2 . 12H2 O
SrCl2 . 6H2 O
(NH4) Cr(SO4)2 . 12H2 O
Sr(OH)2 . 8H2 O
BaO2 . 8H2 O
ZnF2 . 4H2 O
Cr2 (SO4)3 . 18H2 O
Zn(NO3)2 . 6H2 O
CoCl2 . 6H2 O
ZrOCl2 . 8H2 O
Fe(SO4) . 7H2 O
CaCl2 . 6H2 O
Mg3 (PO4)2 . 22H2 O
CoBr2 . 6H2 O
NiSO4 . 7H2 O
CuSO4 . 5H2 O
KAl(SO4) . 12H2 O
Fe2 (SO4)3 . 9H2 O
K[Cr(SO4)2 ] 12H2 O
Mg(H2 PO2)2 . 6H2 O
KMgPO4 . 6H2 O
MgSO4 . 7H2 O
KNaCO3 . 6H2 O
MgSO3 . 6H2 O
K2 PO3 . 4H2 O
MnCl2 . 4H2 O
RbFe(SeO4)2 . 12H2 O
NdCl3 . 6H2 O
Na2 B4 O7 . 10H2 O
Na3 PO4 . 12H2 O
Na3 Li(SO4)2 . 6H2 O
NiSO4 . 6H2 O
Na2 H2 P2 O6 . 6H2 O
Na2 HPO4 . 12H2 O
NaSiO3 . 9H2 O
Na2 SO4 . 10H2 O
Oxygen generator canisters of the type disclosed and claimed in
the aforesaid U.S. Pat. No. 3,736,104 housing the sodium
chlorate-sodium oxide composition of my aforesaid U.S. Pat. No.
3,702,305 and when ignited with ignition cone material of my
aforesaid U.S. Pat. No. 3,725,156 and sized to produce an average
of about 5.5 liters per minute of medically pure oxygen for 15
minutes reach surface temperatures of around 460 DEG F. which, of
course, is far too hot to handle with bare hands. Insulation of
these canisters with bulky one-half inch thick blankets of
refractory fibrous materials of the best known efficiency only
reduce the outer surface temperature of these canisters to 310 DEG
F. which is still too hot to handle with bare hands. By placing a
layer of a hydrate salt such as Epsom salt within the insulation
according to this invention, the maximum outer surface temperature
of the canisters was reduced to 160 DEG F. which can be
comfortably handled. It is pointed out that the apparent surface
temperature of an object to a person touching it depends on the
thermal conductivity of the surface and, therefore, a metal
surface of 130 DEG F. will feel warmer than an insulated surface
of 160 DEG F. Therefore, while 160 DEG F. would normally sound
high for handling with bare hands, the canisters of this invention
can be comfortably grasped especially where the outer surface is
composed of an insulating material.
The mechanism of heat absorption according to this invention is
apparently the decomposition of the hydrate as indicated by the
following formula:
Epsom salt MgSO4 . 7H2 O .fwdarw. MgSO4 + 7H2 O (g) .DELTA. Hr =
98.6 K Cal/mole
which can absorb 400 cal/(gm of MgSO4 . 7H2 O).
Tri sodium phosphate
100 DEG C.
Na3 PO4 . 12H2 O
.fwdarw. Na3 PO4 + 12H2 O(g)
.DELTA. Hr = 155.4 K Cal/mole
which can absorb 408.8 cal/ (gm of Na3 PO4 . 12H2 O)
Glauber's salt
100 DEG C.
Na2 SO4 . 10H2 O
.fwdarw. Na2 SO4 + 10H2 O (g)
.DELTA. Hr = 124.58 K Cal/mole
which can absorb 386.7 cal/ (gm Na2 SO4 . 10H2 O).
The heat is actually used to break down the hydrate and vaporize
the water of hydration so the heat is not really absorbed but is
converted from sensible heat to the heat of vaporization for the
water. Where the hydrate salt is sandwiched between two layers of
aluminum foil backed refractory fibrous material blankets, water
can sometimes be observed escaping from the top of the inner
aluminum foil barrier. If the foil is omitted the hydrate breaks
down and vapor escapes radially and axially through the
insulation, the process appearing to be one of hydrate break-down
with condensation of moisture in the outer layer of insulation. As
the "heat wave" penetrates the insulation, the water is
reevaporated until it escapes from the outermost surface of the
insulation. The canister can be handled comfortably but the
insulation may become damp.
Glauber's salt has the disadvantage of being efflorescent so
canisters equipped with this insulation material should be sealed
in a moisture-proof envelope before use.
It is then an object of this invention to provide a heat insulator
including a layer of a hydrate salt.
Another object of this invention is to provide oxygen generator
canisters of a combustion material which, when ignited, undergoes
exothermic reaction with evolution of oxygen, which canisters are
heat insulated by a layer of a salt which releases water at
temperatures generated by the composition and convert sensible
heat into heat of vaporization so that the canisters can be
grasped by bare hands without discomfort.
Another object of this invention is to provide an oxygen generator
canister with an envelope of insulating material including a layer
of hydrate salt sandwiched between aluminum foil-backed refractory
fiber material.
A still further object of the invention is to provide a chlorate
candle oxygen generator in the form of a disposable tin can with
one end thereof having an oxygen dispensing orifice with a
puncturable seal and a surrounding bead receiving a snap-on cap
with mechanism for piercing the seal and activating the chlorate
candle to dispense oxygen through a tube to a face mask carried by
the cap and with the side wall of the can covered by a multi-layer
envelope of insulating material including an inner layer of a
hydrate salt enabling the can to be comfortably grasped even when
the tin can reaches its highest temperature during oxygen
generation.
A still further object of the invention is to provide a disposable
oxygen generator insulated canister with a snap-on activating and
dispensing cap.
A specific object of this invention is to eliminate heretofore
required carriers and envelopes for oxygen generators which
release heat and to so insulate the generator that it can be
comfortably grasped with bare hands during oxygen generation.
Other and further objects of this invention will be apparent to
those skilled in this art from the following detailed description
of the annexed sheets of drawings which by way of a preferred
example only, illustrate one embodiment of the invention.
A BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, with parts broken away and
shown in vertical cross section, of an insulated oxygen
generator canister according to this invention;
FIG. 2 is a vertical cross sectional view along the line
II--II of FIG. 1 and also including a vertical cross section of
an actuator and dispensing cap snapped on the top of the
canister;
FIG. 2-A is a fragmentary vertical sectional view of the
generator of FIG. 2 with the foil backings of the blankets
removed according to this invention.
FIG. 3 is a fragmentary view similar to FIG. 2 but showing
the canister and cap in oxygen dispensing position;
FIG. 4 is a plan view of the cap taken along the line
IV--IV of FIG. 3; and
FIG. 5 is a cross section view of the cap taken along the
line V--V of FIG. 2.
A BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIGS. 1 and 2, the oxygen generator 10 includes a tin
plated steel can 11, hereinafter referred to as a tin can,
providing a casing for a compacted sodium chlorate candle 12
having the composition of my aforesaid U.S. Pat. No. 3,702,305
which is covered with an ignition cone composition 13 disclosed
and claimed in my aforesaid U.S. Pat. No. 3,725,156. A glass vial
14 filled with water 15 rests on or is embedded in the ignition
cone 13. If desired, a first fire composition 16 ca1n surround the
vial 14 and have the following formula:
NaClO3 18% by weight
NalO3 38% by weight
Na2 O 44% by weight.
The tin can 11 has the conventional cylindrical side wall 17 with
flat bottom and top end walls 18 and 19 connected and sealed to
the side wall by beads 20 and 21, respectively. The bottom wall 18
is imperforate but the top wall 19 has a central circular orifice
22 closed by a puncturable metal foil seal 23 secured either to
the top or bottom face of the end wall 19.
The cylindrical wall 17 of the tin can 11 is covered to a level 24
just below the bead 21 by insulation 25 and the bottom wall 18 is
covered by insulation 26. The top wall or end 19 and the bead 21
remain uncovered.
In accordance with this invention the insulation 25 includes a
layer of a hydrate salt 27 sandwiched between aluminum foil-backed
refractory fiber blankets 28 and 29 with a cardboard, plastics
material or metal sleeve 30 surrounding the outer blanket 29. If
the aluminum foil around the hydrate layer is omitted as shown in
FIG. 2-A, the outer sleeve 30 should be porous to allow water
vapor to escape through the periphery in a radial direction as
well as through the ends in an axial direction. As shown, the
blanket 28 has a relatively thick layer 28a composed of refractory
fibrous material surrounding the cylindrical side wall 17 of the
tin can and backed by a backing layer of thin aluminum foil 28b.
The blanket 29 has a relatively thick outer layer 29a of
refractory fibrous material on a backing 29b of the aluminum foil.
The outer fibrous layer 29a is covered by the sleeve 30. Thus, the
hydrate salt 27 is sandwiched between the aluminum foil backings
28b and 29b of the refractory fibrous blankets 28 and 29.
The blankets 28 and 29 are preferably composed of a product sold
under the trademark "Fiberfrax" by the Carborundum Company of
Niagara Falls, New York where the fibers have approximately the
following chemical analysis in percent by weight:
Al2 O3 50.9 percent
SiO2 46.8 percent
B2 O3 1.2 percent
Na2 O 0.8 percent
Trace Inorganics 0.3-0.5 percent.
Other suitable insulating blankets include "Foamglas" (sold by
Pittsburgh Corning Corp., Pittsburgh, Pa.) and "Ceramic Foam"
(sold by Dow Chemical Co., Midland, Mich.). These materials have
an advantage of being non-porous and can be used without the
aluminum foil.
The aluminum foil backing is about 0.002 inches thick and the
thickness of each blanket is about one-quarter inch.
The layer of hydrate salt 27 may vary in thickness to provide the
desired insulating effect. When one quarter inch Fiberfrax
blankets are used, the layer 27 need only be about one quarter of
an inch but it should be understood that the thickness of the
blankets and the hydrate salt layer can be varied to suit use
conditions of the generator.
The bottom blanket 26 covering the bottom end wall of the tin can
may be as thick as desired and also covers the ends of the
insulation layers 27-29. Since the blanket 26 is porous, it will
be noted that the bottom end of the insultion layer 27 is vented
through the porous blanket to the atmosphere.
It will also be noted that the top end of the insulation layer 27
is vented to the atmosphere and as will be more fully hereinafter
explained, the cap which is snapped on the top of the can to
activate the chlorate candle 12 and dispense oxygen to a face mask
will not block the open top venting of this layer.
The following calculations illustrate the superiority of the
insulation of this invention as compared with ordinary insulation.
For illustrative purposes high temperature reacting chlorate
candles containing iron fibers, barium peroxide and glass fibers
in a tin plated steel can were used.
EXAMPLE I -- BARE CANISTER, NO INSULATION
Canister details:
tin plated steel
emissivity = 0.60 (tin oxide)
diameter = 2 inches
length = 4.5 inches
Candle details:
Average flow rate -- 4 LPM
Duration of flow = 15 minutes
Fe = 2.3% BaO2 = 4%, Glass Fibers = 6%, sodium chlorate balance
Length = 3.1, heat output = 154.1 BTU
Calculation of surface temperature:
Neglecting heat storage within the canister and unsteady state
conditions, the surface temperature can be calculated from the
expression:
q = (hc + hr) Ao .DELTA.t (4)
where
q = Rate of heat transfer, BTU/hr.
(hc + hr) = combined heat transfer coefficient for natural
correction plus radiation, BTU/(sq. ft.) (hr.) ( DEGF.)
ao = the surface area, sq. ft.
.DELTA.t = the difference in temperature between the canister and
its surroundings, DEGF.
For purposes of calculation:
hc = 0.27 (.DELTA.t /Do)@0.25 (5)
where
Do is the diameter, ft.
hr = 4 .epsilon. .sigma. Tavg (6)
where
.epsilon. is the emissivity;
.sigma. is the stefan-Boltzmann constant,
Btu/ (sq. ft.) (hr) (@o R)@4 ; and
Tavg is the average of the canister temperature and that of its
surroundings, DEGR.
With the appropriate substitutions, equation (4) becomes:
(154.1/0.25) = (hc + hr) (0.24) (t - 75) (7)
The canister surface temperature from this equation is 659 DEG F.
EXAMPLE II -- INSULATED CANISTER
The canister details, dimensions, heat output, etc. are the same
as in Example I, with a thickness of 1/2 inch of mineral wool
insulation surrounding the tin can
k = 0.024 BTU/ (ft.) (hr.) ( DEGF.) over the canister and
.epsilon. = 1 at its outer surface, equation (4) becomes
(154.1/0.25) = (hc + hr) (0.46) (t - 75) (8)
and the outer surface temperature of the insulation is 411 DEG F.
There is another disadvantage to a simply insulated canister; when
the canister temperature is increased the reaction rate is
accelerated. Heat flow through the insulation on the canister is
given by: ##EQU1## where Am = the mean area of insulation, sq.
ft., .DELTA.t is the temperature change across the insulation,
DEGF., x is the thickness of insulation, ft., and k is the thermal
conductivity of the insulation BTU/ (ft.) (hr.) ( DEGF). Solution
of this equation for the canister wall temperature gives a value
in excess of 3,000 DEG F. Hence the reaction rate must be
increased. In practice the insulation would probably melt and the
tin plate ignite.
EXAMPLE III -- INSULATION PLUS HEAT ABSORBENT
In this case the canister is covered by a layer of mineral wool
0.05 in thickness, or the equivalent amount of some other material
with the same value of (k/x). This is followed by a layer of Na3
PO4 . 12H2 O approximately 0.2 in. thick, depending on its bulk
density. The trisodium phosphate is sandwiched between two layers
of aluminum foil. A final layer of mineral wool 1/4 inch thick
covers the outer surface.
The hydrate decomposes at 100 DEG C. (212 DEG F.). To calculate
the outer surface temperature it is necessary to equate the heat
flow through the outer thickness of insulation to that transferred
to the surroundings, as: ##EQU2## or ##EQU3##
The solution to this equation is 118.5 DEG F. which is low enough
for comfortable handling. The amount of heat absorbing chemical
required in this geometry is 91.9 gm., while the canister surface
temperature will be 627 DEG F. Note that the canister surface
temperature is near enough to the uninsulated case (659 DEG F.)
that the reaction rate is not likely to be effected.
In this example, the vapor from the hydrate was vented outside the
insulation, so that the thermal properties of the insulation were
not changed.
Thus it will be seen that the insulation 25 of this invention
actually dissipates heat from the generator cell 12 and does not
so isolate the candle 12 against heat radiation as to increase its
temperature.
The oxygen generator canister 10 is activated and dispenses oxygen
to a mask or cannula by means of a snap-on cap 35 shown in FIGS. 2
to 5. This cap 35 includes a plastic cylindrical body member 36
housing activating mechanism and an outlet tube and a removably
cylindrical cover portion 37 housing a face mask and connecting
tube. The body member 36 has a cylindrical side wall with an open
cylindrical top and a plurality, such as three, flexible fingers
38 extending inwardly from the bottom thereof to snap under the
head or rim 21 of the top wall 19 of the tin can 17 and rest on
top of the insulation 25. It will be noted from FIG. 5 that these
fingers 38 are spaced circumferentially to provide open spaces
therebetween venting the tops of the insulation layers to the
interior of the body.
The open top of the cylindrical body 36 has a plastics spider 39
with three legs 39a secured therein by screws 40 and projecting
thereabove. This spider 39 has a central aperture 41 with a
counterbore 42 slidably mounting a circular plastics button 43. A
cylindrical insulating ceramics or plastics (phenolic resin)
member 44 recessed at its top at 45 and at its bottom at 46
underlies the portion of the spider 39 surrounding the counterbore
42 and a metal plate 47 is mounted under this member 44 and spaced
therefrom by spacer sleeves 48. Pins or bolts 49 bottomed on the
plate 47, extending through the sleeves 48 and body member 44 and
threaded at 50 into the bottom face of the spider 39, assemble the
plate 47 and member 44 to the spider.
The plate 47 mounts a central inverted cup 51 with an outturned
lip 51a below the plate receiving a silicone rubber sealing ring
52 therearound. This ring 52 is tightly pressed against the end
wall 19 around the orifice 22 when the cap is snapped on the bead
or ring 21. A metal tube 53 is secured in the side wall of the cup
51 and extends between the plate 47 and member 44 to an insulated
rubber tube 54 which extends alongside the member 44 into the
cover 37.
The button 43 carries a depending pin 55 extending through the
member 44 and cup 51 to an enlarged pointed head 56. A coil spring
57 in the recess 45 of the member 44 surrounds the pin 55 and
urges the button 43 against the shoulder 58 between the aperture
41 and the counterbore 42 of the spider 39. In this position, the
head 56 depending from the button 43 is bottomed on the top wall
of the cup 51 so that its pointed end 56a will be about flush with
the outturned lip 51a of the cup.
When the cap 35 is snapped onto the top of the can 11 with the
fingers 38 underlying the bead 21 thereof, the seal ring 52
provides a sealed connection joining the orifice 22 with the
interior of the cup 51. Then, when the button 43 is depressed to
advance the head 56 through the orifice, the pointed end of the
head will pierce the orifice seal 23 and fracture the vial 14 to
release water to the ignition cone material, thereby activating
the chlorate candle 12 and generating oxygen which will flow
through the orifice and cup 51 into the tube 53.
The cover or lid 37 has a mouth portion 59 sized to surround and
engage the fingers 39a projecting from the cylindrical body member
36 to be bottomed on the top end of the cylindrical wall 36. This
cover member or lid houses a flexible rubber face mask 60 which is
anchored at one end 61 to the interior of the cover beyond the
mouth portion 59. As shown in FIG. 2, this face mask 60 is folded
into the cover 37 when it is assembled on the cap 35 and the
insulated tube 54 is also folded into the cap. However, when the
cover or lid 37 is removed to a use position as shown in FIG. 3,
the face mask 60 is pulled out of the cover 37 so that the tube 54
will feed oxygen from the activated generator to the face mask.
The face mask 60 is a flexible rubber tube which flares outwardly
to a very thin end lip portion 62 which can be easily depressed to
fit the contours of the face around the mouth and nose of a user.
Vent holes 63 are provided around the face mask to relieve excess
oxygen and to accommodate exhaling of the user.
The tube 54 may only be insulated at 64 in the area of the metal
tube 53 and the insulation can be any desired flexible material.
The tube slips over the metal tube 53 at one end and over a nipple
65 projecting from a side wall of the face mask 60.
From the above descriptions it will be understood that disposable
oxygen generating canisters 10 of this invention are quickly and
easily made available for use by a cap 35 which is easily and
quickly mounted on unused canisters and removed from used
canisters. The cap is not appreciably heated in use and can be
successively used without discomfort. The fingers 38 of the cap
are merely snapped over the bead 21 and the cap bottomed on top of
the insulation. Then the cover or lid 37 is removed from the cap,
the face mask pulled out of the lid, and the button 43 depressed
to pierce the canister seal and fracture the water containing vial
in the canister for releasing water to activate the ignition
material and thereby start the candle to "burn" for releasing
oxygen which will flow through the sealed cup 51 and tubes 53 and
54 to the face mask. Vapor released from the hydrate layer 27
between the foil layers 28b and 296 is vented through the cap body
36 and bottom insulation pad 26 so that a user may grasp the
sleeve 30 without coming into contact with the hot vapor. The cap
35 acts as a chimney to direct the released water vapor away from
the sleeve 30. If the foil layers 28b and 29b are omitted as shown
in FIG. 2-A and the outer peripheral surface or circumference of
the assembly is porous, the vapor freely escapes in a radial as
well as in an axial direction, and while the surface may become
damp it can be comfortably grasped throughout the burning of the
oxygen generating candle.
It will also be understood that the heat generated by the
"burning" of the candle 12 in the tin can 11 is insulated by the
heat dissipating insulation of this invention which by converting
sensible heat into heat of vaporization does not raise the
temperature in the can and keeps the exterior of the cell at a
depressed temperature which is low enough so that the cell can be
grasped with bare hands without discomfort.
US3971372
Oxygen-generating apparatus for scuba diving
Oxygen generation by means of electrolysis is used for underwater
swimming. The apparatus includes a back-pack containing an oxygen
generator, a battery, a storage tank and a purifier, plus
breathing equipment, including hoses and mask. The generator
comprises a cylindrical housing in which an electrolytic cell is
rotatably mounted in such a manner that its center of gravity
always maintains the electrode of the electrolytic cell in a
vertical attitude irrespective of the pitch or diving position of
the swimmer in the water.
BACKGROUND OF THE INVENTION
Scuba diving, as it is generally practiced today, utilizes one or
more tanks of compressed oxygen which are strapped to the back of
the swimmer. These systems require heavy, bulky equipment which
make mobility difficult both in and out of the water. This
invention eliminates the use of large storage tanks and uses an
electrolytic oxygen generator.
The principles of electrolysis for oxygen generation have long
been known. Electrolysis involves the splitting of compounds, such
as water, into ionic-charged components of hydrogen and hydroxyl
parts. These ions carrying, respectively. positive and negative
charges, are known as cations and anions. The cations and anions
are induced to migrate in an electrolytic cell under the influence
of an electric potential impressed between an anode and a cathode
so that the negative ions (the anions) are attracted to the anode
and the positive ions (the cations) are attracted to the cathode.
In order to provide a high concentration of ions of a low
electrical resistance the electrolyte comprises a solution of
water and sulfuric acid. In lieu of sulfuric acid, other
electrolytes, such as sodium hydroxide or potassium hydroxide, are
also used.
Prior efforts have been made in the past to generate oxygen by
electroylsis for underwater swimming. For example, U.S. Pat. No.
3,504,669 to Albert uses a vest-type apparatus in which electrodes
are spaced. But this system does not take into account the effect
of body attitude, i.e., it makes no provision for supplying oxygen
to the mask when the swimmer is diving.
Other patents showing the use of electrolysis for generating
oxygen are shown in U.S. Pat. Nos. 3,119,759, 3,616,436,
3,565,068, 3,674,022, 2,984,607, 3,216,919 and 3,725,236.
SUMMARY OF THE INVENTION
This invention provides an electrolytic system of oxygen
generation which is useful in scuba diving applications and which
is capable of supplying oxygen irrespective of body pitch position
when diving. The apparatus is sufficiently lightweight and compact
so that it can be mounted on a swimmer's back and carried in a
conventional manner. Means are also provided for momentarily
blocking the breathing apparatus when the swimmer rolls.
As in conventional electrolytic systems, the apparatus uses spaced
electrodes consisting of an anode and a cathode connected to the
appropriate terminals of a battery and immersed in an electrolytic
solution of sulfuric acid. In accordance with the invention, the
electrolyte is contained in a rotatable cell mounted within a
fixed cylinder. Connections to the cell are made through slip
connections so that the cell is free to rotate on its pitch axis
within the cylinder under the effect of gravity and thereby
maintain a vertical orientation for efficient and continuous
operation. Automatically operated valves are provided for
temporarily blocking the oxygen hoses when the swimmer rolls in
the water.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration showing the overall breathing
apparatus strapped to the back of a swimmer;
FIG. 2 is a schematic representation of the overall system;
FIG. 3 is a cross-sectional view of the electrolytic cell
used in accordance with this invention; and
FIG. 4 is a section taken through the line 4-4 of FIG. 3.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
The general arrangement of the apparatus is shown in FIG. 1 in
which the breathing apparatus is depicted strapped to the back of
a swimmer. The apparatus includes a harness 10 worn as a shirt
over the swimmer's shoulders and fastened fore and aft by means of
a strap 12 laced through slots 14. The breathing apparatus is
secured to the harness by conventional support members, including
a support 16 and tank straps 18.
As seen in FIGS. 1 and 2, the breathing apparatus includes a face
mask 20 to which oxygen is supplied through a flexible hose 22 and
a demand supply valve 24. The apparatus includes an oxygen storage
tank 26 from which the oxygen is supplied to the swimmer as he
inhales, and a conventional rebreather or purifier 28 which
purifies the unconsumed exhaled oxygen. The partially consumed
exhaled oxygen is supplied to the purifier 28 through flexible
hose 30 and 32 and one-way valve 34. Oxygen from the purifier 28
is returned to the storage tank 26 through flexible hose 38 and 40
and a one-way valve 42. A meter 44 displays the pressure of the
oxygen in the storage tank 26.
The oxygen generator, as illustrated in FIG. 2, comprises an
electrolytic tank 46 rotatably mounted on its pitch axis in a
cylindrical housing 48. As used in this application the pitch axis
is defined as the horizontal axis of the tank when the swimmer is
standing in a vertical upright position. A roll axis is an
imaginary horizontal axis perpendicular to the pitch axis.
The tank 46 contains two electrodes, an anode 50 connected via
insulated wiring 51 to the positive side of a battery 52, and a
cathode 54 connected to the negative side via insulated wiring 59
and a switch 60. The battery 52 and switch 60 are housed in a
waterproof insulating casing 61.
With a sulfuric acid electrolyte in the tank, and with the switch
60 closed, oxygen is formed at the anode 50 and passes through
hoses 62 and 63 and a one-way valve 65 to the storage tank 26. In
addition, hydrogen is formed at the cathode 54 and is pumped into
the environment via hoses 64 and 66 by means of a motor-operated
pump 68 energized from the battery 52.
The details of the electrolytic generator are shown in FIGS. 3 and
4. The tank 46 is formed of a rigid noncorrosive material and, as
seen in FIG. 4, has a cross-section which comprises a portion of a
cylinder just slightly smaller in diameter than the diameter of
the cylindrical housing 48. The tank 46 has integral projecting
shafts 70 and 72 which are rotatably supported within annular
slots formed in projections 74 and 76. Plastic sleeve bearings 78
and 80, and 82 and 84, provide a bearing support and seals for the
shafts 70 and 72, respectively. The hose 62 is clamped to the
projection 76 by a spring clamp 86 while hose 64 is clamped to the
projection 74 by a spring clamp 88.
Gas conduits 90 and 92 are formed on the interior of the cells 46
to provide passageways for the hydrogen and oxygen gases,
respectively. The conduits 90 and 92 are essentially extensions of
hollow shafts 70 and 72 formed on the inner side walls 94 and 96
of the cell. The conduit 90 has a caged ball float valve 97 while
the conduit 92 has a caged ball float valve 95. The valves 95 and
97 serve to close the respective conduits whenever the cell is
rotated on its roll axis. As shown in the drawings, the valve 95
will float up to a closed position to close the conduit 92 when
the cell rotates clockwise by an amount which would otherwise be
sufficient to admit fluid to the hose 62. The valve 97 similarly
protects the hose 64 when the cell rotates counterclockwise.
An anode 50 is mounted from within the conduit 92, while a cathode
54 is mounted from within the conduit 90. An electrical connection
to the anode 50 is made through the wall 96 to a conducting ring
102 secured thereon. A similar connection is made from the cathode
54 to a conducting ring 104. Brushes 106 and 108 supported from
the side walls 110 and 112 of the housing 48 are positioned
against the rings 102 and 104, respectively. The brushes 106 and
108 are connected to the positive and negative sides,
respectively, of the battery through leads 51 and 59.
In operation, the electrolytic cell 46 is initially filled with an
electrolytic solution of fresh water and sulfuric acid. Sufficient
electrolyte is used to cover the electrodes 50 and 54 but not so
much that the liquid can enter the hoses 62 and 64. When the axis
of the cell is horizontal, as noted before, the valves 95 and 97
prevent the electrolyte from entering the hoses 62 and 64 when the
swimmer rolls.
When the switch 60 is closed a positive potential is applied to
the anode 50 and a negative potential is applied to the cathode
54. In addition, the motor for the hydrogen pump 68 is energized.
Hydrogen ions are attracted to the cathode 54 where a hydrogen gas
is formed. The hydrogen gas rises through the conduit 90 to the
level of shaft 70 from where it is then pumped out of the system
by means of the pump 68. Similarly, hydroxyl ions are attracted to
the anode 50 where oxygen gas is formed, rising through the
conduit 92 to the surface of the electrolyte and then through the
shaft 72 and hose 62 to the storage tank 26.
The center of gravity of the rotatable cell 46 is such that the
electrodes 50 and 54 within the cell are maintained in a vertical
orientation as the swimmer's body attitude rotates on the
horizontal axis of the cell 46, thereby giving the swimmer freedom
to dive and ascend without the electrolyte entering the hoses 62
and 64. When the axis of the cell 46 is not horizontal, as when
the swimmer rolls when his body is in a horizontal position, the
float valves 95 and 97 close the conduits. This is not a serious
problem since there will generally be some reserve oxygen in the
tank 26, and since the swimmer will simply take care not to
maintain his body in such a roll position for an extended period
of time. Normally, a swimmer would be in such a position only
momentarily.
The illustrated embodiment is intended to be exemplary of the
invention and many variations of within the scope thereof. For
example, the cell 46 may be a full cylinder provided its center of
gravity is below its axis of rotation. This may be accomplished by
means of weights at the appropriate location on the cell.
Furthermore, bearing and sleeve arrangements different from the
simple arrangement shown may be substituted and indeed may be
preferred. In addition, depending on system requirements, the pump
68 may not be needed, and if additional pressurization of the
storage tank 26 is desired an oxygen pump may be used in the line
38 or 40.
US4278637
Chemical oxygen generator
A chemical oxygen generator which is operable by movement of a
starter member or thrust member comprises an outer closed
container having an end wall on the interior of which an ignition
actuation liquid container is mounted. The ignition actuation
liquid container is made of a foil material and it is mounted over
an ignition mixture container having an ignition mixture which
when mixed with the liquid ignites so as to ignite a spark plug
for the oxygen generator material.
The invention relates in general to chemical oxygen generators and
in particular to a new and useful oxygen generator with an oxygen
spark plug disposed in a container and arranged in series for
activation with a starter and with a closed element containing a
liquid, which can be destroyed from the outside, and with an
ignition mixture activated by the liquid.
Chemical oxygen generators contain oxygen in combined form. Known
are respirators which use chlorate spark plugs, generally called
oxygen spark plugs, and respirators which use KO2 cartridges.
After the start by means of a starter, the oxygen spark plug
supplies oxygen continuously. The KO2 cartridge requires carbon
dioxide and moisture from the exhaling air for the reaction by
which the oxygen is released.
Since this reaction can naturally only start after a few breaths,
an oxygen spark plug takes over the oxygen supply in an apparatus
with a KO2 cartridge, until the KO2 cartridge is activated.
A known chemical oxygen generator has in a container an ignition
mixture activated by water, etc. and an oxygen spark plug
activated by the ignition mixture. Above the ignition mixture
under the cover of the container is arranged a water-filled glass
ampoule in the cavity of a pot-shaped dish. The dish has a
deformable convex bottom in the manner of a spring diaphragm. The
cover of the container is provided with a center with an opening
which is tightly sealed with a foil. For starting the oxygen
generator by activating the oxygen plug, a thrust bolt is pressed
down, which is arranged on the cover of the container and which is
operated from the outside. It penetrates the foil and then presses
on the convex bottom of the dish. The dish jumps out of its normal
position into a concave position and destroys the glass ampoule.
The issuing water activates the ignition mixture and thus starts
the oxygen generator. A disadvantage of this starter is the
sensitive glass ampoule. It must be arranged shock-proof in the
container between the oxygen spark plug and the thrust bolt and
must be kept in close contact with the ignition mixture. This
requires a special arrangement in an additional part, which is not
simple, due to the design of its bottom as a spring diaphragm.
(DOS No. 26 20 300).
SUMMARY OF THE INVENTION
The invention provides a chemical oxygen generator with a starter
which operates in response to the reaction of an activating liquid
with an ignition mixture, and which includes a liquid container
which is simple in design and which works reliably and is arranged
shock-proof mounting.
In accordance with the invention there is provided a chemical
oxygen generator which includes an outer housing which has a top
wall which is welded on its interior to a liquid capsule. The
liquid capsule is made of a foil material and it contains a liquid
which acts as an igniter or reactor for an ignition material. The
ignition material is contained in a container mounted directly
below the foil container and sealed with the foil container by the
welding of the flanges of the foil container directly to the
container for the ignition material. The container for the
ignition material also contains an opening directly under the
liquid in the capsule and it contains a removable foil member
sealing this opening which can be removed by depressing the
capsule downwardly into the ignition material container. This
causes the reaction liquid to mix with the ignition mixture
material and produce ignition thereof and the subsequent ignition
of a spark plug which is mounted directly below the ignition
material.
The advantages of the solution result clearly from the use of the
liquid capsule of foil material. It is thus shock-proof, which
ensures that the liquid will not escape, even after shock
stresses, so that the ignition mixture can not be accidentally
activated. The manufacture of the simple starter is moreover
economical and reliable.
In accordance with the invention there is provided a chemical
oxygen generator which is operable by movement of a starter member
which comprises an outer closed container having an end wall, an
ignition actuation liquid container made of foil material mounted
in said container adjacent the end wall, and an ignition mixture
container mounted in said container adjacent the actuation liquid
container and having an end wall facing the actuation liquid
container with an opening covered by a rupturable foil which when
removed permits the actuation liquid to enter into the ignition
mixture of the ignition mixture container.
A further object of the invention is to provide a chemical oxygen
generator which is simple in design, rugged in construction and
economical to manufacture.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its uses, reference is made to the accompanying
drawings and descriptive matter in which a preferred embodiment of
the invention is illustrated.
BRIEF DESCRIPTION OF THE DRAWING
The only FIGURE of the drawing is an exploded transverse sectional
view of a chemical oxygen generator and actuator therefor
constructed in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in particular the invention embodied
therein comprises a chemical oxygen generator generally designated
1 which includes an exterior container wall 3 having an end or top
portion such as a cover 4. In accordance with the invention a
liquid capsule 6 is secured by a welded seam 10 to the cover 4
directly below an opening 9 thereof. The bottom edge of the liquid
capsule 6 contains an annular flange 6a which is closed by a top
wall 13 of an ignition material container generally designated 7.
The capsule is sealed at its flange 6a to the top wall 13 by an
annular weld 12. The top wall 13 contains an opening 14 which is
closed by a foil material 15 which when removed will permit
actuation liquid 19 in the capsule 6 to flow into ignition
material or a mixture 20 contained in the ignition material
container 7.
Oxygen generator 1 comprises an oxygen spark plug 2 in a container
3. Between cover 4 and oxygen spark plug 2 is arranged a starter
5. The starter 5 comprises a liquid capsule 6, made of a metal
foil material and mounted above an ignition mixture container 7
made of any plate material. Ignition mixture container 7 provides
the necessary support for the oxygen spark plug 2. Liquid capsule
6 is arranged with its end wall or bottom 8 underneath hole 9 in
cover 4. Liquid capsule 6 is held there by a welded seam 10. The
interior of the container 3 is sealed gas-tight to the outside.
Liquid capsule 6 is joined, liquid- and gas-tight with its
turned-over edge 11 by a welded seam 12 with an end wall 13 of the
ignition mixture container 7. A connecting opening 14 formed in
end wall 13 as a connection between liquid capsule 6 and ignition
mixture container 7 is sealed liquid-tight by means of foil 15.
Filter mats 16 fill the empty space between cover 4 and oxygen
spark plug 2. They serve as shock absorbers and insulators.
A starter member in the form of thrust bolt 17 is arranged in a
known manner (not shown) above the cover 4. After release by
pressure from the top, point 18 pierces the bottom 8 of liquid
capsule 6 and foil 15, thus opening the way for an actuator liquid
19 to control an ignition mixture 20 in the container 7. On the
further path of the thrust bolt 17 the bolt end 21 pushes liquid
capsule 6 in front of it, after welded seam 10 has broken off, and
pushes liquid 19 fully into ignition mixture 20. With the end of
the downward movement of thrust bolt 17 gasket 22 seals a hole 9
in the cover 4 from the outside.
The oxygen released after the activation of spark plug oxygen 2
issues through a specially provided opening (not shown) in
container 3 and is fed to a respirator for supplying oxygen to
breathing air. Hole 9 can also be used for this purpose in a
special design.
US4526758
Starting device for heating apparatus comprising
brick of oxygen generating material
A starting device for a breathing apparatus employing
chemically-fixed oxygen which incorporates a brick of oxygen
generating material superposed by a resilient diaphragm giving
support to an ampule with an ignition liquid. The ampule is broken
by an ignition means located on the diaphragm under a gas-tight
cap in an opening whereof there is provided a resilient bushing
containing a removable detent arranged to interact with a retainer
of the ignition means so as to keep same in a position ready for
operation.
FIELD OF THE INVENTION
The invention relates to constituent components of self-contained
breathing apparatus employing chemically-fixed oxygen which are
used to protect the respiratory system of man. It may be used to
advantage in breathing apparatus of the type worn in collieries
during accidents when the atmosphere is unsuitable for breathing,
as may be the case due to fire and gas outbursts. Oxygen-breathing
apparatus providing short-time protection to the respiratory
system of man in hazardous surroundings at chemical plants and in
other industries is another field of application of the invention.
BACKGROUND OF THE INVENTION
There is known a starting device for a chemical oxygen generator
(cf. Application No. 2,818,250 of Dragwerk AG, Fed. Rep. of
Germany; U.K. Patent Specification No. 2,019,729 and U.S. Pat. No.
4,246,229) including a casing with a chemical oxygen generating
material therein, an ampule containing an ignition liquid wherein
the ampule is cradled adjacent the oxygen generating material, and
an ignition means having a spring-loaded thrust bolt held fast in
an opening within the casing by a locking pin. A sealing ring at
the external end of the thrust bolt tightly fits adjacent the
casing, sealing off the interior thereof when the locking pin is
withdrawn. The sealing ring thereby prevents oxygen leaks.
The disadvantage of the known design is the possibility of the
tilting of the thrust bolt due to fragments of the ampule or an
obstacle between the sealing ring and casing (e.g. coarse
particles of dust, chip, burrs, etc.) which impairs the sealing
effect.
Also known is a starting device for a self-contained breathing
apparatus (cf. USSR Inventor's Certificate No. 338,227, Int. Cl.
A62B 21/00) incorporating a brick of an oxygen generating
material, an ampule containing an ignition liquid cradled in a
socket of a resilient diaphgram, and an ignition means in the form
of a spring-loaded lever with an ignition pin held ready for
operation by a detent.
The disadvantage of this design is its poor reliability resulting
from leaks of oxygen through the diaphragm, which can be damaged
by the ignition pin in starting the apparatus.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a starting device
ensuring reliable functioning of a self-contained breathing
apparatus.
The essence of the invention is that the starting device for a
self-contained breathing apparatus employing chemically-fixed
oxygen incorporates a brick of oxygen generating material with an
overlying glass ampule having an ignition liquid for rendering the
brick operable on contact therewith. The ampule is cradled in a
socket of a resilient diaphragm attached to the brick so that the
socket bore faces the brick, above which is located an ignition
means for breaking the ampule. The ignition means includes a
spring-loaded lever with an ignition pin held ready for operation
by a retainer, and is provided with a rigid, gas-tight cap
overlying the diaphragm and having an opening stoppered by a blind
resilient bushing containing a detent. The detent is arranged to
interact with the cap and retainer through the wall of the bushing
so as to keep the lever in a position ready for operation and is
provided with a means of withdrawing from the bushing.
The starting device designed on the above lines improves the
reliability of self-contained breathing apparatus, because any
oxygen leakage is prevented even if the diaphragm is damaged in
starting the apparatus.
It is expedient that the detent is made of a magnetically hard
steel capable of magnetization and the cap is in a diamagnetic
material. This plan simplifies the construction of the starting
device, for the detent is held fast to the cap by the force of
magnetic attraction.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention will be now described by
way of an example with reference to the accompanying drawings in
which:
FIG. 1 is a sectional elevation of the starting device of a
self-contained breathing apparatus according to the invention
and employing chemically-fixed oxygen;
FIG. 2 are sections taken on lines II--II and III--III of
FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
The starting device for a self-contained breathing apparatus
employing chemically-fixed oxygen incorporates a cap 1 (FIG. 1), a
resilient diaphragm 2 with an ampule 3 containing an ignition
liquid and cradled in a socket of the diaphragm, a brick 4 of
oxygen generating material and an ignition means 5. The brick 4,
the cap 1, the diaphragm 2 and the ignition means 5 are
accommodated in a recess of the regenerative canister (not shown)
of the breathing apparatus. The ignition means 5 comprises a lever
7 pivotable about a pin 6 due to the action of a torsional spring
8. An ignition pin 9 with a hook 10 is attached to the end of the
lever 7. The hook 10 engages a bend of a retainer 11 which, in its
turn, holds the lever 7 in a position ready for operation. The pin
6 and the retainer 11 are fitted to a bracket 12a connected to
base plate 12, which is held fast to a flange of the regenerative
canister together with the cap 1 and the diaphragm 2. The opposite
bend of the retainer 11 engages a detent 13 (FIG. 2) fitting into
a blind resilient bushing 14 which is accommodated in an opening
of the cap 1, thus preventing the retainer 11 from rotating. In an
embodiment of the invention, the detent 13 is attached to the cap
1 by bendable tabs 15 and is linked with the removable cover (not
shown) of the container, in which the breathing apparatus is
contained by a flexible member, e.g., a cord 16. In another
embodiment of the invention, the detent is made of a magnetically
hard steel capable of magnetization or of an alloy with magnetic
properties. If the cap is made of a diamagnetic material (steel),
the tabs 15 are redundant, for the detent 13 will be held fast by
the force of magnetic attraction.
The disclosed starting device operates as follows. As soon as the
cover of the container is removed preparatory to wearing the
apparatus, the cord 16 connected to the cover withdraws the detent
13 from the bore of the resilient bushing 14 against the action of
the tabs 15 or the force of magnetic attraction. Once the detent
13 is removed, the end of the retainer 11 turns clockwise due to
the action of the spring 8 (FIG. 1), setting aside the resilient
bushing 14, by an amount causing the hook 10 to disengage the bend
of the retainer 11. The lever 7 acted upon by the coiled spring 8
pivots about the pin 6 and strikes the ampule 3 with the ignition
pin 9. A crust formed on the surface of the brick 4 is destroyed
by the dropping fragments of the ampule 3, facilitating the
contact between the ignition liquid and the material of the brick
4. The brick starts to decompose, liberating oxygen in an amount
sufficient to meet the user's requirements during the initial
period of operation of the breathing apparatus. The moisture and
heat formed due to the decomposition of the brick 4, in addition
to the liberation of oxygen, promote reactions in the regenerative
canister of the breathing apparatus.
The disclosed starting device for a breathing apparatus employing
chemically-fixed oxygen according to the invention ensures
reliable operation of the apparatus, keeping same always sealed
and preventing oxygen leakage. It also eliminates the possibility
of inhaling toxic gases by the user.
US4536370
Chemical oxygen generator
A chemical oxygen generator includes a candle in which oxygen
is present and which is chemically combined and which is ignited
by starting means to initiate the generation of the oxygen. This
takes several seconds before a substantial quantity of oxygen is
provided. Because a user of this oxygen must be supplied with the
oxygen for respiration immediately, the invention includes a
generator which has a pressure space, preferably above, below and
around the oxygen candle which is located in the space and which
is filled with compressed oxygen. The generator includes a member
which is actuated upon release of the starting means for the
oxygen to permit outward flow of the oxygen in the pressure space
which is supplied until the oxygen being released from the candle
is produced by the ignition of the candle.
FIELD AND BACKGROUND OF THE INVENTION
This invention relates in general to respirating devices and in
particular to a new and useful device for generating oxygen for
use in such respirating devices.
Chemical oxygen generators are used in respirators to make
available an oxygen supply. In chemical oxygen generators the
oxygen is present in a chemically combined form, for example in a
chlorate candle or a KO2 cartridge, and when needed is released in
the course of a chemical reaction. A starting device sets the
oxygen release in motion by manual triggering. It always takes
several seconds before oxygen release takes place in the full
amount required. This presents a difficulty for their use in
respirators. The user cannot be supplied at once with the
necessary respirable gas.
SUMMARY OF THE INVENTION
According to the invention, the empty space of the cartridge
vessel is additionally filled with compressed oxygen during the
stand-by time. The quantity is sufficient to supply the user with
respirable gas during the first seconds after start of the oxygen
generator until there is full O2 by the chemical reaction.
Filling the empty space with compressed oxygen offers moreover an
additional safety against access of moisture, which would be
harmful for the chemical substances.
A known oxygen generator cell unit, which is lodged in a
dispenser, has an expendable vessel, e.g. of tinplate, with a
cylindrical sidewall, a closed bottom wall, and an upper end wall
with a central opening. The opening is sealed by a foil that can
be pushed through. An oxygen candle of compressed sodium or
potassium chlorate, to which is admixed a sodium or potassium
oxide, is retained in the vessel by means of elastic fiber mats in
such a way that its flat sides are spaced from the vessel wall so
that flow paths remain for the formed oxygen. At its head end the
oxygen candle has an ignition cone, which is centered with the
opening in the upper end wall of the vessel.
The dispenser in which the cell unit is lodged contains a
concentrically surrounding cylindrical sidewall and perforated
bottom and top walls. The top wall has a movable pressure bolt and
a casing around the latter with an oxygen outlet pipe leading out.
To activate the oxygen generator cell unit, a bolt is pushed
through a foil seal in the upper end wall of the vessel, and a
glass bulb above an ignition cone is shattered. The ignition cone
is activated, and by it the combustion of the oxygen candle is
then initiated. The oxygen then released flows through the flow
paths between the vessel and the oxygen candle and through the
casing into the oxygen outlet pipe.
A disadvantage is that the evolved oxygen is not available at the
moment the chemical reaction is triggered. It always takes several
(up to 10) seconds before the oxygen generator reaches its full
nominal delivery, and this is true also of the other known
ignition by means of a primer, percussion cap or electrical
incandescent wire. This known oxygen generator cell unit,
therefore, is not suitable for cases where the oxygen is needed
immediately, as for example for emergency supply in airplanes or
in self-rescuers carried on the body. (German AS No. 26 20 300).
Another known oxygen emergency supply device has an oxygen
reservoir consisting of individual pressure bottles. Connected to
it are oxygen candles in tubular vessels. Normally, the oxygen
reservoir is connected to the system on board as a main supply
means. Upon failure of the board system, the oxygen candles are
ignited and supply is assured thence via the oxygen reservoir
utilizing the filling thereof with compressed oxygen. On jumping
from the airplane with this emergency supply device, it is
entirely separated from the board system. For this case it
possesses two additional solid oxygen cartridges, so as to have a
relatively large supply available. The total supply then comprises
of the reservoir with the compressed oxygen, filled up from the
board system, and the additional oxygen from the oxygen candles
then to be ignited. A disadvantage is the complicated construction
consisting of the storage bottles individually connected with one
another and the solid oxygen cartridges (German PS No. 19 53 754).
Another chemical oxygen generator contains a tightly closed
pressure vessel, a conventional oxygen cartridge, or an oxygen
candle in a vessel. It is equipped with the usual ignition means.
The oxygen cartridge is supported concentrically in the pressure
vessel by ceramic fiber mats. The empty space between the pressure
vessel and the cartridge container is filled with compressed
oxygen before being made ready. As ignition is triggered, a valve
opens toward the outlet, so that the oxygen can flow to the
consumer. When the pressure of the oxygen evolving from the oxygen
candle in the cartridge exceeds the decreasing pressure in the
empty space, it opens a membrane, so that the oxygen can then flow
off via the empty space and the outlet. This oxygen generator is
compact but short. For cases where a smaller volume widthwise but
a possible greater length is required this is disadvantageous.
(German No. P 30 45 111).
The invention provides a device to supply the user of the
respirator in which a chemical oxygen generator is employed, from
the start of use, that is immediately after actuation of the
starting means, with a respirable gas, hence with sufficient O2
content, in adequate quantity. The chemical oxygen generator, as a
device to be carried on the body should not be cumbersome and be
as small as possible in its external dimensions.
In accordance with the invention, a chemical oxygen generator
comprises a pressure vessel which has an outlet which is connected
to an interior pressure space in which is positioned an oxygen
generating candle. The device includes a starter for the oxygen
candle which is set off by a releasable member of a trigger
mechanism. In accordance with the invention a membrance is located
in the path of movement of the starter and this normally seals the
pressure space in the container from the outlet. The membrane is
ruptured at the time the oxygen candle is ignited so that the
oxygen in the pressure space flows out of the outlet as soon as
the starter means is put in motion.
By a simple construction with smallest external dimension of the
chemical oxygen generator and the additional previous filling of
the empty spaces in the pressure vessel, the supply of the user
with oxygen until the chemical oxygen delivery starts is assured.
In addition, the user is satisfactorily supplied by the oxygen
additionally already present previously during the first seconds
until the chemical oxygen production sets in.
Accordingly, it is an object of the invention to provide a
chemical generator which includes an oxygen supply which is
liberated at the same time that an oxygen generating candle is
ignited.
A further object of the invention is to provide a chemical oxygen
generator which is simple in design, rugged in construction and
economical to manufacture.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its uses, reference is made to the accompanying
drawings and descriptive matter in which a preferred embodiment of
the invention is illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
The only FIGURE of the drawing is a transverse sectional view of a
chemical oxygen generator constructed in accordance with the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing in particular, the invention embodied
therein comprises a chemical oxygen generator generally designated
1 which comprises a pressure vessel having an outlet 13 which is
communicatable with an interior pressure space which in the
embodiment illustrated comprises a lower space 5, an upper space 6
and an intermediate space 7 around an oxygen generating candle 2.
The oxygen candle 2 is ignitable by a starter 3 which is set off
by a trigger mechanism 4. The space 7 also contains support
elements which are cross-hatched and located around the candle 2.
In accordance with a feature of the invention, the pressure space
is filled with a compressed oxygen and the starter mechanism
trigger ruptures a membrane 12 which comprises a removable or
rupturable member which blocks the communication of the pressure
space to the outlet 13.
In a pressure vessel 1 is lodged an oxygen candle 2. It comprises
the usual starting means 3, actuated by a trigger 4. A lower empty
space 5 and an upper empty space 6 in the pressure vessel 1 are
filled with compressed oxygen in the readiness state together with
the free space 7 around the oxygen candle 2. Thus, the spaces 5, 6
and 7 are in common open flow communication with each other and
with the oxygen candle 2 and such spaces are filled in a ready
state with the stored oxygen under pressure prior to starting the
operation of the oxygen candle 2. The empty spaces 5 and 6 are
connected together via the free space 7 through vertically spaced
perforated disks 8 and 8' mounted with the vessel and supporting
the oxygen candle 2. Trigger 4 comprises a striker 11 actuated by
a compression spring 9 and held in an inoperative position by a
release pin 10. After the release pin 10 has been pulled, the
striker 11, cutting open a membrane 12, strikes against the
starting means 3 and causes it to ignite. The compressed oxygen
contained in the spaces of the pressure vessel 1 and the oxygen
being released later from the oxygen candle 2 then flow through an
outlet 13 to the consumer.
A lower button or bottom wall 14 provides a closure of the lower
empty space 5 and carries a pressure gauge 15.
US4548730
Portable self-contained oxygen generator apparatus
and method
An oxygen generator is provided in the form of a housing
having isolated first and second chambers. Oxygen-generating
material is placed in the first chamber and a catalyst for
activating the oxygen-generating material is placed in the second
chamber. A heat-absorbing hydrated salt is also provided so as to
be present during the reaction to absorb the excessive heat
released upon the exothermic chemical decomposition of the
oxygen-generating material. The salt has an endothermic
dehydration reaction temperature below 50 DEG C. A membrane is
operationally connected to the reaction chamber to allow the
generated oxygen to be expelled from the reaction chamber while
retaining the material contents therein.
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to the exothermic generation of oxygen and
more particularly to a portable self-contained oxygen generator
apparatus and method of generating oxygen well suited for medical
and industrial usage.
Emergency medical oxygen is used extensively to meet the
requirements of critically ill or injured persons. Small emergency
medical oxygen supplies are common in ambulance, fire, police, and
medical emergency operations. Generally, emergency medical oxygen
supplies are in the form of small tanks containing oxygen at high
pressure. These tanks are relatively expensive since they must be
equipped with a precision gas regulator and valves to control the
flow and pressure of the oxygen during use. Maintaining sufficient
numbers of these tanks is sometimes prohibitive because of their
cost. In many cases, the requirements of an actual emergency will
overwhelm the available number of oxygen supplies, such as during
a fire with a large number of smoke-inhalation victims. Moreover,
these devices exhibit significant weight so as to be inconvenient
to store and handle, and must be refilled after use.
Notably, emergency medical oxygen supplied from such tanks is
often of inferior quality. Such oxygen is commonly too dry and can
be too cold when the tank has been stored in a cold place. In
hospital respirators, expensive systems are utilized to warm and
moisturize the oxygen before providing it to the patient. However,
such a conditioning of the oxygen is difficult, if not impossible,
to achieve during the use of emergency oxygen supplies due to the
size and weight of the equipment required to provide such
conditioning.
Portable sources of oxygen are also utilized in athletics and
industry. For example, athletic teams in such sports as football
often provide on-site oxygen supplies for use by the players.
Joggers, athletes, and people performing rigorous exercise also
have the need for portable sources of oxygen. The need is also
present in a wide variety of other diverse applications such as on
trains, planes, and boats to counter motion sickness.
The disadvantages of storage tanks render them unacceptable for
many applications and, heretofore, portable oxygen generators have
also been unacceptable in many respects. In oxygen generators,
oxygen-rich chemicals are decomposed in an exothermic chemical
reaction to evolve oxygen. Excess heat produced by the chemical
reaction is undesirable and may render the oxygen generator
hazardous to operate and may render the oxygen produced
unacceptable for medical use. For example, hydrogen peroxide is a
common oxygen-rich chemical material. Without some means for
removing excess heat, the heat generated by the decomposition of
hydrogen peroxide is sufficient to generally discourage the use of
a solution of hydrogen peroxide having a concentration greater
than 10 percent. A solution of hydrogen peroxide greater than 10
percent, when decomposed, would generate an amount of heat
sufficient to seriously overheat the oxygen generator. In
addition, the vapor pressure of the hydrogen peroxide would be
substantial at these elevated temperatures and would represent a
significant toxicological problem. Excessive heating would also
result in autocatalytic decomposition of the peroxide and can
bring about a dangerous runaway reaction. The excessive
temperature would also eventually boil the aqueous solution in the
generator and excessively heat the product oxygen which would be
uncomfortable or dangerously hot to consume in medical
applications and would generate large amounts of steam thereby
begetting additional problems. Prior means for removing excess
heat, such as a heat exchanger, are not desirable in a portable
oxygen generator because of size restrictions and severe cost
constraints. Such means for controlling excessive heating would be
so costly as to greatly restrict the economic utility of such
devices.
Consequently, the heat generated by the exothermic reaction has
substantially restricted the use of such oxygen generators for
medical and industrial applications where convenient portability
is required.
The portable oxygen generator apparatus and method of the present
invention overcome these and other problems found in prior
portable oxygen supplies by providing an oxygen generator
comprising a housing having isolated first and second chambers. A
predetermined amount of oxygen-generating material is provided in
the first chamber of the unit and a predetermined amount of
catalyst for activating the oxygen-generating material is provided
in the second chamber. A heat-absorbing chemical material is also
provided so as to be present during the reaction to absorb the
excessive heat released upon the exothermic chemical decomposition
of the oxygen-generating material. An admixing apparatus is
selectively actuable for selectively admixing the
oxygen-generating material into operative contact with the
catalyst in the presence of the heat-absorbing material in one of
the chambers, being the reaction chamber. A membrane is
operationally connected to the reaction chamber to allow the
generated oxygen to be expelled from the reaction chamber while
retaining the material contents therein.
The method of producing oxygen in accordance with the present
invention includes the steps of providing an oxygen-generating
material, a catalyst, and a heat-absorbing material, bringing the
catalyst and the oxygen-generating material into operative contact
to promote the exothermic generation of oxygen gas in the presence
of the chemical heat-absorbing material, whereby the temperature
of the reaction is controlled without adversely influencing the
production of oxygen. The generated oxygen is isolated from and
allowed to pass from the site of the exothermic reaction for
subsequent use. The chemical heat-absorbing material is present in
an amount sufficient to be effective in absorbing a portion of the
excessive heat generated by the exothermic decomposition of the
oxygen-generating material.
Accordingly, it is an object of the present invention to provide a
light-weight, self-contained, high-capacity oxygen generator with
an extended shelf life which provides, upon actuation, a steady
regulated flow of warm, conditioned oxygen for medical use.
It is a further object of the invention to provide an oxygen
generator which is comprised of chemicals that are easy and safe
to store and use.
A still further object of the invention is to provide a method for
generating oxygen from decomposable oxygen-rich materials which
controls excessive generated heat in an economical space-efficient
manner.
Yet another object of the invention is to provide an oxygen
generator which is economical to manufacture, economical and
simple to use, and safely disposable after use.
Other objects will be in part obvious and in part pointed out more
in detail hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially diagrammatical sectional view of the
oxygen generator apparatus of the present invention, and
FIG. 2 is a view similiar to FIG. 1 of an alternative
embodiment of the oxygen generator apparatus of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings in detail wherein like parts are
correspondingly numbered, FIG. 1 shows the oxygen generator
apparatus of the present invention. The generator is comprised of
a housing 12 forming an interior cylinder 14 which is separated
into an upper chamber 16 and a lower chamber 18 by a slidably
mounted plunger or diaphragm element 20. The housing 12 exhibits
holdable configuration being approximately the size of two
12-ounce soft-drink cans arranged end to end and can be fabricated
of injection molded polypropylene or other suitable material. A
tube 22 fluidly connects the lower chamber 18 to the upper chamber
16 and is provided with a normally closed control valve 24 to
permit regulation of the flow through the tube 22.
At the upper end of the housing 12, a hydrophobic membrane 26
operationally interconnects the upper chamber 16 to a delivery
tube 28. As will be explained in detail subsequently, the oxygen
gas will pass from the upper chamber 16 through the membrane 26 to
the delivery tube 28 for conduction to an apparatus for
application, e.g., a mask (not shown). A releasable cap 30 is
detachably secured to the housing 12 to protect the delivery tube
28 from dirt and contamination when not in use.
A second hydrophobic membrane 32 is mounted within the lower end
of the housing 12 to operationally interconnect the lower chamber
18 with the atmosphere. Similar to the membrane 26, the
hydrophobic membrane 32 functions to easily pass gas but retain
liquids and will allow any excess oxygen formed during storage of
the oxygen generator to be vented to the atmosphere without loss
of liquid. A support substrate 33 with drainage ports 35 is
mounted adjacent the membrane 32.
The plunger 20 is slidably mounted within a lubricated seal or
flange 34 in the cylinder 14 so that the plunger 20 is slidable
along the length of the cylinder 14. A compression spring 36 is
mounted within the upper chamber 16 between the membrane 26 and
the plunger 20 to urge the plunger 20 in a downward direction
toward the lower chamber 18. Consequently, the plunger 20 is
biased downwardly toward the lower chamber 18 to apply a pressure
upon any liquid within the lower chamber 18. The pressure applied
by the plunger 20 on the liquid within the lower chamber 18 will
force the liquid up through the tube 22 and into the upper chamber
16 upon actuation of the control valve 24. Thus, an actuable
subassembly is provided for selectively admixing or conducting the
liquid within the lower chamber 18 to the upper chamber 16. Other
alternative methods can be utilized for selectively admixing or
conducting the liquid from the lower chamber 18 to the upper
chamber 16 including the use of vacuum techniques to pressurize
the liquid in chamber 18.
The hydrophobic membrane 26 operationally interconnects the
delivery tube 28 and the upper chamber 16 and functions to allow
passage of the oxygen gas from the upper chamber 16 to the
delivery tube 28 while restraining liquids within the upper
chamber 16. The membrane 26 also functions to purify the evolved
oxygen by filtering out contaminating bacteria, particulate matter
and free aerosolized water. Importantly, the membrane 26 prevents
any water aerosols carrying hydrogen peroxide from passing from
the generator to the patient.
The design of the membranes is based upon regulating the size of
the pores within the fabric of the membrane and the use of a
hydrophobic filter medium that tends to reject fluids but easily
passes gaseous components. The pores must be small enough to
prevent the passage of liquid even at the highest pressure
differential expected but must be large enough to allow the
desired gas flow to occur within the range of allowed differential
pressures across the membrane. Thus, there must be a balance
between the size of the pores required to retain liquid and the
size and number of pores required to obtained the desired flow of
oxygen therethrough.
The pressure required to pass a fluid through a pore by capillary
force is:
P=2S(cos.theta.)/r
where S is the surface tension of the fluid, .theta. is the fluid
and membrane contact angle, and r is the radius of the pore. A
wettable membrane having pores with a diameter of 16 micrometers
would be sufficient to retain pure water under a pressure of 0.1
atmosphere. Modifying the membrane to provide a contact angle of
70 degrees would allow the membrane to contain pores having a
diameter of 50 micrometers. For adequate safety, pores of less
than 10 micrometers in diameter on a nonwettable membrane are
desired.
Gas flow, Q, through the pores of the membrane, of radius r, and
at a differential pressure of P, is described by:
Q=r@4 P/8vL
which describes the flow of gas through a single pore when the
length of the pore is L, and where the viscosity of the gas is v.
The number of pores in a given membrane is:
N=F (Rm@2 /r@2)
where F is the fraction of open space and Rm is the radius of a
round membrane section.
Total gas flow through a given membrane disc of radius Rm, or area
Rm, is:
QN=r@2 PFRm@2 /8vL
Based upon this equation and testing, it has been found that
membranes having pores that are 2-10 micrometers in diameter and
having a total surface area of at least 20 cm@2 can easily pass 20
liters of gas/minute. In the illustrated embodiment, the membranes
26, 32 are glass fiber membranes either unsupported or supported
on a coarse cellulose-fiber substrate, impregnated with silicon
and/or tetrafluoroethylene resins to impart hydrophobicity, and
having a pore size of approximately 5 micrometers.
To load the oxygen generator for eventual actuation, the lower
chamber 18 is filled with a solution of an oxygen-generating
solution which may also contain some of the heat-absorbing
material. The upper chamber 16, in turn, is filled with a solution
of the heat-absorbing material at an appropriate concentration
together with a nucleating agent and a solid catalyst that
promotes the rapid decomposition and release of oxygen by the
material in the lower chamber when it is brought into contact with
the catalyst. The catalyst can be supported on the walls of the
chamber 16 or on a porous support medium (not shown) or can be
added as a solid powder or liquid. Additional chemicals may be
added to enhance or control the performace of the heat-absorbing
material, to reduce foaming, etc.
In this deactivated or storage mode, the drive spring 36 is
compressed or loaded and the reactants are separated by the
movable plunger 20 which also maintains the lower chamber 18 under
pressure due to the biasing force of the spring 36. The valve 24
is normally closed to prevent communication between the upper and
lower chambers. In this mode, the oxygen generator can be stored
and is ready for use upon actuation of the control valve 24. With
stabilizers, a storage life of at least five years can be
expected.
In operation, the control valve 24 is opened to actuate the oxygen
generator to produce oxygen gas. Upon opening the valve 24, the
solution in the lower chamber 18 is caused to flow up the tube 22
due to the pressure applied by the spring 36 through the plunger
20. The solution flows into operative contact with the catalyst
contained in the upper chamber 16 and the reaction commences. The
control valve 24 can be adjusted to provide a selectable steady
flow rate into the upper chamber 16 or to provide an intermittent
burst.
When the heat generated by the oxygen-producing reaction within
the upper chamber 16 causes the temperature of this chamber to
rise above a predetermined critical value, for example,
approximately 30 DEG C., the heat will start to be absorbed by the
heat-absorbing material, due to the endothermic nature of that
material, to maintain the upper chamber at an acceptable operating
temperature. Further buffering of the temperature is provided by
the heat capacity of the chemicals and the liquid as well as
through the dissipation of heat by convection and conduction
through the walls of the housing.
The evolved oxygen gas passes through the hydrophobic membrane 26
to the delivery tube 28 for distribution to the user. The
hydrophobic membrane 26 functions to allow passage of the oxygen
gas therethrough but restrains the passage of liquid. In this
manner, the oxygen gas is purified for use for medical purposes.
As the oxygen gas is evolved, the oxygen-generating solution
continues to be moved from the lower chamber 18 to the upper
chamber 16 by the displacement of the plunger 20. The control
valve 24 is adjustable to allow the user to vary the rate of
oxygen gas evolution over a wide range. In the illustrated
configuration, the oxygen generator can produce a total of about
55 liters of oxygen. The medical use of oxygen usually specifies a
flow rate of 2-6 liters of oxygen per minute and, under normal
conditions, the oxygen generator of the illustrated embodiment is
sufficient for 10-25 minutes. Since the chemical components are
aseptic, the generated oxygen is sterile in addition to being
filtered or purified by the hydrophobic membrane. Accordingly, the
oxygen generator is of relatively high capacity for its compact,
lightweight size (i.e., 3 lbs.) and produces warm, sterile, and
pure oxygen for medical applications. Upon exhaustion of the
chemical reactants, the container and residue components are
safely disposable.
Referring to FIG. 2, an alternative embodiment of the oxygen
generator apparatus of this invention is shown wherein like
numerals are used to designate the same or like parts. In this
embodiment, the housing 12 forms an internal cavity 38 having an
upper end portion 40 and a lower end portion 42. The lower end
portion or lower chamber 42 contains a dry powder mixture of a
decomposable oxygen-generating chemical and a heat-absorbing
material. A rupturable pouch 44 is mounted in the upper end
portion 40 of cavity 38. The pouch 44 contains a liquid 46 having
a catalyst to promote the decomposition of the oxygen-generating
material in the lower end portion 42. The oxygen-generating
material is thus separated from the catalyst solution by the
rupturable pouch 44.
A striker element 48 is slidably mounted within a guide sleeve 50
extending through the upper end 52 of the housing 12. The striker
element 48 has a pointed end 54 adjacent the pouch 44 and a handle
portion 56 extending above the upper end 52 of the housing 12. The
depression of the handle end 56 will thus slidably displace the
striker element 48 downwardly to cause the pointed end 54 to
rupture the pouch 44. To prevent an unintended depression of
handle 56, a safety ring 58 locks the striker 48 in a withdrawn
position. The safety ring 58 is removed by a simple pulling action
to allow subsequent actuation of the striker element 48.
The upper end 52 of the housing 12 contains an outlet orifice 60
in communication with the cavity 38. A filter plug assembly 62 is
mounted within orifice 60 and comprises a packed bed of stainless
steel mesh 64 coated with silicon oil to provide a foam breaker.
An alternative respiratory therapy filter or hydrophobic membrane
(not shown) is mounted adjacent the foam breaker within the plug
assembly 62 and functions in substantially the same manner as
discussed hereinbefore in connection with membrane 26. An
acceptable respiratory therapy filter is manufactured by Pall
Corporation of Glen Cove, Long Island, N.Y. A delivery tube 66 is
located at the top of the filter plug 62 and is covered by a
removable cap 68. During storage of the oxygen generator, the cap
68 maintains the delivery tube 66 in a clean condition.
To actuate the oxygen generator, the cap 68 is removed from
delivery tube 66 and the safety ring 58 is removed from the
striker element 48. The handle 56 of the striker element 48 is
depressed to rupture the pouch 44. Upon rupture, the catalytic
solution contained in the pouch 44 is intermixed with the
oxygen-generating material in the presence of the chemical
heat-absorbing material. As previously described with respect to
the embodiment of FIG. 1, the catalyst promotes an exothermic
decomposition of the oxygen-generating material to evolve oxygen
gas and as the reaction temperature reaches a predetermined value,
the chemical heat-absorbing material endothermically absorbs the
excess heat to maintain a stable and acceptable operating
temperature. The evolved oxygen gas passes through the hydrophobic
membrane and outward to the delivery tube 66 while the foam
breaker 64 prevents the passage of any foam caused by the chemical
reaction.
Other acceptable containers for the catalytic solution may be
utilized as well as alternative means for selectively rupturing
the container. For example, the pouch 44 can be pressurized as
well as the interior of housing 12. When the housing 12 is opened
to the atmosphere, the pressure is released so that the pouch
expands and bursts to cause the catalytic solution to intermix
with the oxygen-generating material.
As mentioned hereinbefore, the method of the present invention
provides for the generation of oxygen only at the time it is
needed through the utilization of an oxygen-generating composition
which, in the presence of an appropriate catalyst, will provide a
controlled release of oxygen gas. The composition not only
produces the oxygen gas but, at the same time, controls the heat
generated by the oxygen-releasing reaction and obviates the hazard
associated with excessive heat generation within the container. In
accordance with this system, the oxygen is produced by the
exothermic decomposition of the chemical oxygen-rich composition
while the excessive heat produced thereby is absorbed by an
appropriate heat-absorbing material present within the vicinity of
the reaction site.
As can be appreciated, a number of different oxygen-rich or
oxygen-generating materials may be utilized as the source of the
desired oxygen gas. Many of these materials such as the peroxides
and chlorates are well known and this invention should not be
unduly restricted to a specific type of material. However, it is
generally preferred that the oxygen-generating material be capable
of producing the highest possible amount of free oxygen relative
to the weight and volume of the initial oxygen-producing material.
Accordingly, it is generally preferred that the percent, by
weight, of free oxygen released by the material should be greater
than five percent and preferrably should be greater than ten
percent, keeping in mind the necessity to balance the
oxygen-generating capability of the material against the handling
and storage characteristics thereof. For example, although
alkaline superoxides and peroxides or strong solutions of hydrogen
peroxide may be used in accordance with the present invention,
such materials are highly caustic and frequently require great
care due to their toxic and hazardous nature. Other materials
which may be employed, such as barium peroxide or potassium
permanganate are far more expensive and although they may be
employed, their costs tends to be prohibitive. Still others, such
as sodium persulfate, contain a low level of oxygen gas-generating
potential and therefore are less desirable in a system of the type
described in this invention. When seeking a balance of the various
factors involved, it has been found that the preferred material
should be relatively safe and stable during handling. Materials of
this type include peroxide hydrated salts, such as potassium
percarbonate, which has been used in laundry bleach formulations
and contains about 13 percent free oxygen. This material also
advantageously provides release of the oxygen in a controlled
manner over a brief period of time. Such materials are
particularly beneficial when the oxygen supply is to be used for
medical purposes. However, where industrial application is
envisioned, other materials may be employed.
As mentioned, the utilization of materials such as peroxides
results in the production of excessive amounts of heat and it is
necessary during the reaction to control the temperature level at
the reaction site to avoid autocatalytic acceleration of the
reaction rate. This is achieved in accordance with the present
invention by stabilizing the exothermic reaction through intimate
admixture therewith of a heat-absorbing material that prevents the
reaction temperature from exceeding an established limit. This is
achieved without seriously reducing the oxygen-generating
capability of the system. In this manner, the production of the
oxygen gas and the absorption of the excess heat generated thereby
is carried out substantially simultaneously. Accordingly, a proper
balancing of the appropriate mixture of oxygen-generating and
heat-absorbing materials can result in the reliable maintenance of
a constant temperature throughout the course of the oxygen gas
producing reaction.
As will be appreciated, several materials will exhibit the
necessary endothermic characteristics whereby heat will be
absorbed by the material without interfering with the generation
of oxygen. For systems of the type described herein it has been
found that salts which undergo reversible dehydration are
particularly useful. These highly hydrated salts will absorb the
excess heat generated by the oxygen-producing reaction. Other
materials that may be used are those which undergo endothermic
phase transitions or chemical transformations as the result of
heat absorption. For example, certain salts having significant
heats of solution could be used. While the choice of the
appropriate heat-absorbing component depends upon the desired
temperature and the quantity of energy absorbed per unit of
chemical utilized, the temperature at which the heat-absorbing
component is most effective is an important consideration.
Accordingly, it is generally preferred that the material exhibit
an endothermic reaction at a temperature below 50 DEG C. Where the
gas is to be utilized for medical purposes the temperature of the
gas at the point of use should not substantially exceed 30 DEG C.
to insure full comfort by the user.
In the system of the present invention, the preferred
energy-absorbing materials are hydrated salts which exhibit a
dehydration temperature of about 30 DEG-50 DEG C. Materials of
this type include alkaline sulfates, thiosulphates and
biphosphates. However, the preferred material for use as the
heat-absorbing compound in the present invention combines both a
high endothermic heat of reaction with a low dehydration
temperature. These conditions are met by sodium sulfate
decahydrate and sodium biphosphate.
It is a feature of the present invention that both the oxygen
producing material and the energy-absorbing material may take the
form of either a solid or may be stored as an aqueous solution.
Additionally, as mentioned, the energy-absorbing material may be
admixed with the oxygen-producing material prior to the reaction
or the materials may be partially separated and only brought into
intimate engagement at the time of reaction. Thus, the composition
of the present invention provides a high degree of flexibility
with respect to the design of the oxygen-generating structure and
the manner of its operation. As can be appreciated, where the
energy-absorbing material is initially admixed with the
oxygen-generating compound of the system, it is preferred that the
energy-absorbing material also be present at the reaction site if
this site is remote from the storage location for the
oxygen-generating material. Also it is preferred that the amount
of energy-absorbing material be greatest at the reaction site in
order to insure appropriate energy absorption at the time of
reaction.
The specific amounts of energy-absorbing compounds employed may
vary with the specific oxygen-generating material employed.
Generally, the ratio of energy absorber to oxygen generator will
fall within the range of 1:2 to 2:1 with the preferred composition
having equal amounts of the two materials. Where a portion of the
energy-absorbing material initially is placed within the
compartment containing the catalyst, the mix of absorber and
oxygen generator falls within the lower portion of the foregoing
ratio range.
By way of example, it may be noted that when a solution of the
oxygen generator is utilized as the source of the oxygen gas, the
energy-absorbing material, such as the sodium sulfate decahydrate,
should be present at a concentration of about 500 grams per liter
while at the reaction site, the energy-absorbing material should
exhibit a concentration which is approximately twice that
concentration prior to admixture at the reaction site.
Additionally, small amounts of nucleating agents such as borax may
also be included within the solution located within the reaction
chamber. Typically, amounts on the order of 0.1 percent by weight
are employed.
Thus it can be seen that a lightweight, self-contained,
high-capacity generator with an extended shelf life is disclosed
which provides a steady regulated flow of warm, moist, sterile
oxygen for a variety of medical and industrial applications. The
oxygen generator is composed of chemical components that are
nontoxic and safe for storage, use, and disposal. Importantly, the
oxygen generator is economical to manufacture and simple to use.
As will be apparent to persons skilled in the art, various
modifications and adaptations of the structure and method
described above will become readily apparent without departure
from the spirit and scope of the invention, the scope of which is
defined in the appended claims.
US5804146
Chemical oxygen generator
A chemical oxygen generator with a chemical mass, which is
accommodated inside a container, generates oxygen by a chemical
reaction, and is held in the container by a gas-permeable fibrous
material. The fibrous material is arranged around the chemical
mass. The fibrous material is designed as a chemical sorption
filter.
FIELD OF THE INVENTION
The present invention pertains to a chemical oxygen generator with
a chemical mass, which is accommodated inside a container,
generates oxygen by a chemical reaction and is held in the
container by a, gas-permeable fibrous material arranged around it.
BACKGROUND OF THE INVENTION
Oxygen generators based on chlorate are, in general, pressed
objects containing a chemical releasing oxygen, e.g., potassium
chlorate, wherein certain additives are added to the fuel to
maintain the chemical reaction or to remove harmful components.
For example, iron and manganese are added to maintain the oxygen
production, whereas, e.g., barium peroxide is used to remove
chlorine. Such an oxygen generator has become known from DE-OS 20
26 663. In the prior-art oxygen generator, the heat generated
during the reaction is kept away from the sheet-metal housing of
the generator by an insulating jacket, which consists of a fibrous
material. The dusts generated during the reaction of the chemical
mass, e.g., salt dusts, are also retained by the fibrous material.
Harmful components, which must be captured, can still be formed
during the conversion of the chemicals into oxygen despite the
additives. An additional chemical filter, through which the oxygen
generated flows along with its impurities, is used for this
purpose. The impurities are bound in this filter by chemisorption
(catalytic decomposition) or by physical adsorption. The dusts
(particles) are retained by chemical separation in a physical
filter (particle filter) located at a short distance before the
outlet. The installation of an additional filter for removing the
impurities appreciably increases the weight of the oxygen
generator. Oxygen generators with minimal weight are needed
especially in aviation because of economic requirements. An
additional chemical filter in these oxygen generators also
increases the cost in connection with a subsequent disposal,
because the substances contained in the filter usually must be
treated as special waste.
SUMMARY AND OBJECTS OF THE PRESENT INVENTION
The primary object of the present invention is to improve an
oxygen generator such that the harmful gases generated during the
chemical reaction can be removed in a simple manner.
According to the invention, a chemical oxygen generator is
provided with a chemical mass. The chemical mass is accommodated
inside a container and generates oxygen by a chemical reaction.
The chemical mass is held in the container by a, gas-permeable
fibrous material arranged around it. The fibrous material
comprises a sorption filter.
The advantage of the present invention is essentially that the
impurities formed during the chemical reaction are removed by the
fibrous material designed as a sorption filter and are thus
removed directly at the site at which they are generated.
The sorption filter advantageously consists of the fibrous
material impregnated with a sorbent. The suitable substances for
the impregnation are chemicals of a basic character, e.g.,
hydroxides and carbonates. Sodium hydroxide and calcium hydroxide
have proved to be particularly effective for removing chlorine.
These substances may be applied in the form of an aqueous solution
or suspension containing a few weight percent by briefly immersing
the fibrous material into the solution or the suspension or by
spraying the fibrous material with the solution or the suspension
and subsequently freeing the parts of water in a desiccator.
The weight of substance applied to the fibrous material is about 1
g to 3 g, depending on the type of the generator. This is in the
range of variation of the overall weight of the generator during
its manufacture. In contrast, a prior-art chemical filter has a
weight between 20 g and 50 g, depending on the design of the
generator.
One exemplary embodiment of the present invention is shown in the
drawing and will be explained in greater detail below.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its uses, reference is made to the accompanying
drawings and descriptive matter in which a preferred embodiment of
the invention is illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a longitudinal sectional view of an oxygen
generator;
FIG. 2a is a diagram showing the oxygen production as a
function of time; and
FIG. 2b is a diagram showing chlorine production as a
function of time.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in particular, the oxygen generator 1
shown in FIG. 1 contains in a container 2 a reactive chemical 3,
which is surrounded by a fibrous layer 4 that is permeable to gas.
An igniting device 6 is arranged on the top front side 5 of the
container 2 in the known manner in order to start the chemical
reaction. The oxygen generated escapes via an outlet opening 9
located on the lower top side 8 of the container 2. The igniting
device 6 is designed as a percussion fuse in the known manner. The
fibrous layer 4 consists of a pot-shaped ceramic fiber molding 10
and a ceramic fiber disk 11 lying on the open front side of the
ceramic fiber molding 10. The molding 10 and the disk 11 are
impregnated with sodium hydroxide by briefly immersing the molding
10 and the disk 11 into an aqueous solution of sodium hydroxide
and subsequently drying them.
The oxygen generated by the chemical 3 first enters the molding 10
and from there it flows to the outlet opening 9 via the disk 11.
The dusts and particles generated during the chemical reaction of
the chemical 3 are first filtered out in the molding 10. The
chlorine formed during the decomposition of the chemical 3 is
bound by the sodium hydroxide impregnation during the flow through
the molding 10 as well as through the disk 11.
The effectiveness of the impregnation according to the present
invention will be illustrated by the following FIGS. 2a, 2b.
Curve A in FIG. 2a shows the oxygen production as a function of
the reaction time of the oxygen generator 1. FIG. 2b shows the
chlorine production belonging to curve A, specifically as a curve
B for a device according to the state of the art without
impregnated fibrous layer and as a curve C with the impregnation
of the fibrous material according to the present invention. The
chlorine concentration is under a value of 0.2 ppm of chlorine in
the case of curve C.
US5823181
Handy oxygen generator
A handy oxygen generator including a casing defining a reaction
chamber, an air accumulator and an air passage between the
reaction chamber and the air accumulator, a hand pump for pumping
air into the reaction chamber to increase its inside pressure, a
chemical module mounted in the reaction chamber and containing two
separated chemicals, a plunger mounted on the reaction chamber for
operation by hand to break the chemical module, enabling the two
chemicals to induce a chemical reaction and to release oxygen into
the air accumulator during the chemical reaction, an air outlet
pipe with an air filter suspending in the air accumulator, and a
mouthpiece connected to the air outlet pipe for the user to
breathes in oxygen from the air accumulator.
BACKGROUND OF THE INVENTION
The present invention relates to a handy oxygen generator which
can be conveniently carried by the user and operated to release
oxygen for breathing during an emergency case.
According to statistics, a high percentage of victims in fire
accidents died from breathing in an excessive amount of carbon
dioxide. Therefore, many of fire victims can survive if they have
a personal respirator means.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide an oxygen
generator which releases oxygen for breathing through a chemical
reaction. It is another object of the present invention to provide
an oxygen generator which is handy and convenient for personal use
in an emergent case. According to the preferred embodiment of the
present invention, the handy oxygen generator comprises a casing
defining a reaction chamber, an air accumulator and an air passage
between the reaction chamber and the air accumulator, a hand pump
for pumping air into the reaction chamber to increase its inside
pressure, a chemical module mounted in the reaction chamber and
containing two separated chemicals, plunger means mounted on the
reaction chamber for operation by hand to break the chemical
module, enabling the two chemicals to induce a chemical reaction
and to release oxygen into the air accumulator during the chemical
reaction, an air outlet pipe with air filter means suspending in
the air accumulator, and a mouthpiece connected to the air outlet
pipe for the user to breathes in oxygen from the air accumulator.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a handy oxygen generator
according to the present invention;
FIG. 2 is similar to FIG. 1 but showing the handle pressed
down, the cutting edge of the chemical container cut through the
partition wall;
FIG. 3 is similar to FIG. 2 but showing the catalyzer
mixed with the peroxide, oxygen released; and
FIG. 4 is an elevational view of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, an oxygen generator in accordance with the
present invention comprises a casing 10 defining a first vertical
chamber 11, a second vertical chamber 12, and a transverse chamber
14 communicating between the first vertical chamber 11 and the
second vertical chamber 12. A reaction chamber 20 and an air
accumulator 30 are respectively mounted in the first vertical
chamber 11 and the second vertical chamber 12. The reaction
chamber 20 holds a certain amount (for example about 500 to 100
milliliters.) of water 90. A tube 13 is mounted in the transverse
chamber 14 and connected between the reaction chamber 20 and the
air accumulator 30. The reaction chamber 20 has an externally
threaded mouth 23 disposed outside the casing 10 and covered with
a screw cap 24. A barrel 50 is suspended inside the reaction
chamber 20, having a top mounting flange 51 retained between the
topmost edge of the mouth 23 of the reaction chamber 20 and the
screw cap 24. The bottom side of the barrel 50 is an open side
sealed with an aluminum foil 52. A gasket 103 is mounted within
the screw cap 24 and retained between the top mounting flange 51
of the barrel 50 and the topmost edge of the mouth 23 of the
reaction chamber 20. A press device is provided comprised of a
plunger 44 inserted through a hole (not shown) at the center of
the screw cap 24, a handle 43 connected to the top end of the
plunger 44 and disposed outside the screw cap 24, and a stopper 45
connected to the bottom end of the plunger 44 and disposed inside
the barrel 50. A water-permeable chemical container 40 is mounted
inside the barrel 50 and containing a peroxide 60, having a
concave top side 42 stopped below the stopper 45 and a bottom
cutting edge 46. A partition wall 80 is provided inside the barrel
50 and spaced above the aluminum foil 52 below the bottom cutting
edge 46 of the water-permeable chemical container 40. A catalyzer
70 is mounted in between the partition wall 80 and the aluminum
foil 52 of the barrel 50. The ratio between the peroxide 60 and
the catalyzer 70 is 0.5% to 10% by weight: 90% to 99.5% by weight.
A guide tube 25 is mounted in the reaction chamber 20, having a
bottom end coupled with a porous member 21 and a top end coupled
with a connector 25 disposed outside the casing 10.
Referring to FIG. 4 and FIG. 1 again, a filter device 31 is
mounted in the air accumulator 30, having an output tube 32
coupled with a connector 33 disposed outside the casing 10; a
mouthpiece 100 is connected to the connector 33 to receive oxygen
from the air accumulator 30; a hand pump 101 is connected to the
connector 25 by a connecting tube 102. The filter device 31
comprises active carbon or active aluminum for removing solid
matter from air passing through.
The operation of the present invention is outlined hereinafter
with reference to FIGS. 2 and 3. When in an emergency case, the
handle 43 is pressed down to force the stopper 45 downwardly
against the concave top side 42 of the chemical container 40,
causing the chemical container 40 to be moved downwards. When the
chemical container 40 is moved downwards, the bottom cutting edge
46 of the chemical container 40 is forced to cut through the
partition wall 80, causing the peroxide 60 to mix with the
catalyzer 70. When the handle 43 is continuously pressed down, the
bottom cutting edge 46 is forced to cut through the aluminum foil
52, thereby causing the mixture of the catalyzer 70 and the
peroxide 60 to fall to water 90 in the reaction chamber 20. When
the mixture of the catalyzer 70 and the peroxide 60 falls to water
90 in the reaction chamber 20, a reaction is induced to release
oxygen. Released oxygen immediately passes through the tube 13 to
the air accumulator 40, thus the user can breathes oxygen through
the mouthpiece 100 via the filter device 31. The amount of oxygen
thus obtained is sufficient for the user to breathes for about 15
to 50 minutes (normally set for about 30 minutes). The barrel 50,
the chemical container 40 and the catalyzer 70 are made in a pack
convenient for a replacement. The hand pump 101 is adapted to pump
air into the reaction chamber 20 to increase its inside pressure,
so that released oxygen can be forced out of the reaction chamber
20 into the air accumulator 30. Further, when the hand pump 101 is
detached from the connector 25, outside air can be directly drawn
into water 90 in the reaction chamber 20 through the porous member
21 and then forced by the inside pressure of the reaction chamber
25 into the oxygen accumulator 30 for breathing.
US6143251
Oxygen generating apparatus
An oxygen generating apparatus according to the present
invention includes a reaction vessel and a cartridge. The
cartridge is constructed for insertion into the reaction vessel,
and includes a cartridge plate and a plurality of reagent tubes
holding oxygen-producing reagents. The reagent tubes, which
include at least one short tube and a plurality of standard tubes,
each have an upper end coupled to the cartridge plate and a lower
end which has an opening or port. When the cartridge is inserted
into the reaction vessel, each of the plurality of standard tubes
extends substantially to a floor of the reaction vessel, while the
at least one short tube extends to a point remote from the floor
of the reaction vessel. The cartridge may include an activation
plate which causes the release of the reagents into the reaction
vessel by pulling up a retaining sleeve when the cartridge is
inserted into the reaction vessel. The apparatus may also include
a filter which helps retain the reagents in the reaction vessel
during the reaction.
FIELD OF THE INVENTION
The present invention relates to an oxygen generating unit, and in
particular a portably oxygen generating unit that employs a
chemical reaction in a solvent such as water to produce oxygen.
BACKGROUND INFORMATION
Portable oxygen generating systems have been used to provide
oxygen in a variety of circumstances, including medical
emergencies, athletic events, and high altitude activities.
Portable oxygen may be used to supplement normal breathing in
these circumstances, or to provide life-saving oxygen in cases of
injury. Because portable oxygen systems are often the only means
available to generate an adequate supply of oxygen, it is
important for such devices to provide a high flow rate of
breathable oxygen over an extended period of time. To this end,
for example, the U.S. Food and Drug Administration requires that
in order for an oxygen generating apparatus to be sold without a
prescription, it must provide an average of at least six liters of
oxygen per minute for fifteen minutes.
Known oxygen generating systems often require a user to mix a
number of chemicals in a vessel and then add water after the
chemicals are mixed. These systems typically cannot produce the
FDA-required flow of oxygen because of human error in mixing the
reagents or because the reagents react too quickly or too slowly.
Likewise, other known systems that provide the reagents in a
cartridge format often produce too little oxygen over too short a
period of time, because the reagents are not provided in a manner
that effectively regulates the reaction. In addition, the
exothermic reaction which produces the oxygen also tends to
overheat reaction vessels and provide oxygen at uncomfortable
temperatures, further decreasing the effectiveness of known oxygen
generating units.
SUMMARY OF THE INVENTION
An oxygen generating apparatus according to the present invention
includes a reaction vessel and a cartridge. The cartridge is
constructed for insertion into the reaction vessel, and includes a
cartridge plate and a plurality of reagent tubes holding
oxygen-producing reagents. The reagent tubes, which include at
least one short tube and a plurality of standard tubes, each have
an upper end coupled to the cartridge plate and a lower end which
has an opening or port. When the cartridge is inserted into the
reaction vessel, each of the plurality of standard tubes extends
substantially to a floor of the reaction vessel, while the at
least one short tube extends to a point remote from the floor of
the reaction vessel .
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic side view of a cartridge according
to the present invention.
FIG. 2 is a schematic side view of an oxygen generating
apparatus according to the present invention.
DETAILED DESCRIPTION
As illustrated in FIGS. 1 and 2, an oxygen generating apparatus
according to the present invention generally includes a reaction
vessel 30 and a cartridge 10. Cartridge 10 holds the oxygen
producing reagents, which are preferably contained in a plurality
of standard tubes 13 and at least one short tube 15. The
illustrated apparatus is designed so that the reagents are
released into vessel 30 when cartridge 10 is inserted into vessel
30. The reagents react in a solvent, typically water, to produce
oxygen. The oxygen may then escape to a patient through a tube and
mask (not shown).
Vessel 30 is illustrated in FIG. 2. Vessel 30 may be of any
suitable shape and size, but preferably is substantially
cylindrical in shape, for example with a length of approximately
17.5 inches and a diameter of approximately six inches. Preferably
vessel 30 is formed of a plastic such as high density
polyethylene, but any suitable material may be used. The
illustrated vessel 30 includes a vessel wall 31 and a floor 33 and
has an open end opposite floor 33. In a preferred embodiment,
vessel wall 31 is double-walled to provide insulation between the
user and the contents of the reaction vessel, which may become
uncomfortably hot during reaction. While floor 33 is not shown as
double-walled in FIG. 2, it may be double-walled as well. Thus
where appropriate or not specified, the term "double-walled" as
applied to vessel 30 as a whole should be read to include
embodiments in which the whole of vessel 30 is double walled, as
well as embodiments in which only a portion of vessel 30 (e.g.,
wall 31) is double-walled.
An oxygen generating apparatus according to the present invention
may also include a cap 35. Cap 35 may be constructed to cover the
open end of vessel 30 after cartridge 10 has been inserted. For
this purpose, cap 35 and wall 31 may include a retention formation
such as cooperating threads or locking lugs (not shown).
Alternatively, cap 35 may engage vessel 30 in a snap-fit
arrangement. Preferably cap 35 includes a tubing connector 37,
which is in fluid communication with the interior of vessel 30. In
this manner, a tube and mask may be connected to tubing connector
37, and oxygen produced by the reaction can then escape vessel 30
to a user. While cap 35 is illustrated as a separate element, it
may be constructed integrally with cartridge 10, as described
below.
Cartridge 10 is generally constructed to hold and release the
oxygen producing reagents which will generate oxygen for the user.
Cartridge 10 preferably includes a cartridge plate 11, attached to
which are a plurality of reagent tubes 13, 15. In the illustrated
embodiment, cartridge plate 11 is formed as a generally circular
disk that engages the open end of reaction vessel 30. In this
embodiment, cartridge plate 11 may include, for example, apertures
(not shown) which allow oxygen produced in reaction vessel 30 to
escape to the user. Cartridge plate 11 may be formed integrally
with cap 35, if desired, or may be constructed as a separate
element, as shown in the Figures.
Reagent tubes 13, 15 are connected at an upper end to cartridge
plate 11. Reagent tubes 13, 15 contain the reagents which will
produce oxygen when mixed in a solvent, for example water. Reagent
tubes 13, 15 are constructed to release the reagents in a timed
manner that both allows the reaction to start up quickly and
maintains a constantly high level of oxygen production over an
extended period of time. In particular, reagent tubes 13, 15
include a plurality of standard tubes 13 and at least one short
tube 15, each preferably having an inner diameter of approximately
1.25 inches to 1.75 inches. Each of reagent tubes 13, 15 also
includes an opening 17, 19 at its lower end.
Standard tubes 13 preferably are sized so that, when cartridge 11
is inserted into reaction vessel 30, each of the standard tubes 13
extends substantially to floor 33 of reaction vessel 30. The
reagents inside standard tubes 13 will thus flow out openings 17
in a controlled manner over an extended period of time, because
reagents flowing out of an opening 17 will tend to pile around
that opening 17, partially blocking or restricting flow of the
remaining reagents until the released reagents are used.
Preferably, openings 17 are provided as side ports as shown in the
Figures, as testing has demonstrated that this configuration
provides an optimum flow rate of reagents. In particular, each
opening 17 optimally includes three apertures, each approximately
0.5 inches high and extending approximately 115 DEG around the
circumference of tube 13, the apertures being separated from one
another by small bridges. While the illustrated embodiment is
preferred, each opening 17 may be provided in any suitable shape
and at any suitable location near the lower end of standard tube
13.
At least one short tube 15 is provided along with standard tubes
13, preferably a single short tube 15. Unlike standard tubes 13,
short tube 15 preferably does not extend substantially to floor 33
of reaction vessel 30, but rather to a point remote from floor 33.
In addition, short tube 15 may have a downward-facing opening 19,
if desired. This arrangement allows all of the reagents within
short tube 15 to exit the tube within a relatively short period of
time following the insertion of cartridge 10 into reaction vessel
30. The oxygen-producing reaction can therefore start immediately,
quickly reaching a rate of oxygen generation equal to or greater
than six liters per minute. Thus the provision of short tube 15
allows a quick start-up for the reaction, while standard tubes 13
help maintain a high oxygen production rate over an extended
period of time.
While any standard reagents may be employed in conjunction with an
oxygen generating apparatus according to the present invention,
the reagent composition itself may assist in regulating the
reaction, providing both quick initiation and extended, controlled
oxygen production. Preferably the reagents used include sodium
percarbonate and manganese dioxide, which when reacted in water
produce oxygen. The tubes may contain a total of approximately
1,450 grams of sodium percarbonate and approximately 12 grams of
manganese dioxide, which acts as a catalyst. In addition, to
provide an effective reaction rate, the manganese dioxide is
preferably a mixture of a first powder having a first maximum
grain size and a second powder having a second maximum grain size.
In particular, the first powder may have a relatively small
maximum grain size, for example approximately 0.1 to 10 microns,
while the second powder may have a relatively larger maximum grain
size, for example approximately 100 to 250 microns.
In addition, the placement of the reagents within reagent tubes
13, 15 may control and regulate the reaction. For example,
standard tubes 13 may contain a total of approximately 1,250 grams
of sodium percarbonate equally divided between the three tubes 13.
Short tube 15 may contain approximately 200 grams of sodium
percarbonate and all of the manganese dioxide. The manganese
dioxide may further be provided at the lower end of short tube 15,
so that it enters the reaction vessel 30 almost immediately after
cartridge 10 is inserted. In this manner, all of the manganese
dioxide may be present from the initial stages of the reaction.
As noted above, cartridge 10 preferably releases the reagents
automatically when cartridge 10 is inserted into vessel 30. In the
exemplary embodiment, this is achieved using an activation plate
25 and a sleeve 21, which work in conjunction with a stop 39 of
reaction vessel 30. Sleeve 21 is preferably made of plastic. If
provided, sleeve 21 may be connected to activation plate 25 and
should cover openings 17, 19. Activation plate 25 may be initially
located in a position remote from cartridge plate 11, as
illustrated in FIG. 1, and is preferably slidable along reagent
tubes 13, 15 towards cartridge plate 11. Stop 39 may be located on
reaction vessel 30, preferably near the open end of reaction
vessel 30. Stop 39 may include any type of obstruction, for
example an internal flange, internal shoulder, or other abutment.
When cartridge 10 is inserted into reaction vessel 30, activation
plate 25 contacts stop 39. Stop 39 prevents activation plate 25
from traveling downward into reaction vessel 30. Thus as cartridge
10 is inserted into reaction vessel 30, activation plate 25 moves
towards cartridge plate 11 (in a relative manner). This movement
pulls sheath 21 upwards along reagent tubes 13, 15, exposing
openings 17, 19 and releasing the reagents.
An apparatus according to the present invention may also include a
filter 23, which helps contain the reagents within reaction vessel
30. As the reaction progresses, the reagents and end products
often form bubbles and foam which tend to expand through tubing
connector 37 and into the attached tubing towards the user. This
migration of the reagents can be dangerous to the user if the
reagents are ingested. It can also convey heat from the reaction
vessel into the tubing, increasing the temperature of the
delivered oxygen to uncomfortable and unsafe levels. To prevent
this migration, filter 23 may be included to break up any bubbles
or foam which might enter the tubing. By breaking up the bubbles
or foam, filter 23 helps to retain the reagents and end products
in reaction vessel 30, minimizing the migration of those compounds
into the tubing. Filter 23 may be of any suitable materials and
configuration, but preferably is formed from polyethylene,
polybutylene, or nylon. Filter 23 may also be formed with any
suitable pore size sufficient to break the surface tension of the
bubbles or foam, or to otherwise retain the reagents within vessel
30 while letting oxygen escape. In addition, filter 23 is
preferably coupled to activation plate 25, so that after insertion
filter 23 is located near the upper, open end of reaction vessel
30.
The device according to the present invention has been described
with respect to several exemplary embodiments. It can be
understood, however, that there are many other variations of the
above-described embodiments which will be apparent to those
skilled in the art, even where elements have not explicitly been
designated as exemplary. For example, activation plate 25 may be
shaped not as a plate or disk, but may instead be a simple
abutment that cooperates with stop 39 to pull sleeve 21 upwards.
As another example, sleeve 21 may comprise a plurality of smaller
sleeves, each of which covers a corresponding reagent tube 13, 15
and each of which is connected to activation plate 25. It is
understood that these and other modifications are within the
teaching of the present invention, which is to be limited only by
the claims appended hereto.
US6155254
Self-contained device for chemically producing
high-pressure breathing oxygen
The invention relates to a self-contained device for
generating high-pressure breathing oxygen, of the type comprising
an oxygen-generating chemical candle (3), a gastight confinement
chamber composed of a body (1) and of a cover (2), in which
chamber the candle is housed, means of igniting the candle, means
of percussing the igniter and means of filtering the oxygen
generated, characterized in that the igniting means consist of a
compressed mixture of titanium and boron and in that the filtering
means consist of a mixture of lime or soda lime and of molecular
sieve and are distributed, on the one hand, packed in around the
candle and, on the other hand, in a cartridge having a
generated-oxygen outlet cap. Application to the generation of
oxygen in the medical or paramedical field, the aeronautics field
and the military field.
The present invention relates to a self-contained device for
chemically generating high-pressure breathing oxygen.
The technical sector of the invention is that of the instantaneous
supply of breathing oxygen.
The intended fields are the medical or paramedical field, the
aeronautics field and the military field.
The main known processes used for generating oxygen corresponding
to industrial or medical standards are distillation after air
liquefaction, electrolysis of water, and chemical processes.
Although the first two processes are widely used in industry, in
particular for distillation, the equipment employed is heavy,
bulky and complex. Furthermore, in the case of distillation, it
does not allow the desired gas to be obtained instantaneously,
given that an air-cooling phase is necessary for the liquefaction.
Chemical processes, by contrasts, get around the problem of
complex apparatuses and are particularly suitable for extreme
situations such as remote or isolated sites, natural disasters,
and emergency, crisis or conflict situations.
One of the various known processes for chemically generating
oxygen which may be cited is the process consisting in using solid
agglomerates which release oxygen by thermochemical decomposition.
The basic material used in these agglomerates, known as chemical
candles, is an oxygen-containing salt capable of liberating oxygen
by heating.
Generally, alkali-metal chlorates are used, these being mixed with
a catalyst of the metal-oxide type which lowers the decomposition
temperature and with a combustible substance whose oxidation
releases the heat necessary to maintain the temperature of the
oxido-reduction reaction.
Nevertheless, the devices for chemically generating oxygen have
two major drawbacks:
they do not allow oxygen to be generated at high pressure, e.g.
for filling bottles or tanks, since there is a risk of the
thermochemical reaction of the solid agglomerates used
degenerating, which may thus result in an explosion;
upon initiating the reaction, a considerable amount of carbon
monoxide and dioxide is generated, which prevents the generated
gas being used in the medical field where conformity to the
pharmacopoeia is mandatory.
These drawbacks have been remedied by using a carbon-free fuel of
high reactivity, and avoiding the risk of explosion, namely
magnesium.
French Patent No. 1,403,612 describes an apparatus for generating
breathing oxygen which comprises an active substance based on an
alkali-metal chlorate mixed with a catalyst consisting of
manganese dioxide and with magnesium as the fuel.
However, such an active substance does not have a high yield for
its volume since the relative density of the agglomerate remains
close to that of the alkali-metal chlorate, in this case sodium
chlorate, i.e. about 1.6.
French Patent 2,620,435 discloses agglomerates containing the same
ingredients but having a relative density greater than 1.8. These
solid agglomerates are obtained by compression above 10@8 Pa (1000
bar) of a mixture based on sodium chlorate (NaClO3), sodium
dichromate (NaCr2 O3), manganese dioxide (MnO2), magnesium (Mg)
and water (H2 O). The presence of water is necessary as it acts as
a cohesion agent and ensures that the mixture is very safe to use
by making it inert. Despite the high pressures applied when
manufacturing the agglomerates, the risks of these mixtures
suddenly decomposing and exploding are thus avoided.
The candle confined in a pressurized container must be ignited by
means suitable for this purpose.
French Patent 2,523,867 describes a chemical oxygen generator in
which the pressurized container in which the candle is housed,
held between two perforated discs, forms an empty space all around
the candle in which the oxygen, on passing through a membrane
which is perforated when the igniting means are triggered, can
escape via an outlet orifice. However, the configuration of this
apparatus does not allow the pressure to rise to a high value and,
in addition, the system can be used only once since it is not
possible to replace the candle.
One object of the present invention is to generate oxygen at high
pressure, i.e. greater than or equal to 100 bar, for filling
bottles or tanks, directly in the field by means of a lightweight
and compact device which is simple to use.
Another object of the invention is to provide so-called medical
oxygen, i.e. oxygen whose characteristics and purity comply with
the European Pharmacopoeia, i.e. an oxygen content of 99.5%, a
maximum carbon monoxide content of 5 ppm and a maximum carbon
dioxide content of 300 ppm.
To achieve this, the subject of the invention is a self-contained
device for generating high-pressure breathing oxygen, of the type
comprising an oxygen-generating candle, a gastight confinement
chamber composed of a body and of a cover, in which chamber the
candle is housed, means of igniting the candle, means of
percussing the igniter and means of filtering the oxygen
generated, characterized in that the igniting means consist of a
compressed mixture of titanium and boron and in that the filtering
means consist of a mixture of lime or soda lime and of molecular
sieve and are distributed, on the one hand, packed in around the
candle and, on the other hand, in a cartridge having a
generated-oxygen outlet cap.
Preferably, the percussion means comprise a first part integral
with the gastight confinement chamber and a second part which is
independent of the first part and actuated by an external
actuator.
According to one embodiment, the first part of the percussion
means consist of a movable needle and a seal, the internal face of
the needle taking the pressure of the oxygen generated, and the
second part consists of a hammer translationally guided and
propelled by springs, the hammer being actuated by a manual arming
lever.
The chemical candle is a solid agglomerate composed of sodium
chlorate, sodium dichromate, manganese dioxide, magnesium and
demineralized water.
The solid agglomerate has a relative density of at least 2.4.
According to a preferred embodiment, the filtering means
furthermore comprise a mixture of various oxides, known by the
trade name "hopcalite", and of hygroscopic salts.
Preferably, the hopcalite is in direct contact with the candle and
is placed as a mixture with lime in granules around the candle and
on the rear face inside the filter cartridge.
Advantageously, the molecular sieve is placed at the end of the
candle, as far away from the high-temperature regions as possible.
Preferably, the body and the cover of the chamber are made of a
single material which has undergone a self-lubricating and
wear-resistance surface treatment.
This single material may be titanium or a special steel.
According to an alternative embodiment, the filtering means
include an additional filter lying outside the chamber and
comprising lime or soda lime, a molecular sieve, hopcalite and
activated carbon.
In a preferred embodiment, the filtering means in the cartridge
comprise a fine-particle filter.
This filter consists, for example, of mineral wool.
According to a variant, the oxygen generator includes a discharge
valve allowing the air contained in the chamber to be removed when
the candle ignites.
The oxygen generator of the invention makes it possible to
generate oxygen for medical use.
The device according to the invention is applicable to the
high-pressure filling of oxygen bottles or of tanks.
The candle is a solid agglomerate obtained by compressing a
mixture containing, per 100 parts by mass of sodium chlorate, 5 to
7 parts by mass of manganese dioxide, 2 to 3 parts by mass of
magnesium, approximately 0.3 parts by mass of sodium dichromate
and demineralized water in an amount such that it represents
together with the water optionally contained in the chlorate,
approximately 1% of the mass of the dry chlorate.
The generation of oxygen results from the thermo-decomposition of
the sodium chlorate mixed with the manganese dioxide, which acts
as an oxidizing agent; this oxido-reduction reaction generates a
large amount of heat, enabling the molecular bond between the
oxygen atoms and the rest of the sodium molecule to be broken. The
choice of reducing agent, in this case magnesium, is fundamental
as it makes it possible to confine the candle under very high
temperature and pressure conditions without the reaction
degenerating.
Upon starting the operation of the candle, oxygen is liberated and
the reaction, being inextinguishable and confined, the pressure
rises.
A source of oxygen adjustable to the desired pressure is therefore
available.
The candle consists of blocks which are very highly compressed
until blocks having a relative density of 2.4 and higher are
obtained. This characteristic is very important as it allows the
rate of combustion to be controlled and ensures complete safety
under the conditions of use. Furthermore, the ratio between the
volume of the candle and the volume of oxygen generated is thereby
increased, this being paramount in some applications, such as
applications in submarines or aircraft.
The candle is placed in a casing made of a material suitable for
the high temperature and pressure conditions and for the highly
oxidizing environment. This casing may have any shape,
parallelepipedal, cylindrical or other shape, and its dimensions
may be varied depending on the requirements. This is because the
volume of the casing of the candle is directly related to the
volume of oxygen desired and to the application in question, for
example high-pressure generation, atmosphere regeneration,
oxygenotherapy or industrial requirement.
The weight of the chemical part will vary from a few tens of grams
to more than ten kilograms, depending on the volume of oxygen.
Ignition of the candle is particularly delicate when it is desired
to generate medical oxygen; this is because the initiation must be
reliable and of high performance, without excessive generation of
carbon monoxide.
The igniting part is composed of an igniter holder provided with
its pyrotechnic igniter of the anvil type and with a compressed
body of titanium and boron housed in a pellet for igniting the
highly magnesium-enriched chlorate composition.
Whatever the type of application, the igniting part is the same
with an igniter holder which can take any type of fitting, such as
a striker-holder fitting, a male conical fitting or a female
conical fitting. This standard ensures optimum effectiveness of
the ignition by permanently controlling the spark chamber and the
sealing of the assembly.
The objective of the filtering part is to purify the oxygen
generated.
It comprises an adsorption filter and a particle filter.
The adsorption filter comprises lime, molecular sieve and,
optionally, a mixture of various oxides known by the brand name of
hopcalite.
Furthermore, the fine particles are filtered by a layer of mineral
wool in the candle.
Among the filtering materials used, lime allows carbon dioxide to
be absorbed; the molecular sieve fixes the residual water and
traces of chlorine; the hopcalite removes carbon monoxide by
catalyzing its conversion into carbon dioxide.
The arrangement of the filtering materials is very important.
The hopcalite requires high temperatures in order to operate; it
is therefore placed as close as possible to the candle blocks, as
a mixture with lime in granules around the blocks and on the rear
face.
The molecular sieve must be as far away from the high-temperature
regions as possible; it is placed entirely at the end of the
candle.
A complementary filter, comprising the same components of lime or
soda lime, hopcalite and molecular sieve, but also activated
carbon, may be added in order to improve further the purity of the
oxygen generated.
The cost of the combinations of filtering products which may be
used will vary depending on the application envisaged. This is
because, hopcalite is an expensive catalyst and the price of lime
may vary by a factor of two depending on its source.
A distinction should be made between breathable oxygen and medical
oxygen.
In order to obtain breathable oxygen, it is suitable to use a lime
of average quality and a molecular sieve, which gives a carbon
dioxide content of about 100 ppm, a carbon monoxide content of
between 2 and 6 ppm and a few traces of water.
In order to obtain medical oxygen, use is made of a more reactive
lime and of hopcalite arranged as a mixture and as a pad, which
results in a minimum contamination of 2 ppm of carbon monoxide,
less than 50 ppm of carbon dioxide and less than 60 ppm of water.
The purity of the oxygen generated also arises from the method of
manufacturing the generator, where any source of accidental
contamination is eliminated since the constituents other than the
chemical and pyrotechnical constituents are mounted in a
decontaminated environment.
Furthermore, in the case of medical-grade oxygen, the air
contained in the generator when the candle is ignited is removed
by any suitable means, such as a discharge valve, or by a manual
purge lasting 30 seconds; during this time, the oxygen generated
cleans the lines and reduces the carbon monoxide peak due to
starting the candle.
The confinement chamber is in the form of a mechanical component
made of a material capable of withstanding the stresses, these
being of a mechanical origin, such as the pressure, thermal
origin, due to the exothermicity of the reaction, and of chemical
origin, due to the oxidizing environment.
The body and the lid of the generator are made of titanium or
special steel.
In one embodiment, the mechanical connection between the body and
the lid is provided by a bayonet device, the body and the lid each
having five tenons around the circumference. A screw-closure
system may also be used.
The geometry of the chamber has been optimized by
three-dimensional volume and thermoelastic analysis using the
finite-element method.
The outer wall of the body is corrugated so as to increase its
mechanical resistance to pressure and to improve the cooling of
the reaction chamber by natural convection, because of the
increase in the area of contact with the ambient air.
The appended drawings, show preferred illustrative embodiments of
the invention.
FIG. 1 is a diagram showing the principle of the device
according to the invention.
FIG. 2 is a semi-sectional view of a reaction chamber for
a chemical candle.
FIG. 3 is a sectional view of a chemical candle.
FIG. 1 shows a device according to the invention, comprising:
a reaction chamber 1,
an igniting device 7,
a candle 3, and
a system of apparatuses and accessories which are necessary for
operating and for using the device.
After the candle 3 has been ignited, by means of the igniting
device 7, oxygen leaves the reaction chamber 1 and undergoes, in
the filter 16, a first filtration with respect to suspended solid
particles conveyed by the gas: microparticles of solid components
of which the candle is composed, such as thermal insulation
components and packing products. Next, the gas passes through a
condensing filter 17 which condenses the water-vapour residues
produced during the chemical reaction; the water thus condensed is
purged at every production cycle by means of the valve 18. The
valve 15 and the rupture-disc-type device 27 ensure that the
operation of the reaction chamber is completely safe.
At this stage in the purification, the gas has a purity which
complies with the European Pharmacopoeia.
A third filtration, using the filter 19, makes it possible to
reduce the carbon monoxide and dioxide content, to lower the dew
point and to remove possible traces of unpleasant smells from the
gas produced.
The purity of the gas depends at this point essentially on the
dimensions of the filter 19; the rated values obtained are 99.9%
of oxygen, less than 2 ppm of carbon monoxide and less than 30 ppm
of carbon dioxide.
After leaving the filter 19, two options of using the oxygen may
be envisaged:
a manifold 20 for high-pressure filling of oxygen bottles 22 of
water capacity adapted to the volume generated during the chemical
reaction. These bottles may be connected to the manifold by a
system of quick-release couplings, thus facilitating the filling
operations in the field. The pressure gauge 21 is used to indicate
the pressure within the manifold 20 for the bottles 22; the safety
valve 15 together with that on the reaction chamber provides
redundancy in terms of high-pressure safety;
a high-pressure tank 23 of capacity adapted to the volume of
oxygen generated and acting as a gas storage unit. The valves 24
allow the tank to be isolated. Next, the oxygen is expanded
through the expander 25 in order to be able to be used directly in
a first-aid ventilator connected to the outlet 26 and operating at
3.5 bar in the case of an emergency medical unit; the valve 15 has
the same function as that described above.
FIG. 2 shows an illustrative embodiment of a reaction chamber
designed and manufactured for an internal service pressure of 150
bar. This chamber was subjected to a proof pressure of 225 bar, in
accordance with the regulations on gas-pressure apparatuses.
The confinement chamber is in the form of a cylindrical tube 1,
called the body, and of a cover or lid 2.
The component 3, placed inside, represents the candle with its
pyrotechnic igniter holder 4.
The closure system is sealed between the body 1 and the cover or
lid 2 by a special dynamic seal 5 which can resist the constraints
with regard to pressure, temperature, nature of the gas and
possible ignition due to the high pressure.
A cover support arm allows the movements for opening and closing
the cover or lid 2 with respect to the body 1.
The opening movement is carried out by:
a rotation of the cover 2 about the main axis of symmetry of the
reaction chamber, by means of the handles 6,
a translation of the cover along a guide integral with the support
arm,
a simultaneous rotation of the cover 2 and of the support arm
about an axis lying perpendicular to the main axis of symmetry of
the reaction chamber.
In respect of the opening movement, a mechanism allows indexing in
the fully open position of the support arm and of the cover 2.
In respect of the closing movement, a mechanism likewise allows
strict indexing in the locked position of the cover 2 with respect
to the body 1.
The components 7 to 14 are the components making up the
candle-igniting device.
The mechanical percussion system illustrated in FIG. 2 does not
exclude other processes allowing the candle to be ignited by an
electrical, piezoelectric, thermal or chemical system.
The arming lever 14 makes it possible, by rotation about its
operating axis, to compress the spring 12. The hammer 11 then
undergoes a rearward movement by translation of the guides 13 in
the casing. The movement is interrupted as soon as the lever is no
longer in contact with the hammer. The latter, propelled by the
spring 12, strikes the component 10 integral with the needle 9
sliding in the component 8, the needle in turn violently striking
the igniter holder 4 of the candle.
The igniting device is sealed by means of a system of seals
capable of withstanding the aforementioned constraints.
The needle 9 is initialized automatically as soon as the pressure
rises in the reaction chamber.
The device is then ready for a new ignition of the candle.
Since the oxygen emission is confined within the chamber, the
pressure can rise up to the set pressure of the safety valve, the
pressure of the valve being equal to the maximum operating
pressure increased by 10%. In the event of an anomaly, a second
safety device, of the rupture-disc type, ensures that the
apparatus operates completely safely, the pressure for rupturing
the disc being equal to the maximum service pressure increased by
20%.
FIG. 3 shows an illustrative embodiment of a chemical candle.
The candle comprises a casing 29, made of special steel, which is
provided with an upper gastight cup 30 made of the same material
and containing the active mass 28 of the candle composed of
several stacked and self-centered blocks.
The filter cartridge 33 is composed of two meshes 34, of an
adsorption filter based on soda lime and hopcalite 39 and
molecular sieve 40, and of a particle filter 41 made of mineral
wool; the assembly is closed by an outlet cap 31.
The candle is fitted with an igniter holder 4 provided with an
igniter 37 and an adapting fitting 38.
The copper cup 32 limits the oxycutting effects due to the
ignition of the compressed igniting body 36 and of the igniting
pellet 35.
The non-limiting examples below illustrate the description.
EXAMPLE 1
Breathing-oxygen Candle
Active mass: 7449 grams (with 7, 4 and 2% of magnesium) Relative
density 2.39
Packing lime: 1100 grams of average lime (soda lime) 250 grams of
molecular sieve.
EXAMPLE 2
Medical-oxygen Candle
Active mass: 7449 grams (with 7, 4 and 2% of magnesium) Relative
density 2.39
Packing lime: 700 grams of lime (not soda lime)
Packing hopcalite: 100 grams
Filter cartridge: 100 grams of hopcalite 500 grams of lime (not
soda lime).
The device according to the invention has the following
advantages:
simple device, which can be operated by someone not experienced in
running sophisticated equipment;
excellent reliability and very little maintenance of the device,
since it has few components, most of these being static, capable
of withstanding all types of constraints encountered on the field;
low volume and low mass, facilitating transportation,
transportation by air or even parachuting;
instantaneous oxygen production as soon as the ignition is
triggered, making it possible to meet the requirements of a
medical emergency unit;
the oxygen generated is warm and slightly wet, allowing the use in
oxygenotherapy without subsequent humidification;
supply of a gas which complies with the European and medical
standards; and
the possibility of high-pressure filling of bottles and tanks.
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