GB1588451A

GB1588451A - Chemical cartridges for protective breathing apparatus

Info

Publication number: GB1588451A
Application number: GB3920377A
Authority: GB
Original assignee: Auergesellschaft GmbH
Current assignee: Auergesellschaft GmbH
Priority date: 1976-09-21
Filing date: 1977-09-20
Publication date: 1981-04-23
Also published as: DE2642890C2; DE2642890A1; FR2364667A1; FR2364667B1

Description

(54) IMPROVEMENTS IN OR RELATING TO CHEMICAL CARTRIDGES FOR PROTECTIVE BREATHING APPARATUS (71) We, AuERGEsELLscHAFr GmbH, a German Body Corporate, of 24, Friedrich Krause-Ufer, 1000 Berlin 65 (West), Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment :- The present invention relates to chemical cartridges for in-and-out or circulatory protective breathing apparatus, containing a chemical which traps carbon dioxide and water vapour and releases oxygen.

In known chemical cartridges for breathing apparatus, the breathed air flows through the cartridge predominantly in the axial direction.

It is an object of the invention to effect improvements in chemical cartridges for breathing apparatus.

Accordingly the present invention consists in a chemical cartridge for breathing apparatus comprising a container housing a volume of a chemical for absorbing water vapour and carbon dioxide from exhaled air and releasing oxygen, and having an inlet for exhaled air and an outlet for air purified by the chemical, and wherein said inlet is arranged to lead the air flowing therethrough to a major portion of the outer surface of said volume, said outlet being in communication with a cavity within said volume whereby in use of the chemical cartridge exhaled air flows through said inlet and inwardly into said cavity through said chemical before flowing out through said outlet.

What is achieved in this way is that the breathed air also, and chiefly, flows through the cartridge radially, with exhaled air flowing first through the first surface.

In comparison with known cartridges there are the following advantages. Due to the larger area through which flow takes place and the smaller thickness of material, the resistance to flow is lower. Also this resistance remains almost constant during the period of use. Flow through the chemical is uniformly distributed over the whole of the volume (in known cartridges care has to be taken that the breathed air can reach the edges) and this improves the absorption of carbon dioxide and water vapour and the production of oxygen. The localised overheating which occurs with known cartridges is avoided and the gas exit temperatures are thus lower.When the exhaled air flows from the outside inwards, which is more frequently the case, the outside wall of the cartridge is cooler, the exhaled air is warmed more by the hot layers of chemical at the front, these being of larger area, which has a favourable effect on reaction speed, and with in-and-out respiration the inhaled air is cooled more satisfactorily. In addition, more effective use is made of the chemical in an apparatus having circulatory respiration, even without reversing the respiratory flow, because the period of use is no longer limited by a rise in the resistance to flow and/or in the carbon dioxide content. Melted chemical which makes its way to the bottom is not able to block the opening at the bottom of the cartridge and thus increase the resistance to flow nor is a troublesome amount of it able to run into the breathing bag.

It is also useful in accordance with the invention to adapt the size of the chemical particles to the thickness of the layer situated between the two faces. It is suggested that the ratio of the diameter of the grains of chemical to the mean distance between the faces be between 1/3 and 1/5. In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings, which illustrate two embodiments thereof by way of example.

Referring to these drawings, Fig. 1 shows a first form of chemical cartridge in which a mesh 1 forms a boundary on the outside of a volume 2 which is occupied by the chemical in the cartridge. A major portion of the surface of volume 2 consists of the front end surface la and the circumferential surface lh. A mesh 3 defines a cavity 4 within the volume 2 which extends axially into the volume 2. An inlet opening for the exhaled air is shown at 5 and an outlet opening at 6.

Between the circumferential surface of the cartridge and the mesh 1 is formed a passage 7 for the exhaled air. Flow through the cartridge is indicated by arrows. It will be appreciated that the exhaled air, entering the cartridge via inlet 5, can enter the chemical within volume 2 at any point over the major portion of the surface of the volume 2 as defined by the surfaces la and lb. The air then passes inwardly with respect to the volume 2 until it reaches the cavity 4. Having passed into the cavity 4 the now purified air can escape via outlet 6.

Fig. 2 shows plan and elevation views of a second form of cartridge which is oval in shape, and in which an outer mesh 8 contains pleats 9 whose inner ends lie at approximately the same distance from a mesh 10 in a recess 11. The recess 11 is of a somewhat roof-like shape.

At the bottom end the cartridges form a trough 12 in which melted chemical is able to collect.

WHAT WE CLAIM IS: 1. A chemical cartridge for breathing apparatus comprising a container housing a volume of a chemical for absorbing water vapour and carbon dioxide from exhaled air and releasing oxygen, and having an inlet for exhaled air and an outlet for air purified by the chemical, and wherein said inlet is arranged to lead the air flowing therethrough to a major portion of the outer surface of said volume, said outlet being in communication with a cavity within said volume whereby in use of the chemical cartridge exhaled air flows through said inlet and inwardly into said cavity through said chemical before flowing out through said outlet.

2. A chemical cartridge as claimed in claim 1, wherein the distance between said major portion of the surface of said volume and the surface of said cavity is substantially constant 3. A chemical cartridge as claimed in claim 1 or claim 2, wherein the volume has two parallel end faces, and wherein one end face is part of said major portion of the surface of the voume, said cavity being formed in the other said end face, and wherein the surface area of the cavity is substantially equal to the area of said one end face.

4. A Chemical cartridge as claimed in any one of the preceding claims, wherein said major portion of the surface contains inwardly projecting pleats.

5. A chemical cartridge as claimed in claim 3, wherein the inner ends of the pleats lie at the same or approximately the same distance from the surface of said cavity.

6. A chemical cartridge as claimed in any of the preceding claims, wherein the volume is oval in cross-section, said cavity extending axially into the volume.

7. A chemical cartridge as claimed in claim 6, wherein said cavity is oval in crosssection.

8. A chemical cartridge as claimed in any of the preceding claims, wherein the chemical is in grains and the ratio between the diameter of the grains of chemical and the mean distance between the faces is between 1/3 and 1/5.

9. A chemical cartridge as claimed in any one of the preceding claims wherein the chemical volume is surrounded by a mesh.

10. A chemical cartridge as claimed in any of the preceding claims, wherein the cartridge has at the bottom a receiving trough for melted chemical.

11. A chemical cartridge substantially as hereinbefore described with reference to Fig.

1 of the accompanying drawings.

12. A chemical cartridge substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Between the circumferential surface of the cartridge and the mesh 1 is formed a passage 7 for the exhaled air. Flow through the cartridge is indicated by arrows. It will be appreciated that the exhaled air, entering the cartridge via inlet 5, can enter the chemical within volume 2 at any point over the major portion of the surface of the volume 2 as defined by the surfaces la and lb. The air then passes inwardly with respect to the volume 2 until it reaches the cavity 4. Having passed into the cavity 4 the now purified air can escape via outlet 6. Fig. 2 shows plan and elevation views of a second form of cartridge which is oval in shape, and in which an outer mesh 8 contains pleats 9 whose inner ends lie at approximately the same distance from a mesh 10 in a recess 11. The recess 11 is of a somewhat roof-like shape. At the bottom end the cartridges form a trough 12 in which melted chemical is able to collect. WHAT WE CLAIM IS:

1. A chemical cartridge for breathing apparatus comprising a container housing a volume of a chemical for absorbing water vapour and carbon dioxide from exhaled air and releasing oxygen, and having an inlet for exhaled air and an outlet for air purified by the chemical, and wherein said inlet is arranged to lead the air flowing therethrough to a major portion of the outer surface of said volume, said outlet being in communication with a cavity within said volume whereby in use of the chemical cartridge exhaled air flows through said inlet and inwardly into said cavity through said chemical before flowing out through said outlet.

2. A chemical cartridge as claimed in claim 1, wherein the distance between said major portion of the surface of said volume and the surface of said cavity is substantially constant

3. A chemical cartridge as claimed in claim 1 or claim 2, wherein the volume has two parallel end faces, and wherein one end face is part of said major portion of the surface of the voume, said cavity being formed in the other said end face, and wherein the surface area of the cavity is substantially equal to the area of said one end face.

1 of the accompanying drawings.