GB2238256A

GB2238256A - Water filter

Info

Publication number: GB2238256A
Application number: GB9025637A
Authority: GB
Inventors: Philip James Kempton
Original assignee: SPRING FLEAU WATER FILTERS LIM
Current assignee: SPRING FLEAU WATER FILTERS LIM
Priority date: 1989-11-25
Filing date: 1990-11-26
Publication date: 1991-05-29
Also published as: GB9025637D0

Abstract

A domestic water filter comprises an inward flow, tubular filter element 18 permanently enclosed in a tubular housing having an inlet 22 at one end and an outlet 26 at the other. The filter element comprises several layers, including active carbon, and end caps 36 with tubular extension 38 sealingly located in corresponding extensions 30 on the ends 14, 16 of the housing. The housing body 12 and ends 14, 16 are of ABS plastics, ultrasonically welded together. <IMAGE>

Description

Fluid Filtration The present invention relates to fluid filtration, and in particular but not exclusively to filtration of domestic drinking water.

Various apparatus has previously been proposed for attachment in the drinking water supply of domestic premises, to continuously filter water just before delivery to the user. In one proposal, an elongate canister is packed with filter medium and connected in-line with the water supply pipes. Water which passes into one end of the canister must pass through the filter medium as it travels along the canister to reach the other end, where it leaves the canister. The cross-section of the canister is only slightly larger than the cross-section of the pipe, so that a long canister is required in order to achieve adequate filtration. This results in a device which is vulnerable to clogging by virtue of the small cross-section of filter medium through which the water must pass.

An alternative arrangement uses a container having a cover and a detachable base. The cover is attached beneath a horizontal run of water pipe at a point in which the pipe has been broken to divert the supply into the container below. Water is drawn from the container through an outlet which is protected by a filter medium, to ensure that all water has been filtered before leaving the container. When the filter medium has reached the end of its useful life (often determined by the growth of bacteria in the filter medium), the container is opened by releasing the base from the lid, to allow the base to be lowered for removal of the filter element. After a new element has been installed, the container is again closed. This apparatus has been found unduly bulky for some applications, and normally requires installation in a horizontal pipe run in order to be fully effective.

It is an object of the present invention to obviate or mitigate these or other disadvantages of the prior art.

According to the invention there is provided fluid filtration apparatus comprising a housing and a filter element within the housing, there being a first chamber around the filter element and in communication with the inlet or outlet, and a second chamber within the filter element and which communicates with the outlet or inlet respectively, the filter element comprising a filter medium through which fluid must pass to move between the first and second chambers, wherein the housing has a first face through which the inlet is provided, and a second face through which the outlet is provided, the first and second faces being generally oppositely directed, whereby fluid enters the inlet and leaves the outlet in generally the same direction.

Preferably the filter element is elongate, and the second chamber is a passage within the filter element, the filter medium forming all or part of the passage walls. The filter element is preferably cylindrical.

The passage may be axial.

The filter element is preferably detachably attached to at least one end face of the housing. The or each detachable attachment is preferably formed by a tubular extension of the passage, and a tubular projection on the housing end face, the extension and projection being fittable one inside the other to locate the filter element in relation to the end face. The or each tubular extension may form part of an end cap attached to the filter element. The apparatus may further comprise sealing means between the projection and extension, to provide a seal between the passage and the chamber.

The filter element is preferably detachably attached as aforesaid to both housing end faces, one housing end face having an aperture within the tubular projection to provide an inlet or outlet in communication with the passage, and the other housing end face having an aperture outside the tubular projection to provide an inlet or outlet in communication with the first chamber.

Preferably the housing end faces are formed by caps which are sealingly fitted to respective ends of an elongate hollow member. The caps are preferably permanently sealed to the elongate hollow member. The elongate hollow member is preferably a length of pipe.

The housing and/or filter element is preferably circular in cross-section perpendicular to the direction in which fluid enters and leaves the housing.

The invention also provides an elongate filter element for use in apparatus as aforesaid, and comprising a filter medium, a chamber within the filter medium, whereby fluid may pass transversely through the filter medium between the region surrounding the element and the chamber, and mounting means at both ends of the element for mounting the element for use, the mounting means allowing communication, in use, with the said chamber.

Preferably the said chamber is a passage within the filter element, the filter medium forming all or part of the passage walls. The filter element may be cylindrical. The passage may be axial. The mounting means each preferably comprise a tubular extension of the passage, which may fit inside or around a tubular projection on a member on which the element is to be mounted. The tubular extension means preferably comprises seal means operable to co-operate with a projection as aforesaid to provide a seal between the passage and the region surrounding the extension.

The tubular extensions may form part of end caps located at either end of the filter element. The filter element is preferably circular in cross-section.

One embodiment of apparatus according to the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawing which is a schematic section through the apparatus.

The fluid filtration apparatus 10 shown in the drawing comprises a housing 12, 14, 16 and a filter element 18 within the housing. There is a first chamber 20 around the filter element 18 and in communication with the inlet 22. A second chamber 24 is within the filter element 18 and communicates with the outlet 26. The filter element 18 comprises a filter medium 28 through which fluid must pass to move from the first chamber 20 to the second chamber 24. The housing has a first end cap 14 through which the inlet 22 is provided, and a second end cap 16 through which the outlet 26 is provided, the caps 14 and 16 facing in generally opposite directions, whereby fluid enters the inlet 22 and leaves the outlet 26 in generally the same direction.

In more detail, the housing comprises a length of circular pipe 12 closed at both ends by the caps 14, 16.

The pipe 12 and the caps 14, 16 are preferably made of ABS plastics material and are sealed, for instance by ultrasonic welding, to form a permanently sealed housing.

The caps 14, 16 are circular. At their centre, they carry a short tubular projection 30 which projects into the interior of the housing. The cap 16 has an aperture 32 to allow communication from the outlet 26 to within the tubular projection 30. No corresponding communication from outside the housing to within the projection 30 on the cap 14 is provided, but an alternative aperture 34 provides communication through the cap 14 from outside the housing to the chamber 20.

The filter element 18 consists of a hollow cylinder of filter medium 28 capped at both ends by end caps 36.

The cylinder is circular in cross-section and is hollowed by a central circular bore forming the chamber 24. The end caps 36 prevent liquid entering or leaving the filter medium 28 except by the internal and external curved surfaces of the medium 28.

Each end cap 36 is disc-like, and has at its centre a tubular projection 38 which forms an extension of the cylindrical chamber 24. The caps 36 are sealed to the end faces of the element 18 to prevent communication with the chamber 24 except through the body of the filter medium 28 or through the extensions 38.

In the assembled device, the extensions 38 are located within the projections 30. One or more sealing strips 40 around the circumference of the extensions 38 ensure that the extensions 38 are a tight, sealing fit in the projections 30. Thus, when assembled as shown, the region within the extension 38 is in communication with the region within the projection 30 at each end of the element 18, but the strips 40 prevent communication between the region within the extension 38 and the region around the projection 30 (part of the first chamber 20).

The filter medium 28 may consist of several different annular layers having different filter characteristics. Granular activated carbon may be used as the principal filter material.

The assembled apparatus is installed by connecting the water supply to the inlet 22 by any suitable means, and by connecting the outlet 26 to pipework carrying the filtered water to the point of delivery, such as a tap.

When the tap is opened, the water supply pressure forces water through the inlet 22 into the first chamber 20, surrounding the element 18. The seals 40 prevent water leaving the chamber 20 except by permeating transversely through the filter medium 28 into the central passage 24.

Having been filtered in this way, water can then pass along the passage 24 into the projection 30 on the cap 16, and thence out through the outlet 26.

It will be apparent from the above that the direction of flow into and out of the apparatus is substantially the same, and is parallel to the cylinder axis of the apparatus. The apparatus can thus be installed in-line with a water pipe, rather than as a large unit fitted beneath the pipe. However, unlike previous in-line filters, the present apparatus does not suffer the shortcoming of providing a small filter surface area, because the whole outer curved surface of the filter element 18 is available, so that the risk of clogging of the filter is reduced. In environments where clogging is particular likely, the overall length of the apparatus can be extended, essentially without limit, to increase the filter surface area sufficiently to avoid clogging, but without the apparatus becoming any more inconvenient to fit.The path length of the liquid through the filter medium is determined by the inner and outer radii of the filter medium, because the liquid travels essentially radially. Thus, the path length through the filter, and the cross-section of the path, are independently variable by changing the radii of the filter medium and the axial length of the medium, respectively.

As has been described, the apparatus is in the form of a permanently sealed unit. This makes replacement of the filter element 18 simple to achieve at the end of its useful life, by replacing the whole unit. Replacing the complete unit has the additional advantage that the user does not handle the filter medium 28, so that there is no risk of a user contacting bacteria in the filter medium being removed, and thereby contaminating the filter medium of the new unit being installed.

In order to comply with water supply regulations, it may be necessary to incorporate a non-return valve at the inlet 22.

Various modifications may be made to the apparatus described above, without departing from the spirit and scope of the present invention. Any appropriate filter medium can be chosen, according to the filtration requirements.

Although the apparatus has been described as having an inlet outside the filter medium cylinder, and an outlet from within, the flow direction could be reversed.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims:

1. Fluid filtration apparatus comprising a housing and a filter element within the housing, there being a first chamber around the filter element and in communication with the inlet or outlet, and a second chamber within the filter element and which communicates with the outlet or inlet respectively, the filter element comprising a filter medium through which fluid must pass to move between the first and second chambers, wherein the housing has a first face through which the inlet is provided, and a second face through which the outlet is provided, the first and second faces being generally oppositely directed, whereby fluid enters the inlet and leaves the outlet in generally the same direction.

2. Apparatus according to claim 1, wherein the filter element is elongate, and the second chamber is a passage within the filter element, the filter medium forming all or part of the passage walls.

3. Apparatus according to claim 2, wherein the filter element incorporates seal means which prevent fluid entering or leaving the filter medium except in a direction generally transverse to the fluid inlet and outlet directions.

4. Apparatus according to claim 2 or 3, wherein the filter element is cylindrical.

5. Apparatus according to claims 2, 3 or 4, wherein the passage is axial.

6. Apparatus according to claims 2, 3, 4 or 5, wherein the housing has end faces generally transverse to the inlet and outlet directions, and the filter element is detachably attached to at least one end face of the housing.

7. Apparatus according to claim 6, wherein the or each detachable attachment is formed by a tubular extension of the passage, and a tubular projection on the housing end face, the extension and projection being fittable one inside the other to locate the filter element in relation to the end face.

8. Apparatuss according to claim 7, wherein the or each tubular extension forms part of an end cap attached to the filter element.

9. Apparatus according to claim 7 or 8, wherein the apparatus comprises sealing means between the projection and extension, to provide a seal between the passage and the chamber.

10. Apparatus according to any of claims 6 to 9, wherein the filter element is detachably attached as aforesaid to both housing end faces, one housing end face having an aperture within the tubular projection to provide an inlet or outlet in communication with the passage, and the other housing end face having an aperture outside the tubular projection to provide an inlet or outlet in communication with the first chamber.

11. Apparatus according to any of claims 6 to 10, wherein the housing end faces are formed by caps which are sealingly fitted to respective ends of an elongate hollow member.

12. Apparatus according to claim 11, wherein the caps are permanently sealed to the elongate hollow member.

13. Apparatus according to claim 11 or 12, wherein the elongate hollow member is a length of pipe.

14. Apparatus according to any preceding claim, wherein the housing and/or filter element is circular in cross-section perpendicular to the direction in which fluid enters and leaves the housing.

15. An elongate filter element for use in apparatus as aforesaid, and comprising a filter medium, a chamber within the filter medium, whereby fluid may pass transversely through the filter medium between the region surrounding the element and the chamber, and mounting means at both ends of the element for mounting the element for use, the mounting means allowing communication, in use, with the said chamber.

16. An element according to claim 15, wherein the said chamber is a passage within the filter element, the filter medium forming all or part of the passage walls.

17. An element according to claim 16, wherein seal means prevent fluid entering or leaving the filter medium except in a direction generally transverse to the passage.

18. An element according to claims 15, 16 or 17, wherein the filter element is cylindrical.

19. An element according to any of claims 16, 17 or 18, wherein the passage is axial.

20. An element according to any of claims 15 to 19, wherein the mounting means each comprise a tubular extension of the passage, which may fit inside or around a tubular projection on a member on which the element is to be mounted.

21. An element according to claim 20, wherein the tubular extension means comprises seal means operable to co-operate with a projection as aforesaid to provide a seal between the passage and the region surrounding the extension.

22. An element according to claim 20 or 21, wherein the tubular extensions form part of end caps located at either end of the filter element.

23. An element according to any of claims 15 to 22, wherein the filter element is circular in cross-section.

24. Fluid filtration apparatus substantially as described above, with reference to the accompanying drawing.

25. An elongate filter element substantially as desribed above, with reference to the accompanying drawing.

26. Any novel subject matter or combination including novel subject matter disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.