GB2045107A - Filter device for purifying the atmosphere of an enclosed space - Google Patents

Abstract

A filter device for purification of the atmosphere of an enclosed space has a container (1) with air inflow and outflow pipes (3 and 1) and replaceable, cylindrical filter cores (6,7) containing active charcoal, lithium hydroxide or other chemical, suitably mounted within perforated screens (16, 16', 17, 17'). The device has a cover (5) and a regulating or locking device, eg. a linkage (11) connecting a lever (8) on the cover to a flap valve (13) in-the air inflow pipe (3). A cartridge may be in several segments (7', 7'', 7''') for ease of handling and storage. <IMAGE>

Description

SPECIFICATION Filter device for the atmosphere of an enclosed space This invention relates to a filter device for detoxication and purification of the atmosphere of an enclosed space, for example in a spacecraft, submarine, or shelter, and comprising a container insertible in a ventilation system and having inflow and outflow pipes, a regulating or locking device, a cover, and replaceable filter cores of lithium hydroxide (LiOH), active charcoal or other chemical which is placed in the container.

Among the important conditions for prolonged stay in an enclosed space shut off from an ambient atmosphere, as, for example, in a spacecraft, are the physical environmental conditions to which the crew are exposed. The necessary conditions in such a space may be defined at its habitability, and depend on the nature of the atmosphere prevailing in the space. Adequate habilitability is therefore a precondition for the wellbeing of the crew and hence for proper fulfilment of their work.

Control of the nature and maintenance of a viable atmosphere is therefore one of the functions of the life support system provided in, for example, a spacecraft. Many of the substances produced by metabolism and other processes not only produce unpleasant odours but above certain concentrations can damage health and even be fatal.

Various filtering methods for purifying air are known. One of the oldest methods still used, for example in submarines, is the use of absorptive chemicals such as caustic lime stored in containers in the ventilation system, to absorb carbon dioxide produced by respiration. Another known method for purifying and regenerating spent air uses a combina- tin of cylindrical rings of lithium hydroxide (LiOH) and active charcoal arranged in a row.

The disadvantage of such known arrangements of filtering and purifying substances is that, due to the manner in which they are arranged, they are rapidly consumed by the impure respiratory air flowing through them, rapidly become saturated by it, and are therefore incapable also of sufficiently removing other substances which may be harmful or malodourous. Frequent replacement of the substances is necessary, which means that the whole filtering device together with its container and the active substances in it must be removed or replaced.

It is an object of the invention to provide a filter device comprising a unit which remains as a fixed or replaceable component in a ventilation system or air conditioning installation and in which onlythe required active substances used for filtering, purifying and regenerating the atmosphere in an enclosed working or living space are arranged in the form of loose and replaceable individual parts. The arrangement is particularly designed with the comfort of the crew of a spacecraft or a submarine in mind, to assist in planning of missions for prolonged flight in a spacecraft or under water stay in a submarine, and to enable the crew to fulfil their duties efficiently.In addition to more effective control of the carbon dioxide content in the atmosphere of the enclosed space, the invention may also provide a wide and effective absorption and absorption spectrum for other noxious substances occurring in such an atmosphere.

According to this invention, a filter device comprises a container insertible in a ventilation system and having inflow and outflow pipes, a regulating or locking device, a cover, and replaceable filter cores of lithium hydroxide, active charcoal or other chemical in the container, wherein the filter cores are separate, replaceable cartridges in the container.

One advantage of the invention is that since the cartridges containing filtering, purifying and regenerating substances are replaceable units in containers in a ventilation system or air conditioning installation, a flexible modular type of construction and installation is possible. Thus the use of individual replaceable and suitably shaped filters in the form of cartridges ensure a considerable degree of functional reliability as well as ready replaceability.

In particular, the cartridge-like construction and installation of the individual filter elements provides the advantages of low weight and volume of the individual units and a low overall space requirement.

The latter together with the saving in weight are of considerable importance for the storage of spare cartridges. Since cartridges containing lithium hydroxide (LiOH) are used up more rapidly than cartridges of active charcoal, the former have to be replaced more frequently, and the dimensions, particularly of the cartridges, and their subdivision into individual segments, are advantageous for ease of handling when repeated change of cartridges is necessary, particulary in a confined space. It is noteworthy in this connection that the entire weight of the filter device including cartridges of lithium hydroxide and active charcoal is only approximately half that of comparable filter devices, e.g. those containing caustic lime, and the volume requied for storage is reduced to about 35 to 50%.

The fact that the walls may be made impermeable to dust, particularly the walls of the cartridges containing lithium hydroxide, prevents the escape of such dust particles into the stream of regenerated air. For reserve storage in a spacecraft or submarine, the individual cartridges may be shielded by a covering (e.g. a plastics covering) which is substantially resistant to the environment, and they may be stored in an airtight, metal container.

The arrangement of the individual cartridges in the containers can be varied according to the configuration of the ventilation system or air conditioning plant. Thus for example the containers in the ventilation system or in air conditioning plant of a spacecraft or submarine may be of cylindrical or polygonal or other cross-sectional forms, and may be filled with correspondingly shaped cartridges.

Embodiments of the invention will now be described by way of example, with reference to the drawings, in which: Figure 1 is a perspective view of a cylindrical filter device; Figure 2 is a top plan view of a polygonal filter device; Figure 3 is a longitudinal section of the device of Figure 2; and Figure 4 is a front elevation of the device of Figure 2.

Referring to Figure 1, a cylindrical filter device 1 has a container 2, inflow and outflow pipes 3,4 a cover 5 hinged to the container 2, and filter cores 6,7 in the form of cylindrical cartridge rings one inside the other in the container 2. The cover 5, which is pivoted about a hinge 9 by a lever 8 in the upper part of the container 2 and fastened by a lock 10, is coupled with an air and restrictorflap 13 in the curved part 12 of the inflow pipe 3 by way of a linkage 11. The cylindrical part of the container 2 contains the filter cores, the inner core being a cartridge 6 of active charcoal and the outer a cartridge 7 of lithium hydroxide (LiOH). Both cartridges 6,7 are in the form of cylindrical rings and are coaxial one within the other.The external and internal cylindrical surfaces 14, 14' and 15,15', respectively, of the cartridges 6,7 are covered by a respective perforated screen 16,16' and 17,17' to prevent escape of chemicals into the regenerated airstream. Fold down handles, 7', 7", 7"' are provided on the upper annular surfaces for ease of replacement of the cartridges 6,7. The cover 5 is released from its lock 10 and tipped up by movement of the lever 8 and an attached handle 18, to give access to the coaxial cartridges 6,7 and the folding handles 7', 7", 7 ",.

The air to be regenerated enters the container 2 through the pipe 3 and flows directly into the internal space 19 of the cartridge 6 of active charcoal. After passing through the active charcoal of the cartridge 6, the air uniformly penetrates the cartridge 7, flowing through the LiOH layer. This uniform flow into and through the cartridge is ensured by providing a sufficiently large gap 20 between the cartridges 6,7 and by the pressure resistance produced by the cartridge 6 of active charcoal. In the part 21 of the container 2, which tapers towards the outflow pipe 4, is a perforated screen 23 upstream of the outlet cross-section 22, to give uniform distribution of the regenerated air flowing from the external surface 14' of the outer cartride 7.

If regeneration of the atmosphere is not required during certain phases of a mission (e.g. when a submarine is above water or is using a Schnorkel tube), the filter device can be switched off and separated from the ventilation system or air conditioning plant. The air and restrictorflap 13 in the pipe 3 is then adjusted or closed by the lever 8 on the cover 5 and on the container 2 acting through the connecting linkage 11. Any further flow through the system and hence reduction in the absorption and regeneration capacity of the cartridges 6,7 is thus prevented. The flap 13 may be opened and closed without opening or closing the cover 5. The flap 13 may in some cases be dispensed with.

To instal the filter device 1, the container 2 may be mounted on supports 24.

To prevent escape of particles of dust, in particular of LiOH, from the cartridges 6,7, the walls of the cartridge are made impermeable to dust. As already mentioned, the cartridges 6,7 are in the form of cylindrical rings. To save storage space, and to enable used cartridges to be replaced at different rates, the cartridges, particularly the cylindrical cartridges 7 of lithium hydroxide (LiOH), are subdivided into three separate segments 7', 7", 7"' in the present embodiment. In this way the filter device may also be charged individually at different rates.

Figures 2,3 and 4 show an embodiment of a polygonal filter device 25 which has inflow and outflow pipes 27,28 arranged at the two ends of a container 26. Inside the container 26 are three filter cartridges 29,30,31 in the form of polygonal plates (these may also be circular or of some other shape, or be provided in a different number and made of various filter and regenerating materials). The vertical cartridge 29 situated immediately downstream of the inflow pipe 27 (see the arrow in Figure 2) contains active charcoal, and the two cartridges 30,31 situated downstream thereof and enclosing an angle a with each other contain lithium hydroxide (LiOH). The inflow and outflow sides (see the arrows in Figure 3) of the cartridges 29,30 and 31 are bounded by a perforated diaphragm 32 and screen 33 in a similar manner to the first embodiment. The cartridges 29,30 and 31 (individually or altogether) can be replaced by simply opening one side of the container.

Claims (15)

1. A filter device for the detoxication and purification of the atmosphere of an enclosed space, comprising a container insertible in a ventilation system and having inflow and outflow pipes, a regulating or locking device, a cover, and replaceable filter cores of lithium hydroxide, active charcoal or other chemical in the container, wherein the filter cores are separate, replaceable cartridges in the container.

2. A filter device according to claim 1, wherein the cartridges are in the form of cylindrical rings and one inside another.

3. A filter device according to claim 1, wherein the cartridges are in the form of plates and disposed parallel and one behind another in the direction of air flow.

4. A filter device acaording to claim 1 or claim 3, wherein, in addition to a cartridge disposed perpendicular to the direction of air flow or at an angle thereto, at least one further cartridge is disposed at the said angle.

5. A filter device according to any preceding claim, wherein the or each cartridge of lithium hydroxide is or are larger than the or each cartridge of active charcoal.

6. A filter device according to any of claims 1,3 or 5, wherein the or each lithium hydroxide cartridge is identical in structure to the or each cartridge of active charcoal.

7. A filter device according to any preceding claim, wherein the or each cartridge of lithium hydroxide is built up of removable segments.

8. A filter device according to any preceding claim, wherein the lithium hydroxide is stored as a granulate in an air permeable cartridge.

9. A filter device according to claims 1 to 8, wherein the walls of the or each cartridge of lithium hydroxide is impermeable to dust.

10. Afilter device according to any preceding claims, wherein the external and internal surfaces of the cartridges are covered or surrounded by a perforated screen.

11. A filter device according to claim 7, wherein individual cartridges and their segments are sealed by a resistant covering for storage.

12. A filter device according to any preceding claim, wherein the regulating or locking device is an air restrictor or air flap.

13. A filter device according to any preceding claim, wherein the regulating or locking device is coupled to the cover for movement.

14. A filter device according to any preceding claim, wherein the cover is pivotally attached to the container.

15. A filter device constructed and arranged substantially as herein described and shown in the drawings.