WO2008046153A1

WO2008046153A1 - Improved knock-down filter assembly

Info

Publication number: WO2008046153A1
Application number: PCT/AU2007/001589
Authority: WO
Inventors: Adam Richard Tanton; Shaun Anthony Tanton
Original assignee: Fume-Lok Pty Ltd
Priority date: 2006-10-20
Filing date: 2007-10-19
Publication date: 2008-04-24

Abstract

A knock-down filter assembly for removing particulate matter from a gas stream, the filter assembly including a flexible, textile-based, filter medium formed into a generally cylindrical filter body, the filter body having an interior and a longitudinal axis and being rigidly supported by a generally cylindrical support body within its interior, wherein the support body also includes an interior and is formed from a mesh that is longitudinally rigid but radially flexible, the support body being stiffened radially by at least two radial stiffening rings, the stiffening rings being detachably secured to the support body interior.

Description

IMPROVED KNOCK-DOWN FILTER ASSEMBLY

Related Applications

This international patent application claims priority to Australian provisional patent application 2006905818, the specification of which is hereby incorporated by reference.

Field of the Invention

The present invention relates to a filter assembly for use in removing, for example, particulate matter from a gas stream, such as for removing dust particles or volatile organic compounds (such as undesirable fumes, odours and vapours) from a stream of air in industrial, agricultural, medical and domestic filtration and ventilation equipment.

Background of the Invention

In many filtration installations it is not necessary to use filtration equipment with sophisticated filtration media and thus reasonably simple components and media are able to be used. For such un-sophisticated equipment, there is a wide range of suitable textile-based materials that can be used as the filtration media. Often, different materials are used to provide multiple layered systems, such as where woven or non-woven fabrics are used in conjunction with fibrous activated carbon. A multiple layered system of this type is generally quite flexible, as would be expected of a system using textile-based materials, in terms of them not being rigid materials that would either undergo inelastic deformation or break when flexed.

Due to the flexibility of these textile-based materials, some filtration assemblies that use textile-based materials as their filtration media can encounter a range of unique design problems. In this respect, a commonly required shape for a filtration assembly is cylindrical, where the assembly has a body having a generally circular cross-section along its length (and a generally constant diameter), is open at one end to receive the gas to be filtered, and is closed at the other end to force the gas through the gas permeable filtration media. However, where the filtration media is textile-based, such a cylindrical shape ordinarily requires the provision of rigid support for the flexible filtration media.

Typically, the solution to this problem has been the provision of a rigid cage over which the flexible filtration media can be located. Two such rigid cages are shown in US patent 5,096,476 to Lewis E Hunsberger and US patent 5,173,098 to Howard W Pipkorn. However, both the Hunsberger and Pipkorn cages are reasonably large and complex and do not lend themselves to being readily transported and/or easily disassembled (ideally without the need for highly skilled technicians).

There have been several further attempts at producing filtration assemblies that are simpler and are able to be more readily transported, such as by providing a rigid cage that can be transported in parts for assembly on-site (sometimes referred to as being a "knock-down" assembly). For example, US patent 4,141 ,128 to Harold J Wonderling, US patent 4,290,790 to Kunio Okubo and US patent 5,951 ,726 to Paul Allingham and John Kawola each describe a rigid cage (or support frame) that is said to be compact for transport and also quick and straightforward to erect on site. However, each of the arrangements described in these patents are again extremely complex and generally require the use of highly skilled technicians to construct (rather than merely assemble) the cage on-site.

It is an aim of the present invention to provide a relatively simple and cheap knock-down filter assembly that can be relatively easily transported in a disassembled, or at least partly disassembled, form and that can be easily assembled on site by a relatively unskilled technician. Before turning to a summary of the present invention, it must be appreciated that the above description of the prior art has been provided merely as background to explain the context of the invention. It is not to be taken as an admission that any of the material referred to was published or known, or was a part of the common general knowledge in Australia or elsewhere.

Summary of the Invention

The present invention provides a knock-down filter assembly for removing particulate matter from a gas stream, the filter assembly including a flexible, textile-based, filter medium formed into a generally cylindrical filter body, the filter body having an interior and a longitudinal axis and being rigidly supported by a generally cylindrical support body within its interior, wherein the support body also includes an interior and is formed from a mesh that is longitudinally rigid but radially flexible, the support body being stiffened radially by at least two radial stiffening rings, the stiffening rings being detachably secured to the support body interior.

The present invention also includes a kit for a knock-down filter assembly for removing particulate matter from a gas stream, the kit including:

^■ a flexible, textile-based, filter medium formable into a generally cylindrical filter body, the filter body having an interior and a longitudinal axis;

^■ a generally cylindrical support body for rigidly supporting the filter body within its interior, wherein the support body also includes an interior and is formed from a mesh that is longitudinally rigid but radially flexible; and

^■ at least two stiffening rings for radially stiffening the support body, the stiffening rings being detachably securable to the support body interior. Throughout this specification there will be references to shapes that are said to be "generally cylindrical". It is to be understood that these references are to include shapes that have a circular cross-section along their length, together with a constant (or nearly constant) diameter. However, it is envisaged that such shapes will also include cross-sections that are elliptical or oval (and thus might be regarded for the purposes of this specification as "generally circular"), and also diameters that may gradually vary along the length, such as may be present when the shape is a cone or frusto-cone.

The textile-based filter medium can be any known type of material and can indeed be formed by a combination of materials such as by multiple layers of materials. For example, suitable materials might utilize needled felt, fabrics and non-woven fabrics, and might include as a component thereof (ideally held between other components) an activated carbon filter. These media all rely on the presence of fibres, in the fibrous mats of the needled felt and the non-woven fabrics and in the thread and yarn of the woven fabrics, and preferably upon the presence of fibres that have been impregnated or bonded with carbon molecules, particles or dust.

It can thus be seen that the generally cylindrical filter body will be flexible in that it will collapse or fold upon itself when subjected to either longitudinal or radial forces, this flexibility being such that the body does not undergo inelastic deformation or break. This is useful for the purposes of transportation because the filter body can be formed into its required shape and size and then laid completely flat simply by applying a radial crushing force to its side. The (unsupported) filter body will then fold flat into two halves, or can be rolled or scrolled upon itself into a smaller cylindrical or tubular shape.

As mentioned above, the mesh that forms the generally cylindrical support body is longitudinally rigid (or at least substantially rigid so as not to easily flex longitudinally), but is radially flexible. The mesh may be any suitable material that provides these properties. While it is envisaged that an extruded plastic mesh (sometimes called "netting") in any of square, diamond, rectangular or hexagonal opening configuration would be suitable, it will be appreciated that other forms of wire (plastic coated or not) mesh will be just as suitable, as may many forms of suitably light-weight perforated metal sheeting. In terms of the size of the openings of the mesh, it is envisaged that mesh with openings in the order of 2 mm to 25 mm will be suitable.

Preferably, the mesh is formed from an extruded plastic, such as from one or more of the materials selected from polypropylene, polyethylene, nylon, polyvinyl chloride, or PTFE, depending upon the application of the filter assembly.

In one form, the mesh is made of polypropylene that is chemically and heat resistant and has reasonably high impact strength. Indeed, many forms of polypropylene meet the regulatory requirements for food contact applications, which increases its usefulness. Alternatively, polyethylene materials can be used, which tend to be softer and more flexible than polypropylene. They are also more durable in cold weather, resisting cracking. Further, nylon features high temperature resistance, excellent strength and low elongation, and is thus suitable for other applications, while PVC is characterized by its excellent moisture resistance, general chemical resistance (especially in chlorinated environs) and good "weatherability." PVC products are also easily bonded with glues or epoxy. Finally, PTFE (Teflon) materials tend to have excellent heat and chemical resistance, combined with low friction and high stability. They are thus suitable for high temperature and highly caustic applications.

In a preferred form of the filter assembly of the present invention, the stiffening rings are formed in halves (or at least as two pieces) that are able to be detachably secured together to form a complete ring in situ. This is advantageous in that it permits easier assembly than if the rings were closely sized to fit exactly within the interior of the support body. Ideally, the ring halves include cooperating female and male connecting members at respective ends to permit easy insertion and locking. Given the reference above to the term "generally cylindrical" covering shapes that are not perfectly cylindrical (with a circular cross-section of constant diameter along its length), it will thus be appreciated that the shape formed by the stiffening rings may take a variety of forms, being either precisely the same shape as the interior of the support body, or another similar shape that still allows the stiffening rings to provide the same function.

Preferably, the two pieces that make up a stiffening ring are each of a length such that both pieces are shorter than the length of the filter body, which allows them to be packaged inside or alongside the filter body for transport, minimizing the overall packaging size of the filter assembly when knocked down.

In a further preferred form, the filter assembly of the present invention includes clips secured (preferably detachably secured) to the inner wall of the support body, the clips providing the detachable securement of the stiffening rings to the support body interior. The provision of such clips avoids the need to weld, bolt or otherwise permanently fasten the stiffening rings, and also of course avoids the need for complex tools or equipment to do so. Preferably the clips will simply be retaining clips able to be hooked onto the mesh of the support body and able to receive and retain a portion of a stiffening ring.

Brief Description of the Drawings

Having briefly described the general concepts involved with the present invention, a preferred embodiment will now be described that is in accordance with the present invention. However, it is to be understood that the following description is not to limit the generality of the above description. In the drawings:

Figure 1 is a schematic perspective view of a preferred embodiment of a knockdown filter assembly of the present invention, showing the parts thereof prior to assembly;

Figure 2 is an end view of the open end of the preferred embodiment of Figure 1 after assembly;

Figure 3 is a perspective view of the closed end of the preferred embodiment of Figure 1 after assembly; and

Figure 4 is a perspective view of the open end of the preferred embodiment of Figure 1 after assembly.

Description of a Preferred Embodiment

Illustrated in Figures 1 and 2 is a preferred embodiment of a knock-down filter assembly 10 in accordance with the present invention. The filter assembly 10 includes a flexible, textile-based, filter medium 12a formed into a cylindrical filter body 12 having an interior 12b and a longitudinal axis A-A. The filter body 12 is shown having a circular cross-section of constant diameter along its length.

The filter medium 12a may be any suitable type of filter material and may be a combination of multiple layers of filter media, as has been generally described above. Indeed, in this preferred embodiment the filter medium 12a includes a porous outer cloth layer plus three layers of filter media. The porous outer cloth layer is ideally a lightweight, 100% polyester mesh fabric that readily accepts print (such as would be useful for promotional or identification purposes). The three layers of filter media in this embodiment are ideally:

1. Polyester fibre (Dacron™) impregnated with carbon dust;

2. Activated carbon needled felt; and 3. Polyester fibre (Dacron™) impregnated with carbon dust.

The outer Dacron™ layers are ideally resin impregnated layers and thus are reasonably stiff layers. However, the inner felt layer is non-woven and thus is quite pliable and extremely fragile, therefore needing the support and protection of the two stiffer outer layers. Indeed, in terms of filtration load, it is the inner felt layer that will take up to probably 80% of the filtration load. Thus, if not supported and protected by the two stiffer outer layers, damage to the inner felt layer is quite likely, leading to shorter life spans for filter.

Importantly, the filter medium 12a is flexible in that it will lay flat when a radial crushing force is applied to it. Indeed, being textile-based, if required the filter medium 12a could be folded into useful shapes for transporting.

Given the flexibility of the filter medium 12a, it is desirable to further stiffen the filter body 12 both longitudinally and radially. With this in mind, the filter assembly 10 includes a cylindrical support body 14 formed from a polypropylene mesh 14a that by its configuration is longitudinally rigid but radially flexible, the support body 14 having its own interior 14b. Again, the cylindrical support body 14 is shown having a circular cross-section of constant diameter along its length.

The support body 14 is sized and shaped so as to fit tightly within the interior 12b of the filter body 12 (in the direction of arrow X) so as to support the filter body 12 thereabout. The mesh 14a of the support body 14 is ideally an extruded polyrpropylene mesh having diamond shaped openings (as shown), the openings being in the order of 2 mm to 25 mm wide at their widest points. It will of course be appreciated that these openings may be other shapes, such as squares or rectangles.

However, given that the mesh 14a is itself at least somewhat radially flexible, again permitting it to be generally flattened when a radial crushing force is applied thereto, in use the filter assembly 10 still requires radial stiffening. Therefore, the filter assembly 10 further includes (in this embodiment) two radial stiffening rings 16 that may be located within the interior 14b of the support body 14 (in the direction of arrow Y) to radially stiffen the support body 14.

The rings 16 are ideally metal rings that can withstand reasonably strong radial forces without deforming. As mentioned above, the rings 16 need not be provided in one piece, but can be provided in two pieces (as shown) or more, in order to minimize the transport size of the parts of the filter assembly 10. Where the rings 16 are provided in pieces, such as in halves, any suitable joining system may be used to create a complete ring, ideally being a joining system that does not require complex tools or welding, such as a system using connectable end sleeves 17. Such end sleeves 17 are shown rigidly secured to one end of a ring piece, and sized so as to receive a free end of another ring piece therein.

As shown generally in Figure 2, the stiffening rings 16 can be detachably secured to the inner wall 14c of the support body 14 by clips 18. The clips 18 are retaining clips that are able to be hooked over a portion of the mesh of the support body 14 and then receive one of the stiffening rings 16 therein. The clips 18 are ideally generally U-shaped retaining clips.

Finally, and as is apparent from Figures 3 and 4, it will be appreciated that the knock-down filter assembly 10 will ordinarily be configured so as to be open at one end 20 and closed at the other end 22. The open end 20 may thus be secured about an in-line fan member, or any other fitting or member with which the filter assembly 10 is required to be used, by any suitable securing means.

The closed end 22 of the filter assembly may itself be formed from the same material as the filter medium 12a, to thus also play a role in filtration, or may be a substantially or entirely non-porous material. With this in mind, it will also be appreciated that, in an embodiment that includes a closed end 22, the end member 24 may simply be stitched 26 to the filter medium 12a by any normal stitching technique and configuration, preferably reinforced in such a manner as to prevent damage to the filter media.

Additionally, the filter assembly 10 can include an upper support panel 28 capable of receiving lines 30 for suspending the filter assembly 10 in a suitable location.

In conclusion, it must be appreciated that there may be other various and modifications to the configurations described herein which are also within the scope of the present invention.

Claims

1. A knock-down filter assembly for removing particulate matter from a gas stream, the filter assembly including a flexible, textile-based, filter medium formed into a generally cylindrical filter body, the filter body having an interior and a longitudinal axis, and being rigidly supported by a generally cylindrical support body within its interior, wherein the support body also includes an interior and is formed from a mesh that is longitudinally rigid but radially flexible, the support body being stiffened radially by at least two radial stiffening rings, the stiffening rings being detachably secured to the support body interior.

2. A filter assembly according to claim 1 , wherein the textile-based filter medium is provided by multiple layers of materials.

3. A filter assembly according to claim 2, wherein the materials include needled felt, woven fabrics or non-woven fabrics.

4. A filter assembly according to claim 3, wherein the materials include a chemical absorption layer such as an activated carbon layer.

5. A filter assembly according to claim 1 , wherein the textile-based filter medium is provided by a porous outer cloth layer plus three layers of filter media.

6. A filter assembly according to claim 5, wherein the porous outer cloth layer is a 100% polyester mesh.

7. A filter assembly according to claim 5 or claim 6, wherein the three layers of filter media are a first outer layer of resin impregnated polyester fibre impregnated with carbon dust, an inner activated carbon needled felt layer, and a second outer layer of resin impregnated polyester fibre impregnated with carbon dust

8. A filter assembly according to any one of claims 1 to 7, wherein the mesh is an extruded plastic mesh in any of square, diamond, rectangular or hexagonal opening configuration.

9. A filter assembly according to claim 8, wherein the mesh has openings in the range of 2 mm to 25 mm.

10. A filter assembly according to any of claims 1 to 9, wherein the stiffening rings are formed in pieces that are able to be detachably secured together to form a complete ring in situ.

11. A filter assembly according to claim 10, wherein the ring pieces include cooperating female and male connecting members at respective ends to permit insertion and locking.

12. A filter assembly according to any one of claims 1 to 9, wherein the stiffening rings are formed in half pieces that are able to be detachably secured together to form a complete ring in situ.

13. A filter assembly according to any one of claims 10 to 12, wherein the ring pieces are of a length such that all pieces are shorter than the length of the filter body.

14. A filter assembly according to any one of claims 1 to 13, including clips secured to the inner wall of the support body, the clips providing the detachable securement of the stiffening rings to the support body interior.

15. A filter assembly according to any one of claims 1 to 14, wherein the filter body has an open end and a closed end.

16. A filter assembly according to claim 1 substantially as herein described in relation to the accompanying drawings.

17. A kit for a knock-down filter assembly for removing particulate matter from a gas stream, the kit including:

^■ at least two stiffening rings for radially stiffening the support body, the stiffening rings being detachably securable to the support body interior.