GB2281859A

GB2281859A - Intumescent fire seal

Info

Publication number: GB2281859A
Application number: GB9418381A
Authority: GB
Inventors: Michael John Coles
Original assignee: Dufaylite Developments Ltd
Current assignee: Dufaylite Developments Ltd
Priority date: 1993-09-15
Filing date: 1994-09-13
Publication date: 1995-03-22
Also published as: GB9418381D0; GB9319137D0

Abstract

The seal comprises an intumescent body having a surface at least partly covered by thermally conductive foil. The body is typically in the form of a sheet or strip, and the thermally conductive foil may cover one or both faces of the sheet or strip. Preferred foils are of metal e.g. Al. Utility of the seals is in pipe collars or sleeves, duct grilles or seals for doors and windows.

Description

TITLE: FIRE SEAL DESCRIPTION The invention relates to an intumescent fire seal.

It is known to use intumescent materials in fire seals, e.g. to seal around voids in apertures and to seal ventilation ducts and doors in the event of fire. It is also known to use such materials in collars embracing plastics pipes to close the pipes in the event of fire.

It is an object of the invention to enhance the properties of such intumescent materials, so that in a suitable case less intumescent material is required for a particular application.

According to the invention an intumescent fire seal comprises an intumescent body having a surface at least partly covered by thermally conductive foil. Thus where the intumescent body is in the form of a sheet or strip, the thermally conductive layer can cover one or both faces of the sheet or strip. Where, as in a tubular sleeve for a pipe closer, the intumescent body is in the form of a series of superposed strips formed into a complementary pair of semi-cylindrical parts, the thermally conductive layer may be provided on one side of the strip. We have discovered that enhanced results are obtained if the thermally conductive layer is provided on the radially outer sides of the strips. It will be appreciated that when the intumescent body is formed from a series of superposed layers of strip, a sandwich structure is formed.

This sandwich structure might also be appropriate in situations other than in a sleeve for a pipe.

The thermally conductive layer is preferably of metal foil. We have found aluminum foil to be suitable. The foil may be attached to the intumescent material by means of an adhesive. If desired foil pre-coated with a contact adhesive may be secured to a sheet or strip of intumescent material to form a composite.

The invention is diagrammatically illustrated, by way of example, in the accompanying drawings, in which: Figure 1 is a perspective view of a typical fire seal for a thermoplastic pipe; Figure 2 is a sectional plan view to an enlarged scale of part of the seal of Figure 1; Figure 3 is an enlarged scrap plan view (not to scale) showing in greater detail part of the fire seal shown in Figure 2; Figure 4 is a front view of a fire seal for a duct, and Figure 5 is a side view, partly in section, of the fire seal of Figure 3.

Referring to Figures 1 to 3 of the drawings there is shown a fire seal 3 for a vertical pipe of a thermoplastics material such as UPVC, e.g. a soil pipe, and which is in the form of a collar or sleeve which embraces the pipe and which comprises a metallic outer casing containing an intumescent material which when heated, e.g. in the occurrence of a fire, swells to seal the interior void of the pipe. Such fire seals 3 for pipes are known per se and typically comprise a pair of semi-cylindrical sheet metal shells 1 closed at their ends by metal caps 2, the shells 1 being held together by clamps 4 (only one of which is shown in Figure 1) to form a hollow collar round a pipe 5 (shown in dotted outline). The hollow interior of the collar is filled with a body 7 of intumescent material.

As shown in Figure 2 the intumescent body 7 is generally provided in the form of a pair of semi cylindrical members 7a, 7k each comprising a superposed series of strips 6 of sheet material, the number of strips or layers being related to the diameter of the void to be sealed.

As is shown more clearly in Figure 3 of the drawings, in the present embodiment each of the strips 6 of intumescent material forming the members 7a and 7b is covered on its outer face by a thin, e.g. 40 micron, layer 8 of self adhesive aluminium alloy foil so that after forming the intumescent body it comprises a sandwich construction of layers of intumescent material and aluminum foil with the foil 8 being on the radially outer faces of the intumescent layers 6. We have discovered that, in this way, the performance of the intumescent material is enhanced to the extent that, for any given void size, fewer layers of the intumescent material are needed to seal the void in the event of fire. The result of this is that sleeves of smaller diameter are possible. We believe that the enhanced effect is due to improved heat transmission through the intumescent material due to the presence of the foil and perhaps also due to the fact that the foil enhances the swelling of the intumescent material during an initial heating period, the effect being to increase the speed of reaction.

Preferred intumescent materials for pipe sleeves include sheet material sold under the trade mark TENMAT by TENMAT LIMITED, a unit of T & N plc, under Type 102 rigid.

Although such material is not intended to be bent we have found that it is possible to wind strips of the material into a coil without cracking the material and without moistening the material by passing the strips through the nip of a pair of rollers, and this is how we prefer to form the layers 6.

In Figures 4 and 5 of the drawings there is shown a fire seal 9 for a duct, e.g. a ventilation duct, in the form of a rectangular metal frame 10 dimensioned to fit snugly in the duct and supporting a series of spaced vertical strips or louvres 11 of intumescent material, the vertical strips being maintained in spaced relationship by one or more, e.g. two, horizontal strips 12 of intumescent material which engage the vertical strips 11 e.g. by notching the horizontal and vertical strips at their points of intersection. The edges of the strips 11 are protected by vertical wires 13 mounted on and extending across the frame, which vertical wires overlie the edges of the strips and are joined e.g. by welding to horizontal wires 14, the ends of which are also secured to the frame to form wire mesh panels. The horizontal strips 12 are similarly positioned behind horizontal wires 14 for protection. The strips of intumescent material 11,12 are further supported by wire ties 15 interconnecting the two wire mesh panels and embracing the strips. Such fire seals are known rer li but in the present case the intumescent strips are covered on both sides with aluminium foil (not shown) to improve the intumescent effect as described above with reference to the embodiment of Figures 1 to 3. Thus in the occurrence of fire, the strips swell to close the void, i.e. the duct.

It will be appreciated that although the invention has been particularly described with reference to a pipe collar or sleeve and an intumescent grille for a duct it is equally applicable to other intumescent seals e.g. for doors or windows.

Claims

1. An intumescent fire seal comprising an intumescent body having a surface at least partly covered by thermally conductive foil.

2. An intumescent fire seal according to claim 1, wherein the intumescent body is in the form of a sheet or strip, and wherein the thermally conductive layer covers one or both faces of the sheet or strip.

3. An intumescent fire seal according to claim 1 or claim 2, wherein the intumescent body comprises a series of superposed strips and wherein the thermally conductive layer is provided on one side of each strip.

4. An intumescent fire seal according to claim 3, wherein the intumescent body is generally tubular and where the thermally conductive layer is provided on the radially outer sides of the strips.

5. An intumescent fire seal according to any preceding claim, wherein the thermally conductive layer is of metal foil.

6. An intumescent fire seal according to claim 5, wherein the metal foil is of aluminum.

7. An intumescent fire seal according to any preceding claim, wherein the foil is attached to the intumescent material by means of an adhesive.

8. An intumescent fire seal substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.