GB2185695A

GB2185695A - Filter element

Info

Publication number: GB2185695A
Application number: GB08701620A
Authority: GB
Inventors: Roger John Temple
Original assignee: FLOWTECH FLUID HANDLING LIMITE
Current assignee: FLOWTECH FLUID HANDLING LIMITE
Priority date: 1986-01-28
Filing date: 1987-01-26
Publication date: 1987-07-29
Also published as: GB8701620D0; GB2185695B; GB8601965D0

Abstract

A filter element of hollow disc form comprises filter discs (2) joined by an edge seal (5) with a spacer element (6) held in fixed position between them by connection of its outer periphery to the edge seal. The seal may be polypropylene, moulded on to discs (2) and element (6). Element (6) is also polypropylene, comprises radial ribs connected by concentric rings (10) and a flat outer ring (11). In other constructions the outer ring has tabs, or the ribs extend beyond the outer ring, said tabs or ribs being incorporated in the edge seal (5). <IMAGE>

Description

SPECIFICATION Filter cell The invention relates to a filter cell.

Known filter cells comprise a pair of sheet-likefilter elements for example of square or circular shape, sealingly connected together at their outer edges, with a separator or spacer element enclosed between them.

The sheet material of the filter elements is typically made from a slurry of cellulosic fibre, and the separator or spacer element can be moulded of a suitable plastics material. The spacer element has a central aperture which co-operates with central apertures provided in the filter elements to form a discharge passage. In use, the cell is received within a filter housing, either on its own or in a plurality of the cells assembled together into a vertical stackto make a filter cartridge. The fluid to be filtered passes from the outside of the or each cell through the filter elements, and the filtrate is discharged through a fluid discharge tube communicating with the discharge passage of the cell or cells. Contaminants are deposited on the outside of the filter elements.

In the known filter cells ofthis kind, the spacer element does not extend radially outwardly as far as the rim connection of the filter element, so that it is free to move within the cell to a certain extent. This freedom of the spacer element to move within the cell is unsatisfactory for packaging purposes and tends to give an unfavourable impression of the product. It is another disadvantage of such cells that they are not structurally very strong after use, when the filter elements are saturated with liquid and often distorted by pressure differences between the exterior and interior of the cell. Removal of a cell or cartridge from the filter housing for replacement by a fresh cell or cartridge can consequently be difficult and objectionable, because the filter elements tend to come away from the edge seal during handling.

The present invention is concerned with provision of afiltercell, and of a cartridge made up of a plurality of such cells, in which these disadvantages are over come.

The invention accordingly provides a filter cell comprising two sheet-like filter elements and a spacer element received between them, the spacer element being secured against movement within the cell. The elements may be connected together by a seal at their outer edges, and the spacer element held in place by securement to the edge seal. The spacer element is consequently held in a fixed position in the filter cell and moreover provides a support structure internally of the cell, so that the cell holds together when being handled by the peripheral seal connection, even though the filter elements may be saturated with liquid and weakened by distortion.

The spacer element conveniently has a pattern of ribs for spacing apart the innerfaces of the two filter elements of the cell, and in accordance with the invention, it has also an outer peripheral securement portion, or a plurality of peripheral spaced outer securement portions, for reception between the connected outer edges of the filter elements. The spacer element can be a moulded plastics disc, for example of polypropylene, with the securement portion or portions integrally formed.

The rim connection by which the filter elements are connected together at their outer edges can take any form which ensures an adequate seal and which has no disadvantageous effect on the filtering function. Preferably, the elements are formed with compressed flange portions which are brought into registration with the spacer element securement portions, in a mould in which an edge seal of plastics material, for example polypropylene, is formed. The spacer element securement portion or portions can be contacted by the edge seal material and may extend beyond the filter elements into the body of the seal.

The invention is further described below, byway of illustration, with reference to the accompanying drawing, in which: Figure 1 is a partial cross-sectional side view of a filter cell embodying the invention; Figure 2 is a fragmentary plan view of a spacer element included in the cell of Figure 1; Figure 3 shows a portion of Figure 1 on a larger scale; and Figures 4and 5are fragmentary plan views offirst and second modified forms of the spacer element respectively.

The filter cell shown in Figure 1 comprises two like filter elements in the form of annularfilter discs 2.

Th#e material of the filter discs 2 can be of any appropriate kind, for example, the discs can be made from a slurry of cellulosicfibre in which particulate filter material can be included. The filter discs 2 have compressed flange portions 4 at their outer peripheral edges, at which the sheets are sealingly connected. This peripheral connection is effected by means of an edge seal 5 of plastics material, preferably polypropylene, which is moulded onto the compressed flange portions to hold them sealinglytogether.

Trapped between the two filter discs 2 is a spacer element 6 of generally annularform, with a central aperture corresponding to the central apertures 7 of the two filter discs. The spacer element is integrally moulded of suitable plastics material, for example, polypropylene, and comprises a plurality of radially extending ribs 9 connected together by spaced flat concentric connecting rings 10. The spacer element 6 prevents the inner faces of the filter discs 2 from being forced together into contact in use of the cell, by excess external pressure, to avoid reduction of the effective filtering area.

To locate the spacer element 6 securely within the filter cell,the radial ribs 9 are connected attheir outer ends by a flat outermost connector ring 11 which extends radially outwardly beyond the ribs, and is received between the flange portions 4 of the filter discs 2. The connector ring 11 or at least that part of it received between the filter discs can be quite thin, for example it may beabouttwentythousandths of an inch in thickness. Preferably, the outer diameter of the connector ring 11 equals or approximates to that of the filter discs 2, but it may exceed it, so that the connector ring is received in the seal edge Swhen this is moulded around the edges ofthefiltersheets as better appears from the larger scale of Figure 3.

In this way, the spacer element 6 is very securely connected in place within the cell.

Instead of an outermost connector ring 11 of uniform radial width, as shown in Figure 4,there may be provided a ring 12 having peripherally spaced radially outwardly projecting tabs 14,which tabs only are received between the flange portions of the filter discs.

In a further modified form ofspacerelement shown in Figure 5, the radially directed ribs 9 extend beyond the outermost connecting ring 10 and some or all have outwardly protruding portions 15 of reduced thickness, which may again be ofthe order oftwentythousandths of an inch, which are received between the filter discflange portions.

Where a cell according to the present invention is stacked with other cells in a filter cartridge, separator elements as described in Application 8601 966, the contents of which are incorporated herein by reference are advantageously employed between each adjacent pair of cells.

Claims

1. Afilter cell comprising two sheet-like filter elements and a spacer element received between them,the spacer element being secured against movement within the cell.

2. Afiltercell as claimed in claim 1 wherein the spacer and filter elements have aligned central apertures.

3. Afiltercell as claimed in claim 1 or 2 wherein the spacer element is secured between thefilter elements at their outer peripheries.

4. Afiltercell comprising two sheet-like filter elements each provided with a central aperture, the filter elements being connected together atthe outer peripheries thereof, and a centrally apertured spacer element received between the filter elements, the spacer element being secured to the filter elements at the peripheral connection.

5. Afiltercell as claimed in claim 3 or 4wherein the spacer element has an outer ring portion received between the peripheries of the filter elements.

6. Afiltercell as claimed in claim 3 or 4wherein the spacer element has an outer ring with outwardly protruding tab portions received between the filter elements.

7. Afilter cell as claimed in claim 3 or 4wherein the spacer element has radial ribs with free end portions received between the filter elements.

8. Afiltercell as claimed in any one of claims 3 to 7 wherein the peripheral connection is made by means of a moulded plastics seal.

9. Afiltercell as claimed inclaim8whereinthe spacer element outer periphery is received within the moulded plastics seal.

10. Afiltercell as claimed in any one of ciaims 3 to 9 wherein the spacer element portion or portions received between the filter elements is of lesser thickness than the remainder of the spacer element.

11. Afilter cell substantially as herein described with reference to Figures 1-3, Figure 4 or Figure 5 of the accompanying drawing.

12. Afilter cartridge comprising a stack filter cells each as claimed in any preceding claim.