In order to prevent the spread of fire and combustible gas, buildings must be divided into fire cells, which are separated by structural elements. A fire cell comprises a part of a building, which must meet a certain technical fire classification in relation to other parts of the building and may consist, for example, of bneoom'ofah'associated group of rooms. In the sphere of fire protection, the spread of fire and combustible gas between different fire cells via the ventilation system is a difficult problem. Protective measures to counter the spread of fire through ventilation ducts include fire insulation and the installation of operatable fire restrictors and/or combustible gas restrictors.

SE-9202896-8 discloses a ventilation duct for passing through a fire cell boundary in a building divided into fire cells. The ventilation duct is a prefabricated duct unit, which comprises an inner pipe and an outer pipe with a fireproof insulation fitted between the said pipes. In its original state the insulation is a formable compound, which when it sets forms a solid insulation, thereby bonding the two pipes to one another and forming a unit, a so-called chassis. A restrictor is furthermore rotatably supported in the inner pipe at mid-length.

AT391931 B discloses a fire closure collar for pipelines, especially ventilation ducts or line ducting through walls, a material that expands sharply under the effect of heat being applied to the inside of a collar designed for connection between pipelines or between a pipeline and a wall duct. The area of the inside of the collar provided with the expandable material is thereby open to the pipeline that is to be shut off, or to the inside thereof. The expansion material and the collar extend beyond the ends of the pipeline connecting sleeves and the axial end areas of the collar are curved towards the pipeline that is to be sealed, so that the end areas thereof bear tightly against the pipeline. In a fire, a choke valve arranged in the pipeline closes first, but as the fire progresses the expandable material expands and seals the line.

Reference is made to US-A-4 538 389 as a further example of the prior art. This discloses a fire restrictor generally having the features encountered in the pre-characterising clause of claim 1 of this application. The design described here, however, has a relatively complicated construction in that, among other things, it is assumed that a fireproof compound must form a tight seal between the body of the pipe and the surrounding collar.

The object of the present invention, in a passage of a ventilation duct through a structural element dividing fire cells, is to provide a device which with simplified installation will afford protection against the spread of fire and combustible gas as specified by the appropriate fire classification. This is achieved by a device according to the present invention, which has the characteristic features specified in the characterising part of claim 1.

Further advantages of the device according to the present invention include the fact that it comprises relatively simple, easily produced componenfs, wh'ich give the device a low weight, thereby facilitating the assembly work.

The invention will be explained in more detail below with reference to the drawing attached, which shows a diagrammatic perspective view of one example of a fire restrictor/combustible gas restrictor according to the invention.

In the drawing, 1 denotes a wall, which constitutes a part of building and forms part of a boundary of a fire cell in the building. In the wall 1 is an opening 2, for a ventilation duct (not shown) for example, which extends through the fire cell.

3 generally denotes a fire restrictor and/or combustible gas restrictor according to the invention, inserted into the opening 2. This restrictor 3 comprises a tubular body 4, the outside diameter of which defines the diameter of the opening 2. A restrictor leaf 5 is rotatably supported in the tubular body 4. The shaft Sa of the restrictor leaf 5 is operatively connected directly to the shaft 6a of a control device 6. The function of the control device 6, in this case and electric motor, at a temperature exceeding a predetermined value, is to bring the otherwise open restrictor leaf 5 into the closed position.

As will be seen from the figure in the drawing, the tubular body 4 with the restrictor leaf is intended to be fitted outside the wall 1. The restrictor leaf 5 is conventionally equipped with seals, one of which is made of rubber and intended to provide sealing primarily at temperatures below the predetermined value. The function of another conventional seal, composed of a material that expands rapidly at high temperatures, is to produce secure sealing at the temperatures prevailing in a fire.

According to the invention, the tubular body 4 is surrounded, at least in an area adjoining the closed position of the restrictor leaf 5, by a prefabricated pipe 7 of a so-called fire protection compound. The pipe 7 is situated in direct, open contact with the tubular body 4 and a holder device 8, such as a so-called sheet-metal shroud, is arranged around the pipe 7. This shroud has punched-out fixing lugs 8a, by means of which the restrictor is fixed to the wall 1, for example by means of screws 9, and a motor support 8b for the control device 6.

The prefabricated pipe 7 is preferably assembled from two halves, which are held together by the sheet metal shroud 8, as indicated by lines 10.

Although the invention has been described and shown above in connection with a circular -mbodiment ;-it is obvious that square-shaped embodiments can exist, thaf is to say the valve housing can have a square or rectangular cross-section, without departing from the scope of the invention.