GB2514533A

GB2514533A - Ducting systems

Info

Publication number: GB2514533A
Application number: GB1304209.8A
Authority: GB
Inventors: Michael Ronald Dalgarno; Kenneth James Dalgarno
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-03-08
Filing date: 2013-03-08
Publication date: 2014-12-03
Anticipated expiration: 2033-03-08
Also published as: GB2514533B; GB201304209D0

Abstract

A duct member for an air distribution system, such as a heating, ventilation or air conditioning system, has a plurality of elongate frame elements 4, and thermal insulation boarding 5 secured between adjacent frame elements to define a duct passage. Two opposed flange members 2 may be provided, one at each end of the duct member, the flange members being secured to, and spaced apart by, the frame members. The flange members may be rectangular, and joined to one another by four frame members, one at each corner. A web may extend from each side of each flange member so as to attach it to the boarding. The boarding may extend through each flange member and lie flush with, or slightly proud of, an exterior surface of the flange member. A duct may be formed by connecting a plurality of duct members together at their flange members, the boarding of adjacent duct members being in contact to provide continuous thermal insulation along the duct.

Description

Ducting systems The present invention relates to ducting systems and particularly to a duct for an air distribution system.

Ducting systems for the distribution of ventilating or heating air are widely used in offices, warehouses, shops and factories. In many installations, it is a requirement for the ducts to be thermally insulated. Typically, this is done by first erecting the entire ducting system and when it is in place covering the outside of the ducting with a thermal insulating layer.

There are a number of disadvantages with this arrangement. Since the ducting is typically placed high off the ground, it is necessary to erect scaffolding for the workers installing the thermal installation, but there is still a significant risk of falls which creates a safety hazard. The productivity of workers working under these conditions is inevitably lower than if they were working at ground level. It frequently occurs also that there are difficulties in accessing certain parts of the ducting, where this is close to the roof for example. Furthermore, it is difficult to monitor and check the quality and the uniformity of the installation with the resuit that gaps may be formed in the installation which leads to cold spots and the risk of condensation forming in the ducts.

There are therefore a number of disadvantages with the existing system which risk compromising the integrity of the insulation and also make it very costly to install. One solution is disclosed in the applicant's co-pending application No. GB 1220484.8.

However, for certain applications there is a demand for a lighter weight, lower-cost solution and the present invention seeks to provide a practical solution to this problem.

According to the present invention there is provided a duct for an air distribution system.

elongate duct member for an air disthbution system including a chassis comprising two opposed flange members having an opening therein defining the duct cross-sectional area, the flange members being joined by a plurality of elongate frame elements secured about the periphery of the flange members to define the chassis, thermal insulation boarding being secured between adjacent frame elements to define the duct passage.

Preferably, the flange members are rectangular and are joined by four elongate frame elements secured to respective apices of the flange members.

Preferably, the frame elements each have swages or folds therein to improve the bending resistance of the element.

Preferably, the flange members each have a web extending outwardly from the flange member over the insulating board with means to secure the board to the web, and when the flange members are rectangular, the flange members each have a web on each side of the right angle to enable all four sections of the nsulating boarding to be secured to the frame members. Preferably, the flange members are formed from planar sheet material, the web being formed from the sheet so as to extend outwardly at a right angle from the plane of the flange member so as to overlie the insulating boarding.

Preferably, the insulating boarding extends through the flange members to lie flush with or slightly proud of the exterior surface of the flange members.

The insulating boarding may comprise a foamed or expanded plastics material, which may be of a phenolic resin or polyisocyanurate. Alternatively, the insulating boarding is formed of a mineral or natural wool based material. In all forms, the insulating boarding may have a closed cell vapour proof skin and/or a class 0' foil faced plastic laminate vapour barrier skinifacing and/or a pure aluminium foil applied at manufacture to prevent moisture ingress.

Preferably, the insulating boarding is formed of a single sheet of material having V-shaped grooves cut along fold lines to enable the board to be folded into a rectangular tube forfeeding into the chassis to form the duct passage.

In a preferred arrangement, a duct is formed by a plurality of duct members, Ihe duct members being joined by securing adjacent flanges together, the insulating boarding of adjacent duct members being in contact to provide a continuous thermally insulated lining through the duct passage. A gasket may be located between adjacent flange members.

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a schematic perspective view of a duct member for an air distribution system, Figure 2 shows a scrap view of a transverse section of the duct member, and Figure 3 shows a scrap side view of the duct member.

Referring now to figure 1 there is shown a schematic perspective view of a duct member forming part of a duct for an air distribution system. The duct member consists of 2 opposed flange members 2, only one of which is shown in the interests of clarity. Each flange member consists of a substantially rectangular planar body having four sides 3a to 3d, which enclose an opening which defines the crosssectional area of the duct. On each of the sides of the flange member a web 2a is formed extending at right angles to the plane of the flange towards the other flange member. Four elongate frame elements 4 extend between the associated apices of the corners of the flange members 2 to secure the two flanges together by means of screws 7 in a spaced relationship to form a chassis, the length of the frame elements 4 defining the length of the section.

The elongate frame elements 4 are L-shaped in crosssection and are strengthened by being rolled over at the edges or having swages or recesses (not shown) which serve to strengthen the element against bending stresses.

The chassis thus formed is completely open but it is closed by making a duct wall from a thermally insulating boarding 5. The boarding consists of a foamed or expanded plastics material such as a phenolic resin or polyisocyanurate. Alternative thermal insulation materials such as mineral wool, natural wool or reconstituted paper may be used.

Preferably, the board 5 is covered with a closed cell vapour proof skin and/or a class 0 foil faced plastic laminate vapour barrier skin/facing and/or a pure aluminium foil applied at manufacture to prevent moisture ingress.

As shown, the ducting includes four walls made from the boarding in the rectangular duct member shown. The four walls are made from a single sheet of boarding in which appropriately spaced grooves are formed by culling a 900 Vee groove about which the boarding is hinged to form a rectangular tube defining the duct. The tube is then inserted in the end of the duct and pushed in until the end faces 5a of the tube are aligned with the outer surfaces of the two flanges 2 or to project slightly out&de the plane of the flange outer faces.

Referring now to Figures 2 and 3 in addition, there is shown scrap views of the manner in which the insulating boarding 5 is held securely in position. Further screws 8 are screwed through the walls of the frame elements 4 into the insulation boarding 5 to secure the insulation relative to the chassis. Although not shown, further screws may be used to secure the boarding 5 to the webs 2a.

A duct of the required length is obtained by assembling a plurality of the duct members illustrated together by securing the duct members through their flanges 2 by means of bolts passing through securing holes 9 in the flanges. In a typical installation, a gasket 10 is located between adjacent flanges as shown in Figure 3. When secured together in this way, the end faces of the insulation boarding in adjacent duct members abut to provide a continuous wall of insulated material throughout the duct with no gaps or bridges for leakage to take place. The use of the chassis with its framework on the outside of the insulation material provides a degree of protection to the boarding from cables etc passing over the ducting. This system all but removes the risk of cold bridging since only in extreme conditions of high temperature on one face combined with extreme low temperature on the opposing face and very high humidity would there be a very low risk of cold bridging and these conditions would not be encountered in normal use, At the same time, it provides a much lighter ducting which can be produced at much lower cost than the known schemes.

Although shown as a rectangular duct, it will be appreciated that other cross sections could be used. The sample, the duct could be, in crosssection, circular, flat oval or any shape that would fit in with the building fabric or designer's requirement's, using circular flat oval or any corresponding shape flanges with three or four frame elements securing the flanges together. In this case the cross section of the frame elements would be shaped to suit the profile such being arcuate for a circular duct, The thermally insulated boarding could be made of a flexible material for assembly in a factory or could be made by extruding a preformed rigid tube.

It will also be appreciated that although a single linear duct member is disclosed invention is equally applicable to producing junctions such as T-shapes, bends or any tern as normaUy used withhi the HVAC ndustry. Specia' shaped juncflon boxes coud also be used. Aflhough the embodment described uses the flanges to secure the duct members together it wifi be understood that other forms of fastening may be used, which may be determined by the visual appearance required for the finished duct.

Claims

CLAIMS1. An elongate duct member for an air distribution system including a chassis comprising two opposed flange members having an opening therein defining the duct cross-sectional area, the flange members being joined by a plurality of elongate frame elements secured about the periphery of the flange members to define the chassis, thermal insulation boarding being secured between adjacent frame elements to define the duct passage.
2. A duct member of according to claim I wherein the flange members are rectangular and are joined by four elongate frame elements secured to respective apices of the flange members.
3. A duct member according to claim I or 2, wherein the frame elements each have swages or folds therein to improve the bending resistance of the element.
4. A duct member according to any one of the preceding claims wherein the flange members each have a web extending outwardly from the flange member over the insulating board with means to secure the board to the web.
5. A duct member according to claim 4, wherein when the flange members are rectangular, the flange members each have a web on each side of the right angle to enable au four sections of the insulating boarding to be secured to the frame members.
6. A duct member according to anyone of the preceding daims wherein the flange members are formed from planar sheet material, the web being formed from the sheet so as to extend outwardly at a right angle from the plane of the flange member so as to overlie the insulating boarding.
7. A duct member according to any one of the preceding claims wherein the insulating boarding extends through the flange members to lie flush with or slightly proud of the exterior surface of the flange members.
8. A duct member according to anyone of the preceding claims wherein the insulating boarding comprises a foamed or expanded plastics material.
9. A duct member according to claim 8 wherein the plastics material consists of a phenohc resin or polyisocyanurate.
10. A duct member according to any one of claims 1 to 7 wherein the insulating boarding is formed of a mineral woo! or natural wool based material.
11. A duct member according to anyone of the preceding claims wherein the insulating boarding has a closed cell vapour proof skin and/or a class 0' foil faced plastic laminate vapour barrier skin/facing and/or a pure aluminium foil applied at manufacture to prevent moisture ingress.
12. A duct member according to any one of the preceding claims wherein the insulating boarding is formed of a single sheet of material having V-shaped grooves cut along fold lines to enable the board to be folded into a rectangular tube for feeding into the chassis.
13 A duct formed by a plurality of duct members as claimed in any one of the preceding claims, the duct members being joined by securing adjacent flanges together, the insulating boarding of adjacent duct members being in contact to provide a continuous thermally insulated lining through the duct.
14. A duct according to claim 13, wherein a gasket is located between adjacent flange members.
15. A duct member substantially as described herein with reference to and as illustrated in the accompanying drawings.