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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...










Patents

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.



US6267114
Handy oxygen generator

US7381377
Method for controlled production of a gas

US8147760
Portable chemical oxygen generator




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