AU2006246325C1

AU2006246325C1 - Air duct

Info

Publication number: AU2006246325C1
Application number: AU2006246325A
Authority: AU
Inventors: Gregory Wayne Scott
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-05-11
Filing date: 2006-05-11
Publication date: 2011-10-20
Anticipated expiration: 2026-05-11
Also published as: AU2006246325B2; AU2006246325A1

Abstract

A tubular moulded air duct has an elongated cross section with male/female joins (4, 8) at the ends and contains an effective quantity of flame retardant. The ducts are made by excising the ends (30) from a blow moulded precursor. Moulded corners (20, 22) allow the ducts to be turned through 45° and 90° and installation in hollow stud walls and beside ceiling joists enables ducts to run up and down walls and across ceilings for heating, cooling and air extraction. Adapters (24) join the duct to flexible bellows type hoses.

Description

WO 2006/119586 PCT/AU2006/000776 TITLE: AIR DUCT FIELD OF THE INVENTION 5 This invention concerns blow moulded products and methods for making the same. BACKGROUND OF THE INVENTION In multi-storey dwellings such as apartment blocks, exhaust air cannot be vented into roof 10 space and must be ducted across ceilings to reach wall vents. In this way range hoods WO 2006/119586 PCT/AU2006/000776 -2 and bathroom extractors send air through ducts installed between floors. Ducts of this type are made of sheet steel. Joints between sections of duct must be taped or other wise sealed. Steel is unsuitable acoustically tending to resonate too readily. The high thermal conductivity of steel leads to condensation and this is an unwelcome disadvantage where 5 access for inspection and repair is restricted as in wall and ceiling flow paths. SUMMARY OF THE INVENTION The apparatus aspect of this invention provides a moulded air duct of elongated section 10 capable of installation in wall or ceiling space and containing an effective quantity of flame retardant. Moulding by injection is feasible but blow moulded ducts are preferred in that acceptable uniformity in wall thickness is achievable at lower cost. Wall thickness may be 2.00 15 3.00mm. The ducts may have male/femalejoins at the ends of the ducts which will allow sealant to fill the clearance between the overlapping parts. Individual ducts may be 1000-1500mm in length, but 1200mm is preferable. The duct may have a male join at one end, a female join at the opposite end and one or more joint 20 sites at predetermined spacings. The joint site may be of enlarged section so that cutting the duct through the joint site generates a female join. The joint sites stiffen the duct. Further stiffening is made possible by the inclusion of tubular supports extending from opposite internal faces of the duct. These are created during the blow moulding operation. The sides of the duct may be curved, preferably semi-circular section. 25 The ducts may be moulded from polyolefins such as polyethylene, preferably HDPE. Suitable flame retardants are that the flame retardants are halogenated aromatic flame retardants including tetrabromobisphenol A polycarbonate oligomer, polybromophenyl ether, brominated polystyrene, brominated BPA polyepoxide, brominated imides, 30 brominated polycarbonate, poly (haloaryl acrylate), poly (haloaryl methacrylate), or mixtures thereof. Poly (haloaryl acrylate) is preferred with the most preferably being poly (pentabromobenzyl acrylate). PBB-PA has been known for some time and is a valuable flame retardant material useful in a number of synthetic resins. PBB-PA is prepared by WO 2006/119586 PCT/AU2006/000776 -3 the polymerisation of pentabromobenzyl acrylate ester (PBB-MA). The PBB-PA polymeric -flame retardant material is incorporated into the synthetic resin during processing to impart flame retardant characteristics. These are described in the literature. They are added to the moulded beads to make up 6-10% of the moulding mix. 5 The ducts may be modified by moulding corner components which turn the flow path through 450 or 90*. The ducts may be joined to ducts of both substantially square section and round section by an adapter. 10 A ducting system using the components described above permits the installation of a cooling distribution circuit in the ceiling with wall supplied outlets just above floor level, together with underfloor heating distribution circuit with wall supplied outlets at any desired height. Accordingly the ducts run up and down walls and across ceilings within the existing structure bringing cooling, heating and ventilation. 15 The method aspect of this invention provides a method of making a duct of elongated section by blow moulding a parison to form a duct which is closed at both ends with a joint site at one end and at least one other joint site intermediate the ends and removing both ends to create a male join at one end and a female join at the opposite end. 20 The method may include the step of connecting the internal faces of the duct with a tubular support in the central area of the duct. BRIEF DESCRIPTION OF THE DRAWINGS 25 Various embodiments of the invention are now described with reference to the accompanying drawings, in which: Figure 1 is a plan of a piece of duct. 30 Figure 2 is an end view of the duct of Figure 1. Figure 3 is a 450 corner component in the same plane.

WO 2006/119586 PCT/AU2006/000776 -4 Figure 4 is a perspective of a 90* corner in a different plane. Figure 5 is a perspective of an adapter. 5 Figure 6 is a side view of a moulding before conversion to a duct. Figure 7 is a perspective of a specialised air duct containing a butterfly valve. Figure 8 is a section through part of a two storey building with in wall ducting. 10 Figure 9 is a section through part of a single storey building with ducting in the roof space. Figure 10 is a section through part of a multi-storey apartment building with an air duct 15 in the suspended ceiling space. Figure 11 is a plan of a department with air ducts exhausting the outside air through the ceiling space. 20 DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS Referring now to Figures 1 and 2, the duct is 1200mm long, 335mm wide and 60mm deep. End 2 is square and constitutes a male join 4. End 6 is also square and is enlarged in-section to form a female join 8. The intermediate female joins 10 are equally spaced 25 along the length of the duct. The three areas between joins are each stiffened by the formation, during moulding, of a tubular post 12 which extends from wall 14 to opposite wall 16. The junction 18 between the wall and the post is radiussed to reduce drag. 8% of poly pentabromobenzyl acrylate ester is dispersed in the mix at the moulding stage. 30 In Figure 3 the corner component 20 turns the duct flow direction through 450 and can be used with a second component to achieve a 900 change. One end has a male join 4. The opposite end has a female join 8. Again an intermediate female join 10 and a post 12 import the necessary stiffness and shape to become part of a chain of duct work.

WO 2006/119586 PCT/AU2006/000776 -5 In Figure 4 a 90' bend component 22 is shown. In Figure 5 the adapter 24 has a neck 26 which takes the cross section of the male join into a box-section spigot 28 (170 x 100mm). 5 Figure 6 shows a side view of the moulded duct precursor from which the 1200mm duct is cut. The ends 30 are excised. In Figure 7, a two storey dwelling has a suspended floor 32 and a ceiling fixed to ceiling 10 joists 34. The timber frame 36 stands inside the outer brick veneer 38. The plasterboard lining is pierced to receive a duct outlet 40 which discharges air from duct run 42. Duct run 42 is turned through 90' by bend 22 and bend 22 is connected to adapter 24. Circular flexible pipe 44 is taped to the adapter. The opposite end of the pipe is taped to the outlet of a gas fuelled heater (not shown). The flattened section of the duct fits within the stud 15 depth. Gaps in the floor plate allow the duct to reach the space under the floor. In Figure 8, the space heater 46 warms the air in the room 48 which is to be transferred to room 50 through ceiling vents 52 joined by the duct run 42. The ends of the ducts open into adapters 24 and flexible pipes 44 join the adapters to fan box 54. The fan box 20 is concealed in cupboard 56. Duct runs also discharge room air outside the building. Regulations require that the duct contains a barrier to the reverse flow of air into the building so that for example prevailing winds will not drive unwanted air into the building. Figure 7 shows the valve 25 component which forms part of the duct run for an extraction layout. The component is a blow moulding in polyethylene containing flame retardant as described above. The main tube 60 is 150mm in diameter and 440mm long. One end 62 is plain for-the connection of flexible tubing and the opposite end 64 is enlarged and of capsule section being 135 x 220mm. Transverse branches 64 are of circular section and likewise of 30 150mm diameter. The air barrier in the main tube is a gravity biassed circular plastic disc 66 mounted 30mm off centre. The main tube has two sites 68 where the wall thickening of the tube is increased. Both sites have a central point of weakness which is broken through in order to admit the axle 70 of the disc.

WO 2006/119586 PCT/AU2006/000776 -6 The manner of use of the valve component is shown in Figures 10 and 11. Room 50 has a suspended ceiling 72 with a vent 52. Fan box 54 is fixed to the ceiling slab 74 as is the duct run 42. The valve component 60 is connected between the fan box 5 input and the vent with the valve disc disposed to close when the fan stops. In Figure 11 the duct runs 42 are evident in plan extending from the cooler's extractor fan 76 to the outside vent 78 utilising corners 20. Valve component 66 utilises shaped end to connect to shower vent 52 via a flexible tube 44 and branch 54 to connect a toilet vent 10 52. I have found the advantages of the above embodiment to be: 1. The components are easier to handle than metal components in that the formation 15 of a chain is easier. 2. The components have poor thermal conductivity and therefore improve the thermal efficiency of the system and reduce condensation. 20 3. The finished duct work has better acoustic performance than metal duct work. 4. The ducts fit between studs in a stud wall. 5. Although the ducts provide an air path during a fire, the duct itself will not spread 25 the fire through the building. It is to be understood that the word "comprising" as used throughout the specification is to be interpreted in its inclusive form, ie. use of the word "comprising" does not exclude the addition of other elements. 30 it is to be understood that various modifications of and/or additions to the invention can - be made without departing from the basic nature of the invention. these modifications and/or additions are therefore considered to fall within the scope of the invention.

Claims

1. A moulded air duct of elongated cross-section capable of installation in a wall or ceiling space which contains an effective quantity of flame retardant, having 5 male/female joins at the ends and at least one joint site of enlarged cross-section intermediate the ends which when parted transversely creates a male and female join.

2. A moulded air duct as claimed in Claim 1, wherein the joins overlap with a 10 clearance which allows sealant to occupy the clearance.

3. A moulded air duct as claimed in Claim I or 2, wherein the sides of the duct are of curved section joined by parallel walls. 15

4. A moulded air duct as claimed in any one of Claims 1-3, wherein the opposite parallel walls of the duct are joined by integrally moulded struts.

5. A moulded air duct as claimed in Claim 4, wherein struts are located between the joint site and the end of the duct. 20

6. A moulded air duct as claimed in Claim 4 or 5, wherein the struts are located between joint sites and between the endmost site and the adjacent end.

7. A moulded air duct as claimed in Claim 4 or 5, wherein the strut is waisted. 25

8. A moulded air duct as claimed in any one of Claims 1-7, wherein the wall thickness is 2-3mm.

9. A moulded air duct as claimed in any one of Claims 1-8, wherein the moulding 30 mix contains 6-10% by weight of flame retardant.

10. A moulded air duct as claimed in Claim 9, wherein the flame retardant is a -8 polyhalo acrylate.

11. A moulded air duct as claimed in any one of the preceding claims, wherein the duct walls are curved in order to turn the flow path through 45 or 900. 5

12. A moulded air duct as claimed in any one of the preceding claims when made by excising the ends from a blow moulded precursor.

13. A moulded air duct or precursor thereof substantially as herein described with 10 reference to and as illustrated in Figures 1, 2 and 6 and as modified by Figure 3.

14. A method of making a duct of elongated cross section by blow moulding a parison to form a duct which is closed at both ends with a joint site of enlarged circumferential cross section at one end and at least one other joint site of 15 enlarged circumferential cross section intermediate the ends and excising both ends to create a male join at one end and a female join at the opposite end.

15. A method as claimed in Claim 14, including connecting the internal faces of the duct with a tubular support in the central area of the duct. 20

16. An air duct system comprising multiple ducts as claimed in Claim 1, joined end to end arranged to conduct air from a heating or cooling appliance in one part of a building to outlets in rooms in another part of the building with adaptors at the inlet for connecting the duct to hoses of circular section. 25