The invention relates to a fire retarding seal for sealing slits or gaps in case of fire. It also relates to a fire door and a method of sealing slits.

Nowadays, in order to protect buildings from fire spreading through the interior of the buildings, seals are used to seal slits, cracks and the like by means of foaming strips. These seals may comprise strips that are heat activated and that will start to foam as soon as a certain activation temperature is reached. Once activated, the strips completely seal off doors, windows, gaps and dilatations so that spreading of smoke and fire is avoided or, at least retarded.

Some known foaming seals will withstand continuous exposure to 260 ⁰ C and up to 1090 ⁰ C for 15-20 minutes, and up to 1650 ⁰ C for 15-30 seconds. The foaming seals need to be fixed to a construction in the vicinity of a slit. This fixing is often performed by means of gluing a flat elongated strip onto a surface of the construction. In case of fire, the heat activated strip will start to foam and will expand with an expansion ratio of 1:7 or more. The resulting foam will seal off the slits and will avoid smoke from spreading. However, since the foam is actually no longer fixed to the construction, it may get detached from the construction. In that case a dangerous situation may occur wherein the foam no longer seals the slit and smoke and heat will pass through.

It is a goal of the present invention to provide a fire retarding seal which overcomes the disadvantage of the present seals. This goal is achieved by a fire retarding seal for sealing slits in case of fire, the seal comprising a heat activated foaming strip, and a sleeve surrounding the strip, the sleeve comprising a porous material which is permeable for hot gasses. By enclosing the strip using a sleeve made out of a porous material, hot fire smoke can reach and activate the enclosed foam strip. Once the foam strip is activated, the position of the foaming is

controlled by fixing the sleeve in the vicinity of the slit or a crack. Fixing of the sleeve can be done by means of for example staples, nails, and the like. It is also possible to use an appropriate glue.

In an embodiment, the porous material has a melting point above 300 ⁰ C so that itself withstands substantial heat.

In an embodiment, the material of the sleeve may comprise silicate or glass yarn.

In an embodiment, the material is a woven fabric, but non-woven fabric is possible as well.

In a particular embodiment, the heat activated foaming strip comprises Promaseal™. This material has very good heat properties and expands at a temperature of about 190 ⁰ C.

The invention also relates to a fire door comprising the fire retarding seal as described above.

Finally, the invention also relates to a method of sealing slits, the method comprising:

- surrounding a heat activated foam strip with a sleeve comprising a material which is porous so as to let through smoke, to render a seal;

- mounting said seal in the vicinity of a slit or gap in a building construction, such as a door. Embodiments of the invention will now be

described, by way of example only, with reference to the accompanying drawings in which corresponding reference symbols indicate corresponding parts, and in which:

- Figure 1 schematically shows an embodiment of a fire retarding seal;

- Figure 2 shows a cross section of the embodiment of Figure 1 ;

- Figure 3 shows schematically a top view of a fire door comprising a fire retarding seal.

Figure 1 shows an embodiment of a fire retarding seal 1 comprising a heat activated foaming strip 2, and a sleeve 3 surrounding the strip 2. The sleeve 3 is made out of a woven or non-woven fabric and is folded such that at one outer end a flat end 4 results. This flat outer end 4 may be used to fix the seal to a construction by means of nails and the like.

The sleeve according to an embodiment comprises a porous material which has a melting point above 300 ⁰ C. More preferably the material has a melting point above 1100 °C. In an embodiment, the sleeve is open at the two outer ends. However, it is also possible to completely close the sleeve 3 so that during fire, absolutely no foam can escape from the sleeve 4.

Since the sleeve material is porous so as to let through fire smokeoriginating from the fire, the sleeve 4 can be closed completely at all sides without obstructing the gasses that result from the fire (i.e. smoke) .

The sleeve material may comprise silicate or glass yarn or any other suitable material known by the skilled person. A preferable heat activated foaming strip comprises Promaseal™ manufactured by the company Promat, United Kingdom.

Figure 2 schematically shows a cross section of a mounted seal fixed to a frame 6 by way of staples 7. The frame 6 itself is fixed to a wall 8 by means of screws 9, 9' .

Figure 3 shows schematically a top view of a fire door 10 comprising a fire retarding seal 12,12' according to an embodiment. The seal 12,12' is attached to a frame 14,14' which it attached to a wall 15,15'. The door 10 is mounted onto a rail, not shown, and can be opened by way of moving it sideways. Figure 3 shows the closed position of the door 10. In case of fire, the seal 12,12' will get warmer and eventually, the strip inside the seal 12,12' will start to foam. The seal 12,12' will expand and will seal off the openings between the door 10 and the frame 14,14'. It is noted that in fact the seal 12,12' and the frame 14,14' will be placed on all four sides of the door 10.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described and that the embodiments may be combined.

The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.