GB2182557A - Fire damper - Google Patents

Abstract

A fire damper is made of intumescent synthetic resin and is made as an injection moulding of relatively thin material, axially of the airflow through the apertures in the damper, and has an embedded skeleton of wires (10) serving to conduct heat throughout the damper so that the whole damper may be activated relatively simultaneously when any small area of the damper is exposed to flame or heat, even when relatively large total areas are provided by the damper. <IMAGE>

Description

SPECIFICATION Fire damper This invention relates to fire dampers using intumescent material. This material has the characteristics of swelling, due to an internal chemical reaction,when exposed to heat. It is known to make a fire damper of such material creating a pattern ofaperturesthrough which air can flow in a ventilation duct, but which apertures are effectively closed off when the tem perature rises. Hence the supply of air to the fire through such ducts is restricted orterminated.

One ofthe problems in the design of such dampers has been to provide sufficient structual strength, particularly after activation. Atypical damper ofthis kind has comprised a honeycomb structure with the cells ofthe honeycomb being open ended so that air nor mally fiows through them. In a large area damper, there has been the possibilitythatifthefireaffects one corner or edge first, instead of the damper being completely activated to block the duct, only a few cells might be activated and that might be enough to de-stabilise the damper and create an opening between it and the duct.

Some designs of these dampers have been of relativelythin webs of paper and card coated with the material and with these it has been necessaryto make the cells relatively long in the direction offlow, which has created other problems and been expensive.

in other cases, previous proposals have had the intumescent damper combined with a steel or other shutter in an attemptto provide satisfactory performance.

The object of the present invention is to provide an improved construction, and preferably one which will meet the requirements ofthe current British Standard No.476 Part 8 on the subject.

In accordance with the invention, a fire damper comprises a moulding of an intumescentsynthetic resin which is rigid and self-supporting, and which has an embedded skeleton of heat-conducting material.

The heat conducting material may be steel wires extending in parallel fashion but not interconnected with one another, although an alternative possibility isto provide a complete grid ofwire and mould around all ofthecomponents.

The purpose of the heat conducting material is to ensurethateven if only portion of the damper is exposed to the fire, the heat is conducted throughout the entire damper and the whole damper can be activated.

It has been found that a damper according to the invention can be made relativelythin, that is to say with cells of short axial length and meet the requirements of the mentioned British Standard.

Two embodiments ofthe invention are illustrated with reference to the accompanying drawings in which: Figure lisa perspective view of a rectangularfire damper; and Figure2 is an elevation of a circularfire damper.

Thedampershown in Figure 1 mayforexample comprise apertures ofthe order of 50mm by 10mm, separated around their periphery by webs of about 5mm thick. The axial thickness may be ofthe order of 8mm.

It will be understood that these dimensions are purely by way of example, in order to give an indication of the relatively large aspect ratio (area of aper tures/total area) which has been found possible with the invention.

A number of suitable intumescent materials are available onthe market, and onewhich has been used experimentally is that sold by ICI Limited under the Trade Mark "FIREC". Other materials may be em pl-oyed.

The damper shown in Figure 1 is provided with heat distributing means in the form of a series of par allel wires, made of suitable steel, which may be copperplated prior to arrangement in a mould before the intumescent material is filled into the mould cavities to surround the wires, and these wires may extend parallel to the major axes of the cell shapes, that is to say side-to-side of the grid, the ends of the wires being indicated by the reference numerals 10 in Figure 1. Relatively fine wires are satisfactory for ex ample ones of the order of 22swg .

The damper shown in Figure 2 is intended to be about 120mm in diameter; itcomprisesfourre- ctangular main apertures ofthe orderof 60mm by 10mm, and a surrounding pattern of a smaller and different shaped apertures. Again the grid dimension is of the order of 5mm width and say 1cm axial dimension.In this case the wires may similarly extend as indicated by the dotted lines, along the webs which are parallel to the major axes ofthe rectangular cells, from the side-to-side in secant fashion and diametrically, and for convenience in manufacture ofthe moulding, these parallel wires, generally indicated by the reference numerals 12 may be joined together by cross wires 14which are also moulded around to form the webs atthe ends of the rectangularcells.

Because the heat applied at any one point is rapidly conducted to all parts ofthe damper, the damper is activated as a whole, substantially simultaneously and this avoidsthe damper becoming unstableand crumbling in position so asto leave a gap adjacent one of its edges. Hence the damper can be made relatively short axially, as indicated by the exemplary dimensions.

1. Afire damper comprising a moulding of an intumescent synthetic resin which is rigid and selfsupporting, and which has an embedded skeleton of heat conducting material.

2. A dam per as claimed in Claim 1 wherein the skeleton comprises a series of parallel metal wires.

3. AdamperasclaimedinClaiml orClaim2 wherein the damper comprises a grid of rectangular cells which are open ended, and the heat conducting material comprises a series of parallel steel wires extending from side-to-side of the damper parallel to the major axes of the rectangular cells, with one such wire between each two adjacent cells.

4. Afire damper as claimed in any of Claims 2 or3

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fire damper This invention relates to fire dampers using intumescent material. This material has the characteristics of swelling, due to an internal chemical reaction,when exposed to heat. It is known to make a fire damper of such material creating a pattern ofaperturesthrough which air can flow in a ventilation duct, but which apertures are effectively closed off when the tem perature rises. Hence the supply of air to the fire through such ducts is restricted orterminated. One ofthe problems in the design of such dampers has been to provide sufficient structual strength, particularly after activation. Atypical damper ofthis kind has comprised a honeycomb structure with the cells ofthe honeycomb being open ended so that air nor mally fiows through them. In a large area damper, there has been the possibilitythatifthefireaffects one corner or edge first, instead of the damper being completely activated to block the duct, only a few cells might be activated and that might be enough to de-stabilise the damper and create an opening between it and the duct. Some designs of these dampers have been of relativelythin webs of paper and card coated with the material and with these it has been necessaryto make the cells relatively long in the direction offlow, which has created other problems and been expensive. in other cases, previous proposals have had the intumescent damper combined with a steel or other shutter in an attemptto provide satisfactory performance. The object of the present invention is to provide an improved construction, and preferably one which will meet the requirements ofthe current British Standard No.476 Part 8 on the subject. In accordance with the invention, a fire damper comprises a moulding of an intumescentsynthetic resin which is rigid and self-supporting, and which has an embedded skeleton of heat-conducting material. The heat conducting material may be steel wires extending in parallel fashion but not interconnected with one another, although an alternative possibility isto provide a complete grid ofwire and mould around all ofthecomponents. The purpose of the heat conducting material is to ensurethateven if only portion of the damper is exposed to the fire, the heat is conducted throughout the entire damper and the whole damper can be activated. It has been found that a damper according to the invention can be made relativelythin, that is to say with cells of short axial length and meet the requirements of the mentioned British Standard. Two embodiments ofthe invention are illustrated with reference to the accompanying drawings in which: Figure lisa perspective view of a rectangularfire damper; and Figure2 is an elevation of a circularfire damper. Thedampershown in Figure 1 mayforexample comprise apertures ofthe order of 50mm by 10mm, separated around their periphery by webs of about 5mm thick. The axial thickness may be ofthe order of 8mm. It will be understood that these dimensions are purely by way of example, in order to give an indication of the relatively large aspect ratio (area of aper tures/total area) which has been found possible with the invention. A number of suitable intumescent materials are available onthe market, and onewhich has been used experimentally is that sold by ICI Limited under the Trade Mark "FIREC". Other materials may be em pl-oyed. The damper shown in Figure 1 is provided with heat distributing means in the form of a series of par allel wires, made of suitable steel, which may be copperplated prior to arrangement in a mould before the intumescent material is filled into the mould cavities to surround the wires, and these wires may extend parallel to the major axes of the cell shapes, that is to say side-to-side of the grid, the ends of the wires being indicated by the reference numerals 10 in Figure 1. Relatively fine wires are satisfactory for ex ample ones of the order of 22swg . The damper shown in Figure 2 is intended to be about 120mm in diameter; itcomprisesfourre- ctangular main apertures ofthe orderof 60mm by 10mm, and a surrounding pattern of a smaller and different shaped apertures. Again the grid dimension is of the order of 5mm width and say 1cm axial dimension.In this case the wires may similarly extend as indicated by the dotted lines, along the webs which are parallel to the major axes ofthe rectangular cells, from the side-to-side in secant fashion and diametrically, and for convenience in manufacture ofthe moulding, these parallel wires, generally indicated by the reference numerals 12 may be joined together by cross wires 14which are also moulded around to form the webs atthe ends of the rectangularcells. Because the heat applied at any one point is rapidly conducted to all parts ofthe damper, the damper is activated as a whole, substantially simultaneously and this avoidsthe damper becoming unstableand crumbling in position so asto leave a gap adjacent one of its edges. Hence the damper can be made relatively short axially, as indicated by the exemplary dimensions. CLAIMS

1. Afire damper comprising a moulding of an intumescent synthetic resin which is rigid and selfsupporting, and which has an embedded skeleton of heat conducting material.

2. A dam per as claimed in Claim 1 wherein the skeleton comprises a series of parallel metal wires.

3. AdamperasclaimedinClaiml orClaim2 wherein the damper comprises a grid of rectangular cells which are open ended, and the heat conducting material comprises a series of parallel steel wires extending from side-to-side of the damper parallel to the major axes of the rectangular cells, with one such wire between each two adjacent cells.

4. Afire damper as claimed in any of Claims 2 or3 wherein the parallel wires are part of a grid including transversely extending ones.

5. Afire damper substantially as described with reference to Figure 1 or Figure 2 of the accompanying drawings.