NZ713568A - A fire rated access panel and duct system - Google Patents

Abstract

In figure 1 a section of fire rated duct 100 is shown which has been fabricated using a fire access panel system according to an embodiment of the invention. The duct includes a duct body 110 and a pre-existing air-tight non fire-rated access panel 130 which is affixed into an aperture in the duct body 110 by way of latches 132. A frame member in the form of frame 10 has been attached to the duct body 110 using the preformed holes in the frame, to ensure adequate mechanical fixings. Duct wrap fire insulation material 120 has been wrapped around the duct body 110 and has been fitted into a recess in the frame about the periphery of the frame. A removable laminated fire rated access panel (not shown in figure 1) is to be fitted to frame 10 to complete the installation. The fire rated duct and access panel system includes a plurality of tabs disposed on the frame member, those tabs are bendable to allow for mounting the frame member to the duct.

Description

A FIRE RATED ACCESS PANEL AND DUCT SYSTEM TECHNICAL FIELD The present invention relates to the provision of fire rated access panels on fire rated ductwork. Embodiments of the present invention find application in the field of passive fire protection.

BACKGROUND ART Any discussion of documents, acts, materials, devices, articles or the like which has been included in this specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of this application.

Ductwork is used for the movement of air in buildings for the purposes of heating, ventilation, air conditioning of a building or part thereof of building. Ductwork is also used for exhaust purposes combined with exhaust hoods for applications like fume cupboards and kitchen exhaust systems. Ductwork is also used for fire and smoke control purposes for smoke exhaust and pressurisation systems for smoke control purposes for so called sandwich pressurisation systems or zone smoke control systems.

Ductwork for fire and smoke control purposes and for kitchen exhaust and fume cupboard exhaust applications usually required a fire rating or fire resistance level (FRL) according to Building Control Legislation, the Building Code of Australia, the National Construction Code and Australian Standard AS1668 Part 1. The ductwork is typically referred to as fire rated ductwork.

All ductwork typically requires access panels or access doors to provide convenient access into the ductwork for the purposes of inspection, service, repair or replacement of equipment contained within the ductwork such as filters, volume control devices and the like.

Fire rated ductwork requires the use of a fire rated access panel or hatch which maintains the fire rating of the ductwork and also provide the necessary access.

Conventional means of providing fire rating to ductwork have been by way of cladding with fire rated board materials or by way of spray applied materials referred to as fire sprays. This work is conducted on the construction site after the ducts have been erected.

A recent change in fireproofing of ductwork relates to the use of fire rated insulation material or lagging material which is wrapped around the duct such as Fyrewrap Elite 1.5 material manufactured in USA by Unifrax. These materials are lightweight and flexible and less prone to cracking from building movement and damage from impact or transit, and can be installed off-site. They have also demonstrated significant improvements in microbial resistance over existing technologies, making it more attractive for use in clean environments, such as hospitals, nursing homes, cleanrooms etc.

To date, in order to provide a fire rated access panel in a fire rated duct to which fire rated sprays or boards have been applied it has been necessary to manufacture an access panel on site from a fire rated board material which is attached to the duct using threaded rod or bar and nuts. Their removal for access is not easy and they often get damaged when being removed and are trying to be reinstated. In addition, these fire rated boards are friable, dusty and prone to microbial propagation, causing significant issues for hospital, aged care facilities and cleanroom applications. Furthermore, this existing technique is not well suited for use with a fire rated duct to which fireproofing has been applied.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome, or substantially ameliorate, one or more of the disadvantages of the prior art, or to provide a useful alternative.

In one aspect of the present invention there is provided a fire rated access panel system including: a frame member for mounting to a duct; a fire rated access panel which attaches to the frame member; the frame member includes a recess about its periphery which in use receives a portion of insulating material.

Optionally, the frame member includes a portion which surrounds the edges of the access panel.

Optionally, the system further includes an air-tight seal between the access panel and the frame member.

Optionally, the system further includes an intumescent seal between the access panel and the frame member.

Optionally, the access panel is hingedly attached to the frame member.

Optionally, the access panel is of laminar construction.

Optionally, the access panel includes an outer layer of steel, hardboard or coated hardboard.

Optionally, the frame member includes a number of tabs which are used to mount the frame member to the duct and the tabs are bendable.

Optionally, the frame member includes a number of removable female screw fasteners for attaching the access panel to the frame member.

Optionally, the frame member includes a removable portion and the recess is at least partially defined by the removable portion.

In a second aspect the invention provides a fire rated duct including: a duct body defining an interior flow path of the duct; a fire rated access panel; an insulating material applied to the duct; the access panel overlaps the insulating material about the periphery of the access panel.

The features and advantages of the present invention will become further apparent from the following detailed description of preferred embodiments, provided by way of example only, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 is a perspective view of a section of duct which has been fitted with a system according to an embodiment of the invention; Figure 2 is an upper perspective view of the frame of the system of figure 1; Figure 3 is an underside perspective view of the frame of figure 1; Figure 4 is a rear view of the frame of figure 1; Figure 5 is a cross sectional view along line A-A of figure 4 shown with insulating fire wrap material located in the recess of the frame; Figure 6 is a cross sectional view along line B-B of figure 4; Figure 7 is a front view of a fire rated access panel for use with the frame of figure 2; Figure 8 is a side view of the fire rated access panel of figure 7; Figure 9 is a rear view of an alternative embodiment of a frame; Figure 10 is a perspective exploded view of another embodiment; Figure 11 is a rear view of the embodiment of figure 10; Figure 12 is a cross sectional view along the line C-C of figure 11; and Figure 13 is a cross sectional view along the line D-D of figure 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring to figure 1 a section of fire rated duct 100 is shown which has been fabricated using a fire access panel system according to the invention. The duct includes a duct body 110 and a pre-existing air-tight non fire-rated access panel 130 which is affixed into an aperture in the duct body 110 by way of latches 132. A frame member in the form of frame 10 has been attached to the duct body 110 using the preformed holes in the frame, to ensure adequate mechanical fixings. Duct wrap fire insulation material 120 has been wrapped around the duct body 110 and has been fitted into a recess in the frame about the periphery of the frame. A removable laminated fire rated access panel (not shown in figure 1) is to be fitted to frame 10 to complete the installation.

The exposed ends of the duct body 110 shown in figure 1 are for illustrative purposes.

In a real world installation the entire duct would be wrapped in duct wrap.

Referring to figures 2 to 6, frame 10 is shown in detail. Frame 10 is formed from galvanised mild steel and as best seen in figure 6 is in essence a rectangular box section with four major faces 12, 14, 16 and 18. In use, face 12 lies against the outside face of a side wall of a duct 110. Face 16 provides a surface to seat a fire rated access panel (see figures 7 and 8). Face 18 provides a border which surrounds the edges of the fire rated access panel. Face 14 spaces faces 12 and 16 from each other to create a recess 19 about the periphery of frame . In use, recess 19 accommodates duct wrap fire insulation material or alternate duct fire protection materials such as board or spray. In this way, with the fire rated access panel installed, the access panel overlaps the insulating material about the periphery of the access panel. The frame lends integrity to the assembly, with both the duct wrap and the fire rated access panel contributing to thermal insulation. Because the fire rated panel overlaps the duct wrap fire insulation material there is no direct pathway for heat to radiate to or from the duct.

At the same time, the provision of recess 19 also provides a space between the inner face of the fire rated access panel and the front face of the existing air tight access panel which accommodates latches 132 or the like which may be provided on the outside of the existing air tight access panel.

Frame 10 is fitted with removable female fasteners in the form of speednuts 20. These receive male screw fasteners which are used to affix the fire rated access panel to the frame.

Frame 10 is provided with pre-formed through holes 33 in face 12 of the frame which are used to mount the frame 10 to a duct with rivets or the like. In addition, four tabs in the form of flaps 30 are provided which also include pre-formed holes 34 which may also be fixed to the duct with rivets or the like to provide additional strength to the mounting of the frame 10. As can be seen when comparing figures 3 and 4, the flaps are bendable with respect to the frame by virtue of the provision of slots 32 which create a region of weakness where the flaps meet face 12 of the frame. This allows the flaps to be bent to provide for flexibility in installing the frame and is of particular use when mounting the frame to the side wall of a shallow duct to minimise the effective height of the frame 10. In such an installation the flaps can be bent as shown in figures 2 and 3 to wrap around the top and bottom of the duct in horizontal ductwork or sides for vertical ductwork.

Referring to figures 7 and 8, the fire rated access panel 40 is of rectangular shape to be a close fit within face 18 of frame 10 and includes through holes 42 which correspond with the locations of the female screw fasteners provided in frame 10. Panel 40 is of a laminated construction consisting of a central region of a fire rated board material 44 such as Maxilite calcium silicate material available from Trafalgar Fire (www.trafalgarfire.com.au) and a skin material 46 provided on either side such as hardboard such as Duracoat or steel. Some embodiments may utilise hardboard and an additional steel skin. The edges of the panel may utilise a duct tape to seal the edges or may be fully encapsulated by the steel. Steel or duracoat lamination will also demonstrate a higher level of microbial resistance in field applications.

Referring to figure 9, an alternative embodiment of a frame 10A is shown. This embodiment differs to the embodiment described above in that additional tabs are provide in the form of flaps 60 which are created in the face 12 of the frame by the provision of a region of weakness in the form of rows of slots 64. These flaps are able to be bent to improve flexibility of installation options of the frame such as when the frame is located near to an edge of the duct, either of flaps 60 can be bent to wrap around the duct.

An intumescent perimeter seal such as a graphite based seal may be provided between the fire rated access panel and the frame. It may be applied around the inside of face 18 of the frame in a self adhesive form.

In some embodiments the fire rated access panel may be provided with an additional air-tight seal. In these embodiments the frame may be mounted to the duct in an air-tight fashion with the use of a sealing gasket between the frame and the duct. In these embodiments it is possible to dispense with any pre-existing air-tight access panel.

Systems according to the invention may be constructed in a range of sizes to suit particular applications.

The system of the invention is suitable for use in retrofit applications where a duct has already been wrapped, and the need for switchgear/access hatches is identified. In this case the system is applied as follows: • Remove required sections of duct wrap – number removed dependent on size of panel.

• Install switchgear/maintenance hatch as required • Frame 10 and access panel are selected to suit size requirements • Frame 10 is installed around hatch/switchgear on ductwork – using bendable flaps in either flat or bent position as required • Fire rated access panel is fixed into frame • Duct wrap is re-applied around duct and frame 10 to sit in recess 19 of frame Additional recess height may be required for clearance over protruding surface- mounted items such as junction boxes, switchgear, actuators and the like.

In the embodiment described above the fire rated access panel was completely removable from the frame. In other embodiments the fire rated access panel may be hingedly attached to the frame and so is swung open to gain access to the interior of the duct.

In some embodiments the frame may be integrally formed in the duct at the time of fabricating the duct to provide access points at specified locations in the duct.

In some embodiments the frame may be manufactured in multiple discrete sections that are removable for ease of installation of the fireproofing material. The frame may be installed as a single complete unit, or dismantled for complex installations and reassembled though the use of integrated fixing tabs and female threaded fasteners. Such an embodiment is shown at figures 10 to 13.

Referring to figures 10 to 13, an alternative embodiment of a frame 10B is shown which differs from the embodiments described above in that it is formed in two parts being a rear part 11B and a removable front part 13B. Faces 12B and 14B are found on rear part 11B.

Faces 16B and 18B are found on the front part 13B. Frame 10B is used with the same type of fire rated access panel 40. Rear part 11B has female threaded blocks 20B welded to it. These receive male screw fasteners passed through the access panel 40 and the front part 13B to secure the assembly together.

To install the frame 10B, firstly the rear part 11B is mounted to the duct. Insulating material such as duct wrap is then applied to the duct and around the rear part to cover face 12B. Following the installation of the insulating material the front part 13B and the access panel 40 are fitted. A recess of the same dimensions as recess 19 described above is thereby formed between the front part 11B and rear part 13B which is filled with insulating material.

The access panel 40 overlaps the insulating material in the same fashion as for the embodiments described above.

While a number of preferred embodiments have been described, it will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

THE

Claims (10)

CLAIMS DEFINIG THE INVENTION ARE AS FOLLOWS:
1. A fre rated access panel system including: a fame member fr mounting to a duct; a fre rated access panel which attaches to the fame member; the fame member including a recess about its periphery which in use receives a portion of insulating material; and a plurality of tabs disposed on the fame member, the tabs being bendable so as to confgure the tabs fr mounting of the fame member to the duct.
2. 2. A fre rated access panel system according to claim 1 wherein the fame member includes a portion which surrounds the edges of the access panel.
3. 3. A fre rated access panel system according to either of claim 1 or claim 2 fm1her including an air-tight seal between the access panel and the fame member.
4. A fre rated access panel according to any preceding claim frther including an intumescent seal between the access panel and the fame member.
5. 5. A fre rated access panel system according to any preceding claim wherein the access panel is hingedly attched to the fame member.
6. A fre rated access panel system according to any preceding claim wherein the access panel is of laminar construction.
7. 7. A fre rated access panel system according to claim 6 wherein the access panel includes an outer layer of steel, hardboard or coated hardboard.
8. 8. A fre rated access panel system according to any preceding claim including a number of removable fmale screw fsteners fr attaching the access panel to the fame member.
9. A fre rated access panel according to any preceding claim wherein the fame member includes a removable portion and the recess is at least partially defned by the removable portion.
10. 10. A fire rated duct including: a duct body defning an interior fow path of the duct; a fre rated access panel system including: a fame member fr mounting to the duct; a ame member fre rated access panel which attaches to the fame member; the f including a recess about its periphery; and a plurality of tabs disposed on the fame member, the tabs being bendable so as to confgure the tabs fr mounting of the fame member to the duct; and an insulating material applied to the recess such that the access panel overlaps the insulating material about the periphery of the access panel.