GB2027118A - Device for Destroying Pyrolysable Material in a Container - Google Patents

Abstract

The device comprises a thermally insensitive container (1) for the pyrolysable material, such as paper documents, an electrical heating resistor (9) in the container (1) lying adjacent the pyrolysable material, and an electrical battery (4) connected to the heating resistor (9) and controlled by an actuating device (7, 19) which, when operated, will cause the battery (4) to discharge through the heating resistor (9) to destroy the adjacent pyrolysable material. <IMAGE>

Description

SPECIFICATION Device for Destroying Pyroiysable Material in a Container This invention relates to a device for destroying pyrolysable material in a container.

Highly confidential documents are on occasions transported or stored in containers which if snatched from their bearer or illicitly opened, destroy their contents. Alternatively the courier or person responsible for the documents may wish to destroy documents which are of a compromising or secret nature when discovery or theft of such documents is imminent.

While a number of methods to achieve this destruction of the documents has been proposed, the most popular is to cause the documents to be destroyed by combustion. Thus for example, some couriers and diplomats have interleaved documents with leaves of celluloid containing sodium nitrate which are then ignited.

This method of destruction suffers from serious disadvantages. The combustion of paper with limited access to air is very slow and therefore it is necessary to provide oxidizing agents such as sodium nitrate if the desired result of rendering the documents unreadable is to be achieved.

Ignition in the presence of such oxidizing agents produces a very violent reaction. In addition to the considerable heat generated, large volumes of nitrogen and oxides of carbon are produced which require to escape from the container if they are not to cause an explosion as a result of pressure buildup. It is also necessary to have a highly heat resistant container which is necessary to contain the hot solid products which are left.

Furthermore, in the presence of such oxidizing agents, small quantities of aluminium or magnesium provide a further considerable hazard of explosion.

While under limited circumstances, the disadvantages may be outweighed by the practical need, if such a device was activated in an aeroplane, for example, it would create a considerable hazard to the lives of the passengers and to the safety of the aeroplane as a whole.

The present invention seeks to provide a device for destroying pyrolysable material in containers in which the above hazards are reduced or obviated and which can ensure the effective total destruction of the papers or the documents contained in the container.

According to the invention there is provided a device for destroying pyrolysable material in a container comprising a thermally insensitive container, a heating resistor for location adjacent the pyrolysable material in the container, an electric battery dischargeable through the heating resistor on an actuating device for actuating the battery.

The battery is preferably a reserve actuated lead and cell. The actuating device may comprise means for supplying the electrolyte to the battery, eg mechanically or pyrotechnically. The actuating device may comprise a small propell at charge for facing electrolyte between the battery electrodes or the electrodes may be contained in a receptacle under reduced pressure and may be separated from the electrolyte by a rupturable membrane.

The invention will now be described in greater detail, by way of example, with reference to the drawings in which: Figure 1 is a side view, with one side removed of a briefcase incorporating a device in accordance with the invention, Figure 2 is an end view of the briefcase shown in figure 1, but with the end of the case removed to enable the interior to be seen.

Referring now to the drawings, the content destroying device in accordance with the invention is located in a briefcase 1 of generally case shaped form as opposed to the slimmer syle cases which are common.

The briefcase 1 is provided with a heat insulating layer 2 on the inside to prevent heat to be generated within the case from damaging the exterior of the case and thus causing damage to the surroundings.

Located in a special compartment 3 at the bottom of the case (as shown in the drawing) there is provided a reserve energised electric battery 4 in the form of a lead-acid cell with an adjacent container 5 for electrolyte 6. Such cells have a very heavy high energy output and may consist of porous lead and lead oxide plates with an electrolyte which is added immediately before use. Where electrolytes such as hydrofluoric or hydroborofluoric acid are used whose lead salts, unlike lead sulphate, are freely soluble, the generation of extremely heavy currents can be achieved. For example a battery of this type the size of a text-book, could well deliver 100 amps for several minutes.On the remote end of the electrolyte container there is a propellent 7 in the form of an explosive which when detonated would cause rupture of a membrane 8 between the battery 4 and the electrolyte 6 and cause the electrolyte to be forced directly into the battery, so as to enable the battery to be energised.

Connected to the battery are resistance heater wires a which are supported on a variety of individual frames 10 extending up through the briefcase, each of these frames acting as a support for the resistance wires 9 required for destruction of the documents (not shown). The resistance wires 9 are preferably carried by springs 11 which are held extended by means of thermo sensitives connections 12 which will enable, in certain circumstances, the resistance wires 9 to contact to one side or end of the briefcase for a purpose to be described.

Alternatively the resistance wires 9 remain in position and a rake 1 3 is connected to the ends of the springs 11 as shown.

As can be seen from figure 2, the resistance wire support frames 10 are pivoted at their base at 14 to allow for the insertion of documents between the resistance wires 9.

Since the destruction by this method takes a short but nevertheless, measurable time, it is desirable that it shall not be possible to obtain access to the case 1 until all the documents have become charred and disintegrated. For this purpose, a pyromechanical bolt 1 6 may be provided for holding the briefcase shut against any attempts to open it to extract the documents before they are safely destroyed. This pyromechanical bolt 1 6 is suitably actuated by the same mechanism which causes the actuation of the battery.In this particular example shown, actuation is provide by undoing one end of the case handle 1 7 and pivoting this away from the case by a pivot 1 8 at the other end, this action actuating a firing switch 1 9 which detonates the propellent 7 for the battery electrolyte and also actuates the pyromechanical bolt 1 6. A second battery 20, suitably of standard dry cell type is provided for this purpose.

Sheets of foam plastic or other compressible material may be provided within the case so as to ensure that the resistance wires 9 are maintained in close contact with the documents.

The operation of the destroying device will now be described: With the case 1 initially open, appropriate thicknesses of documents are loaded between the two adjacent hinged resistance carrying frames 10, the maximum thickness being carefully arranged to ensure that the complete charring will result upon actuation. The case is then shut up causing the documents to be placed in close contact with the resistance wires 9. If a snatch of the case is imminent or if for any other reason the documents are to be destroyed, the courier unships one end of the handle 17 and pulls the free end of it upwards, actuating the firing switch device 19. This switch device connects the electric battery 20 to the pyromechanical bolt 1 6 and causes this to be expiosively moved forward to engage in the catch device 21 provided.In this way, the case is now locked and can only be opened by destruction of the case. At the same time, the propellent 7 in the bottom of the case is detonated and forces the electrolyte 6 into the electrical battery 4 containing the electrodes, whereupon a heavy current is passed to the resistance heating wires 9 located against documents so that these wires 9 rapidly become red hot and char the documents with which they are in touch. This heating of the resistance wires 9 takes place very quickly due to the nature of the battery 4 and within a short period the whole of the documents are reduced to carbonised sheets.

In order that the carbonised sheets shall not be extracted and read, the device provides for a spring operated rake action of the wires 9 themselves, the springs 11 being held in tension by means of the thermosensitive connections 12, whereby, the heat generated in carbonisation of the documents will eventually after complete carbonisation of the documents has taken place, act on the connections 12 to release the springs 11 causing the resistance wires to collapse to one end of the case, thus performing a raking effect on the documents to cause them to disintegrate. If, the use of the heating element in this way is not desired, a separate rake 13, operated on the same principal, may be used.

During the pyrolysation of the documents, the only products generated are steam, carbon dioxide and charred particles. It is therefore desirable that the gaseous products should be able to escape from the case and, since these products are relatively harmless, no deleterious effect is to be expected. However, means could be provided within the case for absorbing both the steam and carbon dioxide. For example a container of soda lime could be ruptured for this purpose.

While the proposed equipment is particularly suitable, due to its nature, for use in portable cases, it is to be appreciated that the same principle could be used in other containers which may be of a more permanent nature such as in filing cabinets and other storage arrangements. It will of course be appreciated that, when used for stationary storage arrangements, the larger amounts of documents which would normaliy be required to be destroyed would require the use of larger current generating facilities or the use of several such generating facilities. Thus, in a multidrawer filing cabinet, one drawer could be taken up by the batteries and one or more further drawers could be used for storing the documents.

In stationary circumstances, there is also the faciiity for providing additional devices which could assist in the operation of the main device.

It will be understood that the above described embodiments can be varied without departing from the scope of the invention. For example instead of or as well as providing the raking of the documents in the container, a vibratory device could be included for vibrating the contents of the container so as to break up the carbonised sheets, thus permitting inner documents to come into contact with the resistance heating wires 9. Such vibratory devices range from mechanical motor driven devices in stationery equipment to the provision of a small number percussion caps operated on a thermo sensitive basis. In stationary equipment, it is also possible to include a fan whose blades, together with the turbulance which they produce, reduce the carbonized documents to small fragments. It is however to be noted that all the operable equipment should be driven from one or more batteries provided so as, not to require the use of mains services of any sort and enable the destruction to be effected under any conditions.

The actuation of the device can take places as described with regard to the briefcase by manual operation of an electrical switching element, by mechanical initiation of the start up of the battery by operation of a mechanical linkage without requiring an electrical initiation and the operation may be achieved either at the site or could be achieved, where necessary, by a remote control either by wire or by radio control. Booby trap type arrangements could be provided which cause the destruction of the contents on unauthorised tampering with the container in which they are situated. In the case of a briefcase, this would of course destroy the entire contents but arrangements could be made in larger stationary installations for the destruction to only take place in those containers which are in fact tampered with. This will of course require the use of separate energising devices in the various containers involved, since the battery can only be used effectively once if efficiency of the system is to be maintained.

From the above described embodiments it can be seen that a device is provided for the destruction of pyrolysable materials in containers, such as documents, and enables this to be done in safety, explosive mixtures not being generated and the only waste products being steam and carbon dioxide and documentary fragments in charred condition.

Claims (14)

Claims

1. A device for destroying pyrolysable material in a container comprising a thermally insensitive container, a heating resistor for location adjacent the pyrolysable material in the container, an electric battery dischargeable through the heating resistor or an actuating device for actuating the battery.

2. A device as claimed in claim 1, wherein the electric battery comprises a reserve energised lead-acid cell.

3. A device as claimed in claim 2, wherein the actuating device comprises means for supplying electrolyte to the battery.

4. A device as claimed in claim 3 wherein the actuating means operate mechanically.

5. A device as claimed in claim 3, wherein the actuating means operate pyrotechnically.

6. A device as claimed in claim 3, wherein the actuating device comprises a small propellant charge for forcing electrolyte between the battery electrodes.

7. A device as claimed in claim 3 wherein the battery electrodes are situated in a casing under reduced pressure and are separated from the electrolyte by a rupturable membrane.

8. A device as claimed in any one of claims 1 to 7 wherein means are provided for preventing access to the container while the destruction is in progress.

9. A device as claimed in claim 8, wherein the access preventing means comprise a pyromechanical bolt actuated by the actuating device.

10. A device as claimed in any one of claims 1 to 9 wherein means are provided for causing disintegration of the pyrolysable material after charring by the heating resister.

11. A device as claimed in claim 10, wherein the disintegrating means comprise means for providing a raking action on the charred material.

12. A device as claimed in claim 10, wherein the disintegrating means comprises a vibrator for vibrating the charred material.

13. A device as claimed in any one of claims 1 to 12 wherein the container is in the form of a briefcase.

14. A device for destroying pyrolysable material substantially as described herein with reference to the drawings.