GB2233905A

GB2233905A - Emergency escape breathing apparatus

Info

Publication number: GB2233905A
Application number: GB9015397A
Authority: GB
Inventors: Simon Kugler
Original assignee: Sabre Safety Ltd
Current assignee: Sabre Safety Ltd
Priority date: 1989-07-19
Filing date: 1990-07-13
Publication date: 1991-01-23
Also published as: GB8916449D0; GB9015397D0

Abstract

In emergency escape breathing apparatus a half mask 5 mounted near a visor part of a hood 1 engages the nose and mouth of the wearer so that the gases breathed by the wearer are inhaled from and exhaled to the interior of the half mask 5 and thence to a reservoir of breathable gas such as the interior of the hood 1 outside the half mask 5. Exhaled gases are regenerated by passage through potassium superoxide material 8 or 11 located either in the walls of the half mask 5 (Figs. 1 and 2) or in a container 10 mounted to the hood 1 near to the visor part of the hood 1 (Figs 3, 4 and 5). The potassium superoxide absorbs carbon dioxide in the presence of moisture and generates oxygen in proportion to the carbon dioxide absorbed. The gases pass through the potassium superoxide material 11 during both inhalation and exhalation (Figs 1, 2 and 3) or alternatively make a single passage through the potassium superoxide material 11 either on exhalation (Fig. 4) or inhalation (Fig. 5). <IMAGE>

Description

EMERGENCY ESCAPE BREATHING APPARATUS This invention relates to emergency escape breathing apparatus.

It is known to provide emergency escape breathing apparatus which comprises a hood of transparent plastics material affording all round vision to the wearer, and a compressed air, or oxygen, breathing set supplying breathable gas to the interior of the hood at a predetermined constant rate of flow for a minimum predetermined duration dependent on the size of the gas cylinder. The hood is of a size which can be worn over the ead of a wearer of any age or hair-style, without any adjustment and irrespective of whether the wearer is bearded or wears spectacles. The hood has an elastic neck band past which exhaled gas leaves the hood at a rate determined by the gas flow to the hood.

This known emergency escape breathing apparatus is designed for use in escaping from a location where there may be a toxic or otherwise irrespirable atmosphere, for example a room or corridor which is filled with smoke as a result of fire. The user simply starts the flow of breathable gas to the hood, pulls the hood over his head, and proceeds through the irrespirable atmosphere to a place of safety.

While this equipment provides adequately for the escape of personnel in most circumstances, a difficulty can arise when panic occurs or undue exertion is necessary in order to escape, such as from the cabin of a civil aircraft containing many passengers some of whom may be overcome by fumes before they have time to don their emergency escape breathing apparatus. In such cases the panic or physical exertion necessary to climb over seats or over or past other obstacles can result in an unacceptable level of carbon dioxide building up within the hood with consequent risk to the wearer of the emergency escape breathing apparatus.

This difficulty can be overcome by increasing the preset rate of flow of breathable gas to the hood.

However this action results in an undesirable reduction in the time for which breathable gas is supplied to the hood unless the gas supply is increased by providing a larger gas cylinder. A larger gas cylinder is heavier and adds to the weight carried by the user and to the exertion necessary to escape from the hazard area, so that this is not a satisfactory solution to the problem.

In our prior UK Patent No. 2 189 592 we have proposed the inclusion of a carbon dioxide scrubber for removing carbon dioxide from exhaled gases as these pass between a half mask located within a hood and the remainder of the interior of the hood. In this way the need for a larger gas cylinder may be avoided.

However, the presence of the gas cylinder in itself is inconvenient in that it makes the apparatus bulky and heavy for use by civilian personnel who are unfamiliar with such protective equipment.

In accordance with the present invention there is provided emergency escape breathing apparatus comprising a hood which includes a half mask positioned within the hood for engaging the face of the wearer of the hood around the nose and mouth, and porous means retaining a chemical material which is capable of both absorbing carbon dioxide and generating oxygen in a location so related to the half mask that the gases exhaled by the wearer pass through said chemical material before being further inhaled by the wearer.

The passage of the exhaled gases through the said chemical material may be during either the exhalation stage of the breathing cycle or the inhalation stage, or during both inhalation and exhalation stages of the breathing cycle.

By the use of the emergency escape breathing apparatus according to the present invention the need for a gas cylinder is removed. The emergency escape breathing apparatus according to the present invention is therefore less bulky than all previously proposed apparatus using a hood, and is also lighter and more manageable.

The gases exhaled by the wearer may be passed from the half mask to a breathing bag defining a reservoir of breathable gas separate from the remainder of the interior of the hood outside the half mask. However in the preferred embodiment of the present invention which will be described the interior of the hood outside the half mask constitutes the reservoir of breathable gas.

In accordance with this aspect of the present invention therefore, there is provided emergency escape breathing apparatus comprising a hood which includes a half mask positioned within the hood for engaging the face of the wearer of the hood around the nose and mouth, and means enabling communication during breathing between the interior of the half mask and the interior of the hood outside the half mask, said means enabling communication including porous means retaining a chemical material which is capable of both absorbing carbon dioxide and generating oxygen.

The porous means retaining said chemical material may be so located in relation to the half mask that the gases both inhaled and exhaled by the wearer pass through the said chemical material. This embodiment of emergency escape breathing apparatus according to the present invention thus employs pendulum breathing.

The double passage of gas through the chemical material enables a good scrubbing of carbon dioxide from the breathable gas to be obtained with a relatively small quantity of the chemical material, which also generates a proportionate amount of oxygen.

The chemical material, which is exemplified herein as potassium superoxide, but may be a superoxide of another alkali metal, may be provided either within the hood or in a container attached to the outside of the hood. When the potassium superoxide is provided within the hood it is preferably retained between layers of porous material in a sandwich structure in the walls of the half mask. However, the potassium superoxide may be provided in a container or canister in a gas passage which is either inside or outside the hood and which communicates both with a half mask of impermeable material and with either the interior of the hood outside the half mask or with a breathing bag.Preferably the container or canister is then mounted to the wall of the hood itself In an arrangement which will be specifically described wherein the potassium superoxide is in a container or canister mounted to the outside of the hood, the container or canister is advantageously mounted on the outside of a visor part of the hood so that the container may readily communicate with the interior of the hood both within the half mask and outside the half mask. The potassium superoxide is retained within the container by porous means such as porous screens and the gas breathed by the wearer of the hood is exhaled through the potassium superoxide into the interior of the hood outside the half mask.

The container may be entirely filled with potassium superoxide or it may have a central empty chamber from which the gas passes through porous means such as screens into the potassium superoxide.

It is not necessary for pendulum breathing to be employed in apparatus according to the present invention. The means enabling communication between the interior of the half mask and the interior of the hood outside the half mask may include inhale and exhale valves located in the half mask, and the porous means may then be located relative to the exhale valve such that exhaled gases pass from the half mask through the chemical material to the interior of the hood outside the half mask, or to another reservoir of breathable gas such as a breathing bag. On inhalation, gas passes from the reservoir directly through the inhale valve to the interior of the half mask.

Alternatively to the above arrangement there may be inhale and exhale valves located in the half mask, and the porous means may be located relative to the inhale valve such that gases passing from a reservoir of breathable gas, such as the interior of the hood outside the half mask, to the interior of the half mask pass through the chemical material.

In both these arrangements the porous means retaining the chemical material is preferably located in a container secured to either the inside or the outside of the hood.

When the emergency escape breathing apparatus of the present invention is designed for emergency escape from the cabin of a civil aircraft which is subject to fire, there is a risk of hot materials falling upon the wearer of the breathing apparatus and in order that the breathing apparatus may withstand such application of hot materials, the hood is advantageously made from a clear plastics material which is capable of withstanding temperatures of the order of 2000C. The plastics material sold under the registered trade mark "Kapton" is one example of a suitable material. In this specification the term "heat resistant transparent plastics material" is used to denote clear non-dermatitic plastics materials which are capable of withstanding temperatures of the order of 200"C.

Conveniently the emergency escape breathing apparatus of the present invention includes elastic means extending round the back of the wearer's head for retaining the half mask in engagement with the face of the wearer of the hood.

The present invention will be further understood from the following detailed description of preferred embodiments thereof which will be described by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 shows emergency escape breathing apparatus according to one embodiment of the invention with the hood in position over the head of a wearer, Figure 2 is an enlarged view of the part of the hood of figure 1 incorporating the half mask and showing the potassium superoxide located in the walls of the half mask, and Figures 3, 4 and 5 are. enlarged views similar to Figure 2 of further embodiments of the invention in which the potassium superoxide is located in a container mounted to the hood of the emergency escape breathing apparatus.

In the drawings the same or similar parts are designated by like reference numerals.

Referring to Figure 1 of the accompanying drawings, there is shown emergency escape breathing apparatus according to the present invention which includes a hood 1 of the heat resistant transparent plastics material obtainable under the registered trade mark "Kapton" in position on the head of a wearer.

The hood 1 of the present invention includes a simple half mask 5 secured to the inside of the hood 1 near a part of the hood 1 through which the wearer will look when the hood 1 is being worn. This part of the hood 1 is denoted herein as a visor part of the hood, and may be the only transparent part of the hood 1, although in this embodiment the visor part is an area of the hood 1 which differs from other parts of the hood 1 only in that, when the half mask is engaging the face of the wearer, as shown in Figure 1, it is the part of the hood 1 through which the wearer will see.

The half mask 5 may be of simple shape such as a tube or tunnel as illustrated in Figure 1 or it may be shaped in the more sophisticated manner conventionally provided as a half mask within a full face mask of known breathing apparatus. The half mask is conveniently retained in position against the face of the wearer by elastic 6 incorporated in the hood 1 and engaging the back of the wearer's head.

An elastic neck band 7 retains the hood in a position enveloping the whole of the head of the wearer.

The elastic neck band 7 also constitutes a seal adequate to prevent toxic gases entering the hood 1. Optionally a simple exhale valve (not shown) may be fitted to the hood to prevent undue build-up of pressure in the hood.

In accordance with one embodiment of the present invention the half mask 5 is constructed to incorporate potassium superoxide which absorbs carbon dioxide in the presence of moisture and produces a proportionate amount of oxygen. This embodiment of the invention is illustrated in Figure 2 of the accompanying drawings where the walls of the half mask 5 are shown to be of a sandwich construction in which potassium superoxide 8 is retained between layers 9 of a porous material w as an open cell foamed plastics material, for example foamed polyvinyl chloride or foamed polyurethane.

In operation all gases breathed by the wearer of the hood 1 containing the half mask 5 of Figure 2 in both inhalation and exhalation are caused to pass through the walls of . the half mask 5 in a pendulum breathing operation. On each pass carbon dioxide present in the gases is absorbed by the potassium superoxide.

In this way the amount of carbon dioxide remaining within the hood is kept to a level at which no inconvenience is caused to the wearer of the hood even though he may be forced to make vigorous physical movements while wearing the hood 1. At the same time a proportionate amount of oxygen is generated by the potassium superoxide to maintain a satisfactory oxygen level in the gases breathed by the wearer of the hood.

The absorption of carbon dioxide and generation of oxygen by the potassium superoxide is an exothermic process. In consequence heat is generated in the walls of the half mask 5 in the embodiment of Figure 2. Such generation of heat may cause discomfort to the wearer of the hood 1, and an alternative embodiment of the present invention which reduces this possibility is illustrated in Figure 3 of the accompanying drawings.

In the embodiment of Figure 3 there is shown the hood 1 and the half mask 5, which in this case is made of an impermeable material such as rubber. A container 10 is mounted to the outside of the hood 1 near to the visor part of the hood 1, the container 10 containing potassium superoxide 11 retained by an arrangement of porous screens 12 so as to permit pendulum breathing via the half mask 5 through the container 10 into the reservoir of breathable gas provided by the interior of the hood 1 outside the half mask 5 and back, from the interior of the hood 1 outside the half mask 5, through the container 10 via the half mask 5 to the user. The flow of gases in this pendulum breathing is illustrated by arrows 13 and 14.

The container 10 is preferably made of thin-walled metal, sus as aluminium, so as to provide good heat transfer to the external atmosphere, thus aiding cooling of the exhaled gases. The container 10 may even incorporate simple cooling fins.

The container 10 may have any suitable shape, for example it may be cylindrical in shape in which case the container 10 illustrated in Figure 3 has two sections, an outer annulus containing the potassium superoxide 11 and an inner empty chamber. Alternatively, the container 10 can be designed as a rectangular three chamber box in which case the potassium superoxide 11 is contained in upper and lower chambers separated from the central empty chamber by porous screens 12.

As a further alternative the container 10 can be designed without any central empty chamber but with the porous screen 12 coincident with the portion of the hood 1 which is within the half mask 5, so that the half mask 5 communicates directly through the porous screen with the potassium superoxide.

The amount of potassium superoxide is calculated to cope with the maximum amount of carbon dioxide likely to be produced during an escape and is preferably adequate for about twice the expected time needed to escape.

The embodiment of the invention illustrated in Figure 3 is easier to assemble than the embodiment of Figure 2 and is cooler in operation.

In Figures 4 and 5 there are shown further alternative embodiments in which the container 10 containing potassium superoxide 11 is mounted on the inside of the hood 1, near to the visor part of the hood 1. In the embodiments of Figures 4 and 5 the emergency escape breathing apparatus is constructed so that the gas makes only a single pass through the container 10 containing potassium superoxide 11 during each respiratory cycle.

Referring more specifically to Figure 4 of the accompanying drawings, there is shown emergency escape breathing apparatus in which the container 10 containing potassium superoxide 11 is mounted to the inside of the hood 1 and the half mask 5 is mounted to the container 10.

The impermeable walls of the half mask 5 include an exhale valve 15 which opens on exhalation to permit exhaled gases to pass into the container 10 and thence through the potassium superoxide 11 into the interior of the hood 1 outside the half mask 5 as shown by arrows 16, The half mask 5 also includes upper and lower inhale valves 17. Upon inhalation the exhale valve 15 is immediately closed and the inhale valves 17 both open, permitting breathable gas from the interior of the hood 1 outside the half mask 5 to pass directly through the inhale valves 17 into the half mask 5 for breathing by the wearer, as indicated by arrows 18.

In Figure 5 there is shown emergency escape breathing apparatus which differs from that of Figure 4 in that the half mask 5 has an inhale valve 19 enabling gases to pass from the container 10 into the half mask 5 upon inhalation, and exhale valves 20 permitting exhaled gases to pass from the interior of the half mask 5 direct to the interior of the hood 1 outside the half mask 5.

In the embodiment of Figure 5, therefore, exhaled gases pass direct from the half mask 5 to the gas reservoir in the interior of the hood 1 outside the half mask 5, and the gas to be breathed upon inhalation passes through the potassium superoxide 11 in the container 10 as shown by arrows 21. During such passage carbon dioxide in the gas will be absorbed and oxygen generated, thereby effecting any necessary regeneration of the breathable gas.

In the embodiments of each of Figures 3, 4 and 5, the container 10 may be mounted on either the inside or the outside of the hood 1. If a breathing bag is used to provide a reservoir of breathable gas instead of the hood, the container 10 may be mounted to a partition separating the breathing bag from the hood, and may be inside either the hood or the breathing bag.

As an alternative to the open cell plastic foam, the layers 9 of porous material and the porous screens 12 may be fine metal gauze, mineral wool, glass fibre filter paper, or any other material which will both retain potassium superoxide dust and offer low resistance to breathing gas flow.

In an emergency it may be necessary to provide a quick initial burst of oxygen to fill the hood before sufficient carbon dioxide and moisture has been generated by the wearer to procure a full chemical reaction in the potassium superoxide. The potassium superoxide is therefore fitted with a small starter which is well known in the art such as a small chlorate candle with a cartridge which is arranged to be fired when the smoke hood is taken from its package. Alternatively a plunger is arranged to pierce a small volume of acid, which flows into the potassium superoxide and starts the reaction. Other well-known starting methods may be used as convenient, so that the potassium superoxide becomes operative as the smoke hood is unpacked and donned.

Claims

CLAIMS:

1. Emergency escape breathing apparatus comprising a hood which includes a half mask positioned within the hood for engaging the face of the wearer of the hood around the nose and mouth, and porous means retaining a chemical material which is capable of both absorbing carbon dioxide and generating oxygen in a location so related to the half mask that the gases exhaled by the wearer pass through said chemical material before being further inhaled by the wearer.

2. Emergency escape breathing apparatus comprising a hood which includes a half mask positioned within the hood for engaging the face of the wearer of the hood around the nose and mouth, and means enabling communication during breathing between the interior of the half mask and the interior of the hood outside the half mask, said means enabling communication including porous means retaining a chemical material which is capable of both absorbing carbon dioxide and generating oxygen.

3. Emergency escape breathing apparatus according to Claim 1 or Claim 2 wherein the porous means is so located in relation to the half mask that the gases both inhaled and exhaled by the wearer pass through said chemical material.

4. Emergency escape breathing apparatus according to any one of Claims 1 to 3 wherein the porous means is provided by layers of porous material retaining the said chemical material in the walls of the half mask.

5. Emergency escape breathing apparatus according to any one of Claims 1 to 3, wherein the porous means retaining the said chemical material is located within a container mounted on the hood, the said container permitting gas flow from the half mask to the interior of the hood outside the half mask through the said chemical material.

6. Emergency escape breathing apparatus according to Claim 5, wherein the exhaled gases pass through the half mask into a central space within the container before passing through porous screens into the chemical material.

7. Emergency escape breathing apparatus according to Claim 1 wherein the means enabling communication further includes inhale and exhale valves located in the half mask, and the porous means is located relative to the exhale valve such that exhaled gases pass from the half mask through the chemical material to the interior of the hood outside the half mask.

8. Emergency escape breathing apparatus according to Claim 2 wherein the means enabling communication further includes inhale and exhale valves located in the half mask, and the porous means is located relative to the inhale valve such that gases passing from the interior of the hood outside the half mask to the interior of the half mask pass through the chemical material.

9. Emergency escape breathing apparatus according to Claim 7 or Claim 8 wherein the porous means is located in a container mounted on the hood.

10. Emergency escape breathing apparatus comprising a hood of a heat resistant transparent plastics material for enveloping the head of a wearer, the hood including a visor part near which a half mask is mounted within the hood, the half mask being engageable with the wearer's face to cause all gas breathed by the wearer to be inhaled from or exhaled to the space within the half mask, and the walls of the half mask including layers of porous material retaining potassium superoxide therebetween, the walls of the half mask including the said layers and the potassium superoxide constituting the sole means by which gas may pass between the interior of the half mask and the other space within the hood.

11. Emergency escape breathing apparatus comprising a hood of heat resistant transparent plastics material for enveloping the head of a wearer, the hood including a visor part, an impermeable half mask mounted to the inside of the hood near the visor part, and a container having potassium superoxide therein mounted to the hood near the visor part, the half mask being engageable with the wearer's face to cause all gas breathed by the wearer to be inhaled from or exhaled to the space within the half mask, and the container permitting gas flow to the interior of the half mask and the interior of the hood outside the half mask through porous means retaining the said potassium superoxide within the container.

12. Emergency escape breathing apparatus according to Claim 11, wherein all gas flow between the interior of the half mask and the interior of the hood outside the half mask is through the said container.

13. Emergency escape breathing apparatus according to any one of Claims 5, 6 and 11 wherein the container is mounted to the outside of the hood.

14. Emergency escape breathing apparatus according to Claim 11, which further comprises an exhale valve mounted in the half mask and communicating with the said container, and an inhale valve mounted in the half mask and openable to permit flow of gas from the interior snç the hood nutsrde the half mask direct to the interior of the half mask.

15. Emergency escape breathing apparatus according to Claim 11 which further comprises an inhale valve mounted in the half mask and communicating with the said container, and an exhale valve mounted in the half mask and openable to permit flow of exhaled gas from the interior of the half mask direct to the interior of the hood outside the half mask.

16. Emergency escape breathing apparatus substantially as hereinbefore described with reference to figures 1 to 3 of the accompanying drawings.

17. Emergency escape breathing apparatus substantially as hereinbefore described with reference to figures 4 and 5 of the accompanying drawings.