Note: Descriptions are shown in the official language in which they were submitted.
BREATHING APPARATUS
This invention relates to breathing apparatus,
particularly for aircraft passengers.
In some aircraft accidents lives are lost due to the
consequences of fire and in particular to the inhalation of
smoke and fumes or hot gases. In some accidents passengers
are overcome while still seated but do not show evidence of
severe external burns. Some of these passengers could
perhaps have been saved if a portable respirator, so called
gas mask, had been available for each. Such devices can
remove smoke and noxious gases by filtration and absorption.
However, inhalation of very hot air, in the absence of
noxious gases, can still cause death from thermal damage to
the internal lining of the lungs. The use of a conventional
gas mask would afford little or no protection against such
very hot air. Furthermore in an aircraft fire noxious fumes
from fuel and other sources may be present in such large
amounts that normal filtration or absorption facilities can
become blocked or exhausted. Additionally the fierce
combustion of aircraft fuel can substantially red~ce the
oxygen content of the ~abin atmosphere. In patho-physiological
terms alveolar burns,pulmonary oe~ema and shock may contribute
to acute anoxia which may be of anoxic 7 anaemic, stagnant or
histotoxic type or to a combination of some or all of these.
Lives might also have been saved if each passenger had a
portable respirator with self contained compressed air
cylinderj as used by firemen and subaqua divers, but such
apparatus is not practicable because of cost, weight and
a high degree of sklll and training required to use it.
` ; ~ ; There are three main types oF self contained breathing
apparatus for aircraft passengers: firstly those which have
filters to remove smoke and noxious gases, but these do not
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protect against hot gases; secondly those which provide
a continuous supply of air or oxygen from a pressurised
cylin~er, but large volumes of gas are required and cylinders
are heavy; and thirdly those which use pure oxygen in a
rebreathing system with carbon dioxide absorber, but measures
must be taken to maintain the absorbent material in good
condi~ion until it is needed and to remove nitrogen from the
system.
The efficiency of the absorbent material is dependent
upon many chemical, physical and other factors. Importantly,
the material deteriorates and becomes exhausted if it is
exposed to air but frequent replacement is very expensive in
maintenance costs. The activity is preserved for many
months if the absorbent is sealed to prevent contact with air,
which contains carbon dioxide and water vapour, but this is
not easy to do. There is asubstantial amount o~ space between
absorbent granules and this space is ~illed with air. If both
ends of the container are sealed, the pressure within varies as
the aircraft ascends and descends. This fluctuation may
rupture the seal, even when there is a minimal volume of
retained air.
It is dangerous to rebreath air in the presence of an
absorber, for acute anoxia may occur without warning, but pure
oxygen is safe. Nitrogen should therefore be reduced but this
should be achieved without waste of oxygen. ~he apparatus will
be used by passengers without training or experience and with
very little instruction. Thus the system should be simple to
use and where possible automatic. It may also have the
oxygen source fixed to the conveyance means and may deliver
oxygen to the reservoir. To reduce the risk of pure oxygen
exacerbating a fire, an oxygen-rich atmosphere may be used
rather than a pure oxygen atmosphere. If nitrogen wash out
is not complete, the system is safe to use when the oxygen
inflow is equal to or in excess of oxygen usage. If oxygen
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usage is in excess, then time is limited by the amount of
oxygen remaining.
A harness with adjustable straps may be used to retain
a face mask in position and obtain a good fit to prevent gas
leaks. Provision must also be made for children and for
infants.
It is an object of the present invention to at least
minimize all the problems, includi~g those which are peculiar
in nature and intensity to aircraft fires9 by the use of
a simple9 relatively inexpensive, portable breathing equipment.
There are three main situations which can exist in an
aircraft and which require safety means to operate. These are:-
1) Decompression
2) An in-flight fire
3) Escape of passengers from the aircraft on landing.
Face masks connected to an oxygen supply are already
provided in aircraft in case of sudden decompression at
altitude. The user is supplied with a source of pure oxygen
until the decompression problem has been solved. In the
case of situations 2) and/or 3) an additional respiratory
gas source is required which is independent of the oxygen
supply already provided in aircraft. This additional
respiratory gas source can be used to supplement the existing
oxygen source in aircraft during an in-~light ~ire and/or
the additional gas source can be utilised independently when
escape from the aircraft on landing is necessary~
Thus,~the breathing equipment of the present invention
can be utilised for situations l)and/or 2) and/or 3) referred
to above. Accordingly, in one aspect of the present invention,
the breathing equipment can be utilised to automatically switch
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from a ~irst oxygen supply system to a second oxygen supply
system, when supply of oxygen from said first supply system
is terminated. In a further aspect of the present inventian,
said second oxygen supply system can be brought in to
supplement the first oxygen supply system and thereafter the
second system can itself continue to operate as a second
system when supply of oxygen from the first system is terminated.
According to the present invention there is provided
breathing apparatus for aircraft passengers and others
comprising:
a) means for supplying respiratory gases to a user,
said supply means being detachably connectable to a first
respiratory gas source, and thereby constituting a first
oxygen supply system, said supply means including valve means,
which valve means, when said supply means is detached from the
first respiratory gas source, automatically closes and prevents
admission of noxious or hot gases into said supply means,
b) means for supplying or enabling supply of a second
~0 respiratory gas source to said supply means, and constituting
a second oxygen supply system, in which an absorption means
for absorbing carbon dioxide is included; and either
c) means for automatically switching from sai~ first
oxygen supply system to said second oxygen supply system when
said supply means is detached from said first respiratory
gas source; or
c') means for manually or automatically causing said
second oxygen supply system to become operative to supplement
or replace said first oxygen supply system, said second
oxygen:supply system continuing to be operable when said supply
means is de~tached from said first respiratory gas source.
Pre.ferably, said means fnr supplying respiratory gases
to a user includes means for covering the respiratory apertures
of the user selected from a partial face mask, a complete
face mask, a hood or a bag~
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In an embodiment of the invention, the means for
enabling supply of a second respiratory gas source to said
supply means comprises a filter arrangement.
Desirably, the means for supplying a second respiratory
gas source to said supply means comprises a reservoir for
containing respiratory gases and~or expired gases, so that
said apparatus includes a rebreathing system and functions
as a respirator or ventilator.
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Further preferably, said automatic switching means
includes a release mechanism for rendering said absorption
means operative when said supply means is detached from said
first respiratory gas source. Alternatively, said automatic
switching means comprises a seal/obturator means which renders
the absorption means operative when the supply means is
detached from said first respiratory gas source.
The apparatus of the invention may include one or
more of the following:
a heat sink;
an additional respiratory gas source;
an additional C~2 absorber;
an additional filter;
an additional reservoir;
an additional release means; and
an additional valve or valves.
The reservoir may be enlarged to make a combined
mother and young child unit.
The apparatus of the invention may also include a
logic circuit for controlling automatic delivery of apparatus,
selection and supply of respiratory gases, broadcasting of
instructions to passengers and providing an indication if
apparatus has been tampered with or opened.
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According to an embodiment of the present invention
there is provided breathing apparatus comprising a face mask
attached to but detachable from an oxygen supply tube and
connected to an inflatable reservoir or bag held in a deflated
rolled up condition but releasable to provide ~hen attached
and deflated, an oxygen supply system and, when detached and
inflated a portable respirator or ventilator in a closed
rebreathing system with rebreathing bag and oxygen supply
in a microclimate free from noxious or hot gases.
The functions of the component parts of such equipment
are as follows:
The face mask covers the nose and mouth9 and may be
extended to cover the eyes, and fits onto the face to provide
a seal to prevent inward movement of noxious or hot g3ses
whilst allowing outward movement of the exhaust gases when
the rebreathing bag is rolled up.
The self closing valve when held open by the oxygen
supply tube allows the passage of gases in both directions
within the tube. When the oxygen supply tube is removed the
valve is closed and does not allow the passage of gases in
either direction.
The carbon dioxide absorber absorbs carbon dioxide
from the expired air.
The reservoir may be rolled up and retained thus by
a retain/release mechanism in one position or it may he freed
and able to be inflated when the retain/release mechanism
is in another position. When the reservoir bag~is rolled up
the equipment behaves as a simple oxygen delivery system.
When the bag is released the e~uipment behaves as a closed
rebreathing system.
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The retain/release mechanism may be used to retain the
bag in a rolled up position or to release it from this position
to allow it to be inflated either From the oxygen supply or
with expired air. The guide means a-ttached to the oxygen
- 5 supply tube ensures that pulling the release mechanism
first releases the bag reservoir. The mechanism is also
designed to ensure that the bag is automatically released
when the mask is disconnected from the oxygen supply.
In practice, during an emergency face masks would
be automatically delivered to all passengers, as presently
happens on sudden cabin decompression. Each passenger puts
a face mask in place and inhales oxygen through the oxygen
supply tube. Exhaled air is voided to the cabin atmosphere
and the lungs become filled with oxygen or oxygen enriched
air. Thus the partial pressure of oxygen in the lungs is
increased. This breathing of oxygen may be continued if
necessary at normal atmospheric pressure for fifteen minutes
or longer without side effects. When the passenger has to
leave the aircraft cabin quickly a maximum inspiration is
taken and the breath is held for a moment. The face mask is
then supported with one hand while the oxygen supply tube is
pulled out with the other and this automatically~releases the
rolled up reservoir. Alternatively the release mechanism
may be operated sequentially, firstly to release the inflatable
reservoir and to inflate it with oxygen from the oxygen
supply tube and secondly after a suitable interval to detach
the oxygen supply tube. In either event exhaled air then
passes through the carbon dioxide absorber and in~lates or
further inflates the reservoir which becomes a rebreathing bag.
Rebreathing could take place for several minutes without
ill effect in the absence of an absorber but the presence of
this extends the time for which rebreathing can take place
without dangerous build up of carbon dioxide. Thus each
passenger takes with him his own portable breathing equipment
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with rebreathing system and oxygen supply in a microclimate
at normal temperature, free from noxious or hot gases.
If a passenger is unconscious the same apparatus
s can be used by a member of the cabin staff to secure his
safe evacuation but with slightly different use. Firstly,
the face mask is placed in position and held there by hand.
Secondly, the bag release is operated without disconnecting
the oxygen supply. Thirdly the reservoir is inflated with
oxygen from the oxygen supply. Fourthly, the oxygen supply
tube is disconnected from the face mask. The unconscious
passenger now has his own portable oxygen supply and
rebreathing system. If necessary however, the apparatus
can be used as a ventilator to inflate the lungs by manual
compression of the reservoir while holding the face mask
firmly in contact with the passenger's face.
This invention also relates to improvements in
passenger protection breathing apparatus including a seal
mechanism which is not affected by change of cabin pressure,
a co-axial circuit and valve arrangement to ensure efficient
elimination of nitrogen with economical use of oxygen, means
for switching the carbon dioxide absorber from the closed
sealed storage mode to the open unsealed breathing mode,
an lmproved harness for donning and adjustment and a
modification for protection of infants and young children.
There is automatic unsealing and the apparatus may be used
~by unskilled and untrained persons.
~The functions of the component parts of such apparatus
are as follows:-
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The cover enables breathable gas to be carried to the
~ respiratory~apertures and carries expired gas to the carbon
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dioxide absorber. It may be a half mask covering nose and
mouth, a full mask covering in addition eyes and face, a hood
covering the head, or otherwise and it may be composed of
rubber, plastic or other material.
The sel~ closing valve when held open ~y the oxygen
supply tube allows the passage of gases in both directions
within the tube. When the oxygen supply tube is removed the
valve is closed and does not allow the passage of gases in
ln either direction.
The carbon dioxide absorber absorbs carbon dioxide
from the expired air. It comprises a container, corrugated
plastic tubing or otherwise, which holds absorbent material,
soda lime or otherwise.
The reservoir, a rubber bag or otherwise, holds
breathable gas and functions both as an expansion chamber
during the storage mode and also, during the breathing
mode, as an oxygen collection chamber and rebreathing bag.
The oxygen source is a source of breathing oxygen
contained in a small pressure vessel, cylinder or otherwise,
activated by a cord pull or other mechanism. This may be
part of or attached to the release means. Additional or
alternative sources may be provided from major fixed storage
vessels from chemical generators or from other means.
Where necessary a quick release means is provided to
disconnect portable from ~ixed parts of the apparatus.
The oxygèn source is fixed to the conveyance means to
prevent it from obstructing escape.
The oxygen supply and delivery means comprising
tubes, plastic or otherwise, conveys oxygen from the source
and delivers it to the reservoir where it may be most
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efficiently used. Interposed between -these two tubes is
part of the seal mechanism described later. To avoid separate
tubes which may become entangled one is placed inside the
other in a co~axial arrangement.
An exit valve spring loaded or otherwise, permits gas
to escape from the cover to the exterior when pressure within
the system rises above a determined amount; preset or
otherwise. It must be sited in the cover close to the
respiratory apertures to be most efficient.
The seal means provides in essence an effective seal
at one end of the container which holds the absorbent material.
The main seal, rubber or otherwise7 is attached to an
lS obturator, plastic or otherwise, and these together occlude
completely the lumen of the outer case, which i5 made of
plastic or otherwise, when the mechanism is in the closed
position. This effectively seals one end of the absorb~r
container but the other end opens into the reservoir which
is a closed system not open to the air and in which the
absorbent material will keep for many months. Qdditional
seals, rubber or otherwise, are provided near to the
ends of the obturator to ensure that the obturator remains
parallel to the outer case. The seal nearest to the oxygen
?5 source, called the pneumatic seal, also seals the oxygen
supply tube so that the obturator is automatically moved to
the open position by oxygen under pressure when the oxygen
supply system is activated and the mid seal between the
maln and pneumatic seals prevents passage of oxyge~n directly
into the mask. An external seal is required where the
obturator expansion passes through the case.
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The switch on means comprises an obturator in which
there is an aperture running from proximal to distal in the
obturator. Movement oP the obturator essentially switches
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the absorber from the closed storage mode to the open
breathing mode. In the storage mode the obturator is
close to the oxygen supply tube and the main seal is in
the closed position with the obturator aperture on the
absorber side of the seal. The obturator cannot move beyond
this position because there is an expansion of the obturator
at the other end which is prevented by the outside of the
outer case from moving further~ This expansion, plastic or
otherwise, also serves as a handle to move the obturator
manually, and to indicate its position. In the breathing
mode the obturator is at the opposite end of the outer
case prevented from moving further by the end wall of the
case, the seal is broken and the aperture is in line
with the channels to mask and absorber so that gases can pass
freely to and fro. Thus the conversion means switches the
absorber means from the closed storage mode, in which the
absorber means is sealed and unavailable for use, to the
open breathing mode in which the absorber is unsealed and
available for use. Alternatively the obturator may be moved
by a coiled up spring or otherwise between t~e expanded
end of the handle and the outer side of the outer case. The
spring may be held in the coiled up position by the wall of
the box or container of the breathing apparatus so that
it is automatically released when the apparatus is removed
from the box.
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Thus each passenger takes with him his own portable
breathing apparatus with rebreathing system and oxygen supply
in a microclimate at breathable temperature, free from noxious
or hot gases. If a passenger is unconscious the same
apparatus can be used by a member of the cabin s~aff as a
ventilator to in~late the lungs by manual compression o~
the reservoir while holding the face mask firmly in contact
with the passenger's face. Since the apparatus is for
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use in fire and smoke it should be resistant to chemical
substances found there and to high temperature.
The donning means, comprising a strap or straps
rubber or otherwise, is used to don the mask, or hood,
and to adjust the fit of the mask on the face. The donning
straps are held and are used to pull on the mask. The
same straps are then pulled through the buckles to tighten
the fit on the face but the ends may be dif~icult to find.
This is avoided if each strap is continuous in a figure of
eight loop for the strap to be tightened is the same as
that used for donning.
The passenger prote~tion breathing apparatus may be
used as a hood, plastic or otherwise, with a neck seal,
plastic or otherwise, for older children. In such a system
the dead space is greater and relatively more oxygen will
be required to flush out nitrogen.
2û The adult passenger protection breathing apparatus may
be modi!fied for babies and small children by attaching
a large bag, plastic or otherwise instead of the reservoir.
The distal end is sealed in the storage mode but has a means
to facilitate tearing it open. It also has a draw string
about the middle. A baby is placed completely inside the
hag and the end of the bag is folded over severaltimes and
held closed w1th strong spring clips. AIternatively it is
placed over the head and body of a small child and the
draw string is pulled tight around the abdomen for olosure.
In the meantime the mother or other parent has donned her
face mask and there is now a dual tandem system in which the
mother circulates her expired gases through the absorber.
~Since the large rebreathing bag may initially be filled with
air a larger amount of oxygen will be required to flush
out nitrogen. It will be noted that the passenger has only
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to put on the mask, tighten the straps and breathe normally.
The high pressure in the oxygen source ensures that the
oxygen flow rate is considerably in excess of uptake. Thus
more oxygen is entering the bag than is being removed by the
lungs and there is an oxygen gradient frorn bag to lungs~
When the bag is full, nitrogen rich gas is exhausted from
the system and oxygen levels will approach ~00% in a few
minutes. Relevant anaesthetic principles are described in
a synopsis of anaesthesia by Atkinson et al 1984~ Wright,
Bristol. The circuit described is similar to a Magill circuit
but uses coaxial flow. However this is different from the
~ain and Lack circuits and involves an inventive step to
meet the needs of aircraft passengers using a rebreathing
system and carbon dioxide absorber while breathing
spontaneously and not under anaesthesia.
Obviously improvements and adaptation of the
described system may be made for use by experienced
staff and changes may be made for ease of maintenance.
The oxygen supply may be controlled by a manually
operated valve for nitrogen washout or otherwise and an
"on demand" system may be incorporated for use during
exercise. Soda lime, or other absorbent agents may
be used and indicators which change colour when the
agent is exhausted may be used to confirm at the
time of maintenance that the absorbent is active.
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The present invention will be further illustrated,
by way of example, with reference tn the accompanying
drawings, in which:
S Fig. 1 shows in perspective and cross section the
breathing apparatus with the oxygen supply tube attashed and
the reservoir retained in the deFlated rolled up position by
the retain/release mechanism;
Fig. 2 shows in perspective and cross section the
breathing apparatus with the oxygen supply tube detached and
the reservoir released in the inflated positian with the retain/
release mechanism still attached to the oxygen supply tube;
Fig. 3 schematically shows the inclusion of an
additional reservoir to compensate for the intermittent nature
of breathing of a user;
Fig. ~ schematically shows the use of a combined face
mask and hood arrangement in the inoperative position;
Fig. 5 schematically shows the face mask and hood
arrangement of Fig. 4 in the operative position;
Fig. 6 schematically illustrates a modified system of
the embodiment illustrated in Figs. 1 and 2.
Fig. 7 diagrammatically illustrates a linear type
arrangement of an embodiment in accordance with the invention;
Fig. 8 diagrammatically illustrates the system ~f
Fig. 7 but with the oxygen supply tube removed;
Fig. 9 is an electronic circuit for use in accordance
with the present invention;
Fig. 10 is a schematic view of an alternative embodiment
in accordance with the invention utilising a proximal seal
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assembly, coaxial oxygen supply tube and carbon dioxide
absorber;
Fig. 11 diayrammatically illustrate~ a complete
~ilter assembly and receptacle means which may be utilised
in association with the device of the presen-t invention;
Fig. 12 shows a mother and baby unit;
Fig. 13 diagrammatically illustrates a hood
arrangemPnt in the inoperative position;
Fig.14 diagrammaticaly illu~trates the hood
arrangement of Fig.1`3 in the operative positiun; and
Fig. 15 diagrammatically illustrates a modification
of the apparatus o~ Fig. 1 in which the reservoir i8
replaced by a filter.
As illustrated in the embodiment shown in Figs. 1 and
2, the breathing apparatus comprises a face mask 1, made
for example from plastic or rubber9 connected by ~ay of a
self closing valve 2, made for example of opposing rubber
flaps, to an oxygen supply tube 3, whether plastic or otherwisz,
and by way of a carbon dioxide absorber 4, whether chemical
using soda lime or otherwi e, to a rolled up reservoir 5l
whether an inflatable rubber bag or otherwise, with a manual
release mechanism 6, whether a single cord tied to a rubber
band or otherwise, led through a guide mean~ 7, whether a
metal ring or otherwise and connected to the oxygen supply
tube 3, cord 6A being connected to the reservoir 5. In
Fig. 1 the breathing apparatus is shown attached to the
oxygen supply tube 3, and in Fig. 2 the breathing apparatus
` is shown detached. In particular it should be noted in
Fig. Z that the oxygen supply tube 3 is detached, that the
valve 2 i8 closed, that the manual release mechanism ~ and
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the cord 6A are still connected to the oxyoen supply tube 3
but not to the reservoir 5 which is now inflated.
In order to detach the oxygen supply tube 3, the face
mask 1 is held and the oxygen supply tube 3 i8 pulled out
of the self closiny valve Z. The same rnove~ent will pull
the cord 6A attached to the oxygen supply tube 3 and will
automatically release the rolled up reservoir 5 retained
by the cord 6A of the release mechanism 6. I~ desired,
the rolled up reservoir 5 can be released ~or inflation
with oxygen via the oxyyen supply tube 3 and via the
carbon dioxide ab~orber 4 by manually pulling the release
mechanism 6 through the guide means 7 away from the rolled
up reservoir 5 without pulling the oxygen supply tube 3 out
of the self closing valve 2.
~hilst a ~ace mask has been utilised in Figs. 1 and
2 to envelope the respiratory apertures, it is also possible
to envelope the whole head or oody utilising for example,
a bag or hood. Clearly it would be advantageou~ if the
material used to envelope the respiratory aperture~ or
indeed the entire apparatus is fire resi tant. The volume
of the envelope ~hould be large enough for normal breathing
when used as an oxygen supply system and might itself be
expansible and contractible as is a bag or hood.
- ~hilst the flow of oxygen through tube 3 is constant,
respiratory breathing i8 of an intermittent flow nature.
Accordingly to compensate for such ~ituation as shown in
Fig. 3, an additional reservoir 9 can be added and could
for example be placed adjacent to the mask and connected
by a ~side arm ~ to the oxygen supply tube 3. A one way
valve 10 between the side arm and the mask wouId prevent
rebreathing into bag 9. Expired air pas~e~ along side arm 11
35~ and is vented to the exterior through an additional one
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way valve 12.
The supply tube 3 i9 connected to a supply source of
respiratory gases comprising oxygen either as pure oxygen
or air. The choice of gas would be made by the aircrew
or cabin ~taff. The oxygen might be generated chemically
or stored under pressure in containers designed for the
purpose and with suitable pressure regulation me3ns
associated therewith. Such a supply source might ~erve
a plurality of outlets. Air might be similarly stored or
obtained from another source free from noxious or hot gases.
The valve 2 may be a simple valve to allow free pa3sage of
respiratory gases when open and to allow no passage of gases
in either direction when closed. However, this or another
more complex valve might be used to regulate the gas
flow with reduction from 30urce pressure to delivery pressure.
The supply tube might be reconnectable as well as
disconnectable. Reconnection may be achieved for example
simply by pushing the supply tube 3 through the valve 2,
for example a valve made from opposed flaps of rubber or
otherwise thick at the ba~e and thin at the free edge to
preserve the ability to direct flow.
Whilst valve 2, when closed, prevents admission of
noxiou9 or hot ga9e~ into said supply means it can operate
as an exît valve by removal of the second element of the
valve to permit e~cape of expired air into the atmosphere.
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The absorber 4 and reservoir 5 are excluded from
the breathing circuit when used as an oxygen supply ~ystem
but both are included in the circuit when used as a portable
respirator;or ventilator. In the embudiment u~lng a huod
or a bag, there is an enlaryed cover 1. In a h~od, respiratory
action would probably be sufficient to circulate expired air
but if not, as in the bag for an lnfant, a manually operated
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bellows could be used.
The oxygen supply system utilised in Figs 4 and 5
is that illustrated in Fig~ 3. The face mask 1 i5 part
of the wall of the hood at the dome, or possibly elsewhere,
with the oxygen supply tube 3 at the apex. The dome is
fixed to the face mask and the hood i3 folded like a
concertina with a neck seal 13 fitted round the face mask
to keep the hood interior sealed and therefore to keep the
ln carbon dioxide absorber 4, which is spread out on the
inside of the hood, switched out of the circuit. When
used as an oxygen supply system ~or decompression or, as an
air supply system for in flight fires, the face mask 1 is
used. Additional valves may be provided to prevent back
flow or to allow voiding to the external atmosphere and a
collecting bag may also be provided. For escape, the hood
is pulled over the head, using the handles 14 provided,
and the oxygen supply tube 3 is pulled out. A release
means 6A, attached to the tube 3 and to an integral oxygen
cylinder 15 automatically switches on the oxygen supply
from source 15. ln a relatively large volume hood or
envelope there is no separate rebreathing bag. The absorber
is dispersed on and fixed to the inside surface of the hood.
It is covered by a seal which is peeled back td expose the
z5 absorber when it is switched in to the circuit. However, it is
important to have a smaller volume hood for airflow and a larger
volume for escape when pure oxygen is used. For escape the
oxygen source is activated at the same time as the abosrber i9
switched in to the circui-t. In a completely self contained
system a separate oxygen supply and separate absorber might
be used with a pure oxygen supply 3ystem for decompression.
For in flight fires air flow is required with no ab~orber but
it does~not matter if an absorber is present provided that
there~is a su~ficiently high air flow rate and that another
absorber is available to be switched in for escape.
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A securing means such as a head harness or body
harness, may be used to secure the face mask, hood or bag.
The hood may be ~ecured under a jacket or round the neck by
an elastic grommet3 that is polo neck or turtle neck, or by
other means. The bag rnay be closed by a draw string or
otherwise.
Additional eye protection means may be an eye shield
or goggles with a face mask or may be a tran~parent hood or
bag or with a clear window or visor in it.
nther addition~ might include an ancillary portable
oxygen or air supply, such as a small pressure cylinder
which might also be activated by the same release means
using a third cord. A separate releaYe means could be
used and would make the device more complex and difficult
to use but this could be overcome by incorporating a time
lapse Ywitch to release the oxygen from the sparklet or a
series of sparklets at fixed or presetable time intervals.
A circulation means may comprise an additional
system of one way valve~ and/or circuits to ensure passage of
expired air through the absorption means. This additional
system may be inside the mask or hood and may include a
projection attached to one wall of the mask or hond to be
an additiDnal securing means when gripped by the teeth.
The essence of the invention is a means of switching the
absorption means out of or in to the breathing circuit.
This may be done in other ways 90 that the same reservoir
3D may be u~ed for rebreathing and for collecting. Thi~
system, shown for example in Fig. 6 consists of an
arrangement in line of oxygen supply tube 3; self-closing valve
2, common reservoir 61 cn2 ab~orber 4, additional valve 62
and face mask 1. The additional valve 62 allows gases to
pass in to the face mask but not out. This 9y9tem may be
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converted to a respirator if a release cord 6A attached
tD the guide ring 7 removes or holds open the valve 62
or opens a bypass which bypas~es it. The bypass may for
example be a collapsible rubber tube retained in a folded and
closed condition by an elastic band attached by the cord
and guide ring 7 to the supply tube 3. l~hen the supply tube
3 i5 removed the elastic band is pulled off to release the
bypass to the npen conditian. It will be appreciated
by thoæ skilled in the art that the diagrams illustrate
principles which must be implemented in accordance with
well establiRhed knowledge described for example in
R.S. Atkinson et al l9~Z, a synopsis of anaesthesia, Wright,
Bristol~ It will also be clear that the same result may be
achieved in other way~. For example Fig. 7 shows in
diagrammatic form a linear arrangernent of oxygen supply
tube 3, valve Z, dual purpose bag 71, ab~orber 4, and mask 1.
One way valves with air flow direction i~dicated by arrows
are placed in the mask inlet circuit 16 and in the rebreathing
circuit 17 near the mask. The absorber 4 is occluded by an
zo extension of the supply tube lB. Incoming air or oxygen
enters the bag through holes 19 in the tube which has a
fusiform enlargement ZO to prevent it slipping oùt.
Expired air is vented to the cabin round the side of the
mask. To facilitate reinsertion, a guide means Zl may be
provided for example from metal rods fixed at each end.
~hen, as in Fig. ~, the oxygen supply tube 3 is removed
together with its extension 18, the rebreathing circuit
17 is no longer occluded. The apparatus is now a rebreathing
- system with gas flow from bag 71 by way of inlet circuit 16
to mask 1 and by way of rebreathing circuit l7 back to
bag 71. It is obvious to those skilled in the art that
improvements may be made.~ For example the chamber 71 in
Figs. 7 and B may become a smalI junction chamber more
simple to~manufacture and the rebreathing bag may be connected
to the eurface B (Fiy. R).~ The inlet breathing circult 16
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and rebreathing circuit 17 may be concentric in cross
section with the absorber 4 oentrally placed 50 that
the extension lB may be conveniently inserted. Additional
valves may be inserted and circuit 16 may oe closed
during rebreathing to ensure double passage of gases
through absorber 4 during inspiration and expiration.
As previously mentioned the respiratory gases
comprise oxygen either as pure oxygen or as air and the
choice of gas would be made by the aircrew on the flight
deck or by the cabin staff. An embodiment for automatic
selection of gas or of gas mixture to conserve oxygen
and in particular that stored under pressure for such
pressurised oxygen i9 itself a fire hazard if the delivery
or storage system is penetrated by the fire described with
reference to Fig. 9. An electronic circuit i9 shown
containing logic gates which are well known in the art.
A logic gate having the function OR gives an output
signal when there is an input signal in one input line 0
in any other input line from a plurality of ~uch inputs.
A logic gate having the function AND gives an output signal
when there is an input signal in one input line AND in all
other input lines from a plurality of such inputs. A
logic gate having the function NOT changes the signal state
of input and output. Thus, there is NOT an output signal
when there is an input signal and vice versa.
An embodiment of the logic circuit requ~red for
automatic delivery of apparatus and respiratory gases to
aircraft passenyers is shown in Fig. 9. It is well known
in~the art that additional devices all well known in the
art are required for operation of said logic circuit. The
plurality of additions not shown in the diagram include a
power supply means, circuit closing means, ~or example a
manually operated switch, and signal generatlng means.
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7~313
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All input circuits 24-Z9 are connected to a plurality
of alarm switches or detectors each of which generates
a signal in the appropriate input circuit~ when operated
~anually or automatically to give warning of in fligh'c
candition. Such warning might include an indicator
means, visual or auditory or other, to indicate that the
receptacle means has been opened and thus detect, in an
emergency, that all passengers are using, or attempting to
use, breathing apparatus and, in the absence of an emergency,
that someone is tampering with passenger protection apparatus.
Such manual switches are distributed at convenient sites
in the aircraft to be operated by flight deck or cabin staff.
Such automatic detectors are also conveniently distributed
for exercise of detection functionO All output circuits
30-33 are connected to mechanical or electrical devices,
whether valves or otherwise, to present breathing apparatus
to passengers and to deliver in said oxygen supply tube
appropriate gases or mixture of gases. The logical
control decisions are made by logic gates 34-40 having ~nputs
from ;nput circuits and/or other logic gates and having
outputs connected to other logic gates and/or output clrcuits.
Warning of an in-flight fire is given manually by pressure
on switch or automatically by smoke detection means or
otherwise to generate a signal in circuit 2~. ~arning
of emergency or precautionary landing is given by similar
manual switch or otherwise to generate a signal in circuit
25. ~arning of abort of take off similarly gives a signal
in circuit 26. Cabin pressure may be detected by pressure
sensors in the cabin or otherwise and a signal is
3~ generated in circuit 27 when said pressure is low and in
circuit 2~ when said pressure is normal. Outlet demand may be
detected by breaking of a circu~t when the box is opened or
by pressure detectors in oxygen supply tube, compared if
necessary with cabin pressure, to detect lowered pressure
resulting from inspiration or otherwise and a signal is
generated in circuit 29 when said demand is detected.
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The purpose of supply, only on demand, is to reduce 1099
of oxygen which may fuel a fire. The OR gate 34 has four
inputs connected to circulate 24, 25, 26 and 27 and an
output to secure release of breathing apparatu~ to passengers
in any of the events recognised in said circuits 24 to 27.
The OR gate 35 has three inputs connected to circuits Z5, 26
and 27 and an output to AND gate 36. This has a corresponding
input, an other input from circuit 29 and an output 31 to
secure delivery of pure oxygen to passengers in the event
of outlet demand AND one of the events signalled on
circuits 25 to 27. Th~ AND gate 37 ha~ three inputs
connected to circuits 24, 2B and 29 and output 32 is given
to secure delivery of pure air to passengers. The AND
gate 40 has an input from the output of NOT gate 36 the
input of which is connected to circuit 28 such that AND
gate 40 receives an input signal if input circuit 2B is
NOT indicative of normal cabin pre~sure. A similar
circuit through NOT gate 39 to input circuit 17 is such
that AND gate 40 rec~ives an input signal if input
circuit 27 is not indicative of low cabin pressure. The
third input to AND gate 40 is connected to the input
circuit 29. Thus the output circuit 33 i9 activated if
there is a signal on all three ~nputs of gate 40 to
secure delivery of a mixture of axygen and air.
It is obvious to those skilléd in the art that
another type of logic gate, for example NAND and NOR, may
be used and that other types of device, for example fluid
logic devices, may be used. It i~ al80 obviou~ that
different oressure ranges, other than normal or low, may
be recognised and that the proportion of air and oxygen
may be adjusted accordingly, that is regulation of gases
both~in respect of quantity and quality. It is also
obvious~+hat detection of an excessive demand may indicate
penetration of a supply line by fire ~ith loss of gas and
th in such event the corresponding supply sources should
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be shut off. It is also obviou~ to thoae skilled ;n
the art that other devices such as microprocessors may
be used and have advantages including ease o~ handling
a multiplicity of signal~, ability to deal ~ith complexity
and ease of re-programming in the light of experiznce.
Referring to Fig. 10 the modified breathing apparatus
comprises face mask 1, self cloR~ng valve 2, exit valve 2A,
oxygen supply tube 3, carbon dioxide absorber 4, inflatable
reservoir 5, oxygen source 15, seal a3sembl~ 22 handle and
indicator 23 and oxygen delivery tube 3A. A release cord
6A is assoclated with oxygen source 13 to auto~atically
commence operation thereof when the oxygen supply pipe 3
is pulled out of valve 2. It ~hould be noted that exit
valve 2A i8 in an alternative position to exit valve 12
in Fig. 3. Furthermore, a~ has been noted, valve 2 may be
an exit valve.
The seal assembly may be operated to permit the
rebreathing cycle to be entered~ The device i~ held
firmly against the apparatu~ container wall. In quch
arrangement, it i5 olear that the auxilliary device ie, not
brought into operation. When the devlce has been removed
from the apparatus container wall the indlcator 23 i8
allowed to move and a free pa~sa~e of oxyge~ is
possible be~ween mask l and-reservoir S~;
:
The seal mechanism includes an obturator and a
number of channels. ~hen the oxygen i9 switohed on the
3n pressure of the axygen pushes the obturator along until
the opening is in line with the channels to the reservoir
and mask. The end of the container wall prevent~ further
movement. A~ thi~ point, the end nearest to the oxygen
~snurce has moved beyond~the oxygen ~upply tube and nxygen
~flows do~n thls to the reseFvoir~ The seals prsvent laakaga
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of oxygen o~ movement of gases except where intended.
In Fig. 10 the exit valve 2A is an alternative to
12 in Fig. 3. It should have an adju3table pres6ure
setting with resistance set to be higher that the maximum
pressure required for rebreathing but low enough to allo~
voiding to external atmosphere, when the system is full,to
prevent lung damage from too high pressure due, for example~
from malfunction of pressurised oxygen supply source.
As previously mentioned the respiratory gase3
comprise oxygen either as pure oxygen or as air and the
choice of gas would be made by aircrew in the flight deck
or by cabin staff. It should now be made clear that an
alternative oxygen supply source includes pure oxygen from
a chemical generator or stored oxygen and it also includes
oxygen in air. Furthermore the air supply source may be
ram air or bleed air or compressed air or filtered air.
Filtered air will not protect against hot gases but filters
can provide substantial prbtection until exhausted, until
the air becomes too hot to breathe or until it i5 time
to escape. However, a filter system with a heat sink
added, may provide adequate protection against hot gases
and may be preferred if it has other advantages, for
example lightness o} weight.~A 500 gram filter may, depending
upon smoke density and other factors, provide protection
for 20 to 30 minutes and may oe suitable for some`in flight
fires. It is an advantage that Filters may be fitted
without~major engineering alterations to the aircraft.
Additionally the filter should~ like the carbon dioxide
absorber, be sealed and a method of doing this is
illustrated in Fig. 11. The cover l has a said self closing
valve 2 and oxygen supply tube 3 passes therethrough.
The proximal end of said oxygen supply tube 3 is sealed
3s by a proximal seal means 41 attached by a proximal cord means
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26 -
~2 tn a receptacle means 43 or box or otherwise Fixed to
the aircraft. The distal end of said oxygen ~upply tube 3
i9 connected to or becomes the proximal end of a filter
means 44 and a distal seal means 45 seals the distal or air
intake end of the filter and is connected by the distal cord
means 46 to the receptacle means 43 or otherwise fixed.
Thus removal of the mask and filter from the box automatically
unseals the filter 4~ and proximal end of said oxygen supply
tube 3, by removing the seals 41 and 45. The filter 44 is
also fixed to the receptacle means 43 by an additional
cord means 47O This allows the filtered air system to be
used by a seated passenger but it automatically separates
the filter 44 and oxygen supply tube 3 from the cover 1 and
self closing valve 2 when the passenger leaves his seat to
escape from the aircraft. The said third cord to activate
the stored oxygen source may also be attached ta said filter
44 to ensure that said source is activated auto~atically
at the time of escape. The said filter must be capable
of removing smoke particles, carbon monoxide gas, cyanide
gas and other toxic substances. The combination of a filtered
air course with a pure oxygen rebreathing system may be
described as a hybrid system. The device of Fig. 11 also
includes, but not 3hown, an exit valve and a release
mechanism to bring the rebreathing bag into operatio~.
The functions of the compnnent parts of the apparatus
are as follows.
The cover, the self-closing valve and the oxygen
supply tube are as previously described~
The proximal seal means seals the proximal end of the
oxygen supply tube.
The proximal cord means attaches the proximal seal
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means to the receptacle means~
The receptacle means hold~ the 0pparatus and i9
itself firmly fixed to -the aircraft.
The filter means is the distal part of the oxygen
supply tube and contains substances which remove by
filtration noxious gases.
The di~tal seal means seals the distal or air intake
end of the filter means.
The distal cord means attaches khe distal seal
means to the receptacle means.
The additional cord means attaches the filter means
to the receptacle means and the cord is long enough for
the apparatus to be removed from the box and used by a
seated passenger.
ZO ~ ~
The filter may be remote and may serve several
passengers. It may have a long connecting tube (not short
as shown~ which may have an exit valve 12 as in Fig. 4
and/or collecting bag 9 and non-return valve 10. Such might
be used with a motorlsed filter system.
The modifie~d reservoir in the mother and baby unit
(Fig. I2) is~closed by folding over the end and halding
~ it~cl=sed with spring clips 4~, and in the mother and
yound child unit it i~ closed by a drawstring 49 round the
~ abdomen.
,
~ In the sealed mode af a hoad embodiment as ~hown
in Fig~ 13~ the self closing valve Z and axygen supply tube
3 are cannected ta the cover means 1, which in turn i~
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connecteo to the hood.
The hood i~ folded in the horizontal plane so that the
absorber 4 is in a fold and the reservoir 5 is empty.
5 the fold is kept in position by a series of radially positioned
guide means 7 and by two release means 6A. An additional
release means is required to activate the oxygen 9upply source 15.
Each ring of the guide means is in a vertical plane with
alternate rings attached to upper and lower edges of the fold.
Each release means is attached at one eno to the oxygen
supply tube 3 and is threaded through the ipsilateral set
of rings to keep the absorber 4 switched out of contact with
the inspired and expired gases.
The absorber is shown in Fig. 14 in the open circuit
state. To switch the absorber in to the circuit the oxygen
supply tube 3 is withdrawn and automatically pulls out both
release means 6A. The opposed surfaces of the absorber
4 are no longer held together by the guide means 7 and the
zo fold is unfolded by the pressure of oxygen to expose the
absorber 4 in the cover means 1 and reservoir 5 ~hich are now
combined as one enlarged hood. A separate releas~ means
may be provided to switch in the absorber without pulling
out the oxygen supply tube 3.
It is obvious to those skilled in the art that the
fold in the hood may, alternatively or additionally, be
in a vertical plane, coronal, sagital or other. A coronal
fold would not obstruct vision and any vertical fold would
decrease hood volume. Also the dome may be silvered to
reflect heat. The oxygen supply tube 3, shown as sited low
down, may be sited in the dome or elsewhere and the diagram
is shown by way of example only. As in the face mask model
one or more portable oxygen supply sources may be attached
to the hood, for example a first pure oxygen source and a
first absorber for decompression, a high flo~ air supply
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- 29 -
source for in flight fire and a second pure oxygen source
and second absorber for escape.
The embodiment of Fig. 15 i9 similar to that of
Fig.l, but in ~hich the reservoir 5 has been replaced
by a filter 50.
The release means 6 and 6A unseal the filter 50
(in the manner as shown in Fig. 11). In this embodimen-t,
an exit valve 2~ is shown and there are two entrance valves.
The first valve 2~ is adjacent the carbon dioxide absorber
and the second valve is in the oxygen supply tube 3
(as previously described in Fig. 3 as valve 10). It
should be noted that the opening pressures of valves 25
and 10 should be balanced such that valve 10 opens first
and valve 2~ does not open until no further gas can
be obtained through valve lO, or through oxygen supply
tube 3 at the site of valve 10; thus valve 2~ will
automatically open to supplement breathable gas when
required if manual release 6~has been activated. The filter
seal is required for the purpose of excluding air from the
filter 50 during the storage mode.
It will be apparent to those skilled in the art that
changes may be made in the shape, design and material
composition of the apparatus ano that a variety of manufacture
methods, of types, of sizes and of devices may be used for
the components thereof; face mask, oxygen supply tube, self
closing valve, carbon dioxide absorber, retain/release
mechanism, guide means and inflatable rebreathing bag reservoir.
It will also be apparent to those skilled in the art that
additional or ancilliary apparatus may be used including
means of ensuring a well fitting face mask, including a head
harness to hoid the face mask in position, including goggles
to protect the eyes from noxious gases and very hot air, and
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including an additional system of one way valves and/or
circuits to ensure circulation, to or fro, of air from lungs
to absorber, to reservoir and back to lungs. It will also
be obvious to those skilled in the art that the apparatus
illustrated, the methods suggested and the possibility
for ancilliary apparatus are given by way of example only
and do not exlude the many other methods or possibilities
which are obvious for such breathing apparatus or ancilliary
apparatus.
nne further example may be given because of its
simplicity and suitability for children of different sizes
and ages and particularly for young children. In essence
it is a large clear pla3tic bag connected to the oxygen
supply tube through a self closing valve. The bag is placed
over the head and shoulders and a seal is provided by putting
on a pullover, anorak or jacket fastened up to the neck on
top of the bag. The bag is inflated with oxygen and the
oxygen and the oxygen supply tube is removed just before
the child walks or is carried from ths cabin of the aircraft.
It will be appreciated that the principle i9 the same but
the entire head is inside the rebreathing bag and a carbon
dioxide absorber may not be necessary due to the relatively
large volume of the microenvironment compared with the
lung volume and the relatively short time for which it is
required. Alternatively a young infant could be placed
entirely inside the bag which could be closed at the distal
end opposite to the oxygen outlet. ~owever, it is safer
to have~an oxygen supply and carbon dioxide absorber as
shown in the mother and baby unit.
The absorption of carbon dioxide is an exothermic
reaction and it is obvious that it may be necessary to
cool the gas ooming out of the absorber or to disperse the
heat or both. Cooling may be performed by chemical, physical
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~7~5~;35
- 31 -
or other means, for example by combining it with an
endothermic reaction. Dispersion may be achieved by
using a heat sink, for example contact with copper mesh
or other good heat conductor, or by a circuit arrangement,
for example single pass through the absorber from lungs
to reservoir and return of mixed gases which bypass the
absorber.
The body is an efficient heat sink because the latent
heat of vapourisation of water is high and expired ai~
contains much water vapour. It is nbvious that removal
of water vapour by a hygroscopic or deliquescent agent
or otherwise will ensure the continued efficiency of this
heat sink mechanism.
In any alrcraft system weight is of paramaunt importance
and if, for example, a filter system with a heat sink is
found to provide adequate protectian against hot gases but
is lighter than, for examplè, a closed rebreathing system
then this would be preferred.
~ reathing apparatus may best be stored overhead and
presented to passengers when required but this requires
eng~neering modifications to aircraft. In the meantime, for
apparatus fitted in to a seat back, an indication may
be givem when the container is opened. This will alert cabin
staff ~o unauthorised use by children or others tampering,
pilfering~or attempting to don hoods for other thsn
emergency use. For example a circuit may be broken when
a lid is lifted and an indi:cation given at a crew station.
The rebreathing bag may be the floatatlon chamber
of a~life jacket 90 that~both life support systems, smoke
protection and floatation, are combined.
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It will also be apparent to those skilled in the art
that such apparatus may be used in an industrial environment
and in hotel, shop, office and hou~e fires and may be used
by firemen, miners, sewage workers, civilians and others
and that additional orancilliary apparatus may be used
including means whether automatic or otherwise of delivering
the apparatus to passengers when needed, includlng means
of issuing instructions during the emergency, whether by
automatic recorded message or otherwise, including indicator
lû means, including means of inflating the reservoir directly
~rom a fixed oxygen supply and including adaptation for
use with closed oxygen or air supply 3ystems as well as
closed rebreathing systems. It will be obvious to those skilled
in the art that the apparatuY illustrated, the methods
suggested and the possibility for ancillary apparatus are
given by ~ay of example only and do not exclude the many
other methods or possibilities which are obvious for such
breathing apparatus or ancilliaryapparatus.
ZO 0~ the many obvious places For use of such breathing
apparatus hotels and multi-storey buildings for offices and
shops or stares should be mentioned. Very similar appara-tus
could be kept in each room with a plurality of outlets from
an oxygen cylinder supplying several rooms or a complete
Z5 floor. Fire alarms could be linked to recorded instructions
for using the apparatus. If the apparatus is removed from
its storage place an electrical signal could be automatically
transmitted to reception to indicate which items were being
utilised.~ In hotel fires a longer time might be needed to
escape and ancilliar~Japparatus such as oxygen sparklet or
several such activated automatically at set time intervals
or manually might be useful. Such apparatus might also
be useful in industry in hostile environments to comply with
Section 30 of the Factories Act 1961 and in mines and sewers
where methane may collect. It is also obvious that the
apparatus may be used in converse sequence that is conversion
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from portable breathing apparatus, used for example in
rescuing people from house or hotel fires or mines or
sewers, to an oxygen supply system, when the sarne apparatus
is connected to a static oxygen source, once the victim has
been removed from the hostile environment. The addition
of a small portable oxygen source such as a sparklet
would be particularly suitable for this use. The apparatus
may be used by firemen and by members of the armed forces
during fires in aircraft, ships or buildings and by others.
It will also be obvious that in the case of the armed
forces the conversion may be from portable gas mask using
Filtration means to portable respirator using rebreathing
bag with microenvironment and with Further conversion option
to static supply system.
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