WO2002023098A1

WO2002023098A1 - Grille element, intended for placing in a ventilation opening

Info

Publication number: WO2002023098A1
Application number: PCT/NL2001/000676
Authority: WO
Inventors: Hendrik Ary Verduyn
Original assignee: Seac International B.V.
Priority date: 2000-09-14
Filing date: 2001-09-13
Publication date: 2002-03-21
Also published as: DE60129030D1; EP1322895A1; AU2001294405A1; DE60129030T2; ES2288994T3; ATE365300T1; EP1322895B1; NL1016184C2

Abstract

Described is a grille element (9; 9´) intended for placing in a ventilation opening (8), which element is made up of a number of metal, U-shaped sections (16; 26), which are disposed next to each other and opposite each other with the legs engaging in each other, so that an S-shaped flow route (30) for air flow is defined. A thermoexpansion material (51) is arranged on the inside surface of the bottoms (10; 20) of said U-shaped sections, preferably with a sounddamping material (52) on top of it. In a fire situation, the thermal radiation on the outside surface of the bottoms of said U-shaped sections (16; 26), will cause the thermoexpansion material (51) to swell up, with the result that said S-shaped flow routes (30) are shut off.

Description

Title: Grille element, intended for placing in a ventilation opening

The present invention relates to a grille element as defined in the preamble of claim 1. Such a grille element is known in practice. The ends of the said main strips are fixed to bearing supports which are directed perpendicular to the longitudinal direction of the main strips, and.which form part of a frame serving for fitting of the grille element. If such a grille element is fitted in a ventilation opening in, for example, a door or a wall, the connecting channels extending from the first plane to the second plane will allow an air flow through the grille element that is suitable for ventilation purposes. On the other hand, all openings situated on the front side, in other words the interspaces between the main strips situated on the front side, are covered by the main strips situated on the rear side, while all the openings situated on the rear side are covered by the main strips situated on the front side, so that such a grille element prevents that objects can be pushed through the ventilation opening from the one side of the grille element to its other side. Likewise, such a grille element prevents direct light transmission.

If a fire situation occurs in the room at one side of such a grille element, the hot gases produced as a result can, through the grille element, reach the room on the other side of the grille element. Even if no fire occurs in that other room, that room is still threatened by the hot gases from the first-mentioned room. The known grille elements of the type described above do not offer any protection against this. The known grille elements therefore do not meet safety requirements relating to fire resistance of a dividing wall or door. On the contrary, many of the grille elements of the type described above which are known in practice are an additional hazard in fire situations, because on the inside they are provided with a plastic foam because of the soundproofing properties thereof. In the event of fire, such a plastic foam can give off toxic gases as a result of the heat occurring in the case of fire.

It is a general object of the present invention to provide an improved grille element. More particularly, the present invention aims to provide a grille element which is permeable for ventilation air in normal circumstances, but which automatically shuts off in a gastight manner if fire occurs.

To that end, in a grille element according to the present invention, a layer of a thermoexpansion material is fixed on the inside wall of each strip.

In the context of the present invention, with the term "thermoexpansion material" is meant: a material which has the property that it expands greatly when it is exposed to temperatures occurring in a fire situation. Thermoexpanding materials are known per se, as a person skilled in the art will know. By way of example, reference can be made to thermoexpanding materials based on sodium silicate or based on Wolman salts. A thermoexpanding material that is preferred because of proved suitability is known in the art as expanding graphite. Apart from the above-mentioned materials, a person skilled in the art will also know other thermoexpanding materials which can be used in the present invention. The dimensions of the layer of thermoexpanding material in this case will always be selected in relation to the expansion capacity of the material in question, on the one hand, and the mutual distances between the parts of the grille element, on the other hand.

A second layer, with specific soundproofing characteristics, such as, for example, a plastic foam to which fire retardants have been added, in order to meet the- fire safety requirements, may be fixed on the layer of the thermoexpanding material if desired. Such non-inflammable plastic foam materials are know per se to a person skilled in the art, and require no further explanation.

These and other aspects, features and advantages of the present invention will be explained in greater detail by the following description of a preferred embodiment of a ventilation grille according to the invention with reference to the drawing, in which same reference numerals indicate same or comparable parts, and in which: figure 1A diagrammatically shows a cross section of a preferred embodiment of a grille element according to the present invention; figure IB diagrammatically shows a cross section of a variant of the grille element of figure 1A; figure 2 diagrammatically shows a front view of a grille element according to the present invention; and figure 3 diagrammatically illustrates an important aspect of the functioning of a grille element according to the present invention.

Figure 1A diagrammatically shows a cross section of a grille element 9 according to the present invention, fitted in a ventilation opening 8 in a door 7. Figure IB shows a variant 9' of the grille element shown in figure 1A, in this case fitted in a ventilation opening 8 in a wall 6. Figure 2 shows a front view of the grille element 9.

The grille element 9, 9' comprises a frame 40, which serves for fitting of the grille element 9, 9' to the door 7 or to the wall 6, respectively. The frame 40 in this embodiment is of a rectangular shape with first and second bearing supports 41, 42 directed parallel to each other, the ends of which being connected to each other by connecting supports 43, 44. The ends of first main strips 10, which run parallel to each other and are situated in a first plane 1 with mutual interspaces 11 between them, are fixed to the bearing supports 41, 42. The first main strips 10 are made of a material that conducts heat well, preferably a metal such as steel.

The grille element 9, 9' further comprises a second set of main strips 20, which are parallel to each other and are situated in a second plane 2 with mutual interspaces 21 between them. The second main strips 20 are also made of a material that conducts heat well, likewise preferably a metal such as steel. The second plane 2 is parallel to the first plane 1, and is situated at a distance L from it.

The first main strips 10 and the second main strips 20 are fitted relative to each other in such a way that the first main strips 10 overlap the interspaces 21 between the second main strips 20, and that the second main strips 20 overlap the interspaces 11 between the first main strips 10.

In this way all openings 11 of the ventilation opening 8 left clear by the first main strips 10 are covered by the second main strips 20, and all openings 21 of the ventilation opening 8 left clear by the second main strips 20 are covered by the first main strips 10. When such a grille element 9, 9' is used, it is therefore not possible to push an object from one side of the grille element 9, 9' to its other side. Further, such a grille element prevents direct light transmission.

In the case of the grille element 9 of figure 1A, the second main strips 20 are fixed on bearing supports of a second frame 40' . The grille element 9 according to this embodiment thus comprises two matching components 9A and 9B, the first component 9A being formed by the first frame 40 with the first strips 10 fixed to it, while the second component 9B is formed by the second frame 40' and the second main strips 20 ixed to it. The two said components 9A and 9B are fitted individually in the ventilation opening 8 on either side of the door 7, as is shown clearly in figure 1A. The second embodiment 9' shown in figure IB is intended for situations where the grille element can be fitted in the ventilation opening 8 only from one side. In that case the second main strips 20 are also fixed to the first frame 40, so that the first frame 40 with the first main strips 10 and second main strips 20 fixed to it forms a complete unit. As can be seen clearly from figures 1A and IB, the first main strips 10 are broader than the interspaces 21 between the second main strips 20, and the second main strips 20 are broader than the interspaces 11 between the first main strips 10. Preferably, and as shown, the first and second main strips 10, 20 are equal in width, and the interspaces 11, 21 are equal in width.

In the following, the part of the grille element 9, 9' situated between the two above-mentioned planes 1 and 2 will be indicated as the "inside" or "interior" of the grille element.

First transverse strips 12, 13 are formed on the first main strips 10, said transverse strips 12, 13 being directed towards the interior of the grille element 9, 9' , in other words directed towards the second main strips 20. A combination of a first strip 10 and the first transverse strips 12, 13 fixed to it will be indicated by the term "lamina" 16. The first transverse strips 12, 13 in this embodiment are substantially parallel to each other and extend substantially perpendicular to the corresponding first main strips 10. Although this is not essential per se, the longitudinal edges of the transverse strips 12, 13 preferably abut the longitudinal edges of the main strips 10, so that a main strip 10 and the two corresponding transverse strips 12, 13 have a U-shaped contour. Although the transverse strips 12, 13 and the main strips 10 can be formed independently of each other and can be fixed to each other in order to form a U-shaped profile, a main strip 10 and the two corresponding transverse strips 12, 13 are preferably formed integrally, for example as an extruded section, or are bent integrally out of metal sheet.

In a comparable manner, the second main strips 20 are also provided with second transverse strips 22, 23, which are directed towards the interior of the grille element 9, 9', in other words towards the first main strips 10, again the combination of a second main strip 20 and the corresponding second transverse strips 22, 23 preferably being formed as a substantially U-shaped profile, for example an extruded section, or being bent integrally out of metal sheet. A combination of a second strip 20 and the second transverse strips 22, 23 fixed to it will be indicated by the reference numeral 26. The first transverse strips 12, 13 have respective free end edges 14, 15, while the second transverse strips 22, 23 have respective free end edges 24, 25. The width of each transverse strip 12, 13, 22, 23 is greater than half the perpendicular distance between the first and the second plane 1, 2, so that the first and second transverse strips 12, 13, 22, 23 partially overlap each other in the transverse direction, in other words in the direction perpendicular to the first and second plane 1, 2. In figure 1A, the overlap is indicated by X. The overlap X is preferably at least 5 mm.

On the other hand, the width of each transverse strip 12, 13, 22, 23 is less than the said perpendicular distance L between the first and second plane 1, 2, so that in the direction perpendicular to said planes 1, 2 there is a distance D between the free ends 14, 15 of the first transverse strips 12, 13, on the one hand, and the second main strips 20, on the other hand. In a comparable manner, there is a distance D between the free ends 24, 25 of the second transverse strips 22, 23 and the first main strips 10. This distance D is not critical, and can lie in the range from approximately 10 to approximately 25 mm; preferably, this distance is approximately 15 to 20 mm. It is pointed out that the exact width of the transverse strips 12, 13, 22, 23 will be adapted to the application situation, such as, for example, the width of the door for which the ventilation grille is intended, as will be clear to a person skilled in the art.

Owing to the fact that the main strips are broader than the interspaces, the transverse strips directed towards each other do not touch each other. Thus, the transverse strips in combination with the main strips define S-shaped or labyrinthine connecting channels 30 between the first interspaces 11, on the one hand, and the second interspaces 21, on the other hand. In figure 1A, there is drawn a curved line 30 which illustrates such an S-shaped connecting channel. Going from the first interspace to the second interspace 21, such a connecting channel first follows the surface of a first transverse strip 12, then bends around the free end 14 of said transverse strip 12, between said free end 14 and the main strip 20 situated opposite it, back to the free end 25 of a second transverse strip, and then 5 bends around this free end 25, between this free end 25 and the first main strip 10, back along the surface of the second transverse strip 23 in the direction of the second interspace 21. These connecting channels 30 allow a flow of ventilation air through the grille element 9, 9' . 10

As shown clearly in figure 1A, a layer of a thermoexpansion material 51, is fixed on the inside wall of each main strip 10, 20, in other words on the surface of each main strip 10, 20 facing the interior of the grille 15 element. In the preferred embodiment shown, a second layer of a non-inflammable plastic foam 52 is fixed on this layer 51. Although the second layer 52 can be fixed independently of the first layer 51, the first layer of the thermoexpansion material 51 and the second layer of the non- 20 inflammable plastic foam 52 are preferably formed as a laminated combination product or composite 50, which can be provided separately, the first layer 51 acting as a hard, but flexible carrier layer for the second layer 52. The composite 50 can be fitted in its entirety on the inside 25_. surface of the main strips. Applying the composite 50, or at any rate applying the thermoexpansion material 51, can be simply carried out by gluing. In addition, the surface of the thermoexpansion material 51 to be fixed to the inside surface of the main strips can also be provided with a self- 30 adhesive layer. Likewise, applying the plastic foam 52 to the thermoexpansion material 51 can be carried out by means of gluing, or because the surface of the plastic foam 52 to be fixed on the thermoexpansion material 51 is provided with a self-adhesive layer. 35 The dimensions of the layer of the thermoexpansion material and the dimensions of the second layer of the non- inflammable plastic foam 52 will be selected in relation to the distances D between the main strips and the transverse strips situated opposite, on the one hand, and the expansion capacity of the thermoexpansion material concerned, on the other hand. In a preferred embodiment, the thickness of the layer of thermoexpansion material 51 is in the range from approximately 1/5 to approximately 1/2 times the distance D measured in the transverse direction between a main strip and the free end of a transverse strip situated opposite; more preferably, this thickness is approximately 1/3 of said distance D. In practice, one will preferably use layers as a standard product with a predetermined standard thickness. A suitable value for such a standard thickness lies in the range from approximately 1 mm to approximately 6 mm. In a specific preferred embodiment, the thickness of the layer of the thermoexpansion material 51 is approximately 2 mm.

For the second layer 52, the thickness can be selected in a suitable way in the range from approximately 4 mm to approximately 15 mm, taking into account the desired sound insulation properties. More preferably, the thickness of the second layer 52 is selected in the range from approximately 5 mm to approximately 10 mm; in a specific preferred embodiment, the thickness of the second layer 52 is approximately 5 mm.

Although a person skilled in the art can select the thermoexpansion material from various thermoexpansion materials known per se in the art, on account of proven suitability, special preference is given to a material that is known in the art as expanding graphite. A composite 50, formed by a layer of thermoexpansion material 51 based on expanding graphite, with a second layer of a non-inflammable plastic foam 52 formed on it, is commercially available under the brand name PYROFOAM from the company Safety Engineering & Consulting International in Krimpen a/d IJssel, the Netherlands.

The grille element 9, 9' functions as follows. In normal circumstances, the connecting channels 30 are opened, and they allow an air flow through the grille element, for example from the space to the left of the grille element, indicated by A in figure 1A, to the space to the right of the grille element, indicated by B in figure 1A. In the preferred embodiment, in which the main strips are provided with the. second layers of plastic foam 52, the grille element 9, 9' has a great sounddamping effeςt, in other words sound transmission from space A to space B and vice versa is greatly counteracted. It is pointed out here that the U-shaped combinations 16 of first strips 10 and transverse strips 12, 13 fixed to them (laminas) make no physical contact with the combinations 26 of second main strips 20 with transverse strips 22, 23 fixed to them, so that direct sound transmission is prevented. Furthermore, the first layer 51 fixed on the inside surface of each main strip 10, 20 prevents the occurrence of vibrations in the grille element 9, 9', or at any rate vibrations are counteracted.

If a fire situation occurs in one of the said spaces on either side of the grille element 9, 9' , the connecting channels 30 are closed very quickly, so that a through-going gas flow is no longer possible. Furthermore, as illustrated, the grille element 9, 9' preferably has a symmetrical construction, so that the functioning is also symmetrical. Suppose that a fire situation occurs in the space A to the left of the grille element. If the ventilation flow is directed from space A to space B, the hot ventilation air can contribute to heating of the grille element, but the ventilation flow can also be directed towards the other side. An important advantage of the grille element according to the invention is that the external surfaces of the first main strips 10 facing the space A are exposed to the radiation (infrared) generated by the high fire temperatures, so that the first main strips 10 will rapidly rise in temperature. More particularly, the temperature of the first main strips 10 can reach a value of approximately 300°C within a few minutes. As a result of this, the thermoexpansion material 51 present on the inside surfaces of the first main strips 10, which is activated in the temperature range between approximately 150°C and approximately 300°C, will expand greatly, in this process pushing the possible second layer 52 ahead of it, until the whole comes into contact with the free ends 24, 25 of the transverse strips 22, 23 of the main strips 20 situated opposite. This situation is illustrated in figure 3. As can be seen clearly, an effective blockage of the connecting channels 30 is now achieved. However, the U-shaped laminas 16, 26 placed opposite each other still make no physical contact with each other, the material 51, 52 pressed against the free ends 24, 25 of the second transverse strips 22, 23 preventing any deformation of the grille element from leading to physical contact. Owing to the absence of this physical contact, direct heat transfer is virtually entirely absent, so that the grille element according to the present invention also meets the fire safety requirements in this respect.

It could happen that after some time the first main strips 10 deform as a result of the high temperatures, in such a way that the connecting channels 30 are again opened slightly. In that case, the second main strips 20 provide additional safety, because now the hot gas flowing through the ventilating element will cause the thermoexpansion material 51 on the inside surfaces of the second main strips 20 to expand.

Thus, the present invention succeeds in providing a grille element intended for placing in a ventilation opening, which element is made up of a number of metal, U- shaped sections, which are disposed at a distance from each other, next to each other and opposite each other, with the legs engaging in each other, so that' an S-shaped flow route for air flow is defined. A thermoexpansion material is applied on the inside surface of the bottoms of those U- shaped sections, preferably with a sounddamping material on top of it. In a fire situation, the thermal radiation on the outside surface of the bottoms of those U-shaped sections will cause the thermoexpansion material to swell up, with the result that said S-shaped flow routes are shut off.

It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed above, but that various amendments and modifications thereof are possible without departing from the scope of the invention as defined in the appended claims. It will be clear to a person skilled in the art that for the first layer of thermoexpansion material 51, instead of the said preferred material, in other words based on expanding graphite, other suitable thermoexpanding materials can also be used. It will also be clear to a person skilled in the art that the main task of the second layer 52 is to provide a sounddamping effect in normal circumstances, and that other suitable materials can be used here. Because of safety considerations, the said plastic foam in which fire retardants are incorporated are preferred, but other suitable materials will also be clear to a person skilled in the art.

The main strips 10 and 20, like the transverse strips, are described above as being substantially flat. However, this is not essential; it will be clear to a person skilled in the art that the advantages of the present invention are also achieved if the strips have a certain curvature.

The main strips 10 and 20 are described above as lying in line with each other in a common flat plane 1, 2. However, this is not essential; it will be clear to a person skilled in the art that the advantages of the present invention are also achieved if the strips form a certain angle relative to that common plane, while said plane may also have a certain curvature. It is important only that the U-shaped sections have their bottom parts directed outwards and have their legs directed inwards.

Claims

1. Grille element (9, 9'), intended for placing in a ventilation opening (8) in, for example, a door (7) or a wall (6) , comprising: a number of first main strips (10) of a heat well-conducting material, preferably a metal such as steel, disposed next to each other, substantially parallel to each other, with interspaces (11) between them; a number of second main strips (20) of a heat well- conducting material, preferably a metal such as steel, disposed next to each other, substantially parallel to each other, with interspaces (21) between them; wherein said first main strips (10) overlap said interspaces (21) between said second main strips (20) , and wherein said second main strips (20) overlap said interspaces (11) between said_. first main strips (10); wherein said first main strips (10) are provided with first transverse strips (12, 13) directed towards the second main strips (20) , while the second main strips (20) are provided with second transverse strips (22, 23) directed towards the first main strips (10) , which first and second transverse strips (12, 13; 22, 23) at least partially overlap (X) each other and thus define labyrinthine or S-shaped connecting channels (30) between said first interspaces (11) of the first main strips (10) , on the one hand, and said interspaces (21) of the second main strips (20) , on the other hand; characterized in that a layer (51) of a thermoexpansion material is arranged on the inside wall of each main strip (10; 20) .

2. Grille element according to claim 1, wherein the first main strips (10) are broader than the interspaces (21) between the second main strips (20) , and wherein the second main strips (20) are broader than the interspaces (11) between the first main strips (10) .

3. Grille element according to claim 1 or 2, wherein the first and second main strips (10; 20) are equal in width to each other, and wherein the interspaces (11) between the first main strips and the interspaces (21) between the second main strips are equal in width to each other.

4. Grille element according to any of claims 1 to 3 inclusive, wherein the transverse strips (12, 13; 22, 23) are directed substantially perpendicularly to said main strips (10; 20) .

5. Grille element according to any of claims 1 to 4 inclusive, wherein a main strip (10; 20) is provided with two transverse strips (12, 13; 22, 23) abutting its edges.

6. Grille element according to claim 5, wherein a main strip (10; 20) and the two corresponding transverse strips (12, 13; 22, 23) are formed as a substantially U-shaped section (16; 26) .

7. Grille element according to claim 6, wherein a main strip (10; 20) and the two corresponding transverse strips (12, 13; 22, 23) are bent integrally out of metal sheet, or are formed integrally as an extruded section.

8. Grille element according to any of the preceding claims, wherein the first transverse strips (12, 13) and the second transverse strips (22, 23) overlap each other in the transverse direction, in other words in the direction perpendicular to the first and second plane (1, 2) , the overlap (X) preferably being at least 5 mm.

9. Grille element according to any of the preceding claims, wherein the distance (D) measured in the transverse direction between the free ends (14, 15; 24, 25) of the first and second transverse strips (12, 13; 22, 23), on the one .hand, and the second and first main strips (20; 10) respectively, on the other hand, lies in the range from 10 to 25 mm, and is preferably 15 to 20 mm.

10. Grille element according to any of the preceding claims, wherein the thermoexpansion material is based on expanding graphite .

11. Grille element according to any of the preceding claims, wherein the thickness of the layer of thermoexpansion material lies in the range from approximately 1 mm to approximately 6 mm, and is preferably of the order of approximately 2 mm.

12. Grille element according to any of the preceding claims, wherein the thickness of the layer of thermoexpansion material lies in the range from approximately 1/5 to approximately 1/2 of the distance measured in the transverse direction between a strip and the free end of a transverse strip situated opposite, said thickness preferably being approximately 1/3 of said distance .

13. Grille element according to any of the preceding claims, wherein a second layer (52) of a non-inflammable plastic foam is arranged on said first layer (51) of the thermoexpansion material.

14. Grille element according to claim 13, wherein the second layer (52) is arranged on said first layer (51) of the thermoexpansion material by means of gluing, or by means of a self-adhesive layer provided on the second layer (52) or on said thermoexpansion material (51) .

15. Grille element according to claim 13 or 14, wherein the first layer (51) of the thermoexpansion material and the second layer (52) of the non-inflammable plastic foam are formed as a laminated combination product or composite (50), the first layer (51) acting as a hard, but flexible carrier layer for the second layer (52) .

16. Grille element according to any of the preceding claims, wherein the layer of thermoexpansion material (51) is arranged on the main strips (10, 20) by means of gluing, or by means of a self-adhesive layer provided on said thermoexpansion material (51) .

17. Grille element according to any of the preceding claims, wherein the first main strips (10) are situated substantially in a first plane (1), wherein the second main strips (20) are situated substantially in a second plane (2) , and wherein said second plane (2) is situated at a distance from said first plane (1) .

18. Grille element according to claim 17, wherein said first plane (1) and/or said second plane (2) has a certain curvature or is flat.

19. Grille element according to claim 17 or 18, wherein said first plane (1) and/or said second plane (2) is situated at an angle to the axis of the ventilation opening (8) .

20. Grille element according to any of the preceding claims 17 - 19, wherein the first main strips (10) and/or the second main strips (20) are situated at an angle to said first plane (1) and/or said second plane (2) , respectively.

21. Grille element according to any of the preceding claims, wherein the first main strips (10) and/or the second main strips (20) and/or the first transverse strips (12, 13) and/or the second transverse strips (22, 23) are flat, or have a certain curvature.

22. Grille element according to any of the preceding claims, wherein the first main strips (10) and the second main strips (20) are supported by a common frame (40) .

23. Grille element according to any of the preceding claims 1 - 21, wherein the first main strips (10) and the second main strips (20) are supported by separate frames (40; 40').

24. Grille component (9A; 9B) for use in a grille element according to any of the preceding claims, comprising: a number of main strips (10; 20) of a heat well-conducting material, preferably a metal such as steel, disposed next to each other, substantially parallel to each other, with interspaces (11) between them; wherein the main strips (10; 20) are provided with transverse strips (12, 13; 22, 23), which are preferably directed substantially perpendicularly to said main strips (10; 20); characterized in that a layer (51) of a thermoexpansion material is arranged on the inside wall of each main strip (10; 20) .

25. Grille component according to claim 24, wherein a main strip (10; 20) and the two corresponding transverse strips (12, 13; 22, 23) are formed as a substantially U-shaped section (16; 26) , which is preferably bent integrally out of metal sheet, or is formed integrally as an extruded section.

26. Grille component according to claim 24 or 25, wherein the thermoexpansion material is based on expanding graphite.

27. Grille component according to any of the preceding claims 24 - 26, wherein the thickness of the layer of thermoexpansion material lies in the range from approximately 1 mm to approximately 6 mm, and preferably is of the order of approximately 2 mm.

28. Grille component according to any of the preceding claims 24 - 27, wherein a second layer (52) of a non- inflammable plastic foam is arranged on said first layer (51) of the thermoexpansion material.

29. Grille component according to any of the preceding claims 24 - 28, with one or more of the following characteristics (a) -(c): a) the second layer (52) on said first layer (51) of the thermoexpansion material is arranged by means of gluing, or by means of a self-adhesive layer provided on the second layer (52) or on said thermoexpansion layer (51) ; and/or b) the first layer (51) of the thermoexpansion material and the second layer (52) of the non- inflammable plastic foam are formed as a laminated combination product or composite (50) , the first layer (51) acting as a hard, but flexible carrier layer for the second layer_. (52). and/or c) the layer of thermoexpansion material (51) on the main strips (10, 20) is arranged by means of gluing, or by means of a self-adhesive layer provided on said thermoexpansion layer (51) .

30. Lamina (16; 26) for use in a grille element according to any^' of the preceding claims 1 - 23, comprising: a main strip (10; 20) of a heat well-conducting material, preferably a metal such as steel; which main strip (10; 20) is provided with transverse strips (12, 13; 22, 23) , which are preferably directed substantially perpendicularly to said main strip (10; 20) ; characterized in that a layer (51) of a thermoexpansion material, which is preferably based on expanding graphite, is arranged on the inside wall of the main strip (10; 20) .

31. Lamina according to claim 30, wherein a main strip (10; 20) and the two corresponding transverse strips (12, 13; 22, 23) are formed as a substantially U-shaped section (16; 26), which is preferably bent integrally out of metal sheet, or is formed integrally as an extruded section.

32. Lamina according to claim 30 or 31, wherein a second layer (52) of a non-inflammable plastic foam is arranged on said first layer (51) of the thermoexpansion material.

33. Lamina according to any of claims 30 - 32, with one or more of the following characteristics (a) -(e): a) the second layer (52) on said first layer (51) of the thermoexpansion material is arranged by means of gluing, or by means of a self-adhesive layer provided on the second layer (52) or on said thermoexpansion layer (51) ; and/or b) the first layer (51) of the thermoexpansion material and the second layer (52) of the non- inflammable plastic foam are formed as a laminated combination product or composite (50) , the first layer (51) acting as a hard, but flexible carrier layer for the second layer (52) ; and/or c) the layer of thermoexpansion material (51) on the main strip (10, 20) is arranged by means of gluing, or by means of a self-adhesive layer provided on said thermoexpansion material (51) ; and/or d) the main strip (10; 20) and/or the transverse strips (12, 13; 22, 23) are flat, or have a certain curvature; and/or e) the thickness of the layer of - thermoexpansion material lies in the range from approximately 1 mm to approximately 6 mm, and is preferably in the order of approximately 2 mm.

34. Use of a thermoexpansion material (51), preferably based on expanding graphite, as a sealing agent which reacts automatically in fire situations, on an inside surface of a ventilation grille's metal wall facing a space (A; B) .