GB2274249A

GB2274249A - Breathing apparatus

Info

Publication number: GB2274249A
Application number: GB9400618A
Authority: GB
Inventors: Kenneth Fraser
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-01-16
Filing date: 1994-01-14
Publication date: 1994-07-20
Also published as: GB9300817D0; GB9400618D0

Abstract

Breathing apparatus includes a container (1) which contains a compressed breathing gas. A gas reservoir (3) is coupled to an outlet (2) in the container (1) and a mouthpiece (5) is coupled to the gas reservoir (3). A gas flow control device 8 adjacent the outlet permits a substantially continuous flow of gas from the container (1) in use. In the collapsed state of reservoir (bellows 3) a membrane or disk 8 keeps outlet 2 closed and expansion of the bellows (figure 2), as mouthpiece 5 is pulled towards the mouth, ruptures membrane 8 to allow gas flow. The bellows may be replaced by a flexible conduit 9 and an inflatable bag. A metering device regulates flow from container 1 into a release valve fitting. A gas manifold section 46 includes connection points each permitting coupling of a breathing apparatus through its charge port for testing of the apparatus. <IMAGE>

Description

"Breathing APParatus" The invention relates to breathing apparatus, and especially emergency breathing apparatus which may be used underwater.

The transfer of personnel to and from offshore installations is normally accomplished by the use of helicopters. Strict rules apply to this traffic and those carried routinely receive some training, both theoretical and practical in the art of survival.

Moreover, the wearing of survival suits is mandatory in cold water areas.

In the unfortunate event of the helicopter's ditching in the ocean, the onset of hypothermia is delayed by the protection afforded by the special clothing worn.

However, the sea conditions are likely to be far more hostile than the calm prevailing in the shore-based tanks used for escape drill. In addition, there may be complete darkness and delays caused by escape attempts from wreckage and debris. The situation is also adversely influenced by the fact that, when immersed in water, exercise increases the rate of body cooling at temperatures below 25 C. The chances of survival in cold water, when clothed, are enhanced by remaining as still as possible. To face such problems, probably for the first time in his life, is a daunting prospect even if the victim is in good physical condition and well endowed with subcutaneous fat, but failure to supply his body with sufficient oxygen will reduce his survival chances to zero.

At present there is no emergency breathing apparatus suitable for use in helicopters in the event of a helicopter ditching in water. One of the problems of trying to design such an apparatus has been that the apparatus must be relatively light in weight to ensure that it does not adversely affect the helicopter load.

To date it has not been possible to provide a suitable emergency air supply which is sufficiently light to enable it to be used as standard equipment in helicopters.

In accordance with the present invention, breathing apparatus comprises a container containing a compressed breathing gas, a gas reservoir coupled to an outlet in the container, a mouthpiece coupled to the gas reservoir, and a gas flow control device to permit a substantially continuous flow of gas from the container, in use.

The invention has the advantage of providing breathing apparatus which supplies a substantially continuous flow of gas from the container to a gas reservoir and does not supply the breathing gas on demand of the user. This has the advantage of helping to control the duration of the gas supply to ensure that it is not exhausted prematurely in a panic situation.

Preferably, the gas flow control device is an orifice of fixed cross-sectional area which typically, permits a pre-determined rate of flow of gas from the container.

Typically, the gas flow control device may include means to close and open the outlet in the container.

In one example the means to close and open the outlet could comprise a plug which obturates the outlet, when the outlet is closed, to prevent gas communication from the container to the reservoir.

In a second example the means to close and open the outlet may be in the form of a rupturable membrane or disk which is burst or ruptured by a user wishing to use the breathing apparatus.

Alternatively, the means to close and open the container could comprise some other form of valve mechanism. Similarly, the gas flow control device could comprise a valve mechanism which is not an orifice of fixed cross-sectional area.

Preferably, the means to close and open the outlet may be operated to open the outlet by a user pulling the mouthpiece away from the container. Where a rupturable membrane or disk is provided, this action causes bursting of the disk, for example by means of a line having one end attached to the mouthpiece and the other end attached to the disk. Where a plug is provided, this action causes the plug to pulled away from the outlet to stop the plug obturating the outlet. The plug may be attached to the mouthpiece by means of a line to permit removal of the plug.

Typically, the apparatus may further comprise a pressure relief valve which releases excess pressure in the mouthpiece or gas reservoir and typically, may comprise a Reed valve which may open if the pressure inside the reservoir or mouthpiece rises to more than approximately 2psi above the external pressure.

Preferably, the mouthpiece may be coupled to the outlet in the container by means of the gas reservoir, or alternatively, the mouthpiece could be coupled to both the gas reservoir and the outlet in the container.

Where the mouthpiece is coupled to the gas reservoir and the outlet in the container, then typically, the mouthpiece is coupled to the outlet in the container by means of a flexible conduit.

Typically the gas reservoir is collapsible and expands by the gas flow from the container.

Preferably, exhalation of a user is directed into the gas reservoir. This has the advantage of permitting a portion of the exhaled air which still contains a relatively high percentage of oxygen to be re-breathed using the breathing apparatus.

Typically, the apparatus also includes a nose-clip which a user may position on the nose to close the nostrils during use of the apparatus underwater.

Alternatively, the apparatus could include a combined nose and mouthpiece.

Preferably, the apparatus may also include pressure indicator means to give an indication of air pressure in the container. This could be a two position indicator which may indicate when the air pressure drops below a threshold pressure and may be visual and/or audible.

Typically, the gas reservoir may be in the form of a flexible bag or alternatively may be provided by a bellows type arrangement which is coupled between the container and the mouthpiece.

Preferably, the apparatus may also include a storage device which comprises a gas manifold, a source of pressurised gas to pressurise the manifold and mounting means on the manifold to permit the container to be mounted on the manifold and to permit gas communication between the manifold and the container. Typically, the manifold comprises a plurality of mounting means to permit a corresponding plurality of breathing apparatus to be mounted on the storage device.

Examples of breathing apparatus in accordance with the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 shows a first example of breathing apparatus in a passive or stored position; Fig. 2 shows the breathing apparatus of Fig. 1 in an active or in-use position; Fig. 3 shows a second example of breathing apparatus in an active position; Fig. 4 shows a third example of breathing apparatus in a storage position; Fig. 5 shows the breathing apparatus of Fig. 4 in an active position; Figs. 6A to 6C show a front view, a side view and a top view of a release valve fitting for use in the breathing apparatus shown in Figs. 4 and 5; and, Fig. 7 shows a number of the breathing apparatus of Fig. 4 in their storage positions on a charge and test manifold.

Fig. 1 and Fig. 2 show breathing apparatus which comprises a compressed air bottle 1 which has an outlet 2 which is connected to one end of a bellows 3. The other end of the bellows 3 is connected to a manifold 4 which is coupled to a mouthpiece 5. The manifold 4 includes a pressure release valve 6 in the form of a Reed valve which opens when the pressure inside the manifold 4 exceeds the external pressure by more than approximately 2psi.

Typically, the bellows when it is in the extended position shown in Fig. 2 has a volume of at least approximately 150cc. Typically, the compressed air bottle has a volume of approximately 150cc, which means that the bottle 1 is relatively small and light weight.

The air inside the bottle 1 may be compressed to 124bar or greater. An initial pressure inside the bottle of 124bar equates to a total air volume of approximately 9 litres at an ambient pressure of 2bar. 2bar is the approximate pressure at a submerged depth of 10 metres in a body of water, such as sea water. Typically, nose-clips (not shown) are also provided and are conveniently attached to the mouthpiece 5 or manifold 4. Prior to use, the compressed air bottle 1 is sealed by a disk or membrane 8 to which is attached one end of a line 7, the other end of the line being attached to the manifold 4. Hence, when the breathing apparatus is moved to the active position shown in Fig. 2 movement of the manifold 4 and mouthpiece 5 exerts a pull on the line 7 which causes rupture of the membrane or disk 8 and allows air from the bottle 1 into the bellows 3, manifold 4 and mouthpiece 5.

The outlet 2 comprises an orifice of cross-sectional area such that air is bled from the compressed air bottle 1 at a rate such that preferably, at least 30 seconds of air is available to a user from the breathing apparatus at a depth of 10 metres.

In use, for example with helicopter personnel, the apparatus may be carried by personnel in a survival suit in an appropriate pocket ready for emergency use.

In the event of an emergency arising and the helicopter having to ditch at sea, if and when the helicopter sinks or starts to sink a user may grab hold of the mouthpiece 5 and manifold 4 and pull the mouthpiece 5 towards their mouth. This will move the apparatus from the storage or passive position shown in Fig. 1 to the active position shown in Fig. 2 and cause rupture of the membrane or disk 8. Hence, air will be allowed to bleed from the air bottle 1 into the volume defined by the expanded bellows 3, via the orifice in the outlet 2.

When a user inserts the mouthpiece 5 into his or her mouth and breaths in, air from the bellows 3 will be taken into the user's lungs. On breathing out a proportion of the air breathed out will be breathed back into the volume defined by the bellows 3 and when the pressure in the manifold 4 exceeds the external pressure by more than 2psi, the relief valve 6 will activate so permitting the remaining exhaled air to be vented from the apparatus. During this period unbreathed air is being continually bled from the bottle 1 into the bellows 3 to supplement the exhaled air in the bellows 3. Hence, when a user takes the next breath, the air inhaled will be a mixture of unbreathed air from the bottle 1 and exhaled air from the last breath.This mixing of exhaled air and unbreathed air from the bottle 1 is repeated for as long as the user is using the apparatus or until the air supply in the bottle 1 is exhausted.

Preferably, a user will fit the nose-clips attached to the apparatus over his or her nose prior to use of the apparatus in order to mitigate the possibility of the user accidentally inhaling water through the nasal passages during use of the apparatus.

A second example of breathing apparatus is shown in Fig. 3. In Fig. 3 the operation of the apparatus is substantially identical to the operation of the apparatus described above for Figs. 1 and 2. The main difference being that the bellows 3 is replaced by a flexible conduit 9 connecting the outlet 2 to the manifold 4 and an inflatable bag 10 is coupled to the manifold 4 and is anchored at its lower end, by an anchoring point 13, to the outlet 2. In addition, the line 7 and disk 8 are replaced by an opening device 12 such as a valve which may be operated by movement of the mouthpiece 5 to a user's mouth, or by a manually operable valve. Essentially, the inflatable bag 10 acts as a re-breather air bag and performs essentially the same operation as the bellows 3 in the first example of the invention described above and shown in Figs. 1 and 2.An advantage of using an inflatable bag as shown in Fig. 3 is that it permits a greater volume of air to be re-breathed using the apparatus but, as the bag 10 is collapsible, it is likely to provide a smaller storage volume for the apparatus than the apparatus shown in Figs. 1 and 2 with a comparable bellows volume. Fig. 3 also shows nose clips 11 attached to the manifold 4.

It is possible that the bottle 1 could be provided with an inlet at one end and an outlet at the other end.

This would have the advantage that the outlet 2 could be sealed, for example by using the disk or membrane 8, prior to pressurisation of the bottle 1 which would be likely to facilitate easier handling and refilling of the apparatus.

Typically, the apparatus could also include a visual pressure check device which would permit a user to ensure that the bottle 1 had the appropriate pressure of compressed air prior to use or, for example, before each helicopter trip. A visual pressure check device would also facilitate safety checks to be more easily carried out to ensure that there was always a sufficient air pressure within the bottle 1.

Figs. 4 and 5 show a third example of breathing apparatus. In Figs. 4 and 5 the operation of the breathing apparatus shown is similar to the breathing apparatus shown in Figs. 1 to 3. In Figs. 4 and 5 the bottle 1 has a release valve fitting 20 threadedly coupled to the outlet 2 of the bottle 1 and the fitting 20 incorporates a metering device 21 which regulates the flow of air from the bottle 1 into the release valve fitting 20. Connected to the top of the release valve fitting 20 is a collapsible bladder 22 and the top of the bladder 22 is connected to a manifold 23 which includes a mouthpiece 24 and a nose-clip 25 is mounted on the manifold 23. Also fitted on the manifold 23 is a bleed valve 40. The bleed valve 40 releases excess pressure within the manifold 23 and helps to prevent a user's lung becoming overpressurised.Typically, the bleed valve may operate on a pressure differential of approximately lpsi between the interior of the manifold 23 and the exterior ambient pressure.

The release valve fitting 20 has a pressure gauge 26 mounted on it which permits visual checking of the air pressure within the bottle 1. In addition, the pressure release valve fitting 20 also has a charge port 27 and a release valve plug 28. The release valve plug 28 is coupled to the manifold 23 by means of a line 29.

The release valve fitting 20 is shown in more detail in Figs. 6a to 6c which show a front view, a side view and a top view respectively of the release valve fitting 20. The release valve fitting 20 comprises a main body section 30 which has a screw-threaded fitting 31 at its lower end which engages with threads on the outlet 2.

The main body section 30 and the screw-threaded fitting 31 have a bore 32 which extends from the screw-threaded fitting 31 through the body section 32 to an upper end 33 of the release valve fitting 20. A transverse bore 34 permits fluid communication between the bore 32 and the charge port 27. At the upper end of the bore 32 in the end 33, a transverse bore 35 permits fluid communication between the bore 32 and a recess 36 in which the release valve plug 28 is located. As shown in Figs. 6a and 6b, the release valve plug 28 has an aperture 37 which permits the line 29 to be secured to the plug 28.

The charge port 27 includes a valve mechanism which normally closes the transverse bore 34 to prevent the escape of gas through the charge port 27 during operation of the breathing apparatus and when the breathing apparatus is being carried by a user. The valve mechanism is only open during charging of the bottle 1 of the breathing apparatus when the valve device is opened by inserting the charge port 27 on to a charging device which automatically opens the valve mechanism to permit gas to be passed into the charge port 27, through the transverse bore 34 and bore 32 into the bottle 1. Such a charging device could be a charge and test manifold 45, as shown in Fig. 7. In addition, it will also be noted that the gas pressure on the plug 28 is balanced due to the shape and configuration of the plug 28 and the location of entry of the bore 35 into the recess 36.This permits easier release of the plug 28 from the recess 36.

The breathing apparatus is typically mounted on the charge and test manifold 45, as shown in Fig. 7, when it is not in use.

As shown in Fig. 7 the charge and test manifold 45 includes a main manifold section 46, which in this example is provided with seven connection points. Each connection permits one breathing apparatus to be coupled to the main manifold 46 via the breathing apparatus' charge port 27. This permits seven sets of breathing apparatus to be tested and charged on the charge and test manifold 45, as shown in Fig. 7. The charge and test manifold 45 includes a pressure indicator 47 to permit monitoring of the gas pressure in the main manifold 46 and is also provided with a charge inlet valve 48 at one end of the main manifold 46 and a bleed down/pressure release valve 49 at the other end of the main manifold 46. The charge inlet valve 48 is coupled to a high pressure air supply (not shown) by a conduit 50.

Typically, just before a helicopter flight, persons boarding the flight are provided with a set of breathing apparatus from the charge and test manifold 45 prior to boarding the flight. The charge and test apparatus ensures that each set of breathing apparatus is working correctly and is fully charged. In addition, it is possible to check the air pressure within the bottle 1 by examining the pressure gauge 26 on each set of breathing apparatus.

Typically, the bottle 1 and release valve fitting 20 have a total height of approximately 15cm and so the breathing apparatus can easily be stored in the pocket of a flight suit or submersion suit. Alternatively, the apparatus could be carried in a specially designed holder worn by a user. When the helicopter flight lands, personnel disembarking from the flight hand their breathing apparatus to the person responsible for the breathing apparatus at the destination. The breathing apparatus would then be checked and remounted on another charge and test manifold 45 at the destination.

In the event that the helicopter ditches or crashes in water and becomes submerged, a user pulls the mouthpiece 24 towards their mouth. This causes the line 29 to pull the plug 28 out of the recess 36 in the release valve fitting 20 permitting gas to bleed from the bottle 1 through the outlet 2 and the release valve fitting 20 into the bladder 22. At the same time as inserting the mouthpiece 24 into their mouth, the nose clip 25 will be placed over the nose of a user to help prevent a user accidently breathing water in through the nose.

The operation of the breathing apparatus shown in Figs.

4 and 5 is then substantially identical to the operation of the breathing apparatus shown in Figs. 1 to 3 and described above.

The invention has the advantage of providing a relatively light weight and compact breathing apparatus which is suitable for emergency use, by permitting a user to re-breath exhaled air which still contains a relatively large proportion of oxygen.

In addition, the invention also has the advantage that by permitting air to pass from the bottle 1 at a constant or substantially constant rate the problems of a user exhausting the air supply too quickly in a panic situation are mitigated as the breathing apparatus does not supply air "on demand" to a user.

Improvements and modifications may be incorporated without departing from the scope of the invention.

Claims

1. Breathing apparatus comprising a container containing a compressed breathing gas, a gas reservoir coupled to an outlet in the container, a mouthpiece coupled to the gas reservoir, and a gas flow control device to permit a substantially continuous flow of gas from the container, in use.

2. Breathing apparatus according to claim 1, wherein the gas flow control device comprises an orifice.

3. Breathing apparatus according to claim 2, wherein the orifice has a fixed cross-sectional area.

4. Breathing apparatus according to any of the preceding claims, wherein the gas flow control device comprises means to close and open the outlet in the container.

5. Breathing apparatus according to claim 4, wherein the means to close and open the outlet comprises a rupturable membrane or disk.

6. Breathing apparatus according to claim 4, wherein the means to close and open the outlet comprises a plug which obturates the outlet when the outlet is closed.

7. Breathing apparatus according to any of claims 4 to 6, wherein the means to close and open the outlet is coupled to the mouthpiece so that a force applied by a user to move the mouthpiece away from the container opens the means to close and open the container.

8. Breathing apparatus according to any of the preceding claims, the apparatus also including a pressure relief valve to release excess pressure in the mouthpiece or gas reservoir.

9. Breathing apparatus according to any of the preceding claims, wherein the mouthpiece is coupled to the outlet by the gas reservoir.

10. Breathing apparatus according to any of the preceding claims, wherein the gas reservoir is collapsible.

11. Breathing apparatus according to claim 10, wherein the gas reservoir comprises a collapsible bag or bladder.

12. Breathing apparatus according to any of the preceding claims, wherein at least a portion of the air exhaled by a user is directed into the gas reservoir.

13. Breathing apparatus according to any of the preceding claims, the apparatus also including pressure indication means to provide an indication of the gas pressure within the container.

14. Breathing apparatus according to any of the preceding claims, the apparatus further including a storage device comprising a gas manifold, a source of pressurised gas to pressurise the manifold, and mounting means on the gas manifold to permit the container to be mounted on the manifold and to permit gas communication between the manifold and the container.

15. Breathing apparatus according to claim 14, wherein a plurality of breathing apparatus according to any of claims 1 to 13 are provided and the storage device has a corresponding plurality of connection means on the manifold to permit each container to be mounted on the manifold.

16. A storage device for breathing apparatus according to any of claims 1 to 13, the storage device comprising a gas manifold, a source of pressurised gas to pressurise the manifold, and mounting means on the gas manifold to permit at least one breathing apparatus to be mounted on the manifold and to permit gas communication between the manifold and the container of the breathing apparatus.

17. A storage device according to claim 16, wherein a plurality of breathing apparatus may be mounted on the manifold and gas communicates with the containers of each breathing apparatus simultaneously.

18. Breathing apparatus substantially as hereinbefore described, with reference to the accompanying drawings.

19. A storage device substantially as hereinbefore described, with reference to Fig. 7.