EP0213103A1

EP0213103A1 - Fire retarding structure

Info

Publication number: EP0213103A1
Application number: EP86850282A
Authority: EP
Inventors: Mats Larsson; Rolf Ulfvengren
Original assignee: LAXA BRUKS AB
Current assignee: LAXA BRUKS AB
Priority date: 1985-08-29
Filing date: 1986-08-28
Publication date: 1987-03-04
Also published as: SE8504028D0

Abstract

A fire retarding structure or body adapted to be used in partitian walls or outer walls of large or small volumes to be protected against too high temperatures caused by fire or similar outside the said volume and comprising a supporting fire retarding body part (1, 2) in two or more co-operating parts of an isolation material, for instance mineral wool, which has been made form resistant by means of a binder, and which has been shaped to plane or curved disc like bodies, at least one part of which is formed with one or more spaces (3) extending parallely with the main surfaces of the disc and which spaces (3) carry closed and diffusion tight containers filled with water which is bound in an absorption material providing a fixed mass from which water or steam can be released when the mass is heated to such temperature that the casing (5) of the container (4) bursts.

Description

In addition to traditional fire protection the main purpose of which generally is to prevent the fire from extending, and protection of valuable paper, intended to temporarily protect the valuable papers during fire, a new important field has developed. This field is related to the last mentioned field but is concerned with substantially more heat sensistive materials, namely magnetic tapes, computor discs, electronics and to certain degree also electrical cables. For such materials it is necessary to keep the temperature below the softening temperature for the plastic materials, and also below the temperature at which there is a risk that the magnetic information get lost or at least is damaged. Of course it is intended to prevent a harmful rise of temperature only for a predetermined period of time. This time, of course, should be as long as possible within the limits of reasonable sacrificings. Practically the time often should be long enough to make it possible to take adequate fire protecting measurements and so that the sensitive material is saved before having been destroyed by too high temperatures. Tranditionally several different technical possibilities have been used. The closest possibility is to enclose the sensitive material in rooms or cupboards which are well isolated with a fire resistant or fire retarding isolation material like mineral wool. Relatively thick isolation layers, however, have been needed and this has made the available storing places relatively small within the limits of predetermined outer measurements, at least as concerns fire resistant cupboards.
Another possibility has been to install sprinkler equipments. This is, however, complicated and not always reliable. Further sprinkler equipments are not generally movable and this is considered a serious disadvantage.
A further way of retarding the temperature rise within a fire protected space has been to make the very structure heavy, that is to give the outer surfaces a large heat capacity. In such case the structures also become difficult to move and they get a restricted storing volume.
Lately the idea has developed to embed materials in the walls, for instance Glauber's salt, which by a phase inversion from solid to liquid state retards the temperature rise in the protected area. This is a relatively good solution but there is a limited possibility of stopping the temperature rise depending on the relatively low heat absorption.
The present invention intends to overcome the disadvantages and lacks of the previously known solutions. Like in other solutions the invention is based on the idea that the protective area is delimited or surrounded by walls which are built up by special fire retarding bodies or structures.
According to the invention the said fire retarding structures comprise an isolation material for instance mineral wool, which has been made form resistant by means of a binder and have been shaped to a plane or curved disc in the side surface or the interior of which one or more closed hollow spaces have been formed extending parallelly to the main surfaces of the disc and in which hollow spaces closed and diffusion sealed containers are enclosed, which containers are filled with water bound in an absorption material providing a fixed mass from which water or water steam can be released when the mass is heated.
An obligatory presumption for the good effect of the invention is that the isolation material of the fire retarding structure is heat resistant or possible non-inflammable. In order to provide a good water absorption the material should be of a type having an open porosity, and preferably the material can be unisotropic, so that the water gets a stronger distribution in the surface direction than in the depth direction thereof.
The use of the heat capacity and the evapouration of the water for cooling or damping the temperature rise, of course, is known since very long. It is basicly possible to enclose containers including liquid water in fire retarding bodies of the above mentioned type. There is however, and obvious risk of water leakage, and a product of this type most certainly should not have a large place on the market. By introducing the water of the structure absorbed in a material, so that there is no liquid phase the risk that the material to be protected is damaged by water is practically eliminated. In this way it is possible to provide a very effective protection by means of simple and cheap structures.
It is also advantageous that the Glauber's salt contains water. In such case still increased possibilities of dumping the temperature rise are obtained.
When a structure containing fire retarding bodies according to the invention is subjected to a high temperature the absorbed water is released in the form of liquid or as vapour. In the latter case there is a pressure increased of the containers and by time the containers burst open and water or vapour spreads in the structure. A particularly effected alternative of the invention is that the water which possible flows out is sucked into the isolation material or into a suplementary material so that the main spreading of the water is parallelly to the main surfaces of the fire retarding body.
It is of some importance to control the exact time when water or vapour is let out of the containers. Therefore the containers should be adapted to split up or burst at a temperature slightly above 100°C. This is possible by forming the containers as two co-operating container halves which have been sealed, for instance welded together with a material which has lost at least a substantial part of the joining ability at the said temperature of slightly over 100°C. Generally the containers burst depending on the pressure build up at an elevated temperaure.
It might be believed that the isolation material should be disposed so that a thicker part thereof is located on the inner side of the containers. As long as the water is evapourated the temperature is kept at 100°C and the isolation material should protect the heat sensitive material even from said temperature. It has, however, proved that the best effect is obtained if a larger part of the isolation material on the contrary is disposed on the outer side of the containers.
Of course it is of interest that the water containing containers have a large surface. Preferably the containers have a surface of at least 70% and preferably at least 85% of the surface of the fire retarding body. By placing several layers of containers on top of each other it is basiclly possible to cover more than 100% of the surface of the fire retarding body. In such case a layer of isolation material should be disposed in between each such layers of containers.
It has shown that silica gel is very useful as absorption material. As example of more simple absorbtion materials are mentioned more or less developed products on cellulosis base in the most simple case even ordinary peat litter. There are also useful starch derivates having a very high absorption ability. The choice of absorption material is an economical question in the first place, but also handling questions are to be considered. Obviously the amount of water per m² of the fire retarding structure or body is of importance. Fire retarding bodies according to the invention should contain at least 500 g water/m² of the fire retarding body.
In all structures of the actual type the edges and in particular the corners are critical depending on the relationship between surface and volume of the structure. At an edge and in particular at a corner the surface subjected to fire is large in relation to the volume of the structure material to withstand the fire. Further there may be difficulties in joining the structure, and there are often gaps and cuts at corners and edges. In such case it is advantageous that the structure is formed so as to contain fire retarding bodies likewise having edges and corners. The risk that the bodies are formed with gaps and cuts at the edge or at the corners thereby is eliminated. It is in particular advantageous if the water containing containers extend as far as to the edge of the corner. Therefore the supporting isolation bodies preferably are formed as two parts which can be associated and joined and at least one part of which is formed with one or more cavities for enclosing the water absorbing material. The two parts are joined to provide a water sealed unit while enclosing the water absorbing isolation material.
In the following the invention is to be described by means of forms of execution illustrated in figures 1-7. All figures are cross sections through different fire retarding bodies according to the invention. Figure 1 shows two layers 1 and 2 of isolation material. The layers are formed with recesses to that the layers when combined provide a hollow space 3. In the said space 3 a container 4 is enclosed, which container includes a liquid bearing absorption material enclosed by a casing 5. The two isolation layers 1 and 2 are interconnected at the joint 6, and tabs 7 of the casing extend into said joint 6. The tabs 7 can be the result of the joining of the casing 5. The two isolation body halves 1 and 2 are joined for instance by being glued together or in any other suitable way.
Figure 2 correspondingly shows a cross section through a fire retarding body having two isolation layers 9 and 10 formed with cavities so that the two layers when put together leave a space for three containers 11 with a liquid bearing absorption material.
Figure 3 shows an alternative fire retarding structure or body which is easy to manufacture and which is composed of a isolation body 18 which by partition walls or edges 19 provide pockets 20 for the container having the water bearing absorption material. The fire retarding body also includes a lid 21 which can be a paranenepipedical disc, adapted to be joined with the edges 19 of the isolation body 18.
Figure 4 shows a corresponding form of execution designed as an edge or a corner. An outer isolation body 22 is extending angularly and is formed with ribs 23 providing a number of pockets 24 along the plane sides of the body and an angular pocket 25 at the very corner. Containers with water bearing absorption material are intended to be placed in the pockets 24 and 25. The isolation body 22 is combined with an angular lid 26 which covers the pockets.
In figure 5 the fire retarding body is formed with two outer isolation layers 27 and 28 each having a number of spaced cavities or pockets 30. Between the isolation layers 27 and 28 there is an intermediate layer 29 adapted to close the pockets. Liquid bearing containers are adapted to be enclosed in the pockets 30. The pockets of the two layers 27 and 28 are placed so as to overlap each other.
Figure 6 shows an angularly formed fire retarding body having an outer, U-shaped isolation body 31 and three inner co-operating isolation bodies 32 and 33 each formed with cavities 34 for non-illustrated liquid bearing containers.
Figure 7 finally shows a substantially half eliptical fire retarding body of the same type and combination as described above.
It is to be understood that the embodiments of the invention described above and illustrated in the drawings are only illustrating examples, and that many different modifications may be presented within the scope of the appended claims.

Claims

1. A fire retarding body intended to be used in partitian walls or outer walls of large or small spaces to be protected against too high temperatures caused by fire or similar outside the space, characterized in that the fire retarding body comprises a supporting fire retarding body (1, 2; 9, 10; 18, 21; 22, 26; 27, 28; 31, 33) of an isolation material, for instance mineral wool, which has been made form resistant by means of a binder and which has been shaped to a plane or curved disc which at the interior is formed with one or more closed spaces (e.g. 3) extending parallelly with the main surfaces of the disc, and which spaces carry closed and diffusion tight containers (4; 11) filled with water which has been bound in an absorption material to provide a fixed mass from which water or steam can be released upon heating.

2. Fire retarding body according to claim 1, characterized in that the supporting fire retarding body part is formed as two co-operating halves (e.g. 1, 2), whereby at least one half is formed with a cavity for enclosing the water bearing container (e.g. 4) and which halves have been joined by glueing, welding, or any other equivalent joining method.

3. Fire retarding body according to claim 1 or 2, characterized in that the isolation material of the supporting body part is heat resistant and/or non-inflammable and/or has an open porosity and/or is unisotropic.

4. Fire retarding body according to claim 1, 2 or 3, characterized in that the containers (4; 11) in addition to the content of water contains a substance (for instance Glauber's salt) which can receive energy by means of phase inversion.

5. Fire retarding body according to any of the preceding claims, characterized in that the water bearing containers (e.g. 4) are designed so that the containers burst open at temperatures slightly above 100°C depending on inner pressure or outer heat.

6. Fire retarding body according to any of the preceding claims, characterized in that the isolation material of the supporting fire retarding body part is thinner on the side (21; 26) of the space or spaces located closer to the area to be fire-protected than on the opposite side of the body (18; 22).

7. Fire retarding body according to any of the preceding claims, characterized in that the space (e.g. 3) or the spaces together with the container (4) or containers cover and area of at least 70%, preferably at least 85% of the area of the fire retarding body.

8. Fire retarding body according to any of the preceding claims, characterized in that the containers (in 30) are placed in several layers separated by isolation material (29) (figure 5).

9. Fire retarding body according to any of the preceding claims, characterized in that the absorption means is silica gel.

10. Fire retarding body according to any of the preceding claims, characterized in that the absorption means the water bearing container is a cellulose derivate.

11. Fire retarding body according to any of the preceding claims, characterized in that the amount of water contained in the container (4) is at least 500 g/m² of the area of the fire retarding body.

12. Fire retarding body according to any of the preceding claims, characterized in that the body is formed as an angle having a corner. (Figure 4)

13. Fire retarding body according to claim 12, characterized in that at least one container (25) is located at the angle or corner of the body.