AU2017245305A1 - A Duct - Google Patents

Abstract

ll:\gw\Interwoven\NRPortbl\DCC\GW\15662165_l.docx-10/102017 A duct for delivery or removal of air from an enclosed space, the duct being tubular for the passage of air therethrough and the wall of the duct being formed of polymer foam and wherein the inner and/or outer surface of the wall has a metallic foil thereon such that the wall is impervious to the passage of air or vapour. Figure

Description

- 1 A DUCT [0001] The present invention relates to a duct for delivery or removal of air from an enclosed space. The present invention also relates to a ducting system for ventilation or air conditioning including at least one afore-mentioned duct.

[0002] Galvanised steel sheeting formed into rectangular or round tubing, known as ducts, is used to provide conduits for delivery and removal of air of an enclosed space. The ducts can be wrapped externally or internally lined with fibreglass or polyester blankets to provide insulation. These ducts are generally awkward and heavy, have little flexibility to run with changes of direction and are difficult to shape or cut due to the multiple materials used. Difficulties in sealing sheet metal tubing means that air leaks are common, especially in confined spaces. As such, installation of such ducting is complicated, labour-intensive, energy wasting and expensive.

[0003] According to a first aspect of the present invention, there is provided a duct for delivery or removal of air from an enclosed space, the duct being tubular for the passage of air therethrough and the wall of the duct including polymer foam and wherein the inner and/or outer surface of the wall has a metallic foil thereon such that the wall is impervious to the passage of air or vapour.

[0004] According to an embodiment, the metallic foil is a metallic foil laminate.

[0005] According to an embodiment, the metallic foil laminate includes reinforcement.

[0006] According to an embodiment, the metallic foil/foil laminate includes aluminium.

[0007] According to an embodiment, the polymer foam is a viscoelastic polymer foam.

[0008] According to an embodiment, the polymer foam has a low permeability to air or vapour.

[0009] According to an embodiment, the polymer foam comprises a closed cell physically cross-linked polyolefin foam material.

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-2[0010] According to an embodiment, the wall comprises a composite of polymer foam layers.

[0011] According to an embodiment, surfaces of the polymer foam are meltable and wherein melted polymer foam surfaces are contactable to form a heat weld therebetween.

[0012] According to a second aspect of the present invention, there is provided a method of preparing ducts for installation, including: heat welding an end of one duct as described above to an end of another such duct to form a duct of extended length.

[0013] According to an embodiment, the method includes: removing a wedge-shaped portion or at least two spaced-apart wedge-shaped portions from a generally straight duct as described above, folding the duct at the location of the or each wedge-shaped void thereby formed and heat welding the surfaces exposed by removal of the wedge-shaped portion(s) together to form a bend in the duct.

[0014] According to an embodiment, the method includes: removing four wedge-shaped portions from the generally straight duct to form a bended duct wherein the ends are of the duct are oriented generally transverse to each other.

[0015] According to an embodiment, the method includes: shaping an end of a first duct as described above to form a wedge, removing a corresponding wedge-shaped portion from the wall of a second such duct, and inserting the wedge-shaped end of the first duct into the corresponding void thus formed in the second duct such that the ducts are generally transverse to each other to form a T-intersection and heat welding the abutting surfaces of the two ducts.

[0016] According to a third aspect of the present invention, there is provided a duct prepared by any one of the methods described above.

[0017] According to a fourth aspect of the present invention, there is provided a ducting system for air-conditioning or ventilation of an enclosed space, wherein the ducting comprises ducts as described above.

[0018] The present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

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-3 [0019] Figures 1 to 3 are perspective and cross-section views of a duct according to an embodiment of the present invention;

[0020] Figures 4 to 9 illustrates steps of an example method of joining the duct of Figures 1 to 3 to another such ducting to form duct of extended length;

[0021] Figures 10 and 11 illustrate steps of an example method to cap an end of the ducting of Figures 1 to 3;

[0022] Figures 12 to 16 illustrate steps of an example method to introduce a progression of bends in the duct of Figures 1 to 3;

[0023] Figures 17 to 23 illustrate steps of an example method to join the duct of Figures 1 to 3 to another such duct to form a T-intersection; and [0024] Figures 24 to 29 illustrate steps of an example method to introduce a spigot into the duct of Figures 1 to 3.

[0025] Figures 1 to 3 show various views of a generally straight tubular duct 2 for delivering and removing air from an enclosed space according to an embodiment of the present invention, while Figures 4 to 29 show example methods for preparing the ducts 2 for installation in the enclosed space as a ducting system. The ducts 2 may be used for ventilation or air-conditioning systems. The duct 2 is arranged in a tubular form such that air is movable through the duct 2 from one end to the other, a wall of the duct 2 being formed of polymer foam 4 and an inner surface and/or outer surface of the wall having a metallic foil 6 thereon. Preferably both the inner and outer surfaces have such an aforementioned foil 6. In a preferred embodiment, the metallic foil is a metallic foil laminate.

[0026] The polymer foam material 4 advantageously provides insulating properties to the duct 2 as well as forming the wall of the duct 2. Furthermore, the metallic foil laminate 6 seals the wall of the duct 2 such that it is impervious to fluid, such as air or liquid, without the use of chemical agents. Prior art ducting, such as rectangular or round ducts formed of metal sheeting, are generally sealed against leaks by the use of chemical adhesives and sealants. In a preferred embodiment, the metallic foil laminate 6 is an aluminium foil laminate. It is also

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-4preferred that the metallic foil laminate 6 includes reinforcement, for example with a polypropylene or polyethylene scrim.

[0027] The polymer foam material 4 is preferably formed from flexible polymer foam material which has viscoelastic properties which allows the duct 2, when formed from such material, to be compressed, flattened or otherwise shaped to be inserted into confined spaces during installation of the ducting system. The polymer foam material 4 also preferably has a low permeability, that is, the rate that a fluid, such as a gas or liquid, can penetrate the foam material 4 is low, for example a closed cell polymer material. It is also preferred that the polymer foam material 4 has the property that if the surfaces of two pieces of such polymer foam material 4 is heat-treated, that the melted surfaces can be contacted together to form a join.

[0028] Examples of polymers used to form the polymer foam material 4 include polyolefin, for example polyethylene, polypropylene, polyurethane or polyester. In a preferred embodiment, the polymer foam material 4 comprises a closed cell physically cross-linked polyolefin foam material. In an exemplary embodiment, the polymer foam material 4 has a vapour permeability of 2.3 χ 10'¹⁵ Kg/Pa.s.m, and a permeability resistance factor of μ>80,000. Such polymer foam materials are dense but light enough to be easy to carry and install, yet are also impervious to fluid, and also allow a surface of the polymer foam material 4 to be easily heat bonded or welded to another like surface.

[0029] In an example of manufacturing the duct 2, the surfaces of flat sheets of polymer foam material 4 are bonded together to form a stack of sheets oriented parallel to each other. Each polymer foam material layer 4’ may be between 3 to 7 mm thick, preferably about 5mm thick. The polymer foam sheets 4’ are preferably heat bonded together however alternatively they can be bonded together by an adhesive. The composite stack of polymer foam sheeting is then rolled and opposing edges joined together, for example by heat bonding, to form a cylindrical tubular shape, as illustrated in Figures 1 to 3.

[0030] It will be appreciated that the duct 2 can be formed of a composite polymer foam material 4 having varying numbers of polymer foam material layers 4’ to producedifferent insulating values as required to conform to thermal ratings of building standards or code. For

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-5example, the duct wall can be between 20 to 64 mm thick and have between four to 10 layers of polymer foam material. Examples of wall thickness can be 20 mm (as exemplified in Figures 1 to 3), 32 mm, 52 mm and 64mm. It will be also be appreciated that while the duct 2 is shown as a substantially cylindrical tubular duct, the duct 2 could be in the form of other shapes, such as a rectangular or triangular tube.

[0031] Figures 4 to 9 illustrate an example method of connecting a generally straight duct to another like duct 2’ so as to form a duct of extended length such that the ducts 2,2’ can be installed as a ducting system for air-conditioning or ventilation. The ends of the ducts 2,2’ to be connected are heated, for example by a hot air gun for about one minute (see Figure 7), until the end surfaces are melted. The end surfaces are then held together until cooled, perhaps for about 5 minutes, such that the surfaces are thus bonded together to form a sealed duct of extended length 2 ’ .’ Additional heat can be applied if any holes in the j oin 10 are found to seal the holes (see Figure 8) then the entire join 10 can be sealed with foil tape 12 (see Figure 9) so as to be impervious to fluid. The foil tape 12 is preferably formed of the same material as the metallic foil laminate used for lining the internal and external surfaces of the duct 2, and where one surface of the foil tape 12 has an acrylic adhesive.

[0032] To aid in the connection of the two like ducts 2, 2’, a piece of foil tape 12’ can be used as a temporary hinge connection which can temporarily connect the two end portions of the ducts 2, 2’ together (see Figures 4 to 6) such that they can be fitted together in alignment with each other easily after the surfaces have been melted.

[0033] In another example use of the ducts 2, there is shown a method of sealing an end of a duct 2 with a cap 14 in Figures 10 and 11. The cap 14 is formed of a layer of polymer foam material 4, similar to or the same as that used for the duct wall, which is shaped and sized to cover an end of a duct 2. As illustrated in Figures 10 and 11, the cap 14 is in the form of a disc. The end of the duct wall is heated, for example by a hot air gun 8, and the cap 14 placed in contact with that end until it is cooled such that the cap 14 is bonded to the duct end. The edges of the cap 14 can then be sealed further by the application of foil tape thereabout (not shown).

[0034] In a further example of the use of the ducts 2 to install a ducting system, Figures

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2017245305 10 Oct 2017 to 17 illustrate a method of introducing a progressive bend in a generally straight duct 2 to produce a bent duct 16 with the use of a mitre box 18. The mitre box 18 has a pair of opposing walls 20 joined by a floor 22, the walls 20 spaced apart so as to receive the duct 2. Each wall 20 has two portions 20’, 20’ ’adjacent inner edges of the two portions 20’ , 20’ Being inclined away from each other, for example to form an 22.5° angle therebetween. When the duct 2 is received in the mitre box 18 (see Figure 12), the duct 2 is cut at the adjacent edges of the wall portions 20’ , 20’,’for example with a saw 24 (see Figures 12 and 13), such that a wedgeshaped portion 26 of the duct 2 can be removed thereby forming a wedge-shaped void in the duct wall. The cutting planes intersect at a point in the duct wall leaving a small portion of the duct wall to act as a hinge for the portions of the duct 2 on opposing sides of the wedgeshaped duct void 28.

[0035] This step can be repeated so remove multiple spaced-apart wedge-shaped portions 26 from the duct see Figure 14). The surfaces so exposed by removal of the wedge-shaped portions 26 are then heated, and the duct 2 is folded to connect those melted surfaces while cooling to be bonded together. Each fold progressively bends the duct 2 and as illustrated in Figures 16 and 17, four such folds bend the duct 2 such that the ends of the formerly generally straight duct are now oriented in directions transverse to each other to form bent duct 16.

[0036] Figures 18 to 23 illustrate another example method of connecting a generally straight duct 2’ to another like duct 2’ ’to form a T-intersection 44. First, two lines are marked on opposing sides of each of the ducts 2’ , 2’ parallel to a longitudinal axis of the ducts 2’ , 2’ ’ (see Figure 18) forming a pair of opposing radial lines 30 along the length of the duct 2’ , 2’. ’ A first duct 2’ is placed in a mitre box 32 having a pair of opposing walls 34 joined by a floor 36, the walls 34 spaced apart so as to receive the duct 2’and having edges which incline upwardly away from the floor of the mitre box 32, for example at a 45° angle (see Figure 19). The first duct 2’ is received in the mitre box 32such that the radial lines 30 are substantially at the same height, and the inclined edges of the mitre box 32 is used as a guide to cut the duct 2’ from the top of the duct to the marked radial lines 30 (see Figure 19).

[0037] An additional cut is made along the marked radial lines 30 to intersect with the first angled cutting plane and the resultant tube section 38 is then removed. The first duct 2’ is

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-7then inverted in the mitre box 32, and another angled cut along the inclined mitre box wall edge such that duct end portion now has two surfaces which incline inwardly from the outer surfaces of the wall towards an end of the marked radial lines 30 to form a wedge-shaped end 40. In a similar way, the second generally straight duct 2’ ’can be cut with guidance from the mitre box 32 such that it has a wedge-shaped void 42 which substantially corresponds to the wedge-shaped end 40 of the first duct 2’ , such that theend 40 of the first duct 2’ can be received in the corresponding void 42 of the second duct 2’ ’to form the T-intersection 44 (see Figure 23).

[0038] Figures 24 to 29 illustrate an example method of installing a spigot 44 into a duct, where the spigot 44, for example a bellmouth spigot, is configured to be received in a pipe (not shown) for ventilation or air-conditioning thereon. The spigot 44 has a base 46 in the form of a flange extending transverse from an end of a cylindrical portion 48, the cylindrical portion housing a damper blade (not shown) therein which is movable between a position where the flow of air is allowed to pass through the spigot 44 and another position where the flow of air is occluded.

[0039] To install the spigot 44, first a portion 50 of the outer metallic foil laminate , corresponding to the shape of the spigot base 46, is marked then removed from the duct outer surface, for example by using a knife 52, to expose a portion of the polymer foam material 4 (see Figures 24 to 26), and an opening 54 bored into the duct wall substantially the diameter of the cylinder portion 48 of the spigot 44 (see Figure 27). The outer surface of the base 46 is coated with a foam material similar to that of the duct wall such that the outer base surface and the outer exposed surface of the duct wall can be heat treated, for example by a hot air gun 8 (see Figure 28), and the melted surfaces are brought in contact until they have cooled thereby forming a bond therebetween. A foil layer or tape 12 can then be applied to seal the edges of the base 46 (see Figure 29).

[0040] The above paragraphs describe various example methods of preparing the ducts such that they can be installed as a ducting system for delivering and removing air in an enclosed space. These example methods illustrate particularly the ease, rapidity and efficiency of installation of the light-weight flexible ducts in forming intersections, bends, joins, and

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-8installing spigots with only a few simple tools such as a pre-prepared mitre box, saw, knife, foil tape and hot air gun. Furthermore, the ducting system is easily made leak-proof, without the use of chemical sealants, even in confined spaces and can be adapted to conform to thermal standards by varying the thickness of the duct wall.

[0041 ] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

[0042] Throughout this specification and the claims which follow, unless the context requires otherwise, the word comprise, and variations such as comprises and comprising, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0043] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

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-9THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

Claims (14)

1. A duct for delivery or removal of air from an enclosed space, the duct being tubular for the passage of air therethrough and the wall of the duct including polymer foam and wherein the inner and/or outer surface of the wall has a metallic foil thereon such that the wall is impervious to the passage of air or vapour.

2. A duct according to claim 1, wherein the metallic foil is a metallic foil laminate.

3. A duct according to claim 1 or claim 2, wherein the metallic foil laminate includes reinforcement.

4. A duct according to any one of the preceding claims, wherein the metallic foil/foil laminate includes aluminium.

5. A duct according to any one of the preceding claims, wherein the polymer foam is a viscoelastic polymer foam.

6. A duct according to any one of the preceding claims, wherein the polymer foam has a low permeability to air or vapour.

7. A duct according to any one of the preceding claims, wherein the polymer foam comprises a closed cell physically cross-linked polyolefin foam material.

8. A duct according to any one of the preceding claims, wherein the wall comprises a composite of polymer foam layers.

9. A duct according to any one of the preceding claims, wherein surfaces of the polymer foam are meltable and wherein melted polymer foam surfaces are contactable to form a heat weld therebetween.

10. A method of preparing ducts for installation, including:, heat welding an end of one duct according to claim 9 to an end of another such duct to form a duct of extended length.

11. A method of preparing ducts for installation, including: removing a wedge-shaped

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-10portion or at least two spaced-apart wedge-shaped portions from a generally straight duct according to claim 9, folding the duct at the location of the or each wedge-shaped void thereby formed and heat welding the surfaces exposed by removal of the wedgeshaped portion(s) together to form a bend in the duct.

12. A method of preparing ducts for installation, including: shaping an end of a first duct according to claim 9 to form a wedge, removing a corresponding wedge-shaped portion from the wall of a second such duct, and inserting the wedge-shaped end of the first duct into the corresponding void thus formed in the second duct such that the ducts are generally transverse to each other to form a T-intersection and heat welding the abutting surfaces of the two ducts.

13. A duct prepared by any one of the methods according to claims 10 to 12.

14. A ducting system for air-conditioning or ventilation of an enclosed space, wherein the ducting comprises ducts according to any one of the preceding claims.