GB1589516A - Fire protection means - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO FIRE PROTECTION MEANS (71) I, SECRETARY OF STATE FOR DEFENCE, London, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to means for resisting, preventing, damping or quelling, or resisting of preventing the spread of fire. Such means are hereinafter called fire protection means. The invention is particularly concerned with fire protection in confined spaces such as those found in vehicles and especially aircraft, in the region of containers for flammable fluid substances.

Various fire protection means have been proposed for the protection of bays and spaces adjacent aircraft fuel tanks. Where these bays are large, ie the least dimension is larger than about 30 cm, perhaps containing equipment and conduits, suitable protection includes that described in co-pending UK Patent Application 45396/73. Where the bays are medium sized, ie having one or two of its dimensions in the range 8-30 cm, suitable protection includes that described in UK Patent Specification 1,445,832, 1,453,836, 1,454,492, and 1,454,494. These fire protection means are relatively unsuitable in small bays where one or two dimensions are less than 8 cm, partly because of difficulties in stallation, weight penalties and/or unnecessary complexity.

Such small bays are nevertheless regions where a fuel fire can be lethal, and the present invention provides fire protection means which are simple but adequate for the protection thereof, and which can readily be installed, even as a retro-fit. The invention is a modification of that disclosed in UK Patent Specification 1,453,836, which describes fire protection means comprising at least one reticulated structure formed of polymeric fibre with at least 3 pores per linear cm and contained either external to and contiguous with or within a container for a flammable fluid.

According to the present invention an enclosed bay external to a container for flammable fluid and accessible to fluid leaking from the container is at least substantially filled with at least one fire protective reticulated structure formed of polymeric fibre and not substantially susceptible of being permanently cored, pulverized or splayed by a projectile passing therethrough and also having attached to at least one face thereof a layer on nonflammable projectile passage resistant fabric.

According to an important feature of the invention the at least one reticulated structure may have been formed by melding polymeric fibre, that is to say thermally or chemically achieving coherence of fibres, preferably bi-component fibres, at their contiguity nodes in a non-woven mass thereof.

Preferably also the fibre has a density considerably less than 15 grams per litre, of the order of 3-4 fibres crossing a, or a porosity of 3 pores per linear centimetre, and a resilience such that it does not compress by more than 50% under a loading of lOlb/in2. Suitable materials are described in UK Patent Specification No. 1,453,836 and co-pending UK Patent Application No.

14962/75, 52077/76 and 27191/77. The structure may be hydrophobic as described in copending UK Patent Application No.

7570/77.

According to another feature of the invention the layer of projectile passage resistant fabric is attached to the face of the or each reticulated structure remote from the container for flammable fluid. The fabric preferably conforms to the specification UK SC 3931. A suitable fabric is ballistic nylon cloth having an area density of 400-600 g/m2. High strength aromatic polyamide fibre eg Kevlar (Trade Mark) fabric may also be suitable.

The fabric provides a resistance, that is a degree of impermeability to projectiles including missiles, bullets, shell and explosion products, particles and shrapnel.

A suitable adhesive for attaching the fabric to the reticulated structure is Dunlop adhesive S669. A layer of similar fabric may also be attached to the face of the structure closest to the container. However, a face of the structure other than that to which the fabric is attached may carry a layer of intumescent paint such as a paint of the kind described in UK Specification No.

1,373,908. Intumescent paint swells in the presence of fire to form a char impervious to flame. This extra layer can be particularly useful where rivets etc project into the space and render difficult fitting of the structure unless it is smaller than the space. In such circumstances the extra layer of intumescent paint is available for fire protection of the otherwise unfilled part of the space.

The invention is particularly suitable for use in aircraft in bays between fuel tanks and aircraft skin up to 8 cm thick. Ideally structures in accordance with the invention completely fill the bay, and may therefore be tailored so to do. Where therefore, a bay is partlly or completely spanned by stringers or other structural elements, the structures are preferably tailored so to fit around and between them. While they may be fitted during construction of the aircraft, it is a notable feature of the invention that they can readily be installed as a retro-fit, and even changed, by sliding between the stringers etc. The fabric can impart just the degree of rigidity to the structure to facilitate this. They need not be held in place with adhesive, and a possibility of Ibeing vibrated out can be obviated by making them slightly oversize.

The flammable fluid need not, of course, be engine fuel or even liquid, and the invention may be of value in the environment of containers of flammable gases and particulate substances.

Examples of fire protection means in accordance with the invention will now be described with reference to the accompanying drawings of which: Figure 1 is a perspective view of one fire protection structure, Figure 2 illustrates use of such a structure in an aircraft approximate a fuel tank, Figure 3 is a perspective view of another fire protective structure, and Figure 4 illustrates the use of a structure of the type illustrated in Figure 3.

The fire protective structure shown in Fig. 1 comprises a reticulated slab 10 of melded polymeric fibre having a layer 11 of ballistic nylon attached to a face thereof with an adhesive. The slab 10 is melded polyester fibre and is non-flammable, resilient has a porosity of 3 pores per linear centimetre is not susceptible of being cored, pulverised, or splayed by a projectile passing therethrough, and has a density of 8g/litre.

The ballistic nylon has an areal density of 470g/m2.

Fig. 2 illustrates a typical situation where structures in accordance with the invention are of service, An aircraft skin 20 is supported by a stringer structure 21 which also supports the wall 22 of a fuel tank. The distance between the skin 20 and the wall 22 is about 6 cm and the stringer interstices are fibre/explosion risk areas in the event of a leak from the tank.

Fire protective slabs 23 of the general construction shown in Figure 1 are preformed to conform with the interstitial spaces between the skin and the stringers and the stringers and the tank wall, with ballistic nylon faces 24 arranged to lie adjacent the skin in the former instance and adjacent the stringer in the latter.

The slabs are fitted by being pushed along the spaces and in use are generally successful in preventing shrapnel from penetrating through to a fuel tank and in snuffing out or preventing fuel etc fire in the spaces.

The structure illustrated in Figure 3 comprises a slab of melded fibre 30 carrying a layer of Kevlar (Trade Mark) fabric 31 secured to one face and a layer of intumescent paint 32 on the other. The slab 30 is made in accordance with co-pending UK Patent Application 7570/77 and 27191/77, and the intumescent paint is as described in UK Patent Specification No. 3,173,908.

To protect interstitial spaces between aircraft stringers such as those between an aircraft skin 20, stringers 21 and fuel tank wall 22, structures of the general construction shown in Figure 3 are preformed to fit those spaces as shown in Figure 4. Each structure therein shown comprises a melded fibre strip 40 having Kevlar (Trade Mark) fabric 41 attached to the faces thereof remote from the fuel tank and carrying an intumescent paint layer 42 on the face thereof closest to the fuel tank. The layer 42 is obtained by dipping and need only coat one face. This is because an intumesced layer will tend to push the structure to fill the whole space as it will solidify more rapidly in the presence of the structure than in the free space.

The interior of the fuel tank is protected by a proprietary flame detecting extinguishant device or a passive system such as a partial filling of reticulated foam as described in UK Patent Specifications 1,341,693 and 1,380,420 or more preferably of melded fibre structures as described in UI( Patent 1,453,836 or co-pending UK Patent Applications 14962/75, 52077/76, 7570/77, and 27191/77.

WHAT I CLAIM IS: 1. In or for an enclosed bay external to a container for a flammable fluid and accessible to fluid leaking from the container a substantially complete filling of at least one fire protective reticulated structure

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. also be attached to the face of the structure closest to the container. However, a face of the structure other than that to which the fabric is attached may carry a layer of intumescent paint such as a paint of the kind described in UK Specification No. 1,373,908. Intumescent paint swells in the presence of fire to form a char impervious to flame. This extra layer can be particularly useful where rivets etc project into the space and render difficult fitting of the structure unless it is smaller than the space. In such circumstances the extra layer of intumescent paint is available for fire protection of the otherwise unfilled part of the space. The invention is particularly suitable for use in aircraft in bays between fuel tanks and aircraft skin up to 8 cm thick. Ideally structures in accordance with the invention completely fill the bay, and may therefore be tailored so to do. Where therefore, a bay is partlly or completely spanned by stringers or other structural elements, the structures are preferably tailored so to fit around and between them. While they may be fitted during construction of the aircraft, it is a notable feature of the invention that they can readily be installed as a retro-fit, and even changed, by sliding between the stringers etc. The fabric can impart just the degree of rigidity to the structure to facilitate this. They need not be held in place with adhesive, and a possibility of Ibeing vibrated out can be obviated by making them slightly oversize. The flammable fluid need not, of course, be engine fuel or even liquid, and the invention may be of value in the environment of containers of flammable gases and particulate substances. Examples of fire protection means in accordance with the invention will now be described with reference to the accompanying drawings of which: Figure 1 is a perspective view of one fire protection structure, Figure 2 illustrates use of such a structure in an aircraft approximate a fuel tank, Figure 3 is a perspective view of another fire protective structure, and Figure 4 illustrates the use of a structure of the type illustrated in Figure 3. The fire protective structure shown in Fig. 1 comprises a reticulated slab 10 of melded polymeric fibre having a layer 11 of ballistic nylon attached to a face thereof with an adhesive. The slab 10 is melded polyester fibre and is non-flammable, resilient has a porosity of 3 pores per linear centimetre is not susceptible of being cored, pulverised, or splayed by a projectile passing therethrough, and has a density of 8g/litre. The ballistic nylon has an areal density of 470g/m2. Fig. 2 illustrates a typical situation where structures in accordance with the invention are of service, An aircraft skin 20 is supported by a stringer structure 21 which also supports the wall 22 of a fuel tank. The distance between the skin 20 and the wall 22 is about 6 cm and the stringer interstices are fibre/explosion risk areas in the event of a leak from the tank. Fire protective slabs 23 of the general construction shown in Figure 1 are preformed to conform with the interstitial spaces between the skin and the stringers and the stringers and the tank wall, with ballistic nylon faces 24 arranged to lie adjacent the skin in the former instance and adjacent the stringer in the latter. The slabs are fitted by being pushed along the spaces and in use are generally successful in preventing shrapnel from penetrating through to a fuel tank and in snuffing out or preventing fuel etc fire in the spaces. The structure illustrated in Figure 3 comprises a slab of melded fibre 30 carrying a layer of Kevlar (Trade Mark) fabric 31 secured to one face and a layer of intumescent paint 32 on the other. The slab 30 is made in accordance with co-pending UK Patent Application 7570/77 and 27191/77, and the intumescent paint is as described in UK Patent Specification No. 3,173,908. To protect interstitial spaces between aircraft stringers such as those between an aircraft skin 20, stringers 21 and fuel tank wall 22, structures of the general construction shown in Figure 3 are preformed to fit those spaces as shown in Figure 4. Each structure therein shown comprises a melded fibre strip 40 having Kevlar (Trade Mark) fabric 41 attached to the faces thereof remote from the fuel tank and carrying an intumescent paint layer 42 on the face thereof closest to the fuel tank. The layer 42 is obtained by dipping and need only coat one face. This is because an intumesced layer will tend to push the structure to fill the whole space as it will solidify more rapidly in the presence of the structure than in the free space. The interior of the fuel tank is protected by a proprietary flame detecting extinguishant device or a passive system such as a partial filling of reticulated foam as described in UK Patent Specifications 1,341,693 and 1,380,420 or more preferably of melded fibre structures as described in UI( Patent 1,453,836 or co-pending UK Patent Applications 14962/75, 52077/76, 7570/77, and 27191/77. WHAT I CLAIM IS:

1. In or for an enclosed bay external to a container for a flammable fluid and accessible to fluid leaking from the container a substantially complete filling of at least one fire protective reticulated structure

formed of polymeric fibres and substantially non-susceptable of being permanently cored, pulverized or splayed by a projectile passing therethrough and having attached to at least one face thereof a layer of projectile passage resistant fabric.

2. A bay as claimed in claim 1 and wherein the layer of fabric is attached to a face of the structure remote from the container.

3. Means as claimed in claim 1 or claim 2 and wherein the structure comprises melded fibres.

4. Means as claimed in any one of claims 1 to 3 and wherein the structure is hydrophobic.

5. Means as claimed in any one of the preceding claims and wherein the fabric is ballistic nylon cloth.

6. Means as claimed in any one of claims 1 to 4 wherein the fabric is a high strength aromatic polyamine fibre cloth.

7. Means as claimed in any one of the preceding claims wherein the structure carries a layer of intumescent paint.

8. Means as claimed in any one of the preceding claims and wherein the structure carries a layer of projectile passage resistant fabric on one face and a layer of intumescent paint on another face opposite to the said one face.

9. Means as claimed in any one of the preceding claims and wherein the at least one structure has a density of less than 15 grams per litre.

10. Means as claimed in any one of the preceding claims and wherein the at least one structure has a porosity of 3 pores per linear centimetre.

11. Means substantially as hereinbefore described with reference to any one of the accompanying drawings.