GB2255502A - An inflatable bulkhead arrangement - Google Patents

Abstract

An arrangement 10 of bags 12, 14, 16, 18 adapted to be inflated to form a bulkhead 20 can be used to inhibit e.g. the spread of fire, toxic gases, floods in e.g. ships, submarines, mines, tunnels, liftshafts, trains. Further described is a bag having an internal gusset (64, Fig. 9) with a free end (66, Fig. 9) that can flap to close a compartment of the bag, in case of rupture. Described also is a valve mechanism for use with such bags. <IMAGE>

Description

TITLE SAFETY AND/OR CONTROL ARRANGEMENTS FIELD OF THE INVENTION This invention relates to arrangements that may be used for safety, and/or control particularly (but not exclusively) in a safety context.

BACKGROUND TO THE INVENTION In a passage or enclosure, safety procedures often require use of a closable bulkhead, i.e. partition means that can be closed, e.g.

in an emergency, to separate a volume into two regions to prevent or at least inhibit spread therepast of e.g. flood, fire or noxious or contaminated gases, e.g. a ships bulkhead with a closable door, fire doors in a corridor, and sliding doors e.g. of the portcullis type for use e.g. in a mine. All of the known arrangements are obtrusive, slow-acting or (e.g. the portcullis) potentially dangerous themselves during operation in an emergency.

THE INVENTION According to one aspect of the invention, there is provided an arrangement of bags adapted to be inflated to form a bulkhead. This can be arranged to occur with any desired degree of control and/or response to obstr uctions encountered, or rapidly, even explosively, and/or automatically, e.g. in response to various specified emergencies.

The arrangement could of course be used in a non-emergency situation where a temporary bulkhead is required. The bags may be designed (e.g. by their shape and choice of material) to inhibit flow of fluid therepast completely or partially, asvrequired. This can also be effected by suitably controlled pressurising means to inflate the bags.

The bags may be arranged around the periphery of the cross-section of the space in which the bulkhead is to be formed, e.g. in a suitable recessed channel e.g. connected to a manifold to supply inflating gas. (Alternatively, tkxy might be located uninflated somewhere in the middle of such cross-section, in a self-contained device, or simply connected to an inflating gas supply, and able to expand to fill the cross-section.) The bags, being flexible, can be inflated to-any desired pressure, to form a rigid or flexible bulkhead, etg. so that they can be pushed aside for a moment for a person to pass the bulkhead which will then regain its shape.

The inflating gas can be supplied from a måin and/or from cylinders, e.g. a local cylinder may be provided to act as a back-up for a main supply, either in case of failure thereof or to maintain pressure after the initial inflation by the main supply, or to initiate inflation which is then maintained by the main supply, by suitable valve arrangements.

In the absence of a main supply, at least two local cylinders should be used. For initial high-speed, emergency inflation, a particularly suitable gas is cylindered, white spot, liquid nitrogen which, being dry, can expand rapidly without producing ice to foul up valves. The back-up, to maintain pressure and inflation, may alternatively be an existing compressed air system.

The aforesaid recessed channel, at least in a floor portion (and possibly the sides) of e.g. a tunnel, may be provided with a closure, i.e. individual fingers or plates hinged to one side of the channel at its top edge, possibly with a complementary interdigitating arrangement at the opposite side, top edge of the channel so that the fingers or plates can, individually or in small groups, cover and protect the uninflated bags, e.g. to allow the passage of vehicle wheels and thereover and yet open rapidly/easily to allow the bags to inflate.

The closure may comprise what may be termed a duckts foot covering, i.e. the fingers or plates being gusseted together like a ducks foot. The gussets may also be connected to the bag and they can ensure that all the fingers or plates of the closure open with the inflation of the bag and they may also seal the channel against ingress of liquid before the inflation. The bags may be anchored in such channel fixedly or flexibly, and may be positioned loosely therein. Preferably, the bags are permanently rooted to a gas-tight chassis lining or forming said channel. An inflating gas supply manifold for the bags should be flexible, and flexibly or loosely mounted, or have flexible interconnections with the bags.

The arrangement around the periphery may comprise upper and lower triangular bags and lateral trapezoidal bags to provide a vertical central closure. This would facilitate people passing therethrough and the lower bag's triangular shape would maximise the sealing effect upon inflation with a vehicle parked over that bag.

A plurality of such arrangements have particular application to a long tunnel and, e.g. with reference to the Channel Tunnel, which is designed to have very long trains with individual carriages each carrying several cars or other vehicles and a cover over these forming of each carriage an elongate enclosed space, application to mobile use fixed between vehicles within such elongate spaces. The arrangements are then particularly useful to separate the vehicles on a carriage from one another by forming a bulkhead therebetween in case of fire starting up in one of the vehicles. The arrangements can also be used in ships, particularly oil tankers and submarines, and (horizontally) in lift shafts.

According to another aspect of the invention, a bag or other flexible structure is provided with an internal gusset or other partition having one free end fixed to side walls of the structure and able to flap intermediate them. Preferably, the partition has a flare at the free end to facilitate its flappability. (Alternatively, the side walls might approach each other in this region.) Usually, the partition will be one of several, or many, filling the structure to divide it into parallel or neighbouring elongate compartments, e.g.

like slices of a loaf. Alternate such partitions in the structure may be short and long so that the free ends are staggered and all facing in the same direction. The free ends, in use, face a gas supply or pressure source, e.g. they face towards the interior of a spacecraft, and the structure then has the effect that if one compartment is ruptured this will collapse and the two free ends of the gussets defining the compartment will flap into a position in which they form a partial or complete seal against said gas supply or gas from said pressure source escaping through the ruptured compartment, thus maintaining the integrity of the structure. This could be adapted to flow control of liquids. The arrangement has particular utility in the aforementioned bag arrangement, as will be apparent.It can also be used in airships, space stations, car crash bags (such as those which inflate to cushion the driver against impact), pressure failure situations and many other applications which will readily spring to mind.

The partitions are bonded along both sides to the outside envelope of eOg. the bag, and usually around one extremity, while the opposite (e.g. flare) end is free so that it can flap and is terminated short of the gas manifold so as to remain clear thereof.

The partitions, while arranged substantially parallel, will preferably curve åpart towards their bonded extremities, especially in a region where the envelope has a corner, (somewhat like the lines of a force field near a corner boundary.) The aforementioned shorter such partitions may be particularly introduced in such corner regions.

The compartments may themselves be subdivided by cross partitions, e.g. of similar structure but slightly shorter at the gas supply end, The bag or flexible structure may be formed of a tough woven material, e.g. nylon, bonded to an adhered layer of gas-inpermeable material, e.g. polythene. An example of an apparently suitable such material is the laminated high tensile material already marketed in various applications by Stewkie Limited of Manor Farm House, Melbury Osmond, Dorset DT2 OLS, United Kingdom, and shown on the television programme "TomorrowXs World" on Channel BBC1 on 4 January 1990. Bags of this material can be inflated to 200 atmospheres pressure and have the rigidity of a metal structure, or to a lower pressure depending on the flexibility required. The flexibility can also be used to allow useful inflation of the bags arrangement if there is an obstacle, e.g.

a vehicle or debris, and indeed use the obstacle as part of the bulkhead, allow full inflation if the obstacle is removed, and generally allow adjustment and compensation to maximise efficiency of the bulkhead.

The material used must of course accord with any required specification of fire or flame retardance. The bags arrangement or other flexible structure can be provided at its extremities, periphery or exterior with small compartments like bubbles or pouches that can further strengthen, help to cushion against shock and/or help to capture or stop penetrating fragments, and/or can be provided at its sides with pouches or even large compartments for similar purposes, e.g. to act like a crumple zone of a car.

According to a further aspect of this invention, there is provided a valve arrangement characterised in that it can hold closed against a high inlet pressure and a low outlet pressure, then be triggered to open and then react to the occurrence of outlet back pressure exceeding the inlet pressure to close and hence act as a check valve. As hereinafter described, this mmay comprise a valve which can be armed to hold closed against a high inlet pressure and a low outlet pressure and triggered to flip fully open as an expansion valve and then subject to outlet back pressure greater than the inlet pressure to close and act as a check valve, and thereafter act as a regulatory valve.

Novel features of the valve arrangement are considered to reside in the parts t the centre, the balance of forces mechanism, the flip control arrangement of sprung plates, seating and core valve, the manner of release with triggering, the hollow core which closes ports and has an end valve (for ease of sliding and machining, and coping with large differential expansion of parts when the liquid expands to saturated vapour with consequent high degree of cooling), the solenoid operation through the spring plate "lost motion' mechanism, the capillary bore being in the body of the casing to provide strength and protection when arming, when holding closed and under the back pressure, the capillaryts check valve, and the capillary's use to equalise pressure on the head of the main valve (to ensure it closes automatically).

It will be apparent that such an arrangement is highly suitable for use in a main or local gas supply to the aforementioned bag arrangement.

It should be noted that the high degree of cooling upon the sudden expansion of the liquid. gas increases the bag arrangement1s ability to protect against heat.

The various arrangements described can be armed at any suitable time and triggered either manually or automatically, e.g. in an emergency by the occurrence of crash conditions, impact (e.g. using an inertia switch), fire, heat, alarm signals, explosive or high pressure or shock conditions, or flooding, or any combination of these or other conditions which will be apparent to one skilled in the art.

LIST OF DRAWINGS Reference will now be made by way of example to the accompanying drawings, in which: Fig.l is a schematic elevational view of a bags arrangement embodying the invention arranged around the periphery of the cross-section of a tunnel, after inflation; Fig.2 is a corresponding view of an independent device which is similar except that it is self-standing and located at the centre of the cross-section intended to be occupied by the bulkhead, e.g. for use between cars on a carriage; Fig.3 shows the configuration of the Fig.l arrangement on such a carriage when obstructed by a parked vehicle; Fig.4 shows the configuration of bags in the Fig' .1 or the Fig.3 case when a vehicles wheels are standing over the base bag;; Figs.5 and 6 are schematic plan views showing alternative embodiments of protective fingers covering the uninflated base bag; Fig.7 is a perspective elevational view of one of the Fig.5 arrangements in the Fig.4 position; Fig.8 is a cross-section on the line 88 of Fig.5 but of another embodiment; Fig.9 is a crosssection on the line 9-9 of Figs. 10 and 14; Fig.10 is a longitudinal cross-section of a gusset arrangement embodying the invention, e.g. as used in the triangular base bag of the Figol arrangement; Fig.ll is plan view of a gusset before bonding to a bag envelope;; Fig.12 is a view corresponding to Fig.9 of the Fig.ll gusset bonded into a bag of rectangular cross-section; Fig.13 is a cross-section on the line 13-13 of Fig.9 but of a further embodiment; Fig.14 is an elevational view of one lateral trapezoidal bag of the Fig.l arrangement, but indicating alternative embodiments; and Fig.15 is a cross-sectional view of a valve arrangement embodying the invention and suitable for use with the bags arrangement of Fig.1 or the bag and gusset arrangement of Fig.9.

DESCRIPTION OF PARTICULAR ESBODIMENTS Referring to the drawings, an arrangement 10 of bags 12,14,16,18, shown in dashed lines uninflated in Fig.l is adapted to be inflated to the positions shown in full lines in Fig.l to form a bulkhead 20 sealing tunnel 22. The uninflated bags are located in a channel 24 connected to a manifold 26 which extends right around the periphery of the cross-section of the tunnel illustrated in Fig.l although only a portion of the manifold is actually shown. The bags may toe made of any suitable material, e.g. those mentioned above or an elastomeric material. Depending upon required qualities, any of the materials used in the past for barrage balloons, airships or radiosonde balloons may be suitable.Gas can be supplied to the manifold 26 from a main supply 28 and from a local cylinder supply 30 via a valve 32 to be described below.

In an alternative arrangement 34 shown in Fig.2, bags 12,14,16,18 shown in full lines uninflated are connected to a gas cylinder 30 through valve 32 and manifold 26 and can inflate to the chain line positions shown in Fig.2 from their uninflated positions in the middle of said cross-section of the tunnel 22 where they are supported by the cylinder 30 on a base 36 standing on the floor 38 of the tunnel 22.

However, this free-standing arrangement 34 is more likely to be used mobile, standing on the floor 40 of a carriage 42, Fig.3,and inflatable the cross section of to fill/a canopy 44 over the carriage 42 and vehicles 46 carried thereon. After the vehicles are placed in position with their brakes on, arrangements 34 would be placed between successive vehicles 46.

However, as shown in Fig.3, there is an-arrangement 10 of the )peripheral kind shown in Fig.l and Fig.3 shows how this is inflated when a carried vehicle 46 is parked across the arrangement 10. The bags inflate to fill substantially all of the space around the vehicle 46 and hence use the vehicle itself to form part of the bulkhead. Fig.1 shows that the upper and lower bags 16,14 are triangular and the lateral bags 12,18 are trapezoidal to provide a vertical central closure 48.

has a height 49 which This/is roughly one-third of the height of the tunnel 22 or canopy 44 and spaced about one-third of that height from the top and floor of the tunnel or canopy. Preferably, closure 48 is 35% of that height, spaced 35% from the top and 30 < 0 from the floor, these of course in the unobstructed condition shown. The bottom bag 14 being slightly lower is particularly suitable in case a vehicles wheels 48 are parked on it, as shown in Fig.4.

possibly The recessed channel 24 is provided with a/duck's foot covering closure 50, Fig.5, comprising individual fingers 52, which raay be interconnected by gussets 54, see also Fig.7, connected by hinges 56, at one side of the channel 24 at its top edge, Fig.9. In an alternative embodiment, Fig.6, there is a complementary interdigitating arrangement of fingers 58 similarly connected at the other side of the channel. In either case, the fingers 52,58 rest on the top edges of channel 2 when the bags are uninflated so as to cover these and protect the when vehicles pass over them.By making the hinges 56 in the form of light springs urging the fingers into the closed position shown in chain lines in Fig.9, a particularly simple, cheap and effective arrangement is obtained, while the fingers can yet open easily and rapidly upon inflation of the underlying bag 14 until they stand flexibly in upright positions, as shown in Figs.4 and 7. Fig.8 shows an arrangement in which half fingers 53,55 rest on the top edges of channel 24 with suitable seals 57 and are swung up into the chain line positions on inflation of bag 14 helped by the movement of bag 14 to which they are attached, producing a combination of lifting and sliding them upwardly into the chain line positions.

Referring to Fig.9, the bag 14 is fixed at its root by means of two plates 60 to a gas-tight chassis 62 lining said channel 24. - Each of the other bags 12,16,18 is arranged similarly, except that it may not have closure fingers 52. The bag 14 is provided with an internal gusset 64 having one free end 66 fixed to side walls 68,68 of the bag 14 so that this free end is able to flap intermediate the walls 68,68, i7e. the length of the free edge 66 is greater than the spacing between the walls 68,68. If the gusset 64 is to be fitted to a bag 14 that, when inflated, will have parallel side walls 68,68, it is provided with a flare 70 at its free end so that it has a template shaped as shown in Fig.11. It is then bonded, e.g. by sewing or adhesive or welding, along both sides to the walls 68,68 of the outside at envelope of bag 14 and likewise around one extremity 72, while/the the gusset root of the bag at the free end/is unbonded so that it can flap as just described and also stops short of the manifold 26, see Fig.12.

If the walls 68, when bag 14 is inflated, approach one another towards the root, as seen in Fig.9, the gusset 64 need not have a flaring template. Usually, bag 14 will have a bulging cross-section in the plane of Fig.9 and gussets 64 will be shaped accordingly.

held in brackets 73 Manifold 26/has gas ports 74 clear of edge 66, preferably one port 74 for each compartment between adjacent gussets 64. The action of the gussets, e.g. at a position 74 upon rupture of the bag at a position 78 has been described above and is shown in Fig. 10 with the relevant compartment collapsed. Fig.10 also shows the alternate arrangement of shorter gussets 80 having free ends 82 staggered with respect to free ends 66 of gussets 64, also (in chain lines) the provision of bubble-like compartments or pouches 84 at the extremity of the bag and e.g. provided with their own gussets 86 to seal in case of collapse.

As indicated in Fig.13, there may be circumstances in which it is by partitions 87 desirable to subdivide/the compartments formed by adjacent gussets 64, nevertheless these should have a long, narrow transverse cross-section this to facilitate collapse but/would usually be countereffective because of the extra material introduced that would bulk out the uninflated bag.

Fig;14 shows the shape of one of the trapezoidal bags l2,'l8 when inflated. However, as also seen fròm Fig*14, separate exterior lateral compartments 88 may be provided, acting in much the same way as the pouches 84, Fig.10.

As seen in Fig.15, valve arrangement 32 is designed so that it can be held closed against a high pressure at inlet 90 and a low pressure at outlet 92, then be triggered by means of a solenoid possible arrangement 94 to open, and then react to the/occurrence of high pressure at outlet 92 exceeding the inlet pressure to close and hence act as a-check valve. It thereafter acts as a regulatory valve.

Main valve 96 locates on seat 98, is connected by a flexible joint 100 to core 102 which fits slidably in plate 104 that can be adjusted in height above seat 98 by being rotated in screw thread 106. Core 102 is provided with a plate 108 that serves to close ports 110 in plate 104 and also serves as a reaction plate to spring 112 bearing against a plate 114, itself bearing against the bottom of a piston 116 operable by the solenoid arrangement 94. Core 102 can slide in piston 116 to close its own valve 118 against seat 120 of resilient material and simul taneously close ports 122 of piston 116. Plate 104 is also provided with a check valve 124. Movement of piston 116 is limited by stops 126,128 and casing 130. A capillary 132 in casing 130 is provided with an expansion valve 134 and a check valve 136. Valves 124,136 are reed valves.

In manufacture of the valve arrangement 32, plate 104 is adjusted to the correct height for valve 96 to seat properly when plate 108 seats on plate 104 and closes ports 110. To set up the arrangement 32, piston 116 is, lowered, depressing plate 114 and through spring 112 also plate 108 and core 102 until valve 96 seats. This is in the unenergised condition of solenoid arrangement 94, which for this purpose may include a light spring urging piston 116 downwards.

To arm the valve arrangement 32, liquid nitrogen is! supplied to inlet 90. Some of it passes through capillary 132, expanding at valve 134 and passing check valve 136 to fill the compartment 138 above plate 104 with high pressure nitrogen gas. There is then low outlet pressure above valve 96 and high liquid nitrogen pressure below it. There is low pressure through ports 110 underneath plate 108 and high pressure above it. There is also the spring 112 gently urging plate 108 and core 102 downwards. These forces act to maintain valve 96 engaging its seat 98.

Triggering of valve arrangement 32, e.g. by an alarm signal, actuates solenoid arrangement 94 which withdraws piston 116 until stops 126 engage stops 128. As piston 116 slides off core 102, valve 118 is unsealed and ports 122 opened. The high pressure nitrogen gas then escapes down bore 140 of core 102 and out through ports 142, thus lowering the pressure in chamber 138. This reduces pressure on top of plate 108 which combines with the reduced force through spring 112 to allow the pressure of liquid nitrogen in inlet 90 to lift valve 96 off its seat 98. The liquid nitrogen then expands into gas at valve 96 which thus acts as an expansion valve and a wave of pressure travelling along outlet 92 can rapidly inflate bags 12,14,16,18. The travelling pressure wave may be reflected and a back pressure set up in outlet 92 which is greater than the pressure in inlet 90.In such case, this pushes high pressure gas through check valve 124 into chamber 138, incidentally closing capillary check valve 136. The increased pressure on the top of valve 96 now allows spring 112 to urge downwardly plate 108, core 102 and valve 96 to close the latter. Thus, arrangement 32 acts as a check valve against reverse pressure from outlet 92. After the reflected pressure wave has dissipated, the excess pressure in inlet 90 again opens valve 96 in the manner above described. Any further reflected pressure waves, or e.g. build up of pressure in outlet 92 due to complete filling of bags 12,14,16,18, serves to close valve 96 in the manner just described. Thus, the arrangement 32 then functions as a regulatory valve, allowing supplementary nitrogen or other gas from inlet 90 to pass to outlet 92 but not allowing reverse flow.

The embodiments described with reference to the drawings incorporate the features described beforehand. It will be apparent that the various features herein described can be combined in many different ways to provide useful embodiments. Many variations and modifications of the foregoing will be apparent to one skilled in the art and invention is considered to reside in any novel and unobvious feature or combination of features hereinbefore disclosed.

Claims (29)

1. An arrangement. of bags adapted, to be inflated to form a bulkhead.

2. An arrangement as claimed in claim 1, in which the bags are arranged around the periphery of the crossçsection of the space in which the bulkhead is to be formed.

3. An arrangement as claimed in-claim 2, in which the bags are arranged in a recessed channel.

4. An arrangement as claimed in claim 1, in which the bags are arranged in a self-contained device that can be located in the middle of the cross-section of the space in which the bulkhead is to be formed.

5. An arrangement as claimed in claim 1, in which the bags are arranged in the middle of the cross-section of the space in which the bulkhead is to be formed.

6. An arrangement as claimed in any preceding claim, comprising a local supply of dry liquid-form gas connected for inflation of the bags.

7. An arrangement as claimed in claim 3, in which at least part of said recessed channel is closed over the uninflated bag or bags by means of a closure comprising individual fingers or plates hinged to open to allow said bag or bags to inflate.

8. An arrangement as claimed in claim 7, in which at least some of said individual fingers or plates are gusseted together like a ducks foot.

9. An arrangement as claimed in any preceding claim, in which the bags are arranged around the periphery of the cross-section of the space in which the bulkhead is to be formed and comprises an upper bag and a lower bag, both substantially triangular, and two lateral bags, both substantially trapezoidal, whereby to form an elongate central closure in the unimpeded inflated condition of the arrangement.

10. An arrangement as claimed in claim 9, in which the central closure has a length approximately one third the total height of the cross-section.

11. An arrangement as claimed in any preceding claim, located around the periphery of the cross-section of a tunnel.

12. An arrangement as claimed in any of claims 1 to 10, arranged around the periphery of a vertical cross-section of a carriage and covering canopy.

at least one

13. A bag or other flexible structure provided with / internal gusset or other partition having one free end fixed to side walls of the structure and able to flap intermediate them.

the partition

14. A structure as claimed in claim 13,/having at the free end a flare to. facilitate its flappability.

15. A structure as claimed in claim 13 or 14, comprising many of said partitions to divide it into parallel or neighbouring elongate compartments.

16. A structure as claimed in claim 15, in which alternate such partitions in the structure are short and long.

17. A structure as claimed in any one of claims 13 to 16, or comprising a gas supply, pressure source/ manifold inlet with all of said free ends facing theretowards.

18. An arrangement as claimed in any one of claims 13 to 17, in which said partitions curve apart towards an extremity thereof opposite said free ends.

19. A structure as claimed in any one of claims 13 to 18, comprising small compartments like bubbles or pouches provided at an extremity of the structure opposite said free end/s.

20. An arrangement as claimed in any one of claims 1 to 12, in which at least one of said bags comprises a structure as claimed in any one of claims 13 to 19.

21. A valve arrangement characterised in that it can hold closed against a high inlet pressure and a low outlet pressure, then be triggered to open, and then react to the occurrence of outlet back pressure exceeding the inlet pressure to close and hence act as a check valve.

22. A valve arrangement as claimed in claim 21, able to re-open and rewolose in accordance with its outlet pressure and hence act as a regulating valve.

23. A valve arrangement as claimed in claim 21 or 22, having a setting mechanism for use in the absence of differential pressure between its inlet and outlet, comprising a main valve, a shaft carrying said valve, a secondary valve attached to said shaft and a pressure chamber closed by said secondary valve, whereby, once said valves have been closed, pressure in said chamber on said secondary valve produces sufficient force via said shaft to hold said main valve closed against pressure at said inlet substantially equal to pressure in said chamber.

24. An arrangement as claimed in any one of claims 21 to 23, comprising a main valve carried at one end of a hollow shaft having at its opposite end a seating valve to control ingress to the hollow and further comprising a second shaft in which said first shaft slides having a seat for said end valve and having ports that can be slidably closed by said first shaft, said first shaft sliding in a partition between two chambers of the valve arrangement.

25. An arrangement as claimed in any one of claims 21 to 24, comprising a main valve carried on one end of a first shaft slidable in a partition between two chambers of the arrangement and carrying a closure plate for ports in said partition, the arrangement comprising a second shaft in which said first shaft is slidable and spring means urging said plate away from said second shaft, said first shaft having a passage communicating between said two chambers and able to be closed by said second shaft when said plate is urged to close said ports in said partition, said main valve opening into one of said chambers, the other said chamber being in communication with the other side of said main valve, whereby withdrawal of said second shaft in a direction away from said main valve causes said chambers to intercommunicate and relieves pressure on said plate whereby said main valve can open and carry with it said plate and hence open said ports for more rapid reduction of pressure in said other chamber and more rapid withdrawal of said main valve and said plate to further the opening of said ports and produce a flip action of the arrangement upon said withdrawal which thus acts as a triggering for the arrangement.

26. An arrangement as claimed in any one of claims 21 to 25, comprising a capillary in a casing of the arrangement interconnecting an inlet with a control chamber of the arrangement and having a check valve allowing flow through the capillary into the chamber but not back.

27. An arrangement as claimed in any of claims 21 to 23, in which a main valve is carried by a first shaft slidable within a second shaft with spring means therebetween to allow a lost motion action under control of pressures occurring within the arrangement.

28. An arrangement as claimed in any one of claims 1 to 12 or 20, comprising a valve arrangement as claimed in any one of claims 21 to 27, arranged to control inflation of one or more of said bags.

29. An arrangement of bags, a structure comprising a gusset or a valve arrangement, substantially according to any embodiment hereinbefore described and/or illustrated in the accompanying drawings.