In areas of a building where ventilation is required, e. g. transformer rooms, small boiler rooms, flammable stores, while access thereto has to be restricted, sufficient air has to be provided to ensure that the temperature in the areas is maintained within an acceptable range.

Louvre type ventilators are usually installed on the doors to allow passing of air into such areas. There are in existence fire door ventilators intended for installation on fire doors and walls for preventing the spread of fire and/or smoke when a fire breaks out. In one existing design, a plurality of louvre plates are held by a fusible link mechanism in an open position in which air is allowed to pass through a number of passageways defined by the louver plates for ventilation. When fire breaks out and a pre-determined temperature is reached, the fusible link will break, whereupon the louvre plates will drop on their own weight to close the passageways, to thereby prevent the spread of fire and/or smoke. In another existing design, a closable shutter door is kept in an open position by an electro magnet when the magnet is energised, thus allowing flow of air. When fire breaks out, in particular, when smoke is detected, the electric current to the electro magnet is interrupted, whereupon the shutter door will close, e. g. upon the biasing force of a spring, so as to shut off air and smoke.

In assessing the fire-prevention capabilities of fire door ventilators, the structural integrity of such ventilators has also to be considered. When fire breaks out, the temperature may rise to above 1, 100°C. In such a high temperature, although the material, e. g. steel, with which the louvre plates are made may not yet melt, the plates will expand considerably. If insufficient space is allowed for expansion, the louvre plates will exert considerable force on the door leaf, thus damaging the structure of the fire door. When heated to such a high temperature, and if no sufficient space is allowed for expansion, the louvre plates may also deform, e. g. by bending, thus damaging the structure of the ventilator.

In either case, the fire door cannot perform its fire/smoke prevention function.

It is thus an object of the present invention to prevent a ventilator in which the above shortcomings are mitigated, or at least to provide a useful alternative to the public.

According to a first aspect of the present invention, there is provided a ventilator including at least a louvre plate member with an adjacent air passageway, characterized in that said louvre plate member is secured to at least a rod member which extends into a cavity of a channel member, said cavity of said channel member allowing said rod member, when heated, to expand into.

According to a second aspect of the present invention, there is provided a door incorporating a ventilator including at least a louvre plate member with an adjacent air passageway, characterized in that said louvre plate member is secured to at least a rod member which extends into a cavity of a channel member, said cavity of said channel member allowing said rod member, when heated, to expand into.

Embodiments of the present invention will be described herebelow, by way of examples only, and with reference to the accompanying drawings, in which: Fig. 1A shows a front view of a first door assembly incorporating a ventilator according to a first embodiment of the present invention; Fig. 1B is a sectional view of the door leaf taken along the line B-B in Fig. 1A ; Fig. 1 C is a top view of the door assembly shown in Fig. 1A ; Fig. 2 shows the internal structure of the door leaf of the door assembly shown in Fig. 1A ; Fig. 3A is a front view of the ventilator incorporated in the door assembly shown in Fig. 1A ; Fig. 3B is a sectional view of the ventilator taken along the line C-C in Fig. 3A; Fig. 4A is front view showing in more detail the structure of the ventilator shown in Fig. 3A; Fig. 4B is a top view of the structure of the ventilator shown in Fig. 4A; Fig. 5 is an end view of the channel of the ventilator shown in Fig. 3A; Fig. 6A is a front view of the ventilator shown in Fig. 3A as installed to an opening between two fixed structures of a building; Fig. 6B is a sectional view of the ventilator taken along the line D-D in Fig. 6A; Fig. 7 shows a front view of a second door assembly incorporating two ventilators according to a second embodiment of the present invention; Fig. 8A is a front view of the ventilator incorporated in the door assembly shown in Fig. 7; Fig. 8B is a sectional view of the ventilator taken along the line E-E in Fig. 8A; and Fig. 9 is an enlarged view of a louvre plate of the ventilator shown in Fig. 8A.

A fire-rated door assembly incorporating a. fire-rated louvure type ventilator according to a first embodiment of the present invention is shown in Figs. 1A and 1B, and generally designated as 100. The door assembly 100 includes a steel door leaf 102 pivotally attached to a door frame 104 by a number of hinges 106. The door frame 104 is secured to fixed structures 108 of a building, in the known manner. At the lower part of the door leaf 102 is installed a louvre type ventilator 110 according to the present invention.

Fig. 2 shows the internal structure of the steel door leaf 102. A number of steel plates 112 are interposed between two inner major surfaces of the door leaf 102 for enhancing the structural integrity of the door leaf 102. An opening 114 is provided at the lower part of the door leaf 102 for installation of the ventilator 110, here shown in dotted lines.

Figs. 3A and 3B show, respectively, a front view and a transverse sectional view of the ventilator 110. The ventilator 110 includes a steel outer frame 120 which may be fixed to interior edges of the opening 114 of the door leaf 102 in the usual manner. A column of mild steel louvre plates 122 are disposed between the outer frame 120 of the ventilator, and spaced apart from one another. By way of such an arrangement, an air passageway 124 is provided adjacent each louvure plate 122, and in particular between each respective pair of louvre plates 122, thus allowing passing of air therethrough. As can be seen in Fig. 3B, the louvre plates 122 are substantially of an inverted V-shape cross section. The upper vertex of the louvre plate 122 is generally flat, and is secured to two steel connecting rods 126, as shown in more detail in Figs. 4A and 4B.

Turning to Figs. 4A and 4B, it can be seen that each louvre plate 122 is secured to the two steel connecting rods 126 by a number of bolt and nut arrangements 128. An outer end of each connecting rod 126 is received within a cavity 129 of a respective channel side 130.

The length of the side channels 130 is perpendicular to the length of the connecting rods 126.

As shown in Fig. 5, each channel 130 includes a column of square openings 132, each for receiving therethrough an outer end of a respective connecting rod 126. The size of the opening 132 is larger than the cross section of the connecting rod 126 to allow sufficient space for the connecting rod 126 to expand radially when heated, e. g. during a fire. As the connecting rods 126 are square in cross section, and the openings 132 are also square in

shape, the connecting rods 126 can only slide relative to the channels 130, without exhibiting any relative swivelling movement. Adjacent to the outer end of each connecting rod 126 is provided with a stopper 134 which extends upwardly from an upper surface of the connecting rod 126 beyond the upper edge of the opening 132. By way of such an arrangement, while the connecting rods 126 can, when heated, expand along its length into the cavity 129 of the respective channel 130, the connecting rods 126 cannot be detached from the channels 130.

It can be seen that, with the ventilator 110 as discussed above, even if the vicinity is on fire, sufficient space is provided for in the cavity 129 of the channels 130 for the connecting rods 126 to expand into, so that the structure of the ventilator 110 will not be adversely affected by the expanding connecting rods 126.

As shown in Figs. 6A and 6B, the ventilator 110 may be installed in an opening between two fixed structures, e. g. lintels or wall slabs, of a building, so as to allow ventilation between two areas partitioned by the fixed structures.

A front view of a fire-rated door assembly incorporating two ventilators according to a second embodiment of the present invention is shown in Fig. 7, and generally designated as 200. The door assembly 200 is incorporated with two ventilators 210, one above the other.

As shown in Figs. 8A and 8B, each ventilator 210 includes a column of mild steel louvre plates 222, which are spaced apart from one another to define a number of air passageways 224.

In order to enhance the fire prevention function of the ventilator 210, on top of each louvre plate 222, and secured to the louvre plate 222 and connecting rods 226, is an elongate and top-open container 250, in which an intumescent compound 252 is received. When exposed to fire, the intumescent compound 252 will foam and expand to seal the passageways 224, thus preventing passing of fire and smoke through the passageways 224.

An appropriate intumescent compound may be one traded by The Dixon International Group Limited, of Cambridge, United Kingdom, under the Trade Mark"MASTERSEAL"@.

It should be understood that the above only illustrates examples whereby the present invention may be carried out, and that various modifications and/or alterations may be made

thereto without departing from the spirit of the invention.

It should also be understood that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any appropriate sub-combinations.