GB2488964A

GB2488964A - Devices for deconfining a reactive charge inside a munition envelope

Info

Publication number: GB2488964A
Application number: GB9518976.7A
Authority: GB
Inventors: Nicole Forichon-Chaumet; Alain Kerdraon; Michel Vives
Original assignee: Nexter Munitions SA
Current assignee: KNDS Ammo France SA
Priority date: 1994-09-19
Filing date: 1995-09-15
Publication date: 2012-09-19
Anticipated expiration: 2015-09-15
Also published as: GB2488964B; GB9518976D0; DE19534235A1

Abstract

A device for deconfining a reactive charge (5) inside the envelope (2) of a munition (1) comprises at least one heat-sensitive gas-generating composition (7) which is sensitive to a temperature rise or is ignited by a heat-sensitive device initiator device (10,11,12). The gas-generating composition is located in such a way that the pressure increase resulting from its initiation causes at least one opening in envelope (2) for venting charge (5) to the outside of envelope (2). In the embodiment shown the gas pressure causes ejection of the cover (3) and charge (5) from the envelope (2).

Description

S

DEVICES FOR DECONFINING A REACTIVE

CHARGE INS IDE A MUNITION ENVELOPE

This invention relates to devices for deconfining a reactive charge inside a munition envelope.

It may happen that a munition is exposed to a temperature rise such as that produced by a fire.

In such a case, the temperature rise is transmitted through the munition envelope to the reactive material that it contains (such as a rocket propellant charge or the explosive charge of a shell or missile) The temperature rise decomposes the reactive material with a subsequent pressure build-up which may eventually cause the munition to explode.

In order to prevent extremely serious consequences for the personnel having to fight the fire, means for deconfining the munition envelope have been sought, i.e., means which prevent the pressure from building up inside the envelope to such a point that the reactive material may detonate.

L'S Patent No. 4423683 describes a warhead the envelope of which is closed by covers secured by pins.

The pins are designed so that they break when the pressure inside the envelope exceeds a predetermined level. The pins release the covers and thus prevent the pressure from building up inside the envelope.

This solution is not satisfactory. In fact, it does not allow deconfinement unless the reactive material itself has begun to decompose.

Now, in this case, the reaction may propagate too fast to enable the cover release to provide adequate deconfinement to prevent detonation.

Thus, the cylindrical munition envelope may maintain a sufficient confinement to cause the detonation.

Other means have been devised to deconfine the envelope in response to a temperature rise.

Patent number W090/01635 describes a removable system fitted to the outside of the munition with a S firing pin that a bimetallic membrane actuates as it is deformed by heat.

The firing pin is used to initiate a cut-out charge which opens the munition envelope.

This system has the disadvantage of being separate from the munition. The munition is not therefore protected when the system is removed (e.g., when a munition such as a missile is attached to an aircraft) Moreover, this system is complicated, bulky and costly and cannot be fitted readily inside a munition.

One aim of the invention is to provide a deconfining device which is not affected by these drawbacks.

According to a first aspect of the present invention, there is provided a deconfining device for a munition including an envelope containing a charge of reactive material, characterized in that it comprises at least a gas generating composition which is ignited by an initiator device activated by a temperature rise with the gas generating composition placed in such a way that the pressure increase resulting from its initiation causes at least one opening in the envelope which vents the charge to the outside of the envelope.

Preferably, the initiator device i activated at a temperature ranging from 150°C to 200°C.

The initiator device may comprise at least a mixture of zirconium powder and boron powder.

Alternatively, it may comprise at least a mixture of zirconium powder and carbon powder.

According to a first variant, the gas generating composition comprises at least one oxidizing agent, at least one reducing agent and at least one binding agent.

According to a second variant, the gas generating composition comprises at least one propellant powder, such as a single base powder, a double base powder or a composite powder combining in particular an explosive agent and a binding agent.

According to a third variant, the gas generating composition comprises at least one halogenous polymer, particularly a fluorinated polymer, associated with at least one reducing agent and, possibly, with at least one oxidizing agent.

The oxidizing agent may be selected among the following compounds: arnmonium perchlorate, potassium perchlorate, potassium nitrate, sodium nitrate.

The reducing agent may be selected among the following compounds: aluminum, boron, magnesium, titanium.

A typical gas generating composition may comprise: 10-30% by weight of ammonium perchlorate, 50-70% by weight of aluminum powder, 5-20% by weight of binding agent.

According to a second formula, a typical gas generating composition may comprise: 25-45% by weight of sodium nitrate, 55-85% by weight of magnesium powder, 5-15% by weight of binding agent.

According to a third formula, a typical gas generating composition may comprise: 25-35% by weight of ammonium perchlorate, 10-50% by weight of magnesium powder, 5-20% by weight of binding agent.

According to a fourth formula, a typical gas generating composition may comprise: 90-50% by weight potassium perchlorate, 5-25% by weight of aluminum powder, 5-40% by weight of binding agent. a

According to the third variant, the gas generating composition may comprise: 35-65% by weight of magnesium, 10-40% by weight of polytetrafluoroethylene, 5-251 by weight of fluorinated vinylidene copolymer.

According to a fourth variant, the gas generating composition formula may comprise: 20-45% by weight of ammonium perchiorate, 5-30% of aluminum, 5-50% by weight of polytetrafluoroethylene, 10-15% by weight of fluorinated vinylidene copolymer.

According to second aspect of the present invention, there is provided a deconfining device for a munition including an envelope containing a charge of reactive material is characterized in that it comprises at least one heat-sensitive gas generating composition with the gas generating composition placed in such a way that the pressure increase resulting from its initiation causes at least one opening in the envelope which vents the charge to the outside of the envelope.

The initiation temperature of the gas generating composition is preferably within the range from 150°C to 200°C.

The gas generating composition may typically comprise at least one oxidizing agent and at least one binding agent, the oxidizing agents being preferably selected among the following compounds: ammonium perchiorate, potassium perchlorate, potassium nitrate, sodium nitrate, and the binding agent preferably being hydroxylated polybutadiene (HTPB).

A typical gas generating composition may comprise: 55-80% by weight of potassium perchlorate, 45-20% by weight of hydroxylated polybutadiene.

S

According to a second formula, a typical gas generating composition may comprise: 55-80% by weight of ammonium perchlorate, 45-20% by weight of hydroxylated polybutadiene.

According to a particular embodiment of the invention, the munition envelope has at least one embrittled zone in the vicinity of which is located the gas generating composition.

According to another embodiment of the invention, the envelope containing the charge is closed by a cover which is attached to the envelope by a shearing coupling device, the gas generating composition being placed in such a way that the gas pressure shears the coupling device and ejects the cover.

The gas generating composition may be placed at one end of the munition opposite to the end closed by the cover, and the gas pressure is applied to the shearing coupling device through the charge and a driving device placed between the gas generating composition and the charge.

The driving device may consist of a piston or comprise an inflatable bag.

Thus, the invention proposes simple means which are integral with the munition and provide rapid and dependable deconfinement of the munition envelope as the temperature exceeds a predetermined level.

The envelope is thus deconfined well before the reactive material that it contains begins to decompose.

The means proposed by the invention have a simple structure without involving, in particular, any complicated mechanical devices.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:-

I

Figure 1 is a schematic sectional view through a munition with a deconfining device according to a first embodiment of the invention; Figures la, lb and ic are schematic sectional s scrap views of variants of the embodiment of Figure 1; Figures 2 and 2a are a schematic sectional views through a munition with a deconfining device according to a second embodiment of the invention, Figure 2 being a sectional view in plane AA of Figure 2a; Figure 3 is a schematic sectional scrap view of the envelope of a munition on which a deconfining device is installed according to a third embodiment of the invention.

Referring to Figure 1, a munition 1 comprises a cylindrical envelope 2, integral with a bottom 2a, and closed by a cover 3. The external surface of cover 3 is fitted with a primer device 4 of a known type which is not therefore shown in detail.

Cover 3 is linked to envelope 2 by a coupling device, such as threads.

Envelope 2 contains a charge S of reactive material, an explosive such a cyclonite (RDX) or homocyclonite (HMX) in this case.

To improve munition safety, an explosive little sensitive to bullet or shrapnel impacts is advantageously chosen, such as oxinitrotriazol (ONTA) or triamino-trinitrobenzene (TATE) base explosive.

Charge S is separated from envelope 2 by a cylindrical sleeve 6 which is made of a material providing for heat-insulation between the charge and the envelope, such as a filled silicone elastomer or polyurethane. Such an arrangement improves munition safety by delaying the temperature rise of charge 5 in the event of a fire, thereby reducing the risk of detonation.

According to this first embodiment of the invention, the deconfining device includes a gas generating composition block 7 which is separated from the explosive charge by a piston 8 made of light-weight material (such as aluminum alloy, or composite material) The surface of block 7 in contact with bottom 2a and housings 9, which are cylindrical in the present case. These housings contain heat-sensitive composition pellets 10. Block 7 in the present case bears five evenly distributed pellets, only three of which are illustrated (but a different number of pellets may be used).

Pellets 10 are the means used to initiate gas generating composition block 7.

Pellets 10 are in contact with bottom 2a of envelope 2; they are thus directly heated up by the envelope as the temperature rises.

A material with an initiating temperature ranging from 150°C to 200°C is chosen to make pellets 10.

Thus, the device operates as soon as the munition envelope is exposed to overheating and well before such a heating can transform reactive charge 5.

Pellets are advantageously made of a mixture composed of at least zirconium powder and carbon and/or boron powder.

The zirconium/carbon or zirconium/boron couples are chosen because they are relatively insensitive to mechanical actions and their reaction temperature is well defined and close to 150°C.

Moreover, their reaction is strongly exothermic (reaction temperature higher than or equal to 1500°C) and does not produce gases; this ensures rapid and dependable ignition of the gas generating composition without disorganizing the latter.

Zirconium is associated with carbon or boron in stoichiometric proportions of these elements, that is: 89% by weight of zirconium for 11% by weight of boron, or 88% by weight of zirconium for 12% by weight of carbon.

The powders are chosen with an average grain size smaller than 20 micrometers.

Pellets 10 are shaped by compressing powder compositions.

The skilled person will obviously select materials and the quantities thereof for the desired device initiation temperature. This particularly accounts for thermal transfer characteristics of envelope 2 or the position chosen for the initiator device.

To prepare the gas generating composition, a mixture containing an oxidizing agent, a reducing agent and a binding agent may be chosen.

These components are selected to produce a large volume of gas at a low temperature (lower than 1500°C) in order to prevent reactive charge 5 from decomposing.

The oxidizing agent may typically be selected among the following compounds: ammonium perchlorate, potassium perchlorate, potassium nitrate, sodium nitrate.

Aluminum, boron, magnesium, titanium, for instance, may be selected as metallic reducing agent.

The binding agent allows block 7 to be shaped and provides for its mechanical strength; it also participates in the gas generating process. For this purpose, the binding agent is advantageously chosen among the following compounds: hydroxylated polybutadiene (HTPB), nitrocellulose, nitroglycerine.

Typically, the following gas generating compositions can be prepared (the percentages are percentages by weight of the composition): LflpQJ 10-30% by weight of ammonium perchlorate, 50-70% by weight of aluminum powder, 5-201 by weight of HTPB (binding agent).

Example 2

25-45% by weight of sodium nitrate, 55-85% by weight of magnesium powder, 5-15% by weight of HTPB (binding agent).

Example 3

25-35% by weight of ammonium perchlorate, 10-50% by weight of magnesium powder, 5-20% by weight of HTPB (binding agent).

Example 4

90-50% by weight of potassium perchlorate, 5-25% by weight of aluminum powder, 5-40% by weight of HTPB (binding agent).

All these compositions are initiated by any one of the above described initiator compositions.

They are manufactured by the usual pyrotechnic composition manufacturing processes: compression or casting (casting is used in particular for ammonium perchiorate base compositions) A propellant powder could also be used as gas generating composition, such as single base powder, double base powder or composite powder.

Composite powders are known propellant powders in which at least one explosive (such as hexogene) and a binding agent, such as hydroxylated polybutadiene (HTPB) are associated.

Other propellant powders are also known to the skilled person; they comprise one or more nitrated bases such as nitro-cellulose or nitro-glycerine.

These powders are shaped in the form of block 7 using standard paper manufacturing techniques used by powder manufacturers (compression, extrusion) These powders are initiated by any one of the above described initiator compositions.

Finally, a composition including a halogenous polymer (fluorinated polymer in particular) such as polytetrafluoroethylerie (marketed under the trade name of Teflon), fluorinated vinylidene copolymer (marketed under the trade name of Viton) or preferably a mixture S of both (Viton also performing as a binding agent for Teflon) can be chosen as gas generating composition.

The halogenous polymer is associated with a reducing agent (such as a metal powder -e.g., magnesium, aluminum, zirconium or a mixture of these metal powders) and, possibly, an oxidizing agent (such as ammonium perchlorate, potassium perchiorate, sodium nitrate, or potassium nitrate) Such compositions are highly stable at any temperature below 400°C. They can readily be shaped by moulding, injection, machining.

They generate large quantities of gas from a small initial volume.

The following typical compositions may be made:

Example 5

35-65% by weight of magnesium, 10-40% by weight of polytetrafluoroethylene, 5-25% by weight of fluorinated vinylidene copolymer.

Example 6

20-45% by weight of potassium perchlorate, 5-30% of aluminum, 5-50% by weight of polytetrafluoroethylene 10-15% by weight of fluorinated vinylidene copolymer.

These compositions are initiated by any one of the above described initiator compositions.

The device according to the invention operates as follows: When the temperature of envelope 2 increases (e.g., in a fire), this temperature rise affects pellets 10 forming the initiator device (as a result of their arrangement in direct contact with the bottom of the envelope).

When the temperature reaches the predetermined level, pellets 10 are initiated and ignite in turn the gas generating composition of block 7.

The pressure of the gas thus generated is applied to piston 8 which pushes reactive charge 5. Piston 8 also thermally isolates reactive charge S from the generated gas and also improves pressure distribution.

In the configuration illustrated in Figure 1, charge 5 is not attached to sleeve 6, and the pressure is thus transmitted to cover 3 and to the device coupling the cover to the envelope.

The selected coupling device should hold the cover in position during munition handling phases in normal use and should release the cover when the pressure generated by block 7 reaches the predetermined level.

In the present case, threads are sheared by the applied pressure.

Other coupling devices could be provided in view of the characteristics of the gas pressure generated by the device according to the invention.

The cover/envelope coupling could be provided by pins for instance.

The pins could also be made of a material whose melting temperature is slightly lower than the initiation temperature of pellets 10.

In the latter case, the cover is released from the envelope nearly when the gas pressure generated by block 7 is applied to the cover.

Such a variant enables a munition to be designed with a very small quantity of gas generating composition (this provides for munition safety when there is little space available for the deconfining device) Once the cover is separated from the envelope, the gas pressure is still applied to the reactive charge and ejects the reactive charge out of the envelope.

Such an arrangement is particularly advantageous in the case of an explosive charge as it suppresses any confinement of the explosive charge.

The reactive charge is then ejected out of its envelope before it has begun to decompose. Any risk of detonation is precluded since the ejected charge burns outside the envelope without jeopardizing the safety of personnel having to fight the fire.

According to another aspect of the invention, block 7 and initiator pellets 10 on the munition shown in Figure 1 can be replaced by a single block of special heat-sensitive gas generating composition with an initiation temperature ranging from 150°C to 200°C.

A composition including an oxidizing agent and a binding agent could be selected for instance, with the oxidizing agent selected among the following compounds: ammonium perchlorate, potassium perchlorate, potassium nitrate, sodium nitrate, preferably using hydroxylated polybutadiene (HTPB) as binding agent.

The binding agent of such a composition fulfils the function of a reducing agent in addition to its mechanical functions and participates in the gas generation process.

Typically, the following gas generating compositions can be prepared: Exampl 55-80% by weight of potassium perchlorate, 45-20% by weight of hydroxylated polybutadiene.

55-80% by weight of ammonium perchlorate, 45-20% by weight of hydroxylated polybutadiene.

These compositions are spontaneously initiated when they are heated up to a temperature of about 180°C.

They can be made by casting or compression.

The device according to the invention can S obviously be applied to the deconfinement of other types of munitions. In particular, the device could be used to deconfine rocket or missile motors; in such a case, cover 3 is fitted with a propellant gas exhaust nozzle.

According to the invention, the exhaust nozzle is ejected together with the propellant block.

A munition can also be designed in some cases without insulation sleeve 6 around the reactive charge.

The freedom of movement of charge 5 relative to envelope 2 should however be provided by suitable machining.

Figure la represents a variant of embodiment in which the deconfining device comprises a gas generating composition block 7 and an initiator device consisting of disk 11 made of a heat-sensitive composition.

The compositions described previously are suitable for this variant which offers the advantage of being cheaper since the shapes of all the components are simpler.

Reactive material 5 in this variant is in direct contact with gas generator block 7. It is therefore more particularly suited to cases where the explosive charge is little sensitive to heat or to the deconfinement of missile or rocket motors.

Figure lb illustrates another variant in which the deconfining device is placed in between cover 3 and reactive charge 5.

No insulating sleeve in this variant is provided between charge S and envelope 2.

The gas generator block is made of a heat-sensitive composition alike those described previously.

It features an axial recess which prevents disturbance of the initiation of charge 5 by primer device 4.

When the gas generator block is initiated subsequently to an appropriate temperature rise, the gas pressure is applied to cover 3 and shears the device coupling the cover to envelope 2.

Cover ejection vents the reactive charge to the open air. The charge itself is not ejected by the gas pressure but such a deconfinement may be sufficient in some cases, e.g., when the explosive material is little confined or little sensitive.

Such a solution also has the advantage of separating primer device 4 from charge S as soon as the temperature rise is detected. Munition safety is thus improved and there is no need for a specific protection system isolating the primer device from the charge.

Figure Ic depicts another variant in which block 7 is arranged in housing 14 provided in removable bottom 13. This removable bottom is linked to envelope 2 by conventional coupling devices such as screws.

Block 7 is fitted with a pellet 10 made of initiating material.

Pellet 10 is in contact with the bottom so as to be heated up by the bottom when the munition temperature rises.

This variant differs from the previous ones in that block 7 is isolated from reactive charge S by an

inflatable bag 15.

The inflatable bag is made of polyethylene or reinforced polyester, for instance. Its strength is adequate to hold the gas.

It is held, for instance, by pinching it between removable bottom 13 and envelope 2.

When the gas generating composition block is initiated, the inflatable bag is inflated and takes the shape of the reactive charge surface which is located

S

opposite bottom 13. Charge 5 transmits the thrust to cover 3 and to its coupling device as previously.

The advantage of such an arrangement is that it makes the use of a piston unnecessary while allowing S the ejection of a reactive charge to which the gas pressure could not be applied directly, as in the case of a powder charge or a charge likely to break up inside the envelope. The bag inflated by the gas excellently distributes the pressure provided by block 7.

Figures 2 and 2a depict a second embodiment according to which the gas generating composition has the shape of a cylindrical block 7 separated from reactive charge S by piston 8.

Reactive charge 5 is isolated from envelope 2 by an insulating sleeve consisting of three sectors Ga, Lb and 6c separated by bars 12a, 12b and l2c. The bars are spaced at regular angular intervals and cover nearly the entire length of envelope 2 from cover 3 up to block 7 with which they are in contact.

As previously, the sectors of sleeve 6 are made of heat-insulating material.

Bars 12 are the initiator device for gas generating composition block 7 Hence, they are made of a composition whose initiation temperature ranges from 150°C to 200°C.

For instance, a material of the kind described previously associating at least one metal powder with at least one powdery material capable of reacting with the metal powder.

The advantage of such a variant is that it provides for deconfinement not only when the entire munition is gradually heated up over a long time period but also when there is a sharp temperature rise away from block 7, e.g. on envelope 2 or in the vicinity of cover 3.

S

With this embodiment of the invention, the initiator device is configured as a temperature sensor capable of detecting variations in the thermal environment of the munition and transmitting them to the gas generating composition which provides for deconfinement.

A different number of bars may be used, in particular for improving the sensitivity to sharp temperature rises.

This embodiment can of course be combined with previous variants and particularly: -longitudinal bars can be associated with a block adjacent to cover 3 (as shown in Figure Ib), -the bars and the block can be made as a single block of the same heat-sensitive material, -piston 8 may not be provided.

This embodiment can of course be used to deconfine both explosive munitions and rocket/missile motors.

Figure 3 Is a scrap view of munition envelope 2.

Reactive charge S is placed inside cylindrical envelope 2 which has at least two cylindrical parts 2b and 2c along the same axes and attached to each other by coupling devices such as radial pins 16 (only one axis of which is shown herein) which are distributed at regular angular intervals.

Envelopes 2b and 2c are guided one relative to the other by mating cylindrical bearing surfaces (identified 19a,19b and 20a,20b) and they have mating abutment surfaces (identified l7a,17b and lSa,l8b) which determine their relative axial positions.

Once the envelope sections are positioned one relative to the other, they delineate a housing. A cylindrical ring 21 made of heat-sensitive gas generating composition as described previously is placed in this housing when the envelope sections are assembled together.

S

This composition is in contact with the envelope and heats up at the same time as the envelope. The pin attachment constitutes a brittle zone on the envelope which is located in the vicinity of the gas generating S composition.

When the gas generating composition reacts, the gas pressure shears pins 16 and the munition is divided into two sections, thereby venting charge 5.

A number of rings 19 can advantageously be arranged along the munition body to cut the envelope into a number of sections.

This variant is particularly well suited to large-sized munitions (such a bombs) or large-sized missile motors.

The advantage of this variant is that it does not put the gas generating composition in contact with the reactive material and also it does not reduce the space available for the latter.

It is possible of course to replace ring 19 with two concentric rings, one made of initiator material and the other made of gas generating composition.

Claims

SCLAIMS: 1. Deconfining device for a munition including an envelope containing a charge of reactive material, the device comprising a gas-generating composition and a heat-sensitive initiator device for initiating the gas-generating composition, the arrangement being such that, in use, the pressure increase resulting from initiation of the gas-generating composition creates at least one opening in the envelope to vent said charge to the outside of the envelope.
2. Device according to claim 1, wherein the initiator device has an initiation temperature in the range of from 150°C to 200°C.
3. Device according to claim 2, wherein the initiator device comprises a mixture off zirconium powder and boron powder.
4. Device according to claim 2, wherein the initiator device comprises a mixture of zirconium powder and carbon powder.
5. Device according to any one of claims 1 to 4, wherein the gas-generating composition comprises at least one oxidizing agent, at least one reducing agent and at least one binding agent.
6. Device according to any one of claims 1 to 4, wherein the gas-generating composition comprises at least a propellant powder, such as a single base powder, a double base powder or a composite powder, associating in particular an explosive and a binding agent.
7. Device according to any one of claims I to 4, wherein the gas-generating composition comprises at least a halogenous polymer, in particular a fluorinated polymer, associated with at least a reducing agent and, possibly, at least an oxidizing agent.
8. Device according to claim 5, wherein the oxidizing agent is one or more of ammonium perchlorate,Spotassium perchlorate, potassium nitrate and sodium nitrate.
9. Device according to claim 5 or claim 8, wherein the reducing agent is one or more of aluminum, boron, magnesium and titanium.
10. Device according to claim 5, 8 or 9, wherein the gas-generating composition comprises: 10-30% by weight of ammonium perchiorate, 50-70% by weight of aluminum powder, 5-20% by weight of binding agent.
11. Device according to claim 5, 8 or 9, wherein the gas-generating composition comprises: 25-45% by weight of sodium nitrate, 55-85% by weight of magnesium powder, 5-15% by weight of binding agent.
12. Device according to claim 5, 8 or 9, wherein the gas-generating composition comprises: 25-35% by weight of ammonium perchlorate, 10-50% by weight of magnesium powder, 5-20% by weight of binding agent.
13. Device according to claim 5, 8 or 9, wherein the gas-generating composition comprises: 90-50% by weight of potassium perchlorate, 5-25% by weight of aluminum powder, 5-40% by weight of binding agent.
14. Device according to claim 7, wherein the gas-generating composition comprises: 35-65% by weight of magnesium, 10-40% by weight of polytetrafluoroethylene, 5-25% by weight of fluorinated vinylidene copolymer.
15. Device according to claim 7, wherein the gas-generating composition comprises: 20-45% by weight of ammonium perchlorate, 5-30% of aluminum, 5-50% by weight of polytetrafluoroethylene,S10-15% by weight of fluorinated vinylidene copolymer.
16. Deconfining device for a munition including an envelope containing a charge of reactive material, the device comprising a heat-sensitive gas-generating composition, the arrangement being such that, in use, the pressure increase resulting from initiation of the gas-generating composition creates at least one opening in the envelope to vent said charge to the outside of the envelope.
17. Device according to claim 16, wherein the gas-generating composition has an initiation temperature in the range of from 150°C to 200°C.
18. Device according to claim 17, wherein the gas-generating composition comprises an oxidizing agent and a binding agent.
19. Device according to claim 18, wherein the oxidizing agent is one or more of ammonium perchlorate, potassium perchlorate, potassium nitrate and sodium nitrate
20. Device according to claim 17 or claim 18, wherein the binding agent is hydroxylated polybutadiene (HTPB).
21. Device according to claim 18, 19 or 20, wherein the gas-generating composition comprises: 55-80% by weight of potassium perchlorate, 45-20% by weight of hydroxylated polybutadiene.
22. Device according to claim 18, 19 or 20, wherein the gas-generating composition comprises: 55-80% by weight of ammonium perchlorate, 45-20% by weight of hydroxylated polybutadiene.
23. A deconfining device for a munition substantially as hereinbefore described with reference to, and as shown in, Figure 1, la, lb, ic, 2 and 2a or 3 of the accompanying drawings.
24. A munition comprising an envelope containing a charge of reactive material and a deconfining device as claimed in any preceding claim.
25. Munition according to any preceding claim, wherein the munition envelope has at least one embrittled zone, the gas-generating composition being positioned in the vicinity thereof.
26. Munition according to any preceding claim, wherein the envelope containing the charge is enclosed by a cover which is attached to the envelope by a shearing coupling device, with said gas-generating composition being arranged in such a way that the gas pressure shears the coupling device and ejects said cover.
27. Munition according to claim 26, wherein the gas-generating composition is arranged at one end of said munition opposite to the end closed by said cover, and that the gas pressure is applied to the shearing coupling device through said charge and a driving device arranged between the gas generating composition and said charge.
28. Munition according to claim 27, wherein the driving device comprises piston.
29. Munition according to claim 27, wherein the driving device comprises inflatable bag.Amendments to the claims have been filed as follows I. A munition comprising an envelope, the envelope containing a charge of reactive material and a deconfining device which comprises a gas-generating composition and a heat-sensitive initiator device for initiating the gas-generating composition, the arrangement being such that, in use, the pressure increase resulting from initiation of the as-generating composition creates at least one opening in the envelope to vent the charge to the outside of the envelope.2. A munition as claimed in claim 1, wherein the initiator device has an initiation temperature in the range of from 150°C to 200°C.3. A munition as claimed in claim 2, wherein the initiator device comprises a mixture of zirconium powder and boron powder.4. A munition as claimed in claim 2, wherein the initiator device comprises a mixture of zirconium powder and carbon powder.5. A munition as claimed in any one of claims 1 to 4, wherein the gas-generating composition comprises at least one oxidizing agent, at least one reducing agent and at least one binding agent.6. A munition as claimed in any one of claims 1 to 4, wherein the gas-generating composition comprises at least a propellant powder, such as a single base powder, a double base powder or a composite powder, associating in particular an explosive and a binding agent.7. A munition as claimed in any one of claims 1 to 4, wherein the gas-generating composition comprises at least a halogenous polymer, in particular a fluorinated polymer, associated with at least a reducing agent and, possibly, at least an oxidizing agent. 2?>8. A munition as claimed in claim 5, wherein the oxidizing agent is one or more of arnmonium perchiorate, potassium perchlorate, potassium nitrate and sodium nitrate.9. A munition as claimed in claim 5 or claim 8, wherein the reducing agent is one or more of aluminum, boron, magnesium and titanium.10. A munition as claimed in claim 5, 8 or 9, wherein the gas-generating composition comprises: 10-30% by weight of ammoriium perchiorate, 50-70% by weight of aluminum powder, 5-20% by weight of binding agent.11. A munition as claimed in claim 5, 8 or 9, wherein the gas-generating composition comprises: 25-45% by weight of sodium nitrate, 55-85% by weight of magnesium powder, 5-15% by weight of binding agent.12. A munition as claimed in claim 5, 8 or 9, wherein the gas-generating composition comprises: 25-35% by weight of ammonium perchiorate, 10-50% by weight of magnesium powder, 5-20% by weight of binding agent.13. A munition as claimed in claim 5, 8 or 9, wherein the gas-generating composition comprises: 90-50% by weight of potassium perchlorate, 5-25% by weight of aluminum powder, 5-40% by weight of binding agent.14. A munition as claimed in claim 7, wherein the gas-generating composition comprises: 35-65% by weight of magnesium, 10-40% by weight of polytetrafluoroethylene, 5-25% by weight of fluorinated vinylidene copolymer.15. A munition as claimed in claim 7, wherein the gas-generating composition comprises: 20-45% by weight of ammonium perchlorate, 5-30% of aluminum, 5-50% by weight of polytetrafluoroethylene, 10-15% by weight of fluorinated vinylidene copolymer.16. A munition comprising an envelope, the envelope containing a charge of reactive material and a deconfining device which comprises a heat-sensitive, gas-generating composition, the arrangement being such that1 in use, the pressure increase resulting from initiation of the gas-generating composition creates at least one opening in the envelope to vent the charge to the outside of the envelope.17. A munition as claimed in claim 16, wherein the gas-generating composition has an initiation temperature in the range of from 150°C to 200°C.18. A munition as claimed in claim 17, wherein the gas-generating composition comprises an oxidizing agent and a binding agent.19. A munition as claimed in claim 18, wherein the oxidizing agent is one or more of ammonium perchlorate, potassium perchlorate, potassium nitrate and sodium nitrate 20. A munition as claimed in claim 18 or claim 19, wherein the binding agent is hydroxylated polybutadiene (HTPB) 21. A munition as claimed in claim 18, 19 or 20, wherein the gas-generating composition comprises: 55-80% by weight of potassium perchlorate, 45-20% by weight of hydroxylated polybutadiene.22. A munition as claimed in claim 18, 19 or 20, wherein the gas-generating composition comprises: 55-80% by weight of ammonium perchlorate, 45-20% by weight of hydroxylated polybutadiene.23. A munition as claimed in any preceding claim,ZSTwherein the envelope has at least one embrittled zone, the gas-generating composition being positioned in the vicinity thereof.24. A munition as claimed in claim 23, wherein the envelope comprises two or more sections, the or each embrittled zone comprising the or each abutment between the sections.25. A munition as claimed in any preceding claim, wherein the envelope includes a cover which is attached by a shearing coupling device, the gas-generating composition being arranged in such a way that the pressure increase causes the shearing coupling device to shear and the cover to be ejected.26. A munition as claimed in claim 25, wherein the gas-generating composition is arranged at the end of the envelope opposite to the end closed by the cover, the pressure increase being applied to the shearing coupling device via the charge and a driving device arranged between the gas-generating composition and the charge.27. A munition as claimed in claim 26, wherein the driving device comprises a piston.28. Munition according to claim 26, wherein the driving device comprises an inflatable bag.29. A munition substantially as hereinbefore described with reference to Figure 1, la, ib, Ic, 2 and 2a or 3 of the accompanying drawings.