AU2004203153A1 - Improved Fire Damper - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor Address for service is: Holyoake Industries Limited Scott Noel Holyoake WRAY ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR Invention Title: "Improved Fire Damper" The following statement is a full description of this invention, including the best method of performing it known to me:- IMPROVEMENTS TO DAMPERS TECHNICAL FIELD This invention relates to improvements made in relation to dampers. In particular, the present invention may be adapted to provide a fire damper which can be easily and quickly installed and which provided a high degree of thermal insulation between the interior of the damper and the region in which the damper is installed.

Reference throughout this specification will also be made to the present invention being used as a fire damper associated with an air circulation system. However, those skilled in the art should appreciate that other configurations of the present invention are envisioned such as, for example, use of the present invention as a smoke damper. Reference to fire dampers only throughout this specification should in no way be seen as limiting.

BACKGROUND ART Air circulation systems must run through regions of a building in which air is to be delivered. Such circulation systems can in some instances be used to deliver conditioned air. Ducts can be employed to run through the wall spaces between rooms in a building and also can be used to channel air between the floors of a building. Alternatively, air circulation systems may incorporate channels between specific areas which need not necessarily employ ducting on one or both sides of such channels.

Air circulation systems must also run through walls and floors which are designed to act as fire barriers. These barriers are generally constructed from fire resistant materials which will retard the progress of a fire and prevent it from spreading to other regions or areas of a building.

To prevent the spread of fires over the entire interior of a structure, fire dampers have been developed for air circulation systems. Fire dampers provide components which are sited adjacent to or within a fire barrier surface such as a wall, floor or ceiling and which act as a stop, valve component or closing element in conjunction with an air circulation channel. Such channels are generally employed to circulate air between various rooms, floors or partitioned regions of a structure, with fire dampers in turn being used to prevent the products of combustion such as heat, or smoke from transiting such channels.

In general terms, fire dampers include or consist of a main housing with two open ends adapted to engage with the open ends of a barrier in an air circulation duct or channel. Located within the interior of the damper housing is a jaw, valve or closing element which can move to block or close the passage through the housing and subsequently isolate any fire present within a duct or exterior to a duct or channel. The closing element component located within the interior of the damper is normally held open but can be quickly closed if a thermal sensitive component is triggered or a control signal is generated which indicates the presence of fire or elevated temperatures. This will trigger the closure of the jaws of the damper and subsequently form a physical fire resistant barrier between the opposite ends of the air circulation channel.

Fire dampers are designed to be installed within a wall, floor or ceiling cavity and as such normally have a small gap or space between the perimeter of the surface involved and the exterior surface of the damper. Such mechanical fire dampers expand when heated so an expansion gap between the perimeter of the surface involved and the exterior surface of a damper must be allowed to cope with the changing size of the damper. This expansion gap is usually filled or packed with a high temperature rated compressible material to stop the free flow of the products of combustion through the expansion gap. The packing material employed is generally rated to approximately 1000 0 C and is also considered by some in the industry to have an insulative effect in addition to operating to stop the free flow of the products of combustion through the expansion gap area.

This requirement for a packing material around the sides of the damper can complicate the installation of the damper component. For example, any cavities or gaps formed in a fire barrier wall must be diligently filled with a fire retardant or thermally insulating material.

With holes or channels through masonry fire dampers, no special internal hole preparation work is necessary, other than providing the correct expansion gap tolerance between the installed damper and the raw concrete interior of the fire damper. However, this expansion gap must still again be packed with the compressible high temperature rated material.

Installation procedures are far more complicated for hollow framed fire barriers which are generally lined with plaster board on both sides over a steel or timber framing. In such instances the channel or hole employed must be framed out with the same framing material as the barrier, and the hole must also be lined out with the same cladding materials (normally plaster board) which the walls of the fire barrier are constructed. Furthermore, if multiple layers of lining material are employed, again multiple layers of lining must be applied to the interior of the channel or hole adapted to receive the fire damper.

As can be appreciated by those skilled in the art, hollow fire barriers require a significant amount of work and materials to prepare for a fire damper installation.

One previous attempt made to address this complication in the installation of dampers in hollow fire barriers is described in New Zealand Patent No. 328088.

This document describes a fire damper installation which allows a damper to be surrounded by an external sleeve which is to be fitted within the expansion gap of an air circulation channel in a fire damper. The sleeve is normally packed with fire retardant material and includes a set of moveable locating flanges to allow the sleeve assembly to be locked or located in a wall. The sandwiched fire retarded material is described in New Zealand Patent No. 328088 as having an insulative effect to protect the internal parts of the cavity or channel in which the damper is to be installed from a fire on one side of the fire barrier involved.

However, the applicants believe there are some safety concerns with this type of damper installation system. The exterior sleeve is generally formed from a metallic component (such as steel) which will in turn provide a surface through which heat can be conducted into the interior of a fire barrier. This provides a heat transmission or radiation pathway, as a fire can simply heat the metallic exterior sleeve of the damper and in turn jump directly to exposed areas of a fire barrier.

Furthermore, this type of fire damper installation system relies on the fixing flanges provided being connected directly to plaster board to support the weight of the fire damper. However, as those skilled in the art would appreciate and as referenced on page 3 of this patent specification, the structural integrity and load bearing capacity of plaster board will degrade significantly in the event of a fire.

This can result in the connections between the fire damper installation described and the supporting plaster board failing, allowing the fire damper installation to drop away, and exposing the opposite side of a fire barrier wall to fire damage.

In addition, this type of fire damper installation does not provide a full fire damper system. The installation components described are adapted to receive any form of third party fire damper. This therefore ignores the opportunity to provide a full fire damper system which can be easily and quickly installed into a circulation channel, and which can prevent or negate the effects of heat radiation through such a fire damper. It would be preferable to have an entire fire damper system which addressed heat radiation issues through both the interior of the damper channel and through into the cavity formed for the damper within a fire damper.

Furthermore, a fire damper system which effectively blocked the transmission of the products of combustion through and into a fire barrier would be preferable to the current state of the art.

It would be of advantage to have an improved fire damper and/or fire damper installation system which addressed any or all of the above issues. Specifically an improved damper which could be easily and quickly installed within a wall, floor or ceiling cavity and which also provided adequate thermal insulation to the interior surface of the cavity in which the damper is installed would be of advantage.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a fire damper which includes, a closing element moveable between an open and a closed position, and a housing for said closing element which includes at least two openings adapted to admit gas into said housing, and at least one thermally insulating cover located on or in close proximity to at least one exterior surface of the housing, wherein said at least one thermally insulating cover forms one or more exterior surface or surfaces of the damper.

According to a further aspect of the present invention there is provided a fire damper substantially as described above wherein said at least one thermally insulating cover is engaged with an exterior surface or surfaces of the housing.

According to yet another aspect of the present invention there is provided a fire damper substantially as described above which also includes at least one attachment projection extending from the housing and adapted to connect the damper to a mounting surface.

According to yet another aspect of the present invention there is provided a fire damper substantially as described above wherein said at least thermally insulating cover is located in place with respect to the housing by connection or contact with said at least one attachment projection.

The present invention is adapted to provide a fire damper in preferred embodiments. Fire dampers are generally used throughout the construction of large structures or buildings to prevent the spread of fire between or over fire barriers or the different floors of the structure. Normally fire resistant materials are used to seal off different sections and floors of a building from one another so that in the event of a fire, only a small portion of the structure is at risk.

However, air circulation systems and networks must run to all regions and areas of a building and therefore can provide linking passages across or through the fire barriers. Fire dampers can be used to seal off air circulation channels, ducts and networks in the vicinity of fire barriers in the event of a fire, thereby allowing these barriers to function effectively.

Preferably a fire damper provided in accordance with the present invention may be adapted to be mounted within or extend through a wall, floor or ceiling cavity where the wall, floor or ceiling involved includes or incorporates some form of fire proofing material and creates a fire stop or fire barrier. Portions or elements of the fire barrier provided can be connected to mounting surfaces formed by the exterior of these structures.

Reference throughout this specification will also be made to a fire damper provided in accordance with the present invention being mounted within a fire barrier wall. The fire damper can provide a passage for air and yet may still be closed to maintain the integrity of the fire proofing provided by the wall involved.

However, those skilled in the art should appreciate that other installation locations or configurations of the fire damper provided are also envisioned and reference to the above only throughout this specification should in no way be seen as limiting.

Preferably the present invention may include a housing adapted to define a main damper body which defines the majority of the volume or space occupied by the damper. Preferably the housing may include two or more openings adapted to admit gas into the housing, where these openings can be engaged with the free ends of two or more air circulation ducts.

Reference throughout this specification will also be made to the housing provided having substantially the same cross section shape as any air circulation ducts which can be used to engage or connect to its open ends. Furthermore, reference throughout this specification will also be made to the housing being of approximately the same length as the thickness of the wall through which the housing and associated fire damper is to extend and be installed into. However, those skilled in the art should appreciate other configurations are also envisioned.

Reference throughout this specification will also be made to the housing provided including two openings only and being adapted to engage with the free ends of two separate air circulation ducts only. Those skilled in the art should appreciate the housing may not necessarily engage with ducts, or may include three, four or more openings if required and reference to the above only throughout this specification should in no way be seen as limiting.

Preferably a fire damper provided in accordance with the present invention also includes a closing element. A closing element may be located within the interior of the housing and can be used to close off a passage or channel formed by the housing between its two open ends. The closing element may be capable of movement between two positions, being an open position and a closed position, depending on whether a fire or excess heat is present within the damper housing.

Those skilled in the art should appreciate that any number of various different types of closing elements may be employed in conjunction with the present invention to open or close the passage formed within the interior of the housing.

Any form of closing element which can be moved in response to the detection of elevated temperatures or excess heat within an air circulation system, or within the interior of the fire damper itself may be employed in conjunction with the present invention.

Reference throughout this specification will also be made to the closing element employed being a plate shaped element pivotably mounted into the interior of the housing. This plate like element blade may be pivoted into a position to substantially block flows of combustion products through the housing (being in its closed position) or alternatively to lie substantially parallel with the nominal direction of travel of air through the housing when placed in an open position or configuration. Those skilled in the art should appreciate that other types of closing element may also be employed and reference to the above only throughout this specification should in no way be seen as limiting.

In a preferred embodiment a closing element may also be adapted or used to balance air flows between the two ends of the damper and hence any ducts the damper engages with. The position or orientation of the closing element may be adjusted to in turn control the flow rate of air through the duct or ducts employed as required. For example, in some instances the closing element of a damper may be used to adjust or balance air flows to many different sections of an air circulation network on a single floor from a single air riser unit.

In a preferred embodiment, at least one face, side or surface of a closing element may also include or have applied a thermally insulative material.

Thermal insulation can be applied to a surface or face of a blade which faces towards an open end of the damper, thereby providing a thermal stop or barrier in between the two ends of the damper when the blade is closed. The provision of insulative material can therefore reduce thermal radiation between the two ends of the damper, and across or from the closing element.

In a further preferred embodiment all exposed surfaces or faces of a blade element which face towards the open end of the damper may have a thermally insulative material applied. Presenting such thermally insulative material to both open ends of the damper substantially reduces and potentially eliminates heat radiation between the two regions divided by the damper. Although the blade will prevent combustion products crossing the damper, thermal radiation may still cause fire safety problems on the protected side of the damper installation. The provision of such insulative material, in combination with the thermally insulating cover and closing element, may effectively contain heat radiated from a fire on one side of the fire barrier in addition to preventing combustion products from traversing the fire damper installation.

In a preferred embodiment, the fire damper provided may also include at least one attachment projection. An attachment projection can extend from the housing of a damper and preferably may be used to connect the damper to at least one mounting surface. A mounting surface may be provided through, for example, the exterior surface of a fire wall into which the fire damper is to be installed, or alternatively internal construction components of such a fire wall or barrier when the attachment projection is not to be visible on the exterior of the wall.

In a further preferred embodiment the attachment projection or projections of the fire damper may be adapted to engage with structural elements of the mounting surface which the damper is to be connected to. For example, in one preferred embodiment, an attachment projection may be adapted to engage with a nog or stud used to frame and provide strength to a wall surface where the nog or stud involved is used to support the weight of the fire damper installation provided. In such instances nails, screws or other direct correction mechanisms may be employed when the fire damper is adjacent to a stud or nog. Alternatively, if an attachment projection of the damper cannot be manoeuvred into direct contact with a nog or stud, a supporting strap may be looped, threaded or otherwise connected to an attachment projection at one end and connected to a stud or nog at its opposite end. The weight of the fire damper installation may then be supported through such a strap by a nog or a stud some distance from the position from which the fire damper is to be located when installed.

In a further preferred embodiment, the fire damper may include two attachment projections only. These attachment projections may engage with mounted surfaces on either side of a fire barrier or fire wall to securely hold the fire damper provided in place when installed.

In a further preferred embodiment, the present invention may be provided with two radially projecting flanges as attachment portions. These radially projecting flanges may be provided in instances where the fire damper is engaged with substantially circular air circulation ducting, where these flanges will in turn follow the circular perimeter or cross section shape of the fire damper housing.

In one preferred embodiment an attachment projection may include a locating recess adapted to receive an end of a thermally insulating cover located on the exterior surface of the housing. Preferably such locating recesses may be employed to secure the end or edges of a cover in place between a pair of attachment projections located at either end of the housing.

Reference throughout this specification will also be made to a fire damper provided in accordance with the present invention including two circular projecting flanges at either end of the housing. However, those skilled in the art should appreciate that other configurations of the present invention are envisioned and reference to the above only throughout this specification should in no way be seen as limiting.

In a preferred embodiment the present invention may include at least one thermally insulating cover. An insulating cover or covers may be provided as an integral component or portion of the damper when sold or delivered to an end user. Alternatively an insulating cover or covers may be provided separate to a damper but can be installed or mated with a damper prior to the damper being installed within a fire damper. The insulating cover or covers employed may in effect be pre-installed on the fire damper, thereby allowing the entire composite or integral assembly to be slotted directly into a cavity of a wall or surface without the need for additional insulative material to be packed around the sides, top or bottom of the damper to complete the insulation. Pre-installing one or more thermally insulating covers on the damper may substantially speed up the installation process and also reduce the level of skill required to effectively and safely install these types of fire dampers.

In a preferred embodiment, a damper may include a thermally insulating cover for each and every surface or wall making up the exterior of the damper. If, for example, in one embodiment the damper has a substantially circular cross section, a single thermally insulating cover may be provided to follow the curve of this single exterior circular surface. Conversely, if the damper has a substantially rectangular or square cross section, four separate surfaces defining four separate insulating covers may be provided in accordance with the present invention.

Reference throughout this specification will also be made to a damper employed in conjunction with the present invention having a substantially circular cross section with a single substantially circular corresponding insulating cover being provided for the damper. However, those skilled in the art should appreciate that other configurations of the present invention are envisioned, and reference to the above only throughout this specification should in no way be seen as limiting.

In a preferred embodiment, the insulating cover provided may be located on or in close proximity to the exterior surface of the housing. If in the case of a preferred embodiment the housing has a substantially circular cross section, a single insulating cover may be provided on or in proximity to this single exterior surface of the housing. Conversely, if the housing includes more than one exterior surface, an insulating cover may be provided on or in close proximity to each of the exterior surfaces of the housing provided.

Reference throughout this specification will also be made to a thermally insulating cover being located on and in direct contact with an exterior surface of the housing. However, those skilled in the art should appreciate that small air gaps or inconsistencies in the fit between these two components may exist in some embodiments and reference to the above only throughout this specification should in no way be seen as limiting.

Preferably a thermally insulating cover may form the perimeter of the exterior surface of the damper. This will place the cover provided in direct contact or in proximity to the interior of a wall or other surface cavity within which the damper is to be installed. The thermally insulating material used to form the cover may in effect provide a heat radiation barrier between the main body of the damper in the interior of the cavity or channel within which the damper is located. The thermally insulating cover may prevent heat radiation or transfer between these two regions.

Preferably the cavity into which the damper is to be installed may be formed so as to provide as small a gap as possible between the perimeter of the cavity and the exterior surface of the damper formed by its insulating cover or covers. Due to the thermally insulating nature of the material used to provide a cover, no further insulating material need necessarily be packed around the damper during installation and the insulating cover can protect the interior of the wall from heat within a duct. Furthermore, the insulating cover will also protect the interior of a wall or other mounting surface from heat conducted or radiated through the housing of the damper from a fire or source of heat exterior to any ducts connected to the fire damper.

In a preferred embodiment the thermally insulating cover may be formed from a single integrally formed moulded composite material component.

Preferably a cover formed from a moulded composite material may reduce heat radiation from the housing of the damper provided.

Composite materials which can be moulded, which also exhibits thermally insulated properties, and which reduce heat radiation may be employed in conjunction with the present invention. For example, in some instances particular composites such as lime or plaster mixtures, or alternatively ceramic materials may be moulded relatively easily into the form or shape required to create the cover involved. Furthermore, reinforcing fibres, elements or components may also be added to a base matrix material which can be moulded to form a cover where either or both the mouldable matrix material and such reinforcing components may improve the thermal insulative properties of the cover provided. Reinforcing, or strengthening components may be added to a plaster mix for example which could also including additional strands such as fibreglass screens if required.

In a further preferred embodiment, one composite mouldable material which may be employed form a cover, may be formed from a plaster mixture. Such a plaster mixture may be relatively easily moulded into required shape for a cover and may also include any other component materials which can improve thermal insulative properties of the material employed.

In a further preferred embodiment, a thermally insulating cover may be formed or constructed from a single integrally formed ceramic material component.

Ceramic materials exhibit high thermally insulative and radiation retarding properties and may be moulded or formed into a variety of shapes to mate with or engage with the exterior surfaces of the damper housing. A ceramic insulating cover can also exhibit a degree of structural strength and integrity and will retain its shape and resist breaking, chipping and damage during storage and handling of a damper prior to installation.

In a preferred embodiment, the composite material employed to form a thermally insulating cover may also include a doping of vermiculite to improve the thermally insulative properties of the cover or covers employed.

In some embodiments, a thermally insulating cover may be adhered to an exterior surface of the housing. For example, an adhesive may be applied between the insulating cover and housing or alternatively, the insulating material forming such a cover may be moulded onto the surface of the housing and allowed to dry or can be subsequently baked in place on the housing.

In yet another alternative embodiment, a composite or ceramic based cover may be premoulded and subsequently slid over the exterior surface of a housing where the close friction fit between the cover and the housing will engage both components or elements together. These approaches will either create a friction bond or an adhesion bond between the housing and the interior surface of a cover, thereby retaining the cover in place to form an exterior surface of the damper.

Reference throughout this specification will also be made to the insulating cover or covers provided being adhered or otherwise secured or fitted to the exterior surface or surfaces of the housing. However, those skilled in the art should appreciate that other configurations of the present invention which use various different types of attachment schemes for an insulating cover may also be employed and reference to the above only throughout this specification should in no way be seen as limiting.

For example, in one alternative embodiment, an insulating cover may be retained in place by engagement with at least one attachment projection, extending out from the housing. For example, in such an embodiment an insulating cover may be sandwiched or otherwise trapped between the opposed faces or edges of two attachment projections at either end of the housing, with the covers connection or contact with each attachment projection retaining same in place on the housing.

The present invention may apply many potential advantages over the prior art.

The present invention may be adapted to provide a complete fire damper system. The entire system provided may be easily and quickly installed within a cavity or channel formed in a fire barrier, and can function effectively to retard or prevent heat radiation in addition to preventing the transfer of products of combustion between the regions separated by the fire barrier involved. The use of insulative materials in both a cover for the damper and also on the exposed surfaces of the closing element of the damper retard heat radiation, while the closing element can be employed to prevent the free flow of the product's combustion through the damper. Furthermore, the lateral extension of an insulative cover out to the sides of the damper can prevent the free flow of combustion products through or into the interior of a fire barrier.

The provision of one or more thermally insulating covers forming the exterior surface or surfaces of a fire damper potentially allow a pre-insulated, radiation retarding damper to be manufactured, stored and shipped and then directly installed into a fire wall or other type of fire barrier surface. This may be contrasted with the existing prior art which in general terms requires insulative material to be packed around a damper during installation or alternatively, involve the provision of a metal sleeve to retain such insulation where this sleeve can transmit heat directly into a wall cavity.

In preferable embodiments the use of a moulded composite or ceramic materials in the formation of an insulating cover allows the covers provided to retain their strength, integrity and shape during storage and transportation whilst still performing effectively in the thermally insulative role required.

BRIEF DESCRIPTION OF DRAWINGS Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: Fiqure la shows a side cross section view of a fire damper when installed into a fire barrier wall in accordance with a preferred embodiment, Fiqure lb shows a side perspective view of the fire damper discussed with respect to figure la, Figqures 2a 2b show side cross section views of a fire damper when installed and configured in accordance with a further embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION Figure la and lb show cross section and side perspective view of a fire damper configured in accordance with a preferred embodiment of the present invention.

Figure la also shows a cross section view of the fire damper involved when installed within a fire wall cavity and used to provide a fire proof linking element between two sections of air circulation duct on either side of the wall involved.

The fire damper provided includes a housing with a substantially circular cross section. The housing defines the overall shape of the damper and encloses the majority of the volume and space occupied by the damper. Each end of the housing is open and has a substantially circular cross section allowing same to mate with a circular ducting element (not shown). The housing is also hollow allowing air to pass from one duct connected to an opening at one end through to an exit opening at the opposite end of the housing.

The fire damper also includes a pair of attachment projections shown in this embodiment through a pair of radially extending flanges. These flanges mate with the exterior of the housing and in use are engaged where the exterior surfaces of a fire barrier wall or surface. The surfaces are preferably formed from a fire resistant material, whereas the interior or internal portions of the wall generally employ normal materials which can be susceptible to heat damage and subsequently ignited by a fire. The exterior surfaces of the fire barrier wall protect the interior materials involved. However, the cavity formed in the surfaces for the damper must also be insulated against fire damage or heat transmission again to prevent heat transfer to these flammable components.

To achieve this objective, a single thermally insulating cover is provided as an exterior surface to the damper. This insulating cover has a substantially circular cross section and is adhered to the surface of the housing in the region shown with respect to figures la and lb. In the embodiment shown, the insulating cover is formed from a composite or ceramic material moulded to fit the exterior of the housing. The cover is also held in place in the embodiment shown through the pair of attachment projection flanges which surround or cover the free edges of the cover.

The fire damper also includes a closing element formed by a valve blade (4) substantially within the centre of the damper and in the interior section of the housing. The valve blade shown with respect to figure la is located or orientated in a closed position to block air and combustion product flow through the housing and hence between each of the ducts connected to the open ends of the housing. The valve blade is placed in this position when excess heat is detected in the vicinity of the damper to in turn close the cavity formed in the fire wall. The insulating cover provided will protect the interior components or materials of the fire wall from damage by heat transmitted along the length of the housing.

As can be seen from figures la and lb, the damper may be installed relatively easily and quickly. One of the attachment projections may be pulled away from the insulating cover and the entire damper assembly slotted through a cavity formed in the wall involved. The remaining attachment projection may then be fixed onto the exterior surface of the wall and the second attachment projection subsequently pushed back and fixed in place as shown with respect to figure la. This can substantially reduce installation time and also allows the damper to be installed by those without a high level of construction skill or experience.

Figures 2a 2b show side cross section views of a fire damper when installed and configured in accordance with a further embodiment of the present invention.

Figure 2a illustrates the provision of a fire damper when installed in a hollow fire barrier with steel framing, whereas figure 2a illustrates the same case but with a hollow fire barrier using wooden framing.

The damper system provided incorporates a housing (11) linked to a pair of attachment projections or flanges These flanges (12) are located on either end of an insulating cover (13) which in use surrounds an entire section of the housing (11).

Within the interior of the housing is located a closing element formed by a valve assembly (14a, 14b). A moveable valve blade (14a) is provided where this blade is driven or moved by a drive assembly (14b).

The exposed surfaces of the valve blade (14a) are coated or covered with a thermally insulated material (16) preferably being the same material used to form the thermally insulating cover The use of this material in this application substantially retards, reduces or eliminates heat radiation across both the cover and the valve blade (14a).

The fire damper assembly or system provided is to be received within a cavity formed in a hollow fire barrier formed by an exterior cladding face (15a) which incorporates structural supports or framing elements In the embodiment shown with respect to figure 2a, steel based framing elements (15b) are employed whereas wooden framing is shown with respect to figure 2b. As can be seen from figures 2a and 2b, fixing pins, nails or bolts (17) may be driven through the ends of both the attachment projection flanges (12) through the cladding material (15a) into the framing material (15b) to lock the damper in place and support its weight within the finished fire damper.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims (18)

1. A fire damper which includes, a closing element moveable between an open and a closed position, and a housing for said closing element which includes at least two openings adapted to admit gas into said housing, and at least one thermally insulating cover located on or in close proximity to at least one exterior surface of the housing, wherein said at least one thermally insulating cover forms one or more exterior surface or surfaces of the damper.

2. A fire damper as claimed in claim 1 wherein the fire damper is installed within a fire barrier.

3. A fire damper as claimed in claims 1 or 2 wherein the thermally insulating cover is engaged with an exterior surface or surfaces of the housing

4. A fire damper as claimed in any previous claim wherein the thermally insulating cover is formed from a single integrally formed moulded composite material component.

A fire damper as claimed in claim 4 wherein the moulded composite material component reduces heat radiation from the housing.

6. A fire damper as claimed in claims 4 or 5 wherein the moulded composite material includes vermiculite.

7. A fire damper as claimed in any previous claim wherein the closing element is located within the interior of the fire damper housing. 22

8. A fire damper as claimed in claim 7 wherein at least one surface of the closing element has a thermally insulating material applied.

9. A fire damper as claimed in claim 8 wherein the thermally insulating material applied reduces thermal radiation from the closing element.

A fire damper as claimed in any one of claims 8 or 9 wherein a thermally insulating material is applied to a surface of the closing element facing towards an opening of the housing.

11. A fire damper as claimed in any previous claim wherein the closing element is used to balance air flows through the housing.

12. A fire damper as claimed in any previous claim which includes at least one attachment projection extending from the housing and adapted to connect the damper to a mounting surface.

13. A fire damper as claimed in claim 12 wherein the attachment projection engages with structural elements of the mounting surface.

14. A fire damper as claimed in either claim 12 or 13 wherein an attachment projection includes a locating recess adapted to receive at least a portion of a cover.

A fire damper as claimed in any previous claim wherein said thermally insulating cover is located between a pair of attachment projections located at either end of the housing.

16. A fire damper as claimed in any one of claims 12 to 15 which includes two attachment projections formed as radially projecting flanges.

17. A fire damper substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples.

18. A method of manufacturing a fire damper substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples. Dated this Fourteenth day of July 2004. Holyoake Industries Limited Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant