CARBON DIOXIDE ABSORBER FOR A REBREATHER

Abstract

A carbon dioxide absorber (1) and a closed-circuit breathing apparatus (2) with the carbon dioxide absorber are based on the carbon dioxide absorber having an inlet (3) and an outlet (4) gas-tight connectable by a flow duct (5), in which a material (6) is arranged, which absorbs some carbon dioxide contained in the breathing gas stream sent through the material. The flow duct (5) is enclosed in some areas by a housing (7), in which a window element (8) is arranged. A display element (9) arranged movably in the flow duct (5) is visible through the window element from outside of the housing and/or through which window element the radiation reflected by the display element (9) exits to the outside. A distance between the window element (8) and the display element (9) varies as a function of the quantity of carbon dioxide-absorbing material arranged in the flow duct (5).

Claims

1. A carbon dioxide absorber comprising: an inlet; an outlet, the inlet and the outlet being connectable to a closed-circuit breathing apparatus; a flow duct gas-tight connecting the inlet and the outlet; carbon dioxide absorbing material arranged in the flow duct to absorb at least some carbon dioxide contained in a breathing gas stream sent through the carbon dioxide absorbing material; a housing enclosing the flow duct in at least some areas; a window element arranged at the housing; and a display element arranged movably in the flow duct, the display element being visible from outside of the housing through the window element and/or radiation reflected by the display element exiting to the outside of the housing through the window element, wherein a distance between the window element and the display element varies as a function of a quantity of carbon dioxide-absorbing material arranged in the flow duct.

2. A carbon dioxide absorber in accordance with claim 1, wherein the display element is associated with a pressing unit arranged movably within the flow duct, the pressing unit being indirectly or directly in contact with the carbon dioxide absorbing material.

3. A carbon dioxide absorber in accordance with claim 2, wherein the display element is arranged on the pressing unit and is acted on by a spring force to push and/or pull the display element toward the carbon dioxide absorbing material.

4. A carbon dioxide absorber in accordance with claim 2, wherein the pressing unit has a screen configuration in at least some areas.

5. A carbon dioxide absorber in accordance with claim 1, wherein a mark is arranged on the window element.

6. A carbon dioxide absorber in accordance with claim 1, wherein the display element comprises at least one opaque material.

7. A carbon dioxide absorber in accordance with claim 1, further comprising an optical element through which a light beam entering the window element from the outside from a surrounding area is deflected divergently from a central axis extending from the window element to the display element.

8. A carbon dioxide absorber in accordance with claim 7, wherein the optical element comprises at least one of a lens and a prism.

9. A carbon dioxide absorber in accordance with claim 7, wherein the optical element is integrated into the window element.

10. A carbon dioxide absorber in accordance with claim 1, wherein the carbon dioxide absorbing material is configured as a bulk material.

11. A carbon dioxide absorber in accordance with claim 1, wherein the carbon dioxide absorbing material comprises at least one of calcium hydroxide (Ca(OH).sub.2) and sodium hydroxide (NaOH).

12. A carbon dioxide absorber in accordance with claim 1, wherein the housing is a part of a disposable cartridge.

13. A carbon dioxide absorber in accordance with claim 1, wherein the flow duct comprises a closable filling opening through which the carbon dioxide absorbing material is at least one of filled in and removed.

14. A closed-circuit breathing apparatus comprising: a breathing tube; and a carbon dioxide absorber, the carbon dioxide absorber comprising: an inlet; an outlet, the inlet and the outlet being connectable to the breathing tube; a flow duct gas-tight connecting the inlet and the outlet; carbon dioxide absorbing material arranged in the flow duct to absorb at least some carbon dioxide contained in a breathing gas stream sent through the carbon dioxide absorbing material; a housing enclosing the flow duct in at least some areas; a window element arranged at the housing; and a display element arranged movably in the flow duct, the display element being visible from outside of the housing through the window element and/or radiation reflected by the display element exiting to the outside of the housing through the window element, wherein a distance between the window element and the display element varies as a function of a quantity of carbon dioxide-absorbing material arranged in the flow duct.

15. A closed-circuit breathing apparatus in accordance with claim 14, wherein the display element is associated with a pressing unit arranged movably within the flow duct, the pressing unit being indirectly or directly in contact with the carbon dioxide absorbing material.

16. A closed-circuit breathing apparatus in accordance with claim 15, wherein the display element is arranged on the pressing unit and is acted on by a spring force to push and/or pull the display element toward the carbon dioxide absorbing material.

17. A closed-circuit breathing apparatus in accordance with claim 14, wherein a mark is arranged on the window element.

18. A closed-circuit breathing apparatus in accordance with claim 14, wherein the carbon dioxide absorber further comprises an optical element through which a light beam entering the window element from the outside from a surrounding area is deflected divergently from a central axis extending from the window element to the display element.

19. A closed-circuit breathing apparatus in accordance with claim 14, further comprising a closed-circuit breathing apparatus housing, the breathing tube and the carbon dioxide absorber being connected to the housing.

20. A closed-circuit breathing apparatus in accordance with claim 19, further comprising at least one additional component comprising a breathing bag, an oxygen source and a breathing gas cooler, wherein the at least one additional component is connected to the closed-circuit breathing apparatus housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the drawings:

[0024] FIG. 1 is a schematic view of a closed-circuit breathing apparatus (rebreather) with a carbon dioxide absorber configured according to the present invention;

[0025] FIG. 2 is a sectional view of a carbon dioxide absorber configured according to the present invention; and

[0026] FIG. 3a is a schematic view showing an aspect of the principle of operation for the detection of the filling level of a carbon dioxide absorber configured according to the present invention with the use of a change in the distance between a window element and a display element;

[0027] FIG. 3b is a schematic view showing another aspect of the principle of operation for the detection of the filling level of a carbon dioxide absorber configured according to the present invention with the use of a change in the distance between a window element and a display element; and

[0028] FIG. 3c is a schematic view showing another aspect of the principle of operation for the detection of the filling level of a carbon dioxide absorber configured according to the present invention with the use of a change in the distance between a window element and a display element.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] Referring to the drawings, FIG. 1 shows a closed-circuit breathing apparatus (rebreather) 2, in which a carbon dioxide absorber 1 configured according to the present invention is installed. The closed-circuit breathing apparatus 2 has two breathing tubes 14 for feeding and removing breathing gas into and out of a breathing mask, not shown, which is used by a user of the apparatus. Of the two breathing tubes 14, the breathing tube arranged on the right side is the inhalation tube 14b, and the breathing tube arranged on the left side is the exhalation tube 14a.

[0030] Both breathing tubes 14 are connected to a housing 15 of the closed-circuit breathing apparatus 2. A carbon dioxide absorber 1 is arranged in the housing 15 for at least partially removing the carbon dioxide (CO.sub.2) exhaled by the user of the apparatus during the use of the closed-circuit breathing apparatus 2. A breathing bag 16 is attached to the housing 15 under the carbon dioxide absorber 1. Furthermore, an oxygen source 17, which is formed by a pressurized oxygen gas cylinder, is arranged in the embodiment shown within the housing 15. Since heat is generated during the absorption of carbon dioxide (CO.sub.2), the closed-circuit breathing apparatus 2 shown in FIG. 1 has a breathing gas cooler 18, which removes the heat generated during the absorption of the carbon dioxide from the closed breathing circuit at least partially. The breathing gas circuit is comprised of both breathing tubes 14, the carbon dioxide absorber 1, the breathing bag 16, the oxygen source 17 and the breathing gas cooler 18. During the operation of the closed-circuit breathing apparatus 2 shown in FIG. 1, the breathing gas exhaled by the user of the apparatus enters via the exhalation tube 14a at first the carbon dioxide absorber 1, where it is freed at least partially of the carbon dioxide (CO.sub.2) contained in the breathing gas by the carbon dioxide-absorbing material 6 arranged at the carbon dioxide absorber 1, absorbing a part of the carbon dioxide while heat and water are generated. The breathing gas is then sent into the breathing bag 16, in which the oxygen used up by the user of the apparatus is replaced with oxygen from the pressurized oxygen gas cylinder carried along as a source of oxygen 17. The breathing gas, which is freed from excess carbon dioxide and is enriched with oxygen, then flows through the breathing gas cooler 18, in which a part of the heat of reaction released during the absorption of carbon dioxide is removed from the breathing gas circuit. The breathing gas regenerated as described above is sent via the inhalation tube 14b into a breathing mask, not shown, via which it is inhaled by the user of the apparatus.

[0031] FIG. 2 shows a carbon dioxide absorber 1 configured according to the present invention. Such carbon dioxide absorbers 1 may be configured as a disposable or reusable cartridge. The carbon dioxide absorber 1 is configured as a reusable cartridge in the embodiment shown in FIG. 2. The carbon dioxide absorber 1 can be opened by actuating a closing element, and the housing 7 is taken apart into two parts in the case being shown. The cover element 21 together with the window element 8 and with some components, here a spring element 22 and a pressing unit 10 with a display element 9, which are fastened to the cover element 21 and are arranged in the flow duct 5 in the closed state, are removed now. A filling opening 20, having a size corresponding to the external diameter of the flow duct 5 in the area of the separation point of the housing 7 and through which the carbon dioxide-absorbing material 6 can be removed, especially in the saturated state, and new, unsaturated material 6 can be introduced into the flow duct, is released in this manner.

[0032] The carbon dioxide absorber 1 shown has an inlet 3 and an outlet 4, which can be connected to the breathing gas circuit of a closed-circuit breathing apparatus 2, as it is shown, for example, in FIG. 1, at least in a largely gas-tight manner. The inlet 3 and the outlet 4 are connected via the flow duct 5, in which carbon dioxide-absorbing material 6, the so-called breathing lime, is arranged in the form of a granular bulk material as an absorber material. For example, a mixture of calcium hydroxide (Ca(OH).sub.2) and sodium hydroxide (NaOH) or of potassium hydroxide (KOH) and barium hydroxide (Ba(OH).sub.2) is used as the carbon dioxide-absorbing material.

[0033] A disk-shaped pressing unit 10 is arranged movably in the interior of the flow duct 5, and this is pushed against the absorber material 6 by means of a spring element 22, which has two coil springs. A display element 9 is fastened on the pressing unit 10 arranged movably in the flow duct 5 in the form of a cuboid, which has a red-colored, opaque plastic material. Depending on the quantity of the absorber material 6 filled in within the flow duct 5, the distance between the display element 9 and the window element 8, which is arranged in the housing 7 enclosing the flow duct 5, varies, and the distance becomes greater in case of a smaller quantity of filling.

[0034] The window element 8 shown in FIG. 2 is arranged in the wall of the housing 7 such that the window element 8 allows the view to the display element 9 from an area surrounding the carbon dioxide absorber 1. It is thus possible by a visual checking, i.e., by the view through the window element 8, to check the filling level of the carbon dioxide absorber 1 without this having to be opened for this purpose. A user is thus able to check the filling level in a simple manner, especially prior to the putting into operation of the closed-circuit breathing apparatus 2. It is essential for the present invention in this connection that the distance between the window element 8 and the display element 9 varies as a function of the filling level, so that the size of the image of the display element 9, which image is visible in the window element 8, changes likewise. The smaller the visible image, the lower is the filling level of the carbon dioxide-absorbing material 6 in the carbon dioxide absorber 1 and the lower is consequently the capacity of the material 6 to absorb carbon dioxide. In the extreme case, in which no image of the display element 9 can be detected in the window element, the user can assume that the carbon dioxide absorber 1 no longer contains a sufficient quantity of carbon dioxide-absorbing material 6 for a reliable operation.

[0035] Exhaled breathing air flows through the inlet 3 into the carbon dioxide absorber 1 during the operation of the carbon dioxide absorber 1 shown in FIG. 2, for example, in a breathing circuit of a closed-circuit breathing apparatus. The breathing air enriched with carbon dioxide, which is exhaled by the user of the apparatus, then flows through the absorber material 6, which is arranged in the flow duct 5 of the carbon dioxide absorber 1, and which is formed in this case from a mixture of calcium hydroxide (Ca(OH).sub.2) and sodium hydroxide (NaOH), and the following reactions take place:

CO.sub.2+H.sub.2O.Math.H.sub.2CO.sub.3

H.sub.2CO.sub.3+2 NaOH.Math.Na.sub.2CO.sub.3+H.sub.2O

Na.sub.2CO.sub.3+Ca(OH).sub.2.Math.CaCO.sub.3+2 NaOH

Carbon dioxide is removed now from the breathing gas stream while water is formed and heat is generated. The filling level of the absorber material 6 decreases during continuing operation of a closed-circuit breathing apparatus 2 with the carbon dioxide absorber 1 arranged therein. Based on this change in the filling level, the pressing unit 10, which is pushed, acted on by spring force, against the absorber material, moves to the right, as a result of which the distance between the window element 8 and the display element 9 increases. The detail view “A” shows for this a top view of the window element 8, on which a mark 11 with a plurality of concentric circles is located and in which a centrally oriented image of the display element 9 can be seen. The greater the distance between the window element 8 and the display element becomes, the smaller will be the image of the display element 9 within the window element 8. Based on the mark 11 provided on the window element 8 with concentric circles, having a radius always selected as a function of a defined distance between the window element 8 and the display element, a change in the distance and hence in the filling level of carbon dioxide-absorbing material 6 can be detected by a user rapidly and accurately.

[0036] It is especially advantageous if a closed-circuit breathing apparatus, in which the carbon dioxide absorber shown in FIG. 2 is arranged, also has a window, through which a user, especially the user of the apparatus, can look at the window element 8 of the carbon dioxide absorber 1 from the outside from an area surrounding the apparatus and can thus detect the image of the display element 9, without having to open the closed-circuit breathing apparatus 2. It is consequently unnecessary in this case to open the closed-circuit breathing apparatus 2 in order to check the filling level of the particular installed carbon dioxide absorber.

[0037] The window element 8 is configured such that an optical element 12, which possesses light-refracting properties, is integrated into this, wherein the light beams are always refracted at the edges of the window element 8, at which different media adjoin one another. The optical element 12 is configured such that light beams impacting on the window element 8 from the outside from a surrounding area are deflected divergently from a central axis 13, which extends from the window element 8 to the display element 9, after the passage through the optical element 12 integrated into the window element 8. The principle of operation employed here is shown in FIGS. 3a, 3b and 3c.

[0038] If light beams 25 from the outside from the surrounding area reach the window element 8 with the optical element 12, the light beams 25 are refracted at the edge 23 facing the display element 9 during the transition from the optical more dense medium to the optically thinner medium such that the light beams 25 are deflected divergently away from a central axis 13 extending between the window element 8 and the display element 9. FIG. 3a shows in this connection in a schematic sectional view the window element 8, the display element 9 arranged at a spaced location therefrom in the interior space of the carbon dioxide absorber 1 as well as an image 24 of the display element 9, which image 24 can be detected when viewing the window element 8. The image 24 of the display element 9, which is shown in FIG. 3a, is perceptible in case of an at least nearly maximum filling level and hence minimal distance between the window element 8 and the display element 9.

[0039] As was explained already, the distance of the display element 9 from the window element 8 changes as a function of the carbon dioxide-absorbing material 6 filled in, which is arranged within the carbon dioxide absorber 1.

[0040] FIG. 3b shows for this an operating state in which the filling level of the absorber material 6 has decreased compared to the operating state shown in FIG. 3a. It can be seen that the image 24 of the display element 9, which image is visible in the window element, is markedly smaller than the image shown in FIG. 3a. This can be attributed to the fact that some of the light beams 25 irradiated into the interior of the carbon dioxide absorber, which are deflected divergently from a central axis 13 extending between the window element 8 and the display element 9, do not fall on the display element 9 and are thus also reflected. A viewer, who is looking into the window element 8, will see that the size of the image 24 of the display element 9 has decreased markedly compared to the image according to FIG. 3a and this viewer will infer from this a reduction of the filling level of the carbon dioxide-absorbing material 6 in the carbon dioxide absorber 1, which has taken place in the meantime between the operating states according to FIG. 3a and FIG. 3b.

[0041] FIG. 3c shows another operating state, in which the filling level of the absorber material 6 arranged in the carbon dioxide absorber 1 is lower compared to the operating state according to FIG. 3b or no breathing lime may possibly even be contained in the carbon dioxide absorber 1. The distance between the window element 8 and the display element 9 has likewise continued therefore to increase. The distance between the window element 8 and the display element 9 is so great now that light beams 25 falling into the window element 8, which are deflected divergently away from the central axis extending between the window element 8 and the display element, travel completely past the display element, so that no radiation is reflected by the display element 9 in the direction of the window element 8. Thus, no image of the display element 9 appears in the window element, so that a user looking at the window element 8 receives the information that the filling level of the absorber material 6 within the carbon dioxide absorber 1 is so low that new absorber material 6 must be added or another carbon dioxide absorber 1 must be used.

[0042] It is essential that it is not necessary based on the display provided according to the present invention to open a carbon dioxide absorber 1 or possibly a closed-circuit breathing apparatus in order to obtain information on the filling level of the absorber material 6.

[0043] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMBERS

[0044] 1 Carbon dioxide absorber [0045] 2 Closed-circuit breathing apparatus [0046] 3 Inlet [0047] 4 Outlet [0048] 5 Flow duct [0049] 6 Carbon dioxide-absorbing material [0050] 7 Housing [0051] 8 Window element [0052] 9 Display element [0053] 10 Pressing unit [0054] 11 Mark [0055] 12 Optical element [0056] 13 Central axis [0057] 14 Breathing tube [0058] 14a Exhalation tube [0059] 14b Inhalation tube [0060] 15 Housing of the closed-circuit breathing apparatus [0061] 16 Breathing bag [0062] 17 Oxygen source [0063] 18 Breathing gas cooler [0064] 19 Closing element [0065] 20 Filling opening [0066] 21 Cover element [0067] 22 Spring element [0068] 23 Edge of the window element [0069] 24 Image of the display element [0070] 25 Light beams