SEALED CABLE PENETRATIONS AND A METHOD FOR PULLING CABLE THROUGH SUCH CABLE PENETRATIONS

Abstract: The invention relates to a sealed cable penetration comprising an outer layer of a heat resistant material which expands upon heating and an inner layer of a flexible, compressible, heat resistant material and that the cable is intended to be inserted in the inner layer. The invention further relates to a method for pulling new cables through the sealed cable penetration, where the inner layer of flexible, heat resistant material is removed, while the outer layer of heat expanding material is maintained, whereafter one or more new cables are pulled and the annulus between the new cables and the outer layer is filled with the flexible, heat resistant material.

Description: Title of invention: "Sealed cable penetrations and a method for pulling cable through such cable penetrations." Technical field The present invention relates to sealed cable penetrations and a method for pulling electrical cables through such sealed cable penetrations. Background Art Sealed cable penetrations, such as for example cable penetrations in fire resistant walls and bulk-heads are often complicated and have an unpractical design. Further most known sealed cable penetrations are costly and difficult to install. Due to the lack of good, simple and low cost cable penetration systems, it is often, when new cables are pulled through existing cable penetrations, not made a sufficient sealing about the new cable. The cable penetration thus no longer satisfy the requirement which are set to the fire resistency of such penetrations. As far as it is known, it does not exist a certified cable penetration system which has been tested both before and after cables have been pulled through the penetration. Disclosure of Invention By the present invention it is provided a new sealed cable penetration which satisfies the requirements to fire resistance which such penetrations have to meet. By the present invention it is further provided a method for pulling cables through sealed cable penetrations whereby the sealing of the cable penetrations is not reduced. Thus, according to a first aspect, the present invention relates to a sealed cable penetration said cable penetration comprising an outer layer of a heat resistant material which expands upon heating and an inner layer of a flexible, compressible, heat resistant material and that the cables are inserted in the inner layer. As an outer layer it is preferably used an intumescent, vermiculite-based material. It is especially preferred to use vermiculite-based sheet material, for example a material as described in US patent 3,916,057. When the cable penetration according to the present invention is exposed to high temperature, the outer layer will expand and thus compress the inner layer of flexible, heat resistant material about the cable. Thus the cable penetration according to the present invention is able to meet the requirements which are set to fire resistance of cable penetrations. As an inner layer it is preferably used materials such as mineral wool, ceramic fibre material or the like. The cable penetration according to the present invention function through a cooperation between the heat expanding material in the outer layer and the flexible heat resistant material in the inner layer. This combination ensures that cold smoke is stopped by the flexible, heat resistant material, and that extension of fire through the penetration is prevented due to expansion of the heat expanding material on direct influence of fire. For cables having big dimensions and for cable penetrations where especially strict requirements and set to fire resistance, it is preferably arranged a layer of fire resistant material about the cable on each side of the penetration. According to another aspect, the present invention relates to a method for pulling new cables through an already installed sealed cable penetration according to the present invention, wherein the inner layer of flexible, heat resistant material is removed, while the outer layer of heat expanding material is maintained, whereafter one or more new cables are pulled and the annulus between the new cables and the outer layer is filled with the flexible, heat resistant material. By the method of the present invention new cables can be pulled without reducing the fire resistance of already installed cable penetrations. The cable penetration according to the present invention is simple to produce and gives a very good security against penetration of fire. By use of present invention it is further simple and economic favorable to make ready openings for cable penetrations for pulling of new cables later on. The cable penetration according to the present invention is very flexible in use as standarized cable penetrations can be used for cables of different diameters while maintaining the fire resistance. The only limitation as to the diameter of the cables is that the diameter of the cables must be less than the diameter of the inner layer. The present invention will now be further described under reference to the accompanying drawings, where, Brief Description of Drawings Figure 1 shows a section through a wall having installed a sealed cable penetration according to the present invention, made ready for pulling of a cable, Figure 2 shows the same cable penetration as in Figure 1 with a cable installed, Figure 3 shows a section through a second embodiment of the sealed cable penetration with a cable installed according to the present invention. Detailed Description of Preferred Embodiments In figure 1 it is shown a cut through part of a wall 1 having installed a cable penetration according to the present invention. An opening in the wall 1 is sealed by means of a fire resistant mortar 2. In an opening in the mortar 2 it is arranged a cable penetration according to the present invention. The cable penetration comprises an outer layer 3 made from a heat resistant material which expands when exposed to high temperatures. Inside the outer layer 3 there is arranged an inner layer 4 made from a flexible, compressible, heat resistant material. As a flexible material it is preferably used a loose mineral wool such as Rockwool insulation wool delivered by Elkem-Rockwool, Norway. Alternatively, a flexible compressible ceramic fibre material can be used. The cable penetration shown in Figure 1 is ready for installing of a cable. In figure 2 the cable penetration of figure 1 is shown with a cable 5 installed. In order to install the cable 5 the inner layer 4 of flexible heat resistant material is removed, whereafter the cable 5 is pulled in place through the opening left when the inner layer 4 is removed. Thereafter the annulus between the cable 5 and the outer layer 3 is sealed by means of the flexible, heat resistant material 4. For cables having a big diameter it is often required that the cable is insulated on both sides of the cable penetration. For cable penetrations according to the present invention this can be done as shown in figure 3, where an insulation layer 6 is arranged about the cable 3 on both sides of the penetration. The layer 6 is preferably made from mineral wool or a similar heat resistant material. The cable penetrations shown on the figures comprises one cable. However, it is within the scope of the present invention to arrange more than one cable in the cable penetration. Further, it is within the scope of the present invention to provide more than one cable penetration in an opening for cable penetrations in a wall.

Claims: CLAIMS: 1. A sealed cable penetration, said cable penetration comprising an outer layer of a heat resistant material which expands upon heating and an inner layer of a flexible, compressible, heat resistant material and that the cable is inserted in the inner layer. 2. A sealed cable penetration according to claim 1, characterized in that the outer layer is made from an intumescent, vermiculite-based material. 3. A sealed cable penetration according to claim 1, characterized in that the inner layer is made from mineral wool. 4. A sealed cable penetration according to claim 1, characterized in that the inner layer is made from a ceramic fibre material. 5. A sealed cable penetration according to claim 1, characterized in that a layer of fire resistant material is arranged about the cable on each side of the penetration. 6. A method for pulling new cables through the sealed cable penetration of claim 1-5, wherein the inner layer of flexible, heat resistant material is removed, while the outer layer of heat expanding material is maintained, whereafter one or more new cables are pulled and the annulus between the new cables and the outer layer is filled with the flexible, heat resistant material.

Inventors: EILERTSEN YNGVE, GILBERG ERNST, EILERTSEN, YNGVE, GILBERG, ERNST
Applicants: ROCKWOOL AS, A/S ROCKWOOL
Application year: 1992
Main classification: H02G3
IPC codes: H02G3