GB2376706A

GB2376706A - Fire retardant strip

Info

Publication number: GB2376706A
Application number: GB0115108A
Authority: GB
Inventors: Robert Mcgowan Mann
Original assignee: Lorient Polyproducts Ltd
Current assignee: Lorient Polyproducts Ltd
Priority date: 2001-06-21
Filing date: 2001-06-21
Publication date: 2002-12-24
Anticipated expiration: 2021-06-21
Also published as: GB2376706B; GB0115108D0

Abstract

An intumescent strip 10 for securment to a flat support surface (SS, fig 2), includes an elongate support body 12 defining an outer face 16 and an opposed inner face (14, fig 2) of the strip. At least two spaced apart channels 18 extend longitudinally along the body with the mouths located on the inner surface. Intumescent material 21 is located in each channel. The body has anchorage strips 30 located on each side of each channel to enable the inner surface to be secured to the support surface. A smoke seal may also be mounted on the strip. The construction of the strip allows mounting to a door or door frame without the need for an accommodating groove or rebate, whilst still producing a sufficient intumescent mass.

Description

FIRE RETARDANT STRIP The present invention relates to a fire retardant strip.

It is known to provide fire retardant strips along the edges of doors and/or door frames in order to produce an intumesced fire barrier which seals the gaps between the door and door frame in the event of a fire.

Normally the edge of the door or door frame on which the fire retardant strip is mounted is provided with a groove or rebate to receive the strip.

This enables a relatively thick strip to be accommodated whilst at the same time enabling the outer face of the strip to be substantially flush with the surrounding face of the door or door frame. In this way a sufficient depth of intumescent material may be provided for filling the gaps between the door and door frame in the event of fire whilst at the same time exposing only the outer face of the strip during normal usage and thereby minimising the possibility of damage from abrasion or impacts.

A problem associated with this type of arrangement is that it is necessary to modify the door and/or frame edges in order to provide the necessary groove or rebate for accommodating the strip.

This increases manufacturing costs and also makes it difficult to fix an intumescent strip to existing door and door frame assemblies not provided with such grooves.

A further problem is that housing the intumescent strip within a groove of a wooden door/door frame can delay intumescence in the event of

a fire due to the insulative effect of the surrounding wood. To overcome this problem, it is common to house the intumescent material in a metal casing, such as aluminium, in order to improve the conduction of heat to the intumescent material and thereby enable a quicker response in the event of fire.

A general aim of the present invention is to provide an intumescent strip which is capable of being mounted on a flat support surface without the need for an accommodating groove or rebate and which is capable of producing a sufficient amount of intumesced mass after intumescence in order to sealingly fill a gap between opposed faces such as found between a door and door frame.

According to one aspect of the present invention there is provided an intumescent strip for securance to a flat support surface, the strip including an elongate support body defining an outer face and an opposed inner face of the strip, at least a pair of spaced apart open topped channels extending longitudinally along the body with each having its open top located in said inner face, said body having anchorage strip portions located on each side of each channel to enable said inner face of the strip to be secured in face to face contact with said support surface, and intumescent material located in each channel.

Preferably a layer of adhesive is applied to said inner face defined by said anchorage strip portions to enable the support body to be bonded to said flat support surface such as a door edge or doorframe.

Preferably the support body is an extrusion formed from a suitable plastics material such as polyvinylchloride which, at the temperature of intumescence of the intumescent material, is in a soft state.

Preferably the body has a substantially constant wall thickness across its width and along its length such that the outer face defines outwardly projecting ridges in the region of said channels.

Preferably two channels are provided, the channels being spaced apart widthwise of the body by a common anchorage strip portion which defines a body bridging portion located in-between the channels.

Preferably the intumescent material fills each channel to define an exposed surface in the top of the channel which is co-planar with the surrounding inner face of the strip.

Preferably, the body has one or more elongate smoke seals mounted thereon projecting from its outer surface.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: Figure 1 is a part perspective view of an intumescent strip according to a first embodiment of the present invention; Figure 2 is an end view of the embodiment shown in Figure 1; Figure 3 is a part perspective view of a second embodiment according to the present invention; and Figure 4 is a part perspective view of a third embodiment according to the present invention; Referring initially to Figures 1 and 2, there is shown an intumescent strip 10 having an elongate body 12 which is preferably extruded from a

suitable heat-meltable plastics material such as polyvinylchloride and which defines an inner face 14 and an outer face 16.

In the embodiment of Figure 1, the body 12 is extruded so as to

I'I I a I define a pair of longitudinally extending channels 18 having open tops located within the inner face 14.

The body 12 includes anchorage strip portions 30 located on each side of each channel 18 which enable the body 12 to be secured in face to face contact with the flat support surface SS such as a door edge or door frame.

Preferably each channel 18 is filled with an intumescent material 21.

Preferably the intumescent material is of thickness 0.5-2. 0 mm, capable of expansion to a sufficient thickness to effectively seal the gap between a door leaf and frame, and with properties of sustaining that seal for up to 2 hours according to internationally recognised fire test standards, e. g.

"Technofire"material as manufactured by Technical Fibre Products Ltd.

UK".

Conveniently, the intumescent material 21 in each channel 18 is defined by a strip having an upper face 22 and a lower face 23.

The upper face 22 is preferably bonded to the bottom 24 of the accommodating channel 18 by a suitable adhesive, preferably a pressure sensitive contact adhesive.

The thickness of the strip of intumescent material is preferably chosen such that its lower face 23 is co-planar with the inner face 14.

Preferably an adhesive strip 40 of a pressure contact adhesive is bonded to the inner faces 14 defined by anchorage strip portions 30 and lower faces 23 of the intumescent material. Prior to mounting on a flat support surface SS the adhesive strip 40 is preferably covered by a releasable protective strip (not shown) such as a silicone coated paper.

After removal of the protective strip, the intumescent strip 10 may be simply bonded in face to face contact with a support surface SS by pressing the inner face 14 against the support surface SS.

The width Wa of the anchorage portions 30 are chosen so as to provide a sufficient amount of surface area of inner face 14 in order to provide adequate bonding to take place. Typically, in the embodiment of Figure 1, the outer anchorage portions have a Wa less than 10 mm, more preferably about 8 mm and the central anchorage portion 30 preferably has a width of less then 5 mm, more preferably about 3.5 mm. The depth D1S of the intumescent strip 10 is chosen to be sufficiently small to enable the intumescent strip 10 to be located in a gap between a door and door frame.

Typically, the depth D1S is less than 3 mm, more preferably about 1.5 mm.

The width Wa of the open top of channels 18 is determined by the desired width of intumescent material which it accommodates. This is chosen, in combination with the thickness of the intumescent material 21 in the channel, in order to provide, under fire conditions, an amount of intumescent material which is sufficient to seal the gap between a door and a door frame.

Typically the thickness of the intumescent material is less than 2.0 mm, more preferably about 1 mm.

Typically, in the embodiment of Figure 1, both channels 18 have a width Wa of less than 15 mm, preferably about 10 mm.

The body 12 is preferably extruded so as to have a constant wall

ti- I thickness across iis width and along iis length as shown in Figures 1 and 2.

The wall thickness is preferably relatively thin, preferably less than the depth of the channels 18. This is preferable since it provides a relatively flexible body 12 which is easy to apply to the support surface SS. In addition, it uses a minimum amount of plastics material and so provides a minimum amount of heat insulation to the intumescent material in the event of fire and so enables the intumescent material to quickly rise in temperature to its intumescent temperature. Also, the thinness of the wall provides little resistance to the intumescent material bursting through the wall.

Typically the wall thickness is less than 1 mm, more preferably is about 0.4 mm.

The distance between the adjacent channels 18 not only determines the surface area of inner face 14 defined by the inter-connecting anchorage strip 30 but also serves to provide an insulative barrier the widthwise direction of the strip between the adjacent channels 18. This is advantageous when the intumescent strip 10 is mounted on support surface defined by a heat insulative material such as wood since it enables delayed intumesence of the intumescent material accommodated in the channel 18 which is furthest removed from the fire side of the intumescent strip 10. In these circumstances, the intumescent strip 10 will create a first seal during the initial stages of a fire when the intumescent material in the channel 18 closest to the fire side intumescences.

As the fire conditions continue (and this may cause the first seal to be broken due to movement between the door and door frame caused by the fire), a second seal may be produced to re-establish a seal between the door and door frame by intumesence of the intumescent material accommodated in the channel 18 located furthest away from the fire side.

Due to the thickness of the wall of body 12 being less than the depth of channels 18, the outer face of the strip 10 has ridges 50 corresponding to the position of channels 18 and troughs 51 located in between the ridges 50.

If desired, the body 12 may be extruded such that the troughs 51 in between the ridges 50 are filled with plastics material as indicated by broken lines in Figure 2.

Alternatively, as shown in Figure 4, the trough 51 may provide a suitable location for mounting a smoke seal 54. The smoke seal 54 may be formed from a suitable resilient plastics material and be co-extruded with the body 12.

As illustrated in Figure 3, a tubular smoke seal 55 may be mounted on the outer face of one of the anchorage strip portions.

It will be appreciated that with an intumescent strip of the present invention, as described above, the outer face of the intumescent material is bonded to the support surface SS. Should the support surface be made of a heat conductive material, such as a metal or metal alloy, it will be appreciated that the intumescent material, due to its large surface area of contact with the support surface SS, will rapidly respond to increases of temperature caused by a fire.

It is also envisaged that adhesive may be applied to the inner surface 14 defined by the outer anchorage strip portion 30 only.

Also, anchorage strip portion 30 may be secured to the support surface by types of fixing means other than adhesive, e. g. staples or pms.

Claims

1. An intumescent strip for securance to a flat support surface, the strip including an elongate support body defining an outer face and an opposed inner face of the strip, at least a pair of spaced apart open topped channels extending longitudinally along the body with each having its open top located in said inner face, said body having anchorage strip portions located on each side of each channel to enable said inner face of the strip to be secured in face to face contact with said support surface, and intumescent material located in each channel.

2. A strip according to Claim 1 wherein a layer of adhesive is applied to said inner face defined by said anchorage strip portions to enable the support body to be bonded to said flat support surface such as a door edge or doorframe.

3. A strip according to Claim 1 or 2 wherein the support body is an extrusion formed from a suitable plastics material such as polyvinylchloride which, at the temperature of intumescence of the intumescent material, is in a soft state.

4. A strip according to Claim 1,2 or 3 wherein the body has a has a substantially constant wall thickness across its width and along its length such that the outer face defines outwardly projecting ridges in the region of said channels.

5. A strip according to any of Claims 1 to 4 wherein the intumescent material fills each channel to define an exposed surface in the top of the channel which is co-planar with the surrounding inner face of the strip.

6. A strip according any preceding claim wherein the body has one or more elongate smoke seals mounted thereon projecting from its outer surface.

.

7. A strip according to any preceding claim wherein two channels are provided, the channels being spaced apart widthwise of the body by a common anchorage strip portion which defines a body bridging portion located in-between the channels.

8 An intumescent strip substantially as herein described with reference to and as illustrated in the accompanying drawings.