CA1085141A - Gas generating systems - Google Patents
Gas generating systemsInfo
- Publication number
- CA1085141A CA1085141A CA243,035A CA243035A CA1085141A CA 1085141 A CA1085141 A CA 1085141A CA 243035 A CA243035 A CA 243035A CA 1085141 A CA1085141 A CA 1085141A
- Authority
- CA
- Canada
- Prior art keywords
- water
- chamber
- gas
- reaction
- connection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J7/00—Apparatus for generating gases
- B01J7/02—Apparatus for generating gases by wet methods
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
- B63C9/00—Life-saving in water
- B63C9/08—Life-buoys, e.g. rings; Life-belts, jackets, suits, or the like
- B63C9/18—Inflatable equipment characterised by the gas-generating or inflation device
Landscapes
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
- Toys (AREA)
- Hybrid Cells (AREA)
- Primary Cells (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
- Catching Or Destruction (AREA)
- Telephone Function (AREA)
- Saccharide Compounds (AREA)
Abstract
ABSTRACT
A device for generating lighter-than-air gas to inflate a marker buoy or like item, for example in a "man-overboard" situation. The device includes separate chambers for the chemicals and the ambient water used in the reaction. The transfer of a significant quantity of water from the water chamber to the chamber housing the chemicals is automatically delayed until such time as sufficient water to complete the whole of the desired gas-generating reaction has been accepted into the water chamber. The control means for achieving this delay may take various forms. For example it could comprise a wick initially providing substantially the only water path from the water chamber to the reaction chamber housing the chemicals.
Alternatively where there is an unrestricted passageway for a free flow of water between the two chambers, the control means could comprise a mass arranged to move automatically to reorientate the device from an initial position, in which the water chamber is at a lower level than the reaction chamber, to a second position in which the reverse is the. In another version, control is achieved in a heavier-than-water device by so positioning the chemicals within the device that they will only be wetted when the correct amount of water has been taken in. Also described are a particularly suitable form of valve for use with the object to be inflated and a number of water-soluble connections which dissolve to trigger off various stages in the process.
A device for generating lighter-than-air gas to inflate a marker buoy or like item, for example in a "man-overboard" situation. The device includes separate chambers for the chemicals and the ambient water used in the reaction. The transfer of a significant quantity of water from the water chamber to the chamber housing the chemicals is automatically delayed until such time as sufficient water to complete the whole of the desired gas-generating reaction has been accepted into the water chamber. The control means for achieving this delay may take various forms. For example it could comprise a wick initially providing substantially the only water path from the water chamber to the reaction chamber housing the chemicals.
Alternatively where there is an unrestricted passageway for a free flow of water between the two chambers, the control means could comprise a mass arranged to move automatically to reorientate the device from an initial position, in which the water chamber is at a lower level than the reaction chamber, to a second position in which the reverse is the. In another version, control is achieved in a heavier-than-water device by so positioning the chemicals within the device that they will only be wetted when the correct amount of water has been taken in. Also described are a particularly suitable form of valve for use with the object to be inflated and a number of water-soluble connections which dissolve to trigger off various stages in the process.
Description
The present invention relates to gas generatLng systems and in particular to devices for generating gas to Lnflate a marker balloon, life jacket, life raft, or like Lnflatable ob~ect when the devlce is immersed (wholly or partially) in water.
By "gas-generating chemicals" in this Specification is meant chemicals which will react with water to produce a lighter-than-air gas. A sui~able chemical for this purpose is sodium borohydride with a catalyst such as anhydrous cobalt chloride. The g~s generated in this case would be hydrogen. The speed of the reaction may be increased with the use of other catalysts.
Thus, in accordance with the present teachings, a device is provided for generating lighter-than-air gas to inflate an object.
The device comprises chemlcals to react with water to produce a lighter-than-air gas, a reaction chamber which houses the chemicals and a water chamber for containing water for the reaction. A valve means is provided operable when the device is immersed to permit the entry of ambient water into the water chamber with control means operable to delay the closing of the valve means and the transfer of a significant quantity of water from the water chamber to the reaction chamber until such time as sufficient water to complete the whole of the desired gas-generating reaction has been accepted into the water chamber.
Conveniently, closure of the valve means is caused by gas pressure produced in the water chamber during the gas-generating reaction.
In some embodiments, the control means include a wick, or one or more narrow bore tubes, at least initially providing substantially ~J 1 ' ' .
the only water pcl-th from the water challlber to t,he reaction chamber.
Usually in these~ embodinlents, the device will be designed lnitially to float with tlle water chamber at a higher level -than the reac-tion chamber -to enable water to :Elow freely under ~ravi-ty from -the wa-ter chamber -to the reaction chamber once -the gas genera-ting process is under way. This mi~ht be achieved :for example by providing the device with ballast or a floa-t or a region of relatively high buoyancy.
According to a preferred feature of these embodiments, the water chamber and at least that part of the reaction chamber housing the chemicals, are separated by a flexible-walled section which prior to the generation oE significant quantities of gas :in the device is held in a collapsed s-tate by the ambient water pressure acting on -the outer walls of -the sec-tion. This initially isolates the water chamber from the reaction chamber except for the water path provided by the wick or tube(s) referred to above.
However, as soon as the gas generated in the device reaches a sufficient pressure to overcome the collapsing action of the ambient water pressure, the flexible-walled section will inflate to provide a passageway be-tween the -two chambers which will allow water in the water chamber to flow freely into the reaction chamber under ~ravity, When a wick is used, it can be made from any suitable flexible conventional wick material provided it is dense enough to ensure that initially the ambient water pressure will not collapse it and prevent -the flow of water along the wick. The density of the wick ;. ,, ., : : :
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r l may be varied to suit the dalay required. A suitable wick material would be non-woven reinforced nylon material of porous nature such as '3M SCOTCHBRITE' marketed by the ~linnesota Mini,ng and klanufacturing Company Limited.
In other embodiments, the connection between the water chamber and the reaction chamber at all times provides an unrastrirted passageway for a free flow of water between the two chambers but initially this flow is prevented by having the device so orientated that the water chamberis at a lower level than the reaction chamber.
In these alternative embodiments, the control means conveniently comprises a mass which after a certain period of time automatically moves to change the centre of gravity of the device in such a way as to cause the device to take up some new oribntation in which the water chamber is at a higher level than the reaction chamber.
Water in the water chamber is then free to flow unhindered into the reaction chamber.
Devices according to the present invention preferably include a transfer chamber between the reaction chamber and the connection for the object to be inflated. The extra length of path provided by the transfer chamber gives the wa~te products produced during the gas generation process a greater opportunity to settle out from '' the gas during its passage through the device so that the gas ~ ~
should be relatively uncontaminated by the time it reaches the object to be inflated. It is usually considered desirable,however, to exclude the transfer chamber from the reaction space available during at least the initial part of the gas generation procesq, first ' .. . .
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becauso a smaller reclctioll sl)nce Le.lds to ~ more efficient reac-tion, and secondly becau~e when the water entry valve i~ pressur0-responsive, the smallel- the reaction sl)ace the more quiclcly will -the valve-closing pressure be reached after the desired amount of water has been taken into -the device. Accordingly, it is preferable ini-tially to separate the transfer chamber from the other two chambers by a closure member which opens only in response to a pressure on the gas-generating side of-the member indicative of the gas generation process having reached a high enough pressure to close the water entry valve. The clo~sure member may,for e~ample, tak~
the form of a membrane constructed from a material of appropriate bursting strength.
Although for some applications the device of the present invention micJht, for example, include a bellows section which could be manually expanded to suck water into the device for commencement of the gas generating process, other means, preferably of an automatic or semi-automatic nature, are usually more convenient:and to be preferred.
For example the device might include a flexible part which is automatically expanded ~e.g. by a spring) on the release of a catch associated either with the device or with a support or carrying case for the device. In one such example the catch is only released when the device is immersed so that the expanding action of the flexible part will draw in the desired amount of water into the device. In another example, the catch may be released to expand the device when it is out of the water but in this case the device .
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must of COlll'~;e itlClllde some IlleanY (e~ a water-soluble closure member) by which the device is preven~e(l from openirlg until is is imalersed.
ln a varialiotl o~ the ~irst of these two examples the catch could be releclsed autoll1alicaLly by dissolving a water soluble mernber which in the inoperative condition of the device holds the ca-tch closed. Alterna-tively this member could in fact comprise the ca-tch. In a variation of the second of the two examples the flexible part of the device could be replaced by a rigid par-t but the device would then have to be evacuated during its manufacture.
As an alternative to these various systems for getting water into the device, this latter could simply be a rigid or semi-rigid device 50 construc-ted as to sink under its own weight with the water entering the inside of the dovice through some convenient opening. The openin~ could for example be a permanently exposed opening, or one initially sealed off by a water soluble closure member, or one exposed by removal of a conventional lid member either when the device is immersed or prior to or during immersion.
The inven-tion further includes an assembly comprising the device of -the present invention connected up with the object to be inflated and according to a further feature the flow of gas from the device to the object is controLled by a valve.
A preferred valve for this purpose comprises an envelope of flexible resilient material having a first portion apertured to allow ingress of gas from the device into the envelope, a second portion housed inside the object and apertured to permit gas in the :- . .. .
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envelope to escape into the object, ar1d a pair of opposed walL
regions lying between the apertures in the first and second portions and urgecl towards each other into a valve-closirg relationship by the pressure of the gas in the obj0c-t.
The princi~l advantage of this particular valve is that it can be made light in weight to maximise -the lift of the balloon. It will also have low resistance to 1;he ingress of gas from the device i.e. the back pressure exerted by the valve is minimal. This latter characteristic means that the device itself can readily be construc-ted in such a manner and from such materials as to be easily packed snugly in a reasonably sized carrying case when it is desirable that it should be carried round as part of a ~ser'snormal equipment e.g. when intended for use in a marker balloorl assembly for a man who has falLen overboard.
Generally speaking, the valve envelope may be of any rubber or composition material of a suitably elastic nat~re. The envelope may be in the form of a tube or of a balloon. The outline shape of the envelope is not critical but long and bulbous shapes are preferred. It should preferably lie flat in its natural state i.e. with the two main faces touching, or nearly so. The envelope could for example be made with a flat, or nearly flat, former or from two pieces of identical shape which are flxed together at their outer edges.
One version of -the valve is made by perforating a balloon-like envelope (or by cutting the end from it) to form the gas exit. The '' , . : ~
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two abutting surfaces oE the envelope are then held together either by glueing, welding, st~pLing, rivetting, stitchiny, moulding, or any o-ther convenient means, adjacent to -the gas exit. Partially fixing the two naturally abut-ting faces of the envelope together in -this way, results in an inherent stress being crea-ted by the two elastic surfaces when these are forced apar-t by gas passing through the envelope into the object to be inflated. When the gas flow is stopped this inherent stress causes the two surfaces to come together again and the valve is held in this flattened closed L0 condition by the back pressure of ga$ in the object in which the valve is located.
The object to be inflated by the device is conveniently attached to it by a water soluble connection and means may be provided so that this connec-tion is exposed to ambient wa-ter only when the L5 object has been satisEac-torily inflated. In two such embodiments for example the connection is initially held clear of the ambient water by having the device initially in a floating condition. In one of these two embodiments a moving mass is used to change the orientation of the device at a suitable instant to immerse -the connection in the water. In the other of the two embodiments, the device is vented and gas continuing to leak out through the vent results in -the device sinlcing to a level at which the connection is immersed in the ambient water.
Where a movable m~ss is used to immerse the cormection between the device and the balloon and/or to invert the device in those embodiments where inversion is required to bring the water chamber ..,~ , ..
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to a higher level than the reaction chamber or vice-versa, -then -the mass may, for example, be secured to one end of a len~-th of line that at its other end is perrrlanently secured to a first region of the device whilst being temporarily attached at an intermediate portion of the line to a second region of the device.
The temporary attachment conveniently takes the form of a water soluble connection ~or example which when it dissolves in the ambient water in which the device is wholly or partially immersed, releases the mass -to result in the point of application of the force exerted by the mass moving from the second region of the device to the ~`irst region. This change causes the device to take up the desired new orientation. The same method can be used if desired for other related applications e.g. to trig~er a flashin~-ligh-t distress signal etc.
As indicated in the preamble to the Specification, the term "immersed" when applied to the device, should, unless otherwise specified or implied in the context, be taken to include both the situation where the device is fully immersed and the situation where it is only partially immersed. Where immersion of the device is necessary for ambient water to act on a wa-ter soluble item associated with, or forming a part of the device, then obviously in such cases -the device must at least be immersed to the point at which the item is in contact with the water so that the desired action can~take~place.
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Embodiments of the invention will now be described, by way of example only, with reference -to -the partially d:iagrammatic accompanying drawings in which:-~ igures 1 and 2 show a longit~dinal section and an elevation of a first assembly. Although the assembly would not normally assume thecondition shown in these Figures, it has been ~i:Llustrated in this way so as more clearly to indicate the more important features of -the assembly;
Figure 3 shows on an enlarged scale that part of the device connected to the object to be inflated.
Figures 4 to 7 show, on a reduced scales, ~the.asse~bly:of Figures 1 to 3 as it would actually be at variaus stages of its operation;
Figures ~ to 13 show longitudinal sections of other e~bodiments at intermediate stages of -their operation;
Figure 14 shows a vertical section of the last of these embodiments at a later stage of its operation;
Figure 15 shows a vertical section (on an enlarged scale) of a water-soluble link system for attaching a ballast weight to the device; and Figure 16 shows a part of Figure 1 on an enlnrgad scale ancl with components illustrated separated for clarity.
The same reference numerals have been used to indicate corresponding items in the various embodiments.
Thus referring first to Figures 1 and 2, a device 6 according to the present invention comprises a flexible envelope 8 defining ~7 - ;:
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: , : ~ ., a reaction chamber 10, a watar chamber 12, and a transfer chamber 14.
The gas producing chemicals 16 are contained in a water permeable or water soluble bag 18 in the reaction chamber and this is connected to the water chamber by a wick 20.
In the illustrated embodiment, envelope 8 is made from 7034 ~ ~ , .
gauge "Synthene" co-extruded nylon/polythene film (marketed by Smith and Nephew Plas~ics Limited) and bag 18 is made from standard grade water-soluble paper (marketed by ENA~ Limited).
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The chemicals 16 are those mentioned in the preamble to the Specification as being suitable for hydrogen generation.
When free to do so the chamber 12 is expanded (as shown for illustrative purposes in Figure 1) by an expansion spring 22 contained within the chamber. Reference numeral 24 indicates a one-way valve allowing ambient water to enter chamber 12 during this expansion.
In Figure 16, the three basic components of valve 24 are shown separated for greater clarity. These components are an annular rubber diaphragm 200, a peripherally apertured metal disc 202, and an apertured part 204 of the envelope engageable by the disc 202. These components are urged by the spring 22 into a water-tight;relationship in which the apertures 206, 208 in the disc and envelope are covered by the diaphragm 2000 As will be clear from the description of the operation of the valve, although spring 22 urges the valve into a valve-closed position~
whether or not it is closed in practice at any given instant will depend on the pressure differential across the valve at that instant.
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Althoug}1 only two nli(~Jr1ecl apertures 206, 20~ are shown, thesc are conveniently each one ot` two c1inmetricAlly opposed aper-tures in the compor1ents concerne(1.
Returninc1 now -to ~igures l and 2, it will be seen -that the water chamber 12 -is initially separa-ted from the -transfer chamber l4 by a membrane 26. An at-tachment nipple 28 allows the object to be inflated by the device (mar}cer balloon 30) to be connected up with -the transfer chamber. Balloon 30 may be of any convenient design e.g. a conventional metereological balloon. The one used in the illus-trated embodiment is a lO gram~Beritex balloon (marketed by Philips Patents Limited)0 Numeral 32 indica-tes a one-way low-pressure valve preventing gas that has entered balloon 30 from leaking back into transfer chamber L4. This valve will be described in more detail later in the Specification with reference to ~igure 3. The balloon is tethered to the device by a length of line 3~ stored in a fixed reel lO0, also shown in more detail in ~igure 3. In use the line will be unwound from the inside of the reel. This enables the line to be freely unwound from any angleO
The assembly is completed by a line 36 from the balloon end of the device to the user (not shown) and by a line 38 from that same end to a ballast weight 40 which, at least initially, is suspended from the other end of the device by two lines 42, 44 connected together by means of a water soluble link 460 The link 46 etc. which is shown diagrammatically in Figures l ~o 7 and in some of the other figuresj will be described in greater detail . : ~ . , ............................ , :
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later in the Specification with reference to ~igure -l5. With a typically sized device (say two foot long) the weight 40 might be of -the order of one pound.
In the inoperative condition of -the device (with spring 22 compressed and envelope 8 and balloon 30 deflated) the envelope and the balloon will be tightly rolled up and packed snugly in a carrying case (not shown) which amongst other things will be ;~
effective to maintain the expansion spriny in its compressed state.
If the user falls overboard say and desires to use the marker balloon 30 to indicate his positlon for rescue purposes, then with the device immersed in the water he opens the lid of the carrying case and the weight 40 will fall out dragging the rest of the device behind it. Spring 22 as soon as it is free from the restraining action oE the carrier case will expand causing ambient watcr to be sucked into chamber 12 through valve 2k. ~igure 4 shows the device at this stage. Numeral 48 in Figure 4 indicates the surface of the sea of course. Line 36, which is affixed inside the carrying case (itself affixed to the wearer), will ensure that the device remains attached to its user.
The sea water that has entered water chamber 12 will quickly percolate through the wick 20 (e.g. in 5 to 7 seconds) into the reaction chamber 10. While all this i9 happening the opposite walls of those portions of the envelope defining the reaction chamber 10 will be held tight together by the pressure exerted by the sea on the outside of the device. However, after the first water has arrived in the reaction chamber 10 and the gas generating process ' ': :~
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has commenced, the gases producecl in chamber 10 will quickly :increase the internal pressure in this par-t of the device until it excseds the external pressure exerted by the sea and when this happens -the walls of the reaction chamber 10 will be forced apart and the rest of the water in chamber 12 can fali freely into chAmber 10. This is the si-tuation shown in Figure 5. Typically it m:ight take some fifteen seconds to inflate the r0action chamber in this way. It will be seen that the device now has sufficient buoyancy to float with the balloon ehd of the device clear of the sea.
The increased internal pressure in the device will also be effective to close valve 2k thereby preventing further water from being introduced into the device for the gas-producing reaction.
In one typical embodiment put under test, about 20 seconds elapsed from when the valve 2k was opened to when sufficient water has percolated through into -the reaction chamber via wick 20 for -the gases to expand the envelope into the position illustrated in Figure 5. This is adequata time:for the chamber 12 to fill by the required amount.
When the gas generating reaction has progressed to som~thing near its final stage, the pressure in the device will be sufficiently high to rupture the membrane 26 and the gas generated by the reaction will escape through transfer chamber lk to inflate this part of the device and to commence inflation of the balloon 30.
As already explained the purpose of the membrane 26 is to~contain the reaction to a reasonably small volume during at least the major part of the gas generating process.
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~.~B~4~g Sufficient gas is generated in the process for the balloon to be in a satisfactorily infla-ted condi-tion by the time the pressures in the balloon and the device have equalised. At this point the valve 3~ closes (Figure 6).
rhe water soluble link 46 referred -to earlier has all this time been exposed to the action of the sea, and is of such a size, and so designed, that after the balloon has been fully inflated, link 46 will finally dis~olve completely away allowing the two lines 42 and 44 to separate. The mass 40 will now be free to fall under its own weight dragging down the balloDn-end of the device into the sea as shown in Figure 7. Wlth the balloDn end of the device immersed as shown, the sea water will quickly dissolve the water soluble connection 110 and the balloon will rise to the end of its line 34 to indicate the position of the wearer of the de*ice.
Typically, line 34 would be about 100 feet long. Reference numeral 50 in Figure 7 indicates the remains of the exhausted chemical reaction.
Referring now to Figure 8 this shows an embodiment of the invention in which the essential difference from the previous embodiment is that the positions of the water chamber and the reaction chamber have been interchanged. Thus whereas in the embodiment of Figures 1 to 7, the ambient water enters the water chamber 12 and percolates downwardly through wick 20 into the reaction chamber lO(t ïn the embodiment of Figure 8, the wick is omitted and instead the bag of gas generating chemicals extends downwardly from the reaction chamber into the top of the water :. . ~ : . ,: , ~ ~, , f ~
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chamber so that when the desired amount of water has been taken into the water chamber through valve 24, it will come into contact with the lower end of the bag 18 and gas generation will commencen As the bag 18 is made of water soluble material, at least that part of it wetted by water from chamber 12 will very quickly dissolve away (e.g. in 2 or 3 ~ec~nds~ allowing the chemicals 16 to pour freely from the bag into the water chamber for completion of the gas generation process.
In the embodiment of Figure 9, the spring-biassed flexible-walled water chamber 12 of the earlier embodiments, is replaced by a rigid-walled chamber 52 and the valve 22 is covered by a water soluble plug 54 e.g. of an effervesc0nt compound such as Alka-Selzer (marketed by Miles Laboratories Limited)~ Alternatively a water soluble film could be used to cover the valve e.g. of the type used in connection llO.c The devic~ comes with'chamber 52'air free 90 ,that typically after Z or ~ second~ ~hen plug 54 ha3,d~solved,sea uater will'be sucked into the water chamber and the device will commence to operate in an exactly analogous fashion to that already described with reference to the embodiments of Figures 1 to 8~
Figure 10 shows yet another embodiment. In the device of Figure 10, the water chamber and the reaction chamber are provided~by,different portions of a rigid walled part 56 with the '~
chemicals initially housed at the top end section and the water chamber provided by the lower sections. The ballast weight ill2) 25 is secured in the bottom of part 56 by a bolt 114 . At it3 upper end, the device has an apertured lug 116 enabling the device to be attached by a line 118 to a life buoy for example.
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Part 56 is in fact only the lower piece of a larger housing 120 in the top piece of which are contained a flexible transfer chamber envslope 14 and the marker balloon 30 to be inflated. The top and bottom portions of the housing are internally separated by a plat~l22 but this latter is centrally apertured (at 124) to provide a conneotion between the interiors of the transfer chamber and the reaction chamber.
An 0-ring 126 secures tha bottom of envelope 14 to the plate 122~ but other similar fixings oan be used instead if desired.
The top qnd of the housing 120 is in the form of a removable lid 128 which is secured by a short line 130 with a carrying `: -bracket 132 for the device. ~racket 132 might for examPle be secured to a light craft, boat or ship.
Reference numerals 134, 136 indicate two tube~ leading from peripheral apertures in the plate 122 to the bottom of the water chamber 12. The top ends of the tubes are a~sociated with one way entry valves 138, 140 arranged to permit a downwards flow of water through the two tubes. Typically valves 138, 140 might be disc or ball valves.
In operation of this embodiment, the device is removed from its support bracket and is hurled with its lifebuoy tnot shown) into the the sea. The line 130 will be put under tension to jerk the lid 128 off the container so that it is open-topped when it hits the water.
The buoyancy of the device is such that it will begin to sink under its own weight and water will pour in at the top end of the housing.
From there it will drain through tubes 134, 135 into the bottom of -the water chamber 12. When the water has risen to ~ ` :
the level of the chemictlls 16, gas generation will commence and the increase in pressure in -the reaction chamber will close valves 138, 1~0 preventin~J further water from entering -the lower part of the device.
The dimensions of the wa-ter chamber are such, of course that by this stage sufficient water will have been accep1;ed for comple-tion of -the ~as genera-ting process.
At a predetermined pressure produced a-t or near completion of the gas generating process, -the membrane 26 will burs-t and the transfer chamber envelope 14 and the marker balloon 30 will in-~late in the usual way. The transfer chamber 14 is provided with a vent hole 61 at some point above -that at which the balloon is attached.
Gas is allowed -to escape through -this hole from the time that the membrane bursts and gas enters -the transfer chamber but the rate of escape is small in rela-tion to the input into the balloon.
When the reactlon ceases, the pressure in the transfer chamber is roughly the same as -that in the balloon but with valve 32 closed, the residue gas in chamber 14 will continue to vent to atmosphere through hole 61 until the buoyancy of the device is sufficiently reduced for the weight 112 to sink it to a Ievel at~which the neck of the balloon is immersed in the sea. The water soluble connection 110 will dissolve away soon after.
The essential difference between thq embodiment of Figure 11 and that of Figure 10 is that whereas in the earlier embodiment the water enters the top of the devicq and is conveyed from there to the bottom of the water chamber through appropriate tubes, in the embodiment of Figure 11, the water enters the bottom of the device : : :
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directly into the water chamber. As wi-th the previous embodiment however, the water chamber and the reac-tion chamber are still provided in different portions of a common rigid walled part 56 with the chemicals initially housed a-t the top end of the section (at a position indica-ted by numeral 1~2 in Figure 11) so that sufficient watel to compLete the gas-generating reaction must have been talcen into the device before the water can contact the chemicals and the en-try valve (1~) be closed by the gas pressure generated by the reaction.
In the modification shown in Figure 12, an annular mass 62 is included at the bottom of the water chamber so that even when -the gas-producing operation has been completed and membrane 26 has ruptured, the net weight of the device is still sufficient to hold the water soluble connection 110 below sea level. Obviously as before this connection must be such that it will not free the balloon until sufficient time has elapsed for this latter to be fully inflatedO Al-though relatively bulky when compared with the previous embodiment, the embodiment of Figure 12 offers an alternative version of the device in which the need to change the orientation of the device at some stage in i~s operation is done away with.
Figure 13 shows a rigid-walled version of the device in which the transfer chamber and the water chamber are one and the same thing and the reaction chamber (10) is at the opposite end of the device to the ballast weight 40 and the balloon 30.
- -In thi~ embodiment the ballast weight l~0 pulls the device down so that sea water enters the combined transfer/water chamber ~64) via the one way entry ~alve 18. When sufficient water for the complete gas-generating reaction has en-tered the chamber 64, the l-water soluble link 46 will finally dissolve away and the maqs willmove under gravity to pull the device over a~ indicated in Figure 14.
This will cause ths water to be thrown on to the chemicals 16 and the gas producing reaction will commence. When the balloon has fully inflated, a water soluble plug (or 3eal) 66, in what i~ now the lower part of the device, finally dis~olves away allowin~l water to entertthe device to sink it to a level at which only the buoyancy of the balloon in the sea will keep it afloat. Thi~
immerses the water soluble connection 110 in the sea and thi~
connection quickly dissolves away to allow the balloon to rise to the end of its line and the device to sink awayO
Fi~ure 15 shows on an enlarged scale the link 46 referred to above and shown in the various other Figures of the drawings. '~
It will be seen from Figure 15 that the link comprises a casing 67 apertured at 68:and containing a water soluble tablet 69 which traps the line 42 in the casing. The tablet might, ~or example, be a water-soluble 'effervescent~ tablet e.g. an Alka~Selzer tablet of approximately 1 inch diameter and 3/16 inch thick~e~3' with a'ce'ntral `of'hole 3/16 inch diame~e~., TypicalIy th~ di'ssol~ing ti~ of this tablet,might be approximately 11 minutes~
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Line 44 i9 secured to the casing itself. Wherl the tablet has finally dissolved, line ~2 is free to leave the casing through aperture 68 and the mas~ 40 can swing away under gravity supported by the line 38.
Referring now to Figure 3, this shows on an enlarged scale preferred versions of the valve 32 and reel 100 referred to earlier in the Specification. As will be seen from this Figure, the illustrated valve is basically of a flexible balloon-like construction. In the illustrated embodiment in fact, a standard Aeriel balloon ~narkebedby the London Rubber Company Limited) was modified for this purpose by punching a hole 70 through the balloon and then stapiing its two walls together at 74 to encourage them to cling together in response to even a very small excess pressure on the outside faces of the valve. The stem portions of the valve 32 and themarher balloon 30 are secured by 0-rings 71, 72 on to a connector piece 73 which is held in an abutting relationship with the nipple 28 by several turns of water soluble material held in place by 0-rings 72 75~ In the illustrated embodiment, this ~) .
material is a polYvinyl acetate (PVA) film marketed by ENA~ Limited, three turns of 0.002 inch thickness film being sufficient to give the desired dissolving time of 30-60 seconds. Of course if other dissolving times are required, these can be ~btained by changing the number of turns andjor the grade of the PVA film.
At its lower end, nipple 28 is rigidly mounted in an attachment plate 76 welded into the wall of that part of the '. : ' ' '.
4~L
envelope 8 providing the transfer chamber 1l~. Alternatively plate 76 cou1d be attached to the envelope by an adhesive.
In addition to supportirl~ nipple 28, the attachment plate 76 carries an anrlular disc 77 forming the lower one of two such discs 77, 78 which together constitute the reel lO0. The assembly procedure is as folLows. When -the valve 32 and balloon 30 have been assembled as described (in their deflated states of course), then a collapsible mandrel is placed on disc 77 and line 31~ is wound around the outside of the mandrel as a coil 79. The inner end of the coil is secured to a brass ring 80 carried on the neck of the balloon 30 and too large to pass through 0-ring 71. The outer end of the coil is secured -to a top corner of the device as shown at 81 in Figure 2.
The -top disc 78 is now secured in place by a number of attachment ' lugs 82 bent up from the lower disc 77 as shown in Figure 3. ~he mandrel conveniently takes the form of a flat semi-circular spring.
This spring is now compressed to an increased curvature enabling it to be removed through the aperlure in disc 77. This completes the assembling of reel lO0.
.
. . . ...
By "gas-generating chemicals" in this Specification is meant chemicals which will react with water to produce a lighter-than-air gas. A sui~able chemical for this purpose is sodium borohydride with a catalyst such as anhydrous cobalt chloride. The g~s generated in this case would be hydrogen. The speed of the reaction may be increased with the use of other catalysts.
Thus, in accordance with the present teachings, a device is provided for generating lighter-than-air gas to inflate an object.
The device comprises chemlcals to react with water to produce a lighter-than-air gas, a reaction chamber which houses the chemicals and a water chamber for containing water for the reaction. A valve means is provided operable when the device is immersed to permit the entry of ambient water into the water chamber with control means operable to delay the closing of the valve means and the transfer of a significant quantity of water from the water chamber to the reaction chamber until such time as sufficient water to complete the whole of the desired gas-generating reaction has been accepted into the water chamber.
Conveniently, closure of the valve means is caused by gas pressure produced in the water chamber during the gas-generating reaction.
In some embodiments, the control means include a wick, or one or more narrow bore tubes, at least initially providing substantially ~J 1 ' ' .
the only water pcl-th from the water challlber to t,he reaction chamber.
Usually in these~ embodinlents, the device will be designed lnitially to float with tlle water chamber at a higher level -than the reac-tion chamber -to enable water to :Elow freely under ~ravi-ty from -the wa-ter chamber -to the reaction chamber once -the gas genera-ting process is under way. This mi~ht be achieved :for example by providing the device with ballast or a floa-t or a region of relatively high buoyancy.
According to a preferred feature of these embodiments, the water chamber and at least that part of the reaction chamber housing the chemicals, are separated by a flexible-walled section which prior to the generation oE significant quantities of gas :in the device is held in a collapsed s-tate by the ambient water pressure acting on -the outer walls of -the sec-tion. This initially isolates the water chamber from the reaction chamber except for the water path provided by the wick or tube(s) referred to above.
However, as soon as the gas generated in the device reaches a sufficient pressure to overcome the collapsing action of the ambient water pressure, the flexible-walled section will inflate to provide a passageway be-tween the -two chambers which will allow water in the water chamber to flow freely into the reaction chamber under ~ravity, When a wick is used, it can be made from any suitable flexible conventional wick material provided it is dense enough to ensure that initially the ambient water pressure will not collapse it and prevent -the flow of water along the wick. The density of the wick ;. ,, ., : : :
~: . - ~ -: ~ , : ~' " ' ' . ' ' .:~ ' ` ' ` ;
r l may be varied to suit the dalay required. A suitable wick material would be non-woven reinforced nylon material of porous nature such as '3M SCOTCHBRITE' marketed by the ~linnesota Mini,ng and klanufacturing Company Limited.
In other embodiments, the connection between the water chamber and the reaction chamber at all times provides an unrastrirted passageway for a free flow of water between the two chambers but initially this flow is prevented by having the device so orientated that the water chamberis at a lower level than the reaction chamber.
In these alternative embodiments, the control means conveniently comprises a mass which after a certain period of time automatically moves to change the centre of gravity of the device in such a way as to cause the device to take up some new oribntation in which the water chamber is at a higher level than the reaction chamber.
Water in the water chamber is then free to flow unhindered into the reaction chamber.
Devices according to the present invention preferably include a transfer chamber between the reaction chamber and the connection for the object to be inflated. The extra length of path provided by the transfer chamber gives the wa~te products produced during the gas generation process a greater opportunity to settle out from '' the gas during its passage through the device so that the gas ~ ~
should be relatively uncontaminated by the time it reaches the object to be inflated. It is usually considered desirable,however, to exclude the transfer chamber from the reaction space available during at least the initial part of the gas generation procesq, first ' .. . .
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' . . ' ' '''' ' ~ ' . ' ' ' ' "
becauso a smaller reclctioll sl)nce Le.lds to ~ more efficient reac-tion, and secondly becau~e when the water entry valve i~ pressur0-responsive, the smallel- the reaction sl)ace the more quiclcly will -the valve-closing pressure be reached after the desired amount of water has been taken into -the device. Accordingly, it is preferable ini-tially to separate the transfer chamber from the other two chambers by a closure member which opens only in response to a pressure on the gas-generating side of-the member indicative of the gas generation process having reached a high enough pressure to close the water entry valve. The clo~sure member may,for e~ample, tak~
the form of a membrane constructed from a material of appropriate bursting strength.
Although for some applications the device of the present invention micJht, for example, include a bellows section which could be manually expanded to suck water into the device for commencement of the gas generating process, other means, preferably of an automatic or semi-automatic nature, are usually more convenient:and to be preferred.
For example the device might include a flexible part which is automatically expanded ~e.g. by a spring) on the release of a catch associated either with the device or with a support or carrying case for the device. In one such example the catch is only released when the device is immersed so that the expanding action of the flexible part will draw in the desired amount of water into the device. In another example, the catch may be released to expand the device when it is out of the water but in this case the device .
:' ' . ' , ' . : , .
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must of COlll'~;e itlClllde some IlleanY (e~ a water-soluble closure member) by which the device is preven~e(l from openirlg until is is imalersed.
ln a varialiotl o~ the ~irst of these two examples the catch could be releclsed autoll1alicaLly by dissolving a water soluble mernber which in the inoperative condition of the device holds the ca-tch closed. Alterna-tively this member could in fact comprise the ca-tch. In a variation of the second of the two examples the flexible part of the device could be replaced by a rigid par-t but the device would then have to be evacuated during its manufacture.
As an alternative to these various systems for getting water into the device, this latter could simply be a rigid or semi-rigid device 50 construc-ted as to sink under its own weight with the water entering the inside of the dovice through some convenient opening. The openin~ could for example be a permanently exposed opening, or one initially sealed off by a water soluble closure member, or one exposed by removal of a conventional lid member either when the device is immersed or prior to or during immersion.
The inven-tion further includes an assembly comprising the device of -the present invention connected up with the object to be inflated and according to a further feature the flow of gas from the device to the object is controLled by a valve.
A preferred valve for this purpose comprises an envelope of flexible resilient material having a first portion apertured to allow ingress of gas from the device into the envelope, a second portion housed inside the object and apertured to permit gas in the :- . .. .
'.' ' . : ~ .
'' i~5~
envelope to escape into the object, ar1d a pair of opposed walL
regions lying between the apertures in the first and second portions and urgecl towards each other into a valve-closirg relationship by the pressure of the gas in the obj0c-t.
The princi~l advantage of this particular valve is that it can be made light in weight to maximise -the lift of the balloon. It will also have low resistance to 1;he ingress of gas from the device i.e. the back pressure exerted by the valve is minimal. This latter characteristic means that the device itself can readily be construc-ted in such a manner and from such materials as to be easily packed snugly in a reasonably sized carrying case when it is desirable that it should be carried round as part of a ~ser'snormal equipment e.g. when intended for use in a marker balloorl assembly for a man who has falLen overboard.
Generally speaking, the valve envelope may be of any rubber or composition material of a suitably elastic nat~re. The envelope may be in the form of a tube or of a balloon. The outline shape of the envelope is not critical but long and bulbous shapes are preferred. It should preferably lie flat in its natural state i.e. with the two main faces touching, or nearly so. The envelope could for example be made with a flat, or nearly flat, former or from two pieces of identical shape which are flxed together at their outer edges.
One version of -the valve is made by perforating a balloon-like envelope (or by cutting the end from it) to form the gas exit. The '' , . : ~
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two abutting surfaces oE the envelope are then held together either by glueing, welding, st~pLing, rivetting, stitchiny, moulding, or any o-ther convenient means, adjacent to -the gas exit. Partially fixing the two naturally abut-ting faces of the envelope together in -this way, results in an inherent stress being crea-ted by the two elastic surfaces when these are forced apar-t by gas passing through the envelope into the object to be inflated. When the gas flow is stopped this inherent stress causes the two surfaces to come together again and the valve is held in this flattened closed L0 condition by the back pressure of ga$ in the object in which the valve is located.
The object to be inflated by the device is conveniently attached to it by a water soluble connection and means may be provided so that this connec-tion is exposed to ambient wa-ter only when the L5 object has been satisEac-torily inflated. In two such embodiments for example the connection is initially held clear of the ambient water by having the device initially in a floating condition. In one of these two embodiments a moving mass is used to change the orientation of the device at a suitable instant to immerse -the connection in the water. In the other of the two embodiments, the device is vented and gas continuing to leak out through the vent results in -the device sinlcing to a level at which the connection is immersed in the ambient water.
Where a movable m~ss is used to immerse the cormection between the device and the balloon and/or to invert the device in those embodiments where inversion is required to bring the water chamber ..,~ , ..
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1~8~
to a higher level than the reaction chamber or vice-versa, -then -the mass may, for example, be secured to one end of a len~-th of line that at its other end is perrrlanently secured to a first region of the device whilst being temporarily attached at an intermediate portion of the line to a second region of the device.
The temporary attachment conveniently takes the form of a water soluble connection ~or example which when it dissolves in the ambient water in which the device is wholly or partially immersed, releases the mass -to result in the point of application of the force exerted by the mass moving from the second region of the device to the ~`irst region. This change causes the device to take up the desired new orientation. The same method can be used if desired for other related applications e.g. to trig~er a flashin~-ligh-t distress signal etc.
As indicated in the preamble to the Specification, the term "immersed" when applied to the device, should, unless otherwise specified or implied in the context, be taken to include both the situation where the device is fully immersed and the situation where it is only partially immersed. Where immersion of the device is necessary for ambient water to act on a wa-ter soluble item associated with, or forming a part of the device, then obviously in such cases -the device must at least be immersed to the point at which the item is in contact with the water so that the desired action can~take~place.
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: ~ :
Embodiments of the invention will now be described, by way of example only, with reference -to -the partially d:iagrammatic accompanying drawings in which:-~ igures 1 and 2 show a longit~dinal section and an elevation of a first assembly. Although the assembly would not normally assume thecondition shown in these Figures, it has been ~i:Llustrated in this way so as more clearly to indicate the more important features of -the assembly;
Figure 3 shows on an enlarged scale that part of the device connected to the object to be inflated.
Figures 4 to 7 show, on a reduced scales, ~the.asse~bly:of Figures 1 to 3 as it would actually be at variaus stages of its operation;
Figures ~ to 13 show longitudinal sections of other e~bodiments at intermediate stages of -their operation;
Figure 14 shows a vertical section of the last of these embodiments at a later stage of its operation;
Figure 15 shows a vertical section (on an enlarged scale) of a water-soluble link system for attaching a ballast weight to the device; and Figure 16 shows a part of Figure 1 on an enlnrgad scale ancl with components illustrated separated for clarity.
The same reference numerals have been used to indicate corresponding items in the various embodiments.
Thus referring first to Figures 1 and 2, a device 6 according to the present invention comprises a flexible envelope 8 defining ~7 - ;:
: :, . . .
: , : ~ ., a reaction chamber 10, a watar chamber 12, and a transfer chamber 14.
The gas producing chemicals 16 are contained in a water permeable or water soluble bag 18 in the reaction chamber and this is connected to the water chamber by a wick 20.
In the illustrated embodiment, envelope 8 is made from 7034 ~ ~ , .
gauge "Synthene" co-extruded nylon/polythene film (marketed by Smith and Nephew Plas~ics Limited) and bag 18 is made from standard grade water-soluble paper (marketed by ENA~ Limited).
:
The chemicals 16 are those mentioned in the preamble to the Specification as being suitable for hydrogen generation.
When free to do so the chamber 12 is expanded (as shown for illustrative purposes in Figure 1) by an expansion spring 22 contained within the chamber. Reference numeral 24 indicates a one-way valve allowing ambient water to enter chamber 12 during this expansion.
In Figure 16, the three basic components of valve 24 are shown separated for greater clarity. These components are an annular rubber diaphragm 200, a peripherally apertured metal disc 202, and an apertured part 204 of the envelope engageable by the disc 202. These components are urged by the spring 22 into a water-tight;relationship in which the apertures 206, 208 in the disc and envelope are covered by the diaphragm 2000 As will be clear from the description of the operation of the valve, although spring 22 urges the valve into a valve-closed position~
whether or not it is closed in practice at any given instant will depend on the pressure differential across the valve at that instant.
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35~4~1:
Althoug}1 only two nli(~Jr1ecl apertures 206, 20~ are shown, thesc are conveniently each one ot` two c1inmetricAlly opposed aper-tures in the compor1ents concerne(1.
Returninc1 now -to ~igures l and 2, it will be seen -that the water chamber 12 -is initially separa-ted from the -transfer chamber l4 by a membrane 26. An at-tachment nipple 28 allows the object to be inflated by the device (mar}cer balloon 30) to be connected up with -the transfer chamber. Balloon 30 may be of any convenient design e.g. a conventional metereological balloon. The one used in the illus-trated embodiment is a lO gram~Beritex balloon (marketed by Philips Patents Limited)0 Numeral 32 indica-tes a one-way low-pressure valve preventing gas that has entered balloon 30 from leaking back into transfer chamber L4. This valve will be described in more detail later in the Specification with reference to ~igure 3. The balloon is tethered to the device by a length of line 3~ stored in a fixed reel lO0, also shown in more detail in ~igure 3. In use the line will be unwound from the inside of the reel. This enables the line to be freely unwound from any angleO
The assembly is completed by a line 36 from the balloon end of the device to the user (not shown) and by a line 38 from that same end to a ballast weight 40 which, at least initially, is suspended from the other end of the device by two lines 42, 44 connected together by means of a water soluble link 460 The link 46 etc. which is shown diagrammatically in Figures l ~o 7 and in some of the other figuresj will be described in greater detail . : ~ . , ............................ , :
,: . '. ~ , . :
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later in the Specification with reference to ~igure -l5. With a typically sized device (say two foot long) the weight 40 might be of -the order of one pound.
In the inoperative condition of -the device (with spring 22 compressed and envelope 8 and balloon 30 deflated) the envelope and the balloon will be tightly rolled up and packed snugly in a carrying case (not shown) which amongst other things will be ;~
effective to maintain the expansion spriny in its compressed state.
If the user falls overboard say and desires to use the marker balloon 30 to indicate his positlon for rescue purposes, then with the device immersed in the water he opens the lid of the carrying case and the weight 40 will fall out dragging the rest of the device behind it. Spring 22 as soon as it is free from the restraining action oE the carrier case will expand causing ambient watcr to be sucked into chamber 12 through valve 2k. ~igure 4 shows the device at this stage. Numeral 48 in Figure 4 indicates the surface of the sea of course. Line 36, which is affixed inside the carrying case (itself affixed to the wearer), will ensure that the device remains attached to its user.
The sea water that has entered water chamber 12 will quickly percolate through the wick 20 (e.g. in 5 to 7 seconds) into the reaction chamber 10. While all this i9 happening the opposite walls of those portions of the envelope defining the reaction chamber 10 will be held tight together by the pressure exerted by the sea on the outside of the device. However, after the first water has arrived in the reaction chamber 10 and the gas generating process ' ': :~
~' . , ~ - ~
~s~
has commenced, the gases producecl in chamber 10 will quickly :increase the internal pressure in this par-t of the device until it excseds the external pressure exerted by the sea and when this happens -the walls of the reaction chamber 10 will be forced apart and the rest of the water in chamber 12 can fali freely into chAmber 10. This is the si-tuation shown in Figure 5. Typically it m:ight take some fifteen seconds to inflate the r0action chamber in this way. It will be seen that the device now has sufficient buoyancy to float with the balloon ehd of the device clear of the sea.
The increased internal pressure in the device will also be effective to close valve 2k thereby preventing further water from being introduced into the device for the gas-producing reaction.
In one typical embodiment put under test, about 20 seconds elapsed from when the valve 2k was opened to when sufficient water has percolated through into -the reaction chamber via wick 20 for -the gases to expand the envelope into the position illustrated in Figure 5. This is adequata time:for the chamber 12 to fill by the required amount.
When the gas generating reaction has progressed to som~thing near its final stage, the pressure in the device will be sufficiently high to rupture the membrane 26 and the gas generated by the reaction will escape through transfer chamber lk to inflate this part of the device and to commence inflation of the balloon 30.
As already explained the purpose of the membrane 26 is to~contain the reaction to a reasonably small volume during at least the major part of the gas generating process.
: -: .:
.. . . .
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' '' ', ' ': , ' '~: ' ' : . ~ . .
~.~B~4~g Sufficient gas is generated in the process for the balloon to be in a satisfactorily infla-ted condi-tion by the time the pressures in the balloon and the device have equalised. At this point the valve 3~ closes (Figure 6).
rhe water soluble link 46 referred -to earlier has all this time been exposed to the action of the sea, and is of such a size, and so designed, that after the balloon has been fully inflated, link 46 will finally dis~olve completely away allowing the two lines 42 and 44 to separate. The mass 40 will now be free to fall under its own weight dragging down the balloDn-end of the device into the sea as shown in Figure 7. Wlth the balloDn end of the device immersed as shown, the sea water will quickly dissolve the water soluble connection 110 and the balloon will rise to the end of its line 34 to indicate the position of the wearer of the de*ice.
Typically, line 34 would be about 100 feet long. Reference numeral 50 in Figure 7 indicates the remains of the exhausted chemical reaction.
Referring now to Figure 8 this shows an embodiment of the invention in which the essential difference from the previous embodiment is that the positions of the water chamber and the reaction chamber have been interchanged. Thus whereas in the embodiment of Figures 1 to 7, the ambient water enters the water chamber 12 and percolates downwardly through wick 20 into the reaction chamber lO(t ïn the embodiment of Figure 8, the wick is omitted and instead the bag of gas generating chemicals extends downwardly from the reaction chamber into the top of the water :. . ~ : . ,: , ~ ~, , f ~
5~
chamber so that when the desired amount of water has been taken into the water chamber through valve 24, it will come into contact with the lower end of the bag 18 and gas generation will commencen As the bag 18 is made of water soluble material, at least that part of it wetted by water from chamber 12 will very quickly dissolve away (e.g. in 2 or 3 ~ec~nds~ allowing the chemicals 16 to pour freely from the bag into the water chamber for completion of the gas generation process.
In the embodiment of Figure 9, the spring-biassed flexible-walled water chamber 12 of the earlier embodiments, is replaced by a rigid-walled chamber 52 and the valve 22 is covered by a water soluble plug 54 e.g. of an effervesc0nt compound such as Alka-Selzer (marketed by Miles Laboratories Limited)~ Alternatively a water soluble film could be used to cover the valve e.g. of the type used in connection llO.c The devic~ comes with'chamber 52'air free 90 ,that typically after Z or ~ second~ ~hen plug 54 ha3,d~solved,sea uater will'be sucked into the water chamber and the device will commence to operate in an exactly analogous fashion to that already described with reference to the embodiments of Figures 1 to 8~
Figure 10 shows yet another embodiment. In the device of Figure 10, the water chamber and the reaction chamber are provided~by,different portions of a rigid walled part 56 with the '~
chemicals initially housed at the top end section and the water chamber provided by the lower sections. The ballast weight ill2) 25 is secured in the bottom of part 56 by a bolt 114 . At it3 upper end, the device has an apertured lug 116 enabling the device to be attached by a line 118 to a life buoy for example.
r .,~ ~ , 1~.
i 1~11 35~
Part 56 is in fact only the lower piece of a larger housing 120 in the top piece of which are contained a flexible transfer chamber envslope 14 and the marker balloon 30 to be inflated. The top and bottom portions of the housing are internally separated by a plat~l22 but this latter is centrally apertured (at 124) to provide a conneotion between the interiors of the transfer chamber and the reaction chamber.
An 0-ring 126 secures tha bottom of envelope 14 to the plate 122~ but other similar fixings oan be used instead if desired.
The top qnd of the housing 120 is in the form of a removable lid 128 which is secured by a short line 130 with a carrying `: -bracket 132 for the device. ~racket 132 might for examPle be secured to a light craft, boat or ship.
Reference numerals 134, 136 indicate two tube~ leading from peripheral apertures in the plate 122 to the bottom of the water chamber 12. The top ends of the tubes are a~sociated with one way entry valves 138, 140 arranged to permit a downwards flow of water through the two tubes. Typically valves 138, 140 might be disc or ball valves.
In operation of this embodiment, the device is removed from its support bracket and is hurled with its lifebuoy tnot shown) into the the sea. The line 130 will be put under tension to jerk the lid 128 off the container so that it is open-topped when it hits the water.
The buoyancy of the device is such that it will begin to sink under its own weight and water will pour in at the top end of the housing.
From there it will drain through tubes 134, 135 into the bottom of -the water chamber 12. When the water has risen to ~ ` :
the level of the chemictlls 16, gas generation will commence and the increase in pressure in -the reaction chamber will close valves 138, 1~0 preventin~J further water from entering -the lower part of the device.
The dimensions of the wa-ter chamber are such, of course that by this stage sufficient water will have been accep1;ed for comple-tion of -the ~as genera-ting process.
At a predetermined pressure produced a-t or near completion of the gas generating process, -the membrane 26 will burs-t and the transfer chamber envelope 14 and the marker balloon 30 will in-~late in the usual way. The transfer chamber 14 is provided with a vent hole 61 at some point above -that at which the balloon is attached.
Gas is allowed -to escape through -this hole from the time that the membrane bursts and gas enters -the transfer chamber but the rate of escape is small in rela-tion to the input into the balloon.
When the reactlon ceases, the pressure in the transfer chamber is roughly the same as -that in the balloon but with valve 32 closed, the residue gas in chamber 14 will continue to vent to atmosphere through hole 61 until the buoyancy of the device is sufficiently reduced for the weight 112 to sink it to a Ievel at~which the neck of the balloon is immersed in the sea. The water soluble connection 110 will dissolve away soon after.
The essential difference between thq embodiment of Figure 11 and that of Figure 10 is that whereas in the earlier embodiment the water enters the top of the devicq and is conveyed from there to the bottom of the water chamber through appropriate tubes, in the embodiment of Figure 11, the water enters the bottom of the device : : :
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"
directly into the water chamber. As wi-th the previous embodiment however, the water chamber and the reac-tion chamber are still provided in different portions of a common rigid walled part 56 with the chemicals initially housed a-t the top end of the section (at a position indica-ted by numeral 1~2 in Figure 11) so that sufficient watel to compLete the gas-generating reaction must have been talcen into the device before the water can contact the chemicals and the en-try valve (1~) be closed by the gas pressure generated by the reaction.
In the modification shown in Figure 12, an annular mass 62 is included at the bottom of the water chamber so that even when -the gas-producing operation has been completed and membrane 26 has ruptured, the net weight of the device is still sufficient to hold the water soluble connection 110 below sea level. Obviously as before this connection must be such that it will not free the balloon until sufficient time has elapsed for this latter to be fully inflatedO Al-though relatively bulky when compared with the previous embodiment, the embodiment of Figure 12 offers an alternative version of the device in which the need to change the orientation of the device at some stage in i~s operation is done away with.
Figure 13 shows a rigid-walled version of the device in which the transfer chamber and the water chamber are one and the same thing and the reaction chamber (10) is at the opposite end of the device to the ballast weight 40 and the balloon 30.
- -In thi~ embodiment the ballast weight l~0 pulls the device down so that sea water enters the combined transfer/water chamber ~64) via the one way entry ~alve 18. When sufficient water for the complete gas-generating reaction has en-tered the chamber 64, the l-water soluble link 46 will finally dissolve away and the maqs willmove under gravity to pull the device over a~ indicated in Figure 14.
This will cause ths water to be thrown on to the chemicals 16 and the gas producing reaction will commence. When the balloon has fully inflated, a water soluble plug (or 3eal) 66, in what i~ now the lower part of the device, finally dis~olves away allowin~l water to entertthe device to sink it to a level at which only the buoyancy of the balloon in the sea will keep it afloat. Thi~
immerses the water soluble connection 110 in the sea and thi~
connection quickly dissolves away to allow the balloon to rise to the end of its line and the device to sink awayO
Fi~ure 15 shows on an enlarged scale the link 46 referred to above and shown in the various other Figures of the drawings. '~
It will be seen from Figure 15 that the link comprises a casing 67 apertured at 68:and containing a water soluble tablet 69 which traps the line 42 in the casing. The tablet might, ~or example, be a water-soluble 'effervescent~ tablet e.g. an Alka~Selzer tablet of approximately 1 inch diameter and 3/16 inch thick~e~3' with a'ce'ntral `of'hole 3/16 inch diame~e~., TypicalIy th~ di'ssol~ing ti~ of this tablet,might be approximately 11 minutes~
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r . I . j ; .
~08~
Line 44 i9 secured to the casing itself. Wherl the tablet has finally dissolved, line ~2 is free to leave the casing through aperture 68 and the mas~ 40 can swing away under gravity supported by the line 38.
Referring now to Figure 3, this shows on an enlarged scale preferred versions of the valve 32 and reel 100 referred to earlier in the Specification. As will be seen from this Figure, the illustrated valve is basically of a flexible balloon-like construction. In the illustrated embodiment in fact, a standard Aeriel balloon ~narkebedby the London Rubber Company Limited) was modified for this purpose by punching a hole 70 through the balloon and then stapiing its two walls together at 74 to encourage them to cling together in response to even a very small excess pressure on the outside faces of the valve. The stem portions of the valve 32 and themarher balloon 30 are secured by 0-rings 71, 72 on to a connector piece 73 which is held in an abutting relationship with the nipple 28 by several turns of water soluble material held in place by 0-rings 72 75~ In the illustrated embodiment, this ~) .
material is a polYvinyl acetate (PVA) film marketed by ENA~ Limited, three turns of 0.002 inch thickness film being sufficient to give the desired dissolving time of 30-60 seconds. Of course if other dissolving times are required, these can be ~btained by changing the number of turns andjor the grade of the PVA film.
At its lower end, nipple 28 is rigidly mounted in an attachment plate 76 welded into the wall of that part of the '. : ' ' '.
4~L
envelope 8 providing the transfer chamber 1l~. Alternatively plate 76 cou1d be attached to the envelope by an adhesive.
In addition to supportirl~ nipple 28, the attachment plate 76 carries an anrlular disc 77 forming the lower one of two such discs 77, 78 which together constitute the reel lO0. The assembly procedure is as folLows. When -the valve 32 and balloon 30 have been assembled as described (in their deflated states of course), then a collapsible mandrel is placed on disc 77 and line 31~ is wound around the outside of the mandrel as a coil 79. The inner end of the coil is secured to a brass ring 80 carried on the neck of the balloon 30 and too large to pass through 0-ring 71. The outer end of the coil is secured -to a top corner of the device as shown at 81 in Figure 2.
The -top disc 78 is now secured in place by a number of attachment ' lugs 82 bent up from the lower disc 77 as shown in Figure 3. ~he mandrel conveniently takes the form of a flat semi-circular spring.
This spring is now compressed to an increased curvature enabling it to be removed through the aperlure in disc 77. This completes the assembling of reel lO0.
.
. . . ...
Claims (15)
1. A device for generating lighter-than-air gas to inflate an object, the device comprising chemicals to react with water to produce a lighter-than-air gas, a reaction chamber housing said chemicals, a water chamber for containing water for the reaction, a valve means operable when the device is immersed to permit the entry of ambient water into the water chamber, and control means operable to delay the closing of the valve means and the transfer of a significant quantity of water from the water chamber to the reaction chamber until such time as sufficient water to complete the whole of the desired gas--generating reaction has been accepted into the water chamber.
2. A device as claimed in claim 1 in which the control means providing a restricted water flow capacity includes at least one of a wick, one or more narrow-bore tubes, and container walls easily collapsed together by external pressure, the means at least initially providing substantially the only water path from the water chamber to the reaction chamber.
3. A device as claimed in Claim 1 or Claim 2, in which the water chamber and at least that part of the reaction chamber housing the chemicals are separated by a flexible-walled section which prior to the generation of significant quantities of gas in the device is held in a collapsed state by the ambient water pressure acting on the outer walls of the section.
4. A device as claimed in Claim 1 adapted, when initially immersed in ambient water, to assume an orientation in which the water chamber is at a lower level than the reaction chamber, the device including a connection between the water chamber and the reaction cham-ber at all times providing an unrestricted passageway for a free flow of waker between the two chambers, a mass secured to one end of a length of line, a permanent attachment be-tween the other end of the line and a first region of the device, and a water soluble connection providing a temporary attachement between an intermediate portion of the line and a second region of the device.
5. A device as claimed in Claim 1 including a connec-tion for the object to be inflated and a transfer chamber separating the connection from the reaction chamber.
6. A device as claimed in Claim 5 including a closure member between the transfer chamber and the reaction chamber, the closure member being adapted to open only in response to a pressure on the gas-generating side of the member indicative of the gas generation process having reached, or nearly reach-ed, its final stages.
7. A device as claimed in Claim 1 including a flexible part, a catch, and means for automatically expanding said part on the release of said catch.
8. A device as claimed in Claim 7 including a water soluble restraint member which member initially holds the catch closed.
9. A device as claimed in Claim 1 evacuated during its manufacture, the device including closure means adapted to open only when the device is immersed.
10. A device as claimed in Claim 1 adapted to sink under its own weight, the device including surfaces defining an opening through which water enters the inside of the device as it sinks.
11. An assembly including a device as claimed in Claim 1 connected up with the object to be inflated, and a valve to control the flow of gas from the device to said object.
12. An assembly as claimed in Claim 11 in which the valve comprises an envelope of flexible resilient material, a first portion to said envelope apertured to allow ingress of gas from the device into the envelope, a second portion to said envelope housed inside the object and apertured to permit gas in the envelope to escape into the object, and a pair of op-posed wall regions lying between the aperatures in said first and second portions and urged towards each other into a valve-closing relationship by the pressure of the gas in the object.
13. An assembly as claimed in claim 11 including a water soluble connection by which the object to be inflated by the device is initially attached to it.
14. An assembly as claimed in Claim 13 in which the connection is initially held clear of the ambient water by having the device initially in a floating condition with the connection clear of the water, the assembly including a movable mass used to change the orientation of the device at a suit-able instant to immerse the connection in the water.
15. An assembly as claimed in Claim 13 in which the connection is initially held clear of the ambient water by having the device initially in a floating condition with the connection clear of the water, the device including a vent to atmosphere whereby gas continuing to leak out through the vent results in the device sinking to a level at which the connection is immersed in the ambient water.
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB128075 | 1975-01-13 | ||
| GB01284/75 | 1975-01-13 | ||
| GB01279/75 | 1975-01-13 | ||
| GB01280/75 | 1975-01-13 | ||
| GB01285/75 | 1975-01-13 | ||
| GB128475 | 1975-01-13 | ||
| GB128575 | 1975-01-13 | ||
| GB1279/75A GB1505842A (en) | 1975-01-13 | 1975-01-13 | Gas generating systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085141A true CA1085141A (en) | 1980-09-09 |
Family
ID=27447147
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA243,035A Expired CA1085141A (en) | 1975-01-13 | 1976-01-06 | Gas generating systems |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5195385A (en) |
| AU (1) | AU499141B2 (en) |
| CA (1) | CA1085141A (en) |
| DE (1) | DE2601029A1 (en) |
| DK (1) | DK11076A (en) |
| ES (1) | ES444246A1 (en) |
| FR (1) | FR2297077A1 (en) |
| GB (1) | GB1505842A (en) |
| NL (1) | NL7600322A (en) |
| NO (1) | NO143205C (en) |
| SE (1) | SE7600181L (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58174086A (en) * | 1982-04-02 | 1983-10-13 | Yoshifumi Sakamoto | Gas self-generating type floating device |
| CA1313027C (en) * | 1987-10-15 | 1993-01-26 | George Plester | Supply of controlled medium-pressure co -gas in simple convenient disposable packaging |
| US5398850A (en) * | 1993-08-06 | 1995-03-21 | River Medical, Inc. | Gas delivery apparatus for infusion |
| DE19803552C2 (en) * | 1998-01-30 | 2000-05-25 | Eberhard Wistuba | Means for generating gas pressure |
| FR2969934B1 (en) | 2010-12-30 | 2013-01-25 | Snpe Materiaux Energetiques | AUTORAGGED PRODUCTION, IN IMMERED CONDITION, OF A GAS GENERATED BY CHEMICAL REACTION BETWEEN A LIQUID AND A SOLID; ASSOCIATED DEVICE |
| CN103547506B (en) * | 2011-02-25 | 2018-07-13 | 阿基米德私人有限公司 | Buoyancy system |
| CN115337868A (en) * | 2021-05-14 | 2022-11-15 | 广东小天才科技有限公司 | Gas generating device |
| WO2023131942A1 (en) * | 2022-01-05 | 2023-07-13 | Neomare Ltd. | Wearable inflatable flotation device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH199914A (en) * | 1937-11-06 | 1938-09-15 | Ind Patentwerte Kontroll A G | Rescue apparatus. |
| US3355751A (en) * | 1965-12-27 | 1967-12-05 | Bryan M Mcgroarty | Automatically inflatable objects |
| US3461835A (en) * | 1966-11-22 | 1969-08-19 | Lionel Hellier Ltd | Water-activated balloon inflating device |
| US3733180A (en) * | 1971-01-08 | 1973-05-15 | Boeing Co | Solid state cool gas generator |
-
1975
- 1975-01-13 GB GB1279/75A patent/GB1505842A/en not_active Expired
-
1976
- 1976-01-06 CA CA243,035A patent/CA1085141A/en not_active Expired
- 1976-01-09 SE SE7600181A patent/SE7600181L/en not_active Application Discontinuation
- 1976-01-09 AU AU10168/76A patent/AU499141B2/en not_active Expired
- 1976-01-12 NO NO760076A patent/NO143205C/en unknown
- 1976-01-12 FR FR7600646A patent/FR2297077A1/en active Granted
- 1976-01-12 JP JP51003129A patent/JPS5195385A/ja active Pending
- 1976-01-13 NL NL7600322A patent/NL7600322A/en not_active Application Discontinuation
- 1976-01-13 ES ES444246A patent/ES444246A1/en not_active Expired
- 1976-01-13 DE DE19762601029 patent/DE2601029A1/en not_active Withdrawn
- 1976-01-13 DK DK11076*#A patent/DK11076A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| NL7600322A (en) | 1976-07-15 |
| DE2601029A1 (en) | 1976-07-15 |
| AU1016876A (en) | 1977-07-14 |
| GB1505842A (en) | 1978-03-30 |
| NO143205B (en) | 1980-09-22 |
| SE7600181L (en) | 1976-07-14 |
| FR2297077A1 (en) | 1976-08-06 |
| FR2297077B1 (en) | 1981-03-27 |
| ES444246A1 (en) | 1977-10-01 |
| JPS5195385A (en) | 1976-08-20 |
| AU499141B2 (en) | 1979-04-05 |
| NO760076L (en) | 1976-07-14 |
| DK11076A (en) | 1976-07-14 |
| NO143205C (en) | 1981-01-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |