GB2311007A

GB2311007A - Flexible fire barrier

Info

Publication number: GB2311007A
Application number: GB9605566A
Authority: GB
Inventors: Alan William Atkinson; Alan James; David Richard Bridge; John Dinsdale Crabtree
Original assignee: T&N Technology Ltd
Current assignee: Federal Mogul Technology Ltd
Priority date: 1996-03-16
Filing date: 1996-03-16
Publication date: 1997-09-17
Anticipated expiration: 2016-03-16
Also published as: GB9605566D0; WO1997034764A1; GB2311007B; AU1934497A

Abstract

A flexible fire barrier (10) comprises two outer layers (12, 14), and at least two insulating layers (16, 18) positioned between the two outer layers. The outer layers (12, 14) comprise fabric made of glass fibre. Each of the insulating layers (16, 18) comprises a glass fibre insulating mat (16a, 18a) enclosed in an envelope made of metallic foil (16b, 16c, 16d, 18b, 18c).

Description

FLEXIBLE FIRE BARRIERS This invention is concerned with flexible fire barriers.

Flexible fire barriers are used for retarding the spread of fire through spaces where it is not practical or desirable to build dividing walls. For example, the roof space of a building may be sub-divided by such barriers.

Such barriers need to resist penetration by a fire and provide heat insulation. Typically, the barrier is suspended from a frame, to which it is attached by mechanical fasteners, and hangs down like a curtain to the floor of the space. Such barriers are supplied in sheet form, eg in a roll, having a limited width which is often narrower than the space to be sub-divided. In this case, a number of lengths are hung side-by-side with abutting edges to form the barrier. A joint has to be formed at such abutting edges in order to avoid a gap through which fire or gases could spread.

Conventional flexible fire barriers are made of mats formed from fibres, the fibres comprising glass, mineral wool, or other heat-resistant material. In order to meet the required insulation properties, these mats have a significant thickness (up to 5Omm) making the barriers difficult to install because of their weight and low flexibility. It is also difficult to form joints between lengths of such barriers. It has been recognised that the thickness of such barriers can be reduced, while still retaining their insulation properties, by incorporating one or more layers of metallic foil in the barrier. Examples are described in WO 90/09281 and in GB 1 583 744.

Wo 90/09281 describes a fire barrier material which comprises at least one insulating layer of glass fibre formed into a knitted fabric. The barrier also comprises two layers of woven glass fibre fabric positioned on opposite sides of the knitted fabric and separated therefrom by layers of metallic foil about 15 micrometres in thickness. The foil layers are attached to the woven layers.

GB 1 583 744 describes two layers of heat-resistant fibrous material having a layer of foil between them. In one embodiment, a scrim cloth is used to cover the edges of the fibrous material layers, the cloth passing across one outside face of the barrier, around the edges thereof, and being joined to a wire mesh which extends across the other outside face of the barrier.

In the proposals described above, in most cases, relatively-loose fibres are exposed either at the outer surfaces of the barrier or at the edges thereof. Such fibres are unpleasant to work with, sometimes causing skin irritation, and, in some cases, the fibres can be respirable causing a health hazard. Furthermore, edges of lengths of such barriers are difficult to join.

It is an object of the present invention to provide a flexible fire barrier in which the disadvantages of the above-mentioned proposals are overcome.

The invention provides a flexible fire barrier comprising two outer layers, and at least two insulating layers positioned between the two outer layers, the outer layers comprising fabric made of glass fibre, wherein each of the insulating layers comprises an insulating glass fibre mat enclosed in an envelope made of metallic foil.

In a flexible fire barrier according to the invention, the glass fibres forming the insulating mats are enclosed in an envelope made of metallic foil thereby preventing these fibres from being unpleasant to work with or forming a health hazard. The metallic foil serves the dual purpose of enclosing the relatively-loose glass fibres and also of assisting the heat insulating properties of the barrier.

The glass fibres in the outer layers are in continuous lengths and are tightly bound so that they do not form a health hazard. The formation of joints between lengths of the barrier is also facilitated since the metallic foil can be more easily secured to an adjacent length than can fibrous mats or felts. It is also relatively easy to join the outer layers of adjacent lengths to one another, eg by folding them to form seams which are secured by mechanical fastening means.

Preferably, the insulating mats are formed from fibres, eg of E-glass, having a diameter of more than 3 micrometres. Such fibres are essentially non-respirable.

The mats may be in the form of felts, eg needled felts, approximately 5mm in thickness and having a density of 20 to 200 kg/m3.

Preferably, said envelope is formed by sheets of foil each covering one of the faces of the insulating mat, the sheets of foil being joined together around the edges of the mat. The sheets of foil may be joined by adhesive or by folding them over each other to form a seam which may be secured by mechanical fastening means such as stitching, stapling etc. Where a seam is formed, the seam may be flattened against the edge of the mat.

The metallic foil is, preferably, made of aluminium and is, preferably, at least 30 micrometers in thickness, preferably about 50 micrometres. This foil is thicker than has conventionally been used in fire barriers and not only gives greater protection to the mat but also is found to increase the insulating properties of the barrier.

The outer layers may be formed from heat-resistant glass cloth, eg woven cloth which has been treated with a chemical coating to increase its heat resistance, or has been leached with acid. Preferably, the fibres in the cloth have a diameter of at least 3 micrometres. E-glass is a suitable material for the outer layers. The cloth may be about 0.4 mm in thickness.

The layers of the barrier are, preferably, held together by mechanical fastening means which does not compress the insulating mats significantly so that their insulating properties are not unduly reduced. Preferably, the fastening means is sacrificial in the event of fire so that any compression of the insulating mats is removed and potential heat conduction paths through the barrier are removed. Suitable mechanical fastening means is stitching made of polypropylene which melts in a fire.

Alternatively, thin plastics "rivets" may be used, eg those supplied as labelling tags by Dennison International of Farmington, Massachusetts, under the Tradename "Ezi Tag".

The barrier may comprise a joint between edge portions of two adjacent lengths of the barrier. At the joint, the insulating layers of the adjacent lengths may overlap one another, eg by being interleaved, and the outer layers of the adjacent lengths may be joined together to hold the insulating layers in their overlapping condition. If desired, the overlapping insulating layers may be secured together by adhesive. The width of the joint may be 25 to 150mm.

There now follows a detailed description, to be read with reference to the accompanying drawings, of a flexible fire barrier which is illustrative of the invention.

In the drawings: Figure 1 is a horizontal cross-sectional view taken through the illustrative fire barrier, showing a joint between two lengths of the barrier; Figures 2 to 6 are diagrammatic views of alternative ways of joining foil layers at the edges of the insulating layers of the illustrative fire barrier; and Figure 7 is a side elevational view of a fastener used in the illustrative fire barrier.

The illustrative flexible fire barrier 10 comprises two outer layers 12 and 14, and two insulating layers 16 and 18 positioned between the two outer layers. The outer layers 12 and 14 are identical to one another and both comprise a layer of woven fabric made of E-glass fibre which has been treated with a chemical to make it heat resistant. Such a fabric is available commercially from TBA Industrial Products Limited of Rochdale, England under the tradename "Firefly EKO 401". The layers 12 and 14 are formed form fibres having a diameter greater than 3 micrometres and have a thickness of 0.4 mm.

The insulating layers 16 and 18 are identical to one another and each comprises a glass fibre insulating mat, 16a and 18a respectively. Each mat 16a and 18a is a needled felt made from E-glass fibre having a diameter greater than 3 micrometres. Each mat 16a and 18a is approximately 5mm in thickness and has a density of 100 kg/m3. Each mat 16a and 18a is enclosed in an envelope made of two sheets of aluminium foil, 16b and 16c, and 18b and 18c respectively. Each sheet of aluminium foil is approximately 50 micrometres in thickness and extends across one face of a mat 16a or 18a. The edges of the sheets 16b and 16c (or 18b and 18c) are joined together around the edges of the mat 16a (or 18a) to complete the envelope.

The layers 12, 14, 16 and 18 forming the barrier 10 are secured together in overlying relationship by fasteners 19 made of polypropylene. One of the fasteners 19 is shown in Figure 7. The fastener 19 is of the type commonly used for clothes labelling. It comprises a cylindrical shank 19a which passes through the barrier 10, a head l9b at one end of the shank 19a, and a head 19c at the other end thereof. The head 19b is in the form of a cylindrical bar which form a T-shape with the shank 19a. The head 19b is designed to be deformed to the shape of an arrow head which can be forced through the layers 12, 14, 16 and 18 and then returns to its undeformed shape. The head l9c is in the form of a rectangle. The fastener 19 holds the layers 12, 14, 16 and 18 together relatively-loosely in order to avoid compressing the insulating layers 16 and 18 which might reduce their insulating properties. The fastener 19 is designed to melt in the event of fire releasing any compression of the layers 16 and 18. The fasteners 19 are not shown in Figure 1 as they are positioned away from the edges of the lengths of the barrier 10 so that they do not obstruct joint formation.

Figure 2 shows one alternative way of joining the sheets of foil 16b and 16c together around the edges of the mat 16a. The same joining method is used for the sheets 18b and 18c (as is the case with the methods illustrated by Figures 3 to 6). In Figure 2, the edges of the foil sheets 16b and 16c overhang the edges of the mat 16a and are secured together by adhesive. The seam so created can flattened against the edge of the mat.

Figure 3 shows another way of joining the sheets 16b and 16c around the edge of a mat 16a. In this case, the foil sheet 16b is folded over on itself and the foil sheet 16c (which extends further than the sheet 16b) is folded over the edge of the sheet 16b. The seam so-formed is secured together by mechanical fastening means, specifically staples (not shown). Other forms of folded over seam can also be used instead. The seam is then flattened against the edge of the mat.

Figure 4 shows another way of joining the sheets of foil around the edge of the mat. In this case, the sheet 16b terminates at the edge of the mat 16a but the sheet 16c extends around the edge of the mat and over the edge portion of the sheet 16b to which it is secured by adhesive.

Figure 5 shows another way of joining the sheets of foil around the edge of the mat. In this case, the sheets 16b and 16c both terminate at the edge of the mat 16a and an additional sheet of aluminium foil 16d extends across the edge of the mat 16a and across edge portions of the sheets 16b and 16c to which it is joined by adhesive.

Figure 6 shows a way of joining the sheets 16b and 16c around the edges of the mat 16a without using adhesive or fasteners. In this case, the sheet 16c is folded over the sheet 16b (as in Figure 3) and the seam so created is folded over on itself. The folded over seam is found to retain its shape.

Figure 1 also illustrates a joint between edge portions of adjacent lengths of the fire barrier 10. At the joint, edge portions of the insulating layers 16 and 18 of said adjacent lengths overlap one another.

Specifically, the layers 16 and 18 of the two lengths are interleaved. Furthermore, at the joint, the outer layers 12 and 14 of the adjacent lengths are joined together to hold the insulating layers 16 and 18 in their overlapping condition.

To make the joint shown in Figure 1, an installer first bends edge portions of the outer layers 12 of the two lengths towards himself. He then joins these edge portions together, eg by staples, and folds them over to lie parallel to the layers 12. This creates the seam 20 shown in Figure 1. In order that the installer can work from one side only of the barrier, the seam 20 is made facing the installer and towards the centre of the barrier. Next, the installer interleaves the insulating layers 16 and 18 of the two adjacent lengths of barrier 10. As shown in Figure 1, this interleaving results in the foil sheet 16b of one of the lengths contacting the foil sheet 16c of the adjacent length. Similar contacts are also made between a sheet 16b and a sheet 18b, and between sheets 18b and 18c.

If desired, one or more of these contacts between the foil sheets can be secured by adhesive. Finally, the installer makes a folded seam 22 between the outer layers 14 in the same way as he made the seam 20. The seam 22 faces the installer and away from the centre of the barrier.

In a fire test conducted according to British Standard 476 part 22, the illustrative fire barrier gave a time of 26 minutes before the average temperature rise of four fixed thermocouples reached 1400C (the requirement is 15 minutes) and 20 minutes before the temperature rise of an individual thermocouple was 1800C (the requirement is 15 minutes).

In the fire barrier 10, the relatively-loose glass fibres are all enclosed in aluminium foil. Furthermore, the edges of the insulating mats are protected by the foil against damage. Additionally, joining of adjacent lengths of the barrier 10 is relatively easy as described above.

Claims

1 A flexible fire barrier comprising two outer layers, and at least two insulating layers positioned between the two outer layers, the outer layers comprising fabric made of glass fibre, wherein each of the insulating layers comprises a glass fibre mat enclosed in an envelope made of metallic foil.

2 A flexible fire barrier according to claim 1, wherein the insulating mats are formed from fibres having a diameter of more 3 micrometres.

3 A flexible fire barrier according to either one of claims 1 and 2, wherein the insulating mats are in the form of needled felts.

4 A fire barrier according to claim 3, wherein the mats are approximately 5mm in thickness and have a density of 20 to 200 kg/m3.

5 A fire barrier according to any one of claims 1 to 4, wherein said envelope is formed by sheets of foil each covering one of the faces of the insulating mat, the sheets of foil being joined together around the edges of the mat.

6 A fire barrier according to any one of claims 1 to 5, wherein the metallic foil is made from aluminium and is at least 30 micrometers in thickness.

7 A fire barrier according to any one of claims 1 to 6, wherein the outer layers are formed from heat resistant woven glass cloth.

8 A fire barrier according to any one of claims 1 to 7, wherein the layers of the barrier are held together by mechanical fastening means which does not compress the insulating mats significantly.

9 A fire barrier according to claim 8, wherein the fastening means is sacrificial in the event of fire.

10 A fire barrier according to any one of claims 1 to 9, wherein the barrier comprises a joint between edge portions of two adjacent lengths of the barrier, at the joint, the insulating layers of the adjacent lengths overlapping one another and the outer layers of the adjacent lengths being joined together to hold the insulating layers in their overlapping condition.

11 A fire barrier according to claim 10, wherein, at the joint, the insulating layers are secured together by adhesive.

12 A flexible fire barrier substantially as hereinbefore described with reference to and as shown in the accompanying drawings.