GB2168402A - Fire resistant safes - Google Patents

Abstract

A fire resistant safe comprising a container 10 and a lid 11, each having an outer casing 12, 21, an inner lining 14, 15 and 23, 24 and an intermediate insulating layer 13, 22 of high heat resistant material and the inner lining having a filling 20, 25 of phase change material, such as paraffin wax which thus has high heat absorbing properties and the lid 11 engaging the container through a tortuous path sealing arrangement, including surface portions 18, 27 of the intermediate layer 13, 22. <IMAGE>

Description

SPECIFICATION Fire resistant safes This invention relates to fire resistant containers such as fire safes, particularly, though not exclusively for the storage of magnetic discs or tapes used in computers.

The use of combustible or at least heat degradable discs for computers has brought the need for protection of these from fire or other excessive heating, to general notice, particularly in view of the fact that information stored on such discs is often of very substantial value, much information being stored in a small volume. Although the problem of fire protection is particularly acute in relation to magnetic discs or tapes, the need to protect papers or other records against fire also exists in many areas.

There are various standards of fire resistance and it is desirable that a safe should meet as many as possible of the safety standards. Not only should the safe preserve the contents against fire or other heat damage, but the contents should also remain undamaged if the safe is dropped, as might occur in a fire in a building, when a floor or other support gives way. The conditions to which the safe may be subjected can therefore be extremely severe.

There are a number of fire resistant safes available and the higher the heat resistant properties, the larger the safe tends to be, some such safes being extremely large and heavy as well as being expensive. Also the interior space available for storage tends to be small, even in safes of which the external dimensions are large, since the bulk and weight is usually largely accounted for by the use of substantial thicknesses of insulation material.

Many safes are of the traditional shape, namely a rectangular box with a front opening door.

It is therefore the object of this invention to provide a fire resistant safe in which the contents may be protected in an effective manner under heat and possibly also impact conditions and in which the external shape and size may be convenient for transportation and general convenience.

In accordance with the present invention there is provided a fire resistant safe comprising a container and a lid, the container and lid each having an outer casing, an inner lining and an insulating intermediate layer of high heat resistant properties, the inner lining having heat absorbing properties and the lid and the container having respective surfaces which abut to provide a seal between portions of the intermediate layer provided in the lid and in the container respectively.

Preferably the respective surfaces of the intermediate layer which provide the seal are covered with a protective film.

In a preferred form, the intermediate layer is of a powdered insulating material.

The lid and container conveniently define complementary shapes providing a tortuous path from the exterior to the interior of the safe, to limit ingress of hot gases or radiant heat.

The heat absorbing properties of the inner lining may be achieved by providing a space, within the inner lining, containing a material which, under application of heat will change from solid state to liquid state or from liquid state to vapour state, thus absorbing energy as latent heat.

Conveniently the inner lining may be encased in a layer of material which is a good heat conductor, whereby the heat reaching the inner lining is distributed around said lining. This prevents local build up of heat in one zone.

The heat absorbing material which may be contained within the space in the inner lining may be paraffin wax or water.

The film of a protective material on the sealing surfaces of the intermediate layer in the lid and in the container may be a molybdenum-containing surfacing material, coating the otherwise exposed surface of the insulating intermediate layer.

The outer casing may be of steel or other material having strength sufficient to support pressure applied during and after installation of the intermediate layer material.

Preferably the intermediate layer is made from a powdered high heat resistant and insulating material which is under pressure when installed. It is advantageously a hydrophobic material.

Conveniently the safe may be of rectangular form. However, round, oval, square or other shapes may be used.

The lid is preferably arranged to engage the container, at least immediately prior to engagement of the sealing means, in a direction perpendicular to the general plane of the sealing surfaces. The lid conveniently therefore slides or moves into the container in said perpendicular direction. This enables a very accurate and therefore tight seal to be achieved. Means are advantageously provided for releasably securing the lid to the container.

The lid may be hinged to the container and in such a case this is preferably such that the lid can move towards the container, at least just prior to sealing, in said perpendicular direction.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view of a fire resistant safe constructed in accordance with the invention, and Figure 2 is a cross-sectional view in a plane per pendicularto Figure 1.

The safe shown is of relatively small dimensions and in this example is of rectangular form. The device comprises a container 10 into which fits a separate lid 11. In the lid, there are depressions which have sliding catches 32 engaged therein. These act as sliding bolts to be slid into corresponding slots in an upstanding hollow rim of the container. Overcentre toggles or other fastenings may be substituted but any such fastenings, must be operable even after subjection to heat or impact, or both.

The container and lid are both of generally rectangular form, with the main portion of the lid of smaller size but having an external peripheral lip forming the edge of a generally flat top. At the sides of the container are carrying handles fitted at 33.

The container 10 comprises an outer casing 12 formed from sheet mild steel, within which is an intermediate insulating layer of material indicated at 13. Within this is supported a lining having an inner and an outer skin 14, 15. The interior of the inner skin defines an interior cavity 16 within which discs or tapes or other material can be stored.

The outer casing 12 is made in two parts welded together along the bottom peripheral edge and may have a paint finish on the outside. The intermediate layer 13 is preferably, although not essentially, a powdered material known as "Microtherm" (Registered Trade Mark) produced by Micropore International Limited. The material is placed in the container and is in powder form but pressure is applied to it so that when the layer is in place with the inner lining fitted, pressure exists in the layer 13.

At the top of the space containing the lining 13 layers of Microtherm of a harder grade are used.

The zone of such harder grade material is identified at 17.

The container components, namely the outer casing 12 and the outer skin 14 of the lining define a gap, filled by the intermediate insulating layer portion 17, this having an inclined surface. This surface is coated with a film 18 of a molybdenum filled resin material, or other similar material. This layer is also applied over the adjacent surfaces of the outer casing 12 and of the lining and this film serves to protect the powdered material of which the intermediate layer is made up and also acts to bond the outer casing and lining together. The molybdenum filled resin also has the property of high heat resistance as well as being capable of forming a seal against the lid.

The inner lining comprises two skins 14, 15 of a high temperature plastics material such as glass reinforced resin, being made as a hollow moulding. The space between the inner and outer skins 14, 15 is filled with a material with high heat absorption and preferably phase changing properties.

In this example the material is paraffin wax 20. At moderate temperatures this will change from solid state to liquid state, thus absorbing latent heat.

The lid 11 is of similar construction to the container having an outer steel casing 21. Along the centre of the casing a channel 24 is provided to accommodate and guide the sliding catches 32.

There is an intermediate insulating layer 22 of Microtherm. On this is supported an inner lining comprising inner and outer skins 23, 24 with a space between them containing paraffin wax 25.

The lining is made as a hollow moulding, as the container lining. The outer or peripheral layers of Microtherm are of greater hardness as indicated at 26. There is a gap between the edges of the outer casing 21 and the outer skin 24 of the lining and this is filled with the intermediate layer, having an inclined surface corresponding with that of the container. Again this inclined surface is coated with a film 27 of the molybdenum filled resin ma terial. The film is spread over the adjacent surfaces of the outer casing 21 and of the lining, as with the container, but in the lid, this film actually serves to hold the inner lining and the outer casing together.

The inner lining of the lid and of the container are of complementary stepped form. In this way, a substantially uniform thickness space containing the wax 20, 25 surrounds the inner storage space 16.

Although not illustrated, it may be desirable to fit an additional seal between the peripheral lip of the lid and the container, to provide a water seal. This may be a flexible rubber or other similar strip.

The tortuous path offered by the touching sur faces of the lid and of the container prevent direct access to the interior by heat in the form of hot gases or directly by radiation. The intermediate layer is of very high insulating properties and heat arriving at the outer skins 14, 24 of the container and lid penetrates the wax which tends to melt, thus absorbing latent heat and further protecting the contents of the interior space 16 of the safe.

It has been found that the safe will withstand very high temperatures over a very long period and meets many of the current standards in this respect. Also, it is strong and will thus withstand impact so that the contents are protected not only against heat but also against damage if the safe falls from some height.

To further improve the distribution of any heat arriving at the outer skins 14, 24 of the container and lid, the outer skins are covered with a thin film 30, 31 of a good heat conducting material such as aluminium foil. This tends to distribute heat around the container thus avoiding the build-up of a high concentration of heat in any position.

Other insulating materials may be substituted for the Microtherm material described and the wax may be substituted by other phase change mate rials which are able to change from solid state to liquid state or from liquid state to vapour state over the temperature ranges expected in arduous conditions. Water which will convert to steam is one alternative.

In place of the direct fitting lid in which a seal is made by the molybdenum filled resin material films 18, 27 when the lid is placed on perpendicu larly to the container, the lid may alternatively be hinged in place. It is preferred in such a case that the lid will move in such perpendicular direction at 'least during the final portion of its travel towards the closed position. In this way accurate surfaces can be made to provide a good tight seal against ingress of hot gases or of heat by radiation.

In addition to, or in place of the inclined surfaces forming the sealing surfaces of the intermediate layer, other formations may be provided on the container and on the lid to afford a tortuous path between the exterior and the interior.

In an alternative arrangement the intermediate layers are preformed blocks, moulded to the re quired shape, and fitted in place during assembly.

This may be accomplished by inserting, in succes sion, a number of preformed blocks to make up the complete layer, in the container, and similarly in the lid.

Claims (15)

1. A fire resistant safe comprising a container and a lid, the container and lid each having an outer casing, an inner lining and an insulating intermediate layer of high heat resistant properties, the inner lining having heat absorbing properties and the lid and the container having respective surfaces which abut to provide a seal between portions of the intermediate layer provided in the lid and in the container respectively.

2. A safe as claimed in Claim 1 in which the respective surfaces of the intermediate layer which provide the seal are covered with a protective film.

3. A safe as claimed in Claim 1 or 2 in which the intermediate layer is of a powdered insulating material.

4. A safe as claimed in any one of the preceding claims in which the lid and container define complementary shapes providing a tortuous path from the exterior to the interior of the safe, to limit ingress of hot gases or radiant heat.

5. A safe as claimed in any one of the preceding claims wherein the heat absorbing properties of the inner lining are achieved by providing a space, within the inner lining, containing a material which, under application of heat will change from solid state to liquid state or from liquid state to vapour state, thus absorbing energy as latent heat.

6. A safe as claimed in any one of the preceding claims wherein the inner lining is encased in a layer of material which is a good heat conductor, whereby the heat reaching the inner lining is distributed around said lining.

7 A safe as claimed in Claim 5 or Claim 6 in which the heat absorbing material which is contained within the space in the inner lining is paraffin wax or water.

8. A safe as claimed in Claim 2 in which the film of a protective material on the sealing surfaces of the intermediate layer in the lid and in the container is a molybdenum-containing surfacing material, coating the otherwise exposed surfaces of the insulating intermediate layer.

9. A safe as claimed in any one of the preceding claims wherein the outer casing is of a material having strength sufficient to support pressure applied during and after installation of the intermediate layer material.

10. A safe as claimed in any one of the preceding claims in which the intermediate layer is made from a powdered high heat resistant and insulating material which is under pressure when installed.

11. A safe as claimed in Claim 10 in which the material from which the intermediate layer is formed is a hydrophobic material.

12. A safe as claimed in any one of the preceding claims of rectangular form.

13. A safe as claimed in any one of the preceding claims in which the lid is arranged to engage the container, at least immediately prior to engagement of the sealing surfaces of the lid and the container, in a direction perpendicular to the general plane of the sealing surfaces.

14. A safe as claimed in any one of the preceding claims including means for releasably securing the lid to the container.

15. A fire resistant safe substantially as hereinbefore described with reference to and as shown in the accompanying drawings.