Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
  • A62B21/00—Devices for producing oxygen from chemical substances for respiratory apparatus
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
  • C01B13/02—Preparation of oxygen
  • C01B13/0203—Preparation of oxygen from inorganic compounds
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
  • C01B13/02—Preparation of oxygen
  • C01B13/0203—Preparation of oxygen from inorganic compounds
  • C01B13/0218—Chlorate
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
  • C01B13/02—Preparation of oxygen
  • C01B13/0296—Generators releasing in a self-sustaining way pure oxygen from a solid charge, without interaction of it with a fluid nor external heating, e.g. chlorate candles or canisters containing them

Definitions

• This invention relates to gas generators, more especially oxygen generators, and in particular to a generator for providing breathable oxygen.
• Oxygen is generated on an industrial scale by numerous different methods. These include isolation of molecular oxygen from air and decomposition of water by, for example, electrolytic means. On an industrial scale, however, these methods require substantial capital investment, and the resulting plant is large, heavy, and immobile.
• oxygen is generally supplied from an oxygen cylinder, i.e., the oxygen is stored in molecular form, or generated on demand by a chemical reaction, a term used herein to exclude electrolytic decomposition and other methods in which generation requires an external source of energy.
• Breathable oxygen generation by a chemical reaction has been known for a very long time, and portable oxygen candles are articles of commerce.
• a typical candle comprises an oxygen-containing chemical, for example an alkali metal chlorate or perchlorate, in admixture with a catalyst that facilitates lower temperature decomposition of the chemical to oxygen and residual solids and optionally a fuel, for example iron.
• a typical catalyst is manganese dioxide, which reduces the temperature at which potassium chlorate decomposes from about 400°C to below about 240°C.
• the overall reaction is exothermic, and the exterior of the reaction mass generally reaches very high temperatures, of the order of 600°C or more. Considerable efforts have been made to provide portable devices that can safely be held by the user during operation despite the high temperatures reached during the reaction.
• the candle advantageously comprises a metal chlorate or perchlorate, preferably an alkali metal, especially sodium or lithium, chlorate or perchlorate, in admixture with a catalyst, especially manganese dioxide, and a fuel, for example a metal, especially iron or magnesium.
• the candle is provided with ignition means, which may be electrically powered or mechanically driven, or operated by percussion cap or chemical reaction.
• the ignition means may be at one end of the candle or generally centrally located to provide two burn fronts travelling in different directions, preferably opposite directions towards the ends of the candle.
• the invention accordingly also provides an oxygen generator in which the generating device comprises:
• the oxygen generating means may, for example, comprise at least one first element positioned and arranged for ignition by the igniting means, and a plurality of second elements each positioned and arranged for ignition by a first element, so that in operation a plurality of burn fronts is propagated through the at least one first element and through the plurality of second elements, the direction of propagation of one of the burn fronts differing from the direction of propagation of at least one other of the burn fronts .
• the ignition means may, for example, be located in the central region of an oxygen generator of a generally cylindrical shape, the length of the generator being greater than its diameter so that in operation two burn fronts are propagated from the central region toward opposite ends of the generator.
• at least one first element of the generating means arranged for ignition by the ignition means and a plurality of second elements for ignition by a first element.
• elements adjacent to and closer to the ignition means are advantageously more reactive, i.e., contain a greater proportion of fuel, e.g., iron, than elements more remote from it, to improve stability of the candle and render it less susceptible to accidental ignition.
• the most remote element may, if desired, contain no fuel, it having been found that this provides a lower maximum external temperature after reaction is complete. Step-wise gradation of the elements facilitates manufacture, as each element has a uniform composition, and the candle is then assembled from discrete components.
• the interfaces between elements may be of conical or frusto-conical form, assisting in control of burn front propagation between adjacent elements.
• the ignition means may be, for example, an electrically resistive heating device, a percussion cap detonator or a cartridge ignition device, or an exothermic chemical reaction, initiated, for example, by causing or allowing contact between previously separated reagents.
• the candle may include more than one type of ignition device.
• Electrically resistive heating devices have the advantage of being intrinsically safe until energized.
• the generator advantageously further comprises electronic control means for controlling electrical power applied to the heating device to initiate combustion. Use of electronic control means enables an improved degree of ignition control to be achieved.
• the control means preferably includes coupling means for inductively coupling electrical power from the control means to the heating device; such inductive coupling is of benefit in that exposed electrical contacts may be avoided in the generator, such contacts being susceptible to oxidation and being potentially unreliable.
• control means may include timing means for automatically controlling the period during which electrical power is applied to the heating device for initiating combustion.
• control means advantageously includes at least one, preferably more than one, battery providing power for the ignition means to initiate oxygen generation, the control means further comprising battery monitoring means for monitoring remaining power deliverable from the at least one battery.
• the monitoring means indicates to a user the status of the battery needs.
• Other electrically powered ignition means include means for electrically generating a spark, e.g., by piezo-electric generation.
• the ignition means is mechanically operable and more especially comprises a means for generating a spark as, for example, a friction-generated spark.
• a means for generating a spark as, for example, a friction-generated spark.
• friction-induced generation of sparks there may be mentioned, for example, contact of a friction wheel or other friction member with a flint, e.g., a cerium-iron alloy.
• the composition of the element of the oxygen-generating means in which, in use, ignition takes place, e.g., by contact with the spark is extremely reactive. It may contain, for example, in addition to the main candle material, for example, the chlorate or perchlorate and fuel, a strong oxidizing agent, for example, manganese dioxide, or, especially, a permanganate, e.g., potassium permanganate.
• a strong oxidizing agent for example, manganese dioxide
• a permanganate e.g., potassium permanganate.
• Advantageous ranges of proportions in the ignition region of the candle may be, for example, sodium chlorate up to 70%, fuel, e.g., iron, up to 50%, and oxidizing agent up to 50%, the percentages being by weight of the total composition.
• spark-induced generation means for abrading the part of the surface of the element of the generating device to be ignited, preferably immediately before ignition. Such abrasion ensures that any surface changes that might take place during storage do not result in inhibition of ignition and, more importantly, that loosened material, for example in the form of small particles, e.g. dust, is available for ignition by the spark.
• the abrasion means may be, for example, in the case where a friction member is used to generate the spark, the friction member itself or, advantageously, an associated member that is actuated when the friction member is actuated.
• the means for abrading the element surface to be ignited is not in contact with the surface and is moved into contact only when the friction member is actuated.
• the ignition region is firmly compacted, as in preferred embodiments of the invention, it tends to be resistant to ignition by sparking. This, especially when in combination with the abrasion means being, when in the storage position, out of contact with the candle, makes for additional safety in storage and transport .
• the candle is a cylinder of a section other than circular, and advantageously has a cross-section in the form of a major segment of a circle.
• the ignition means is then advantageously positioned close or adjacent to the flat surface (chord) of the cylinder, so that in operation the spark is directed at a flat surface of the candle.
• the portion of the cylinder having the cross-section of the corresponding minor segment of the circle advantageously contains means for actuating the ignition means, preferably extending to a location outside the vacuum jacket, and a conduit for transporting oxygen to a user, the conduit advantageously including filter means.
• the candle is advantageously provided with an apertured, for example perforated, casing, for example, of gauze, of a material, preferably a metal, of high thermal conductivity, for example copper or brass, in good thermal contact with the candle material.
• the casing transmits heat from the burn front and the burnt region to the unburnt region or regions, thereby pre-heating the unburnt region and help establish an even burn.
• the perforations provide channels for the oxygen to flow.
• An intermediate layer or layers of insulation may be provided between the candle or the casing if present and the vacuum jacket.
• This insulation may be rigid or flexible, for example, of ceramic, rockwool , or particulate material.
• the generator according to the invention may be provided with means to blend the oxygen produced with atmospheric air, to deliver oxygen-enriched air, rather than pure oxygen, to a user.
• the generator may also be provided with an absorbent to absorb any traces of impurities, for example carbon monoxide and chlorine, generated with the oxygen; the copper or brass used as a casing may perform this function also, or additional copper or brass for example, in particulate form, may be provided in the oxygen pathway.
• Figure 4 is an isometric view of the abrader, ignition means and actuator device
• Figures 5a and 5b are diagrammatic plan views of the actuator device.
• the teeth 15 are inclined, as in a ratchet wheel, for a purpose explained below.
• the operating handle 26 is shown in its rest or storage position.
• the forwardmost (clockwise from above as viewed in Figure 5) of teeth 32 are in engagement with the gear wheel 22, and the flat surface 16 of the abrasion wheel 13 faces, but does not contact, the candle .
• elements 54 having a lower proportion of fuel. More remote from the element 50 than the elements 54 are elements 56 having no fuel.
• the handle 26 is slowly rotated clockwise from the position seen in Figure 5a until the position shown in Figure 5b is reached.
• the abrasion wheel 13 has turned so that its teeth 15 are in contact with the material of primer 52.
• the slow movement of the friction wheel 14 against the flint 17 removes any oxide film from the flint during this operation.
• disengagement of the teeth 32 takes place, allowing the spring 34 to drive the gear wheel 22 and the shaft 12 rapidly clockwise, causing the forward- facing edges of inclined teeth 15 to abrade the surface of the primer 52.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Inorganic Chemistry (AREA)
• Emergency Management (AREA)
• Pulmonology (AREA)
• General Health & Medical Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Medicine (AREA)
• Oxygen, Ozone, And Oxides In General (AREA)
• Treating Waste Gases (AREA)
• Absorbent Articles And Supports Therefor (AREA)
• Paper (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Respiratory Apparatuses And Protective Means (AREA)
• Investigating Or Analyzing Materials Using Thermal Means (AREA)
• Signal Processing For Digital Recording And Reproducing (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Manufacture Of Motors, Generators (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

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ID=9944144

Family Applications (1)

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Cited By (4)

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Citations (8)

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• 2002
  • 2002-09-16 GB GBGB0221451.8A patent/GB0221451D0/en not_active Ceased
• 2003
  • 2003-09-15 JP JP2004535704A patent/JP4656940B2/ja not_active Expired - Lifetime
  • 2003-09-15 AU AU2003267600A patent/AU2003267600A1/en not_active Abandoned
  • 2003-09-15 GB GB0603548A patent/GB2421023A/en not_active Withdrawn
  • 2003-09-15 WO PCT/GB2003/004072 patent/WO2004024239A1/en not_active Ceased
  • 2003-09-15 DE DE60333569T patent/DE60333569D1/de not_active Expired - Lifetime
  • 2003-09-15 AT AT03748292T patent/ATE475457T1/de not_active IP Right Cessation
  • 2003-09-15 US US10/528,085 patent/US7494624B2/en not_active Expired - Lifetime
  • 2003-09-15 EP EP03748292A patent/EP1539300B1/en not_active Expired - Lifetime
  • 2003-09-15 GB GB0507580A patent/GB2410024B/en not_active Expired - Lifetime

Patent Citations (8)

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