GB2391493A - Filter assembly with vortex flow generation - Google Patents
Filter assembly with vortex flow generation Download PDFInfo
- Publication number
- GB2391493A GB2391493A GB0217763A GB0217763A GB2391493A GB 2391493 A GB2391493 A GB 2391493A GB 0217763 A GB0217763 A GB 0217763A GB 0217763 A GB0217763 A GB 0217763A GB 2391493 A GB2391493 A GB 2391493A
- Authority
- GB
- United Kingdom
- Prior art keywords
- filter element
- filter
- filter assembly
- annular
- assembly according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 57
- 239000000463 material Substances 0.000 claims abstract description 23
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 239000004677 Nylon Substances 0.000 claims abstract description 5
- 229920001778 nylon Polymers 0.000 claims abstract description 5
- 239000011148 porous material Substances 0.000 claims description 13
- 230000008878 coupling Effects 0.000 claims description 5
- 238000010168 coupling process Methods 0.000 claims description 5
- 238000005859 coupling reaction Methods 0.000 claims description 5
- 230000008901 benefit Effects 0.000 description 8
- 238000011001 backwashing Methods 0.000 description 4
- 239000008233 hard water Substances 0.000 description 4
- 239000003973 paint Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- 229910052791 calcium Inorganic materials 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 235000010216 calcium carbonate Nutrition 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L calcium carbonate Substances [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- QWDJLDTYWNBUKE-UHFFFAOYSA-L magnesium bicarbonate Chemical class [Mg+2].OC([O-])=O.OC([O-])=O QWDJLDTYWNBUKE-UHFFFAOYSA-L 0.000 description 2
- 239000002370 magnesium bicarbonate Substances 0.000 description 2
- 235000014824 magnesium bicarbonate Nutrition 0.000 description 2
- -1 polypropylene Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/02—Filters adapted for location in special places, e.g. pipe-lines, pumps, stop-cocks
- B01D35/04—Plug, tap, or cock filters filtering elements mounted in or on a faucet
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
- B01D29/114—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for inward flow filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
- B01D29/90—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for feeding
- B01D29/906—Special treatment of the feed stream before contacting the filtering element, e.g. cutting
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Filtration Of Liquid (AREA)
Abstract
A filter assembly 1 for filtering limescale from a water supply comprises: a housing 2 defining a cavity 5 having an inlet 11 and an outlet 21; and an annular filter element 8 having an internal space communicating with the outlet 21. The cavity 5 has an annular wall 6 extending around the annular filter element 8 and spaced from the annular filter element to define an annular gap 29 between the wall 6 and the filter element 8. The housing 2 is arranged to generate, when water is supplied under pressure to the inlet 11, flow in a vortex around the annular gap 29. Advantageously the filter assembly 1 provides efficient filtering of limescale without the filtered limescale collecting on the filter element 8, because the vortex entrains the limescale particulates. Preferably the filter material is a sheet of nylon mesh (22, Fig 4) supported by a rigid frame (23, Fig 4). The filter assembly 1 may be coupled to domestic water pipes feeding an electric shower unit.
Description
2391 493
-1 Limescale Filter The present invention relates to a filter assembly for filtering limescale from a water supply.
5 The precipitation of limescale from a hard water supply is a significant problem. Hard water is formed when rain water dissolves calcium and magnesium salts as it percolates through limestone or similar rocks before processing for consumer use. Many domestic water supplies around the world are hard. For example, six of the major water supply companies in England are noted as suppliers 10 of hard water and between them they provide the majority of drinking water in England. When hard water is heated, this causes the dissolved calcium and magnesium bicarbonates to precipitate to form a solid carbonate limescale. The particulate limescale is deposited as a hard grey deposit. Whilst the deposits are harmless to health, they can cause significant problems.
15 Limescale deposits can block equipment such as domestic electric showers.
Limescale deposits can reduce the efficiency of water heaters by providing insulation between the heater and the water. Also, limescale deposits on household surfaces such as sinks, baths or shower cubicles are unsightly.
Various techniques for combatting limescale are known, but are not 20 altogether satisfactory. Chemical water softeners which soften the water chemically by replacing or substituting the dissolved calcium and magnesium bicarbonates are known, but are expensive to install and maintain.
There have been proposed assemblies for filtering the limescale, for example associated with a shower. However, such filter assemblies tend to suffer from 25 various ones of the problems of: ineffective removal of the limescale; reducing the pressure of the water supply; limescale collecting on the filter element which in turn causes reduction in the water pressure and ultimately blockage; or being difficult and/or expensive to manufacture.
According to the present invention, there is provided a filter assembly for 30 filtering limescale from a water supply, the filter assembly comprising: a housing
-2 defining a cavity having an inlet and an outlet; and an annular filter element disposed within the cavity and having an internal bore communicating with the outlet, wherein the cavity has an annular wall extending around the annular filter element and spaced] from the annular filter element to define an annular gap between the wall and the 5 filter element, the housing being arranged to generate, when water is supplied under pressure to the inlet, flow in a vortex around the annular gap. ' The filter assembly in accordance with the present invention provides the advantages of providing effective removal of limescale particulates from the water supplied to the inlet, without the filter element receiving significant deposits of 10 limescale which would otherwise cause blockage and increase the water pressure i drop through the filter assembly over time. Instead, the filter limescale particulates collect as a deposit in the bottom of the cavity. Thus the filter element does not need [ to be periodically replaced. The deposited limescale may be removed by periodic back washing, for example by reverse fitting the filter assembly.
15 It is thought that the reason why the limescale particulates do not collect on: the filter element is that the generation of a vortex flowing around the annular gap between the annular wall of the cavity and the annular filter element entrains the limescale particulates in the vortex flow whilst the water is being supplied under pressure. Subsequently, when the water supply is terminated, the limescale 20 particulates drop into the bottom of the cavity where they collect.
These advantages may be achieved with a minimal reduction in the flow rate: between the inlet and the outlet. Indeed, in some test situations, it has been found that the flow from the outlet is smoother, presumably because of the vortex acts to: smooth any turbulence in the flow at the inlet. Also, these advantages may be 25 achieved with a filter assembly which is cheap and easy to construct.
Preferably, the filter element has pores of area at least 2500 imp and at most 25000 gm2. Such a pore size has been found to provide effective removal of limescale in combination with the generation of vortex.
Preferably, the annular filter element is coupled at one end around the outlet, 30 from which end the annular filter element extends part way across the cavity to leave
-3 a portion of the cavity beyond the opposite end of the annular filter element, the inlet opening into said portion of the cavity.
The inlet opening into a portion of the cavity beyond the end of the annular filter element provides the advantage of improving the filtering efficiency. It is 5 thought that this is because the portion of the cavity beyond the end of the annular filter element provides a space to receive the water flow from the inlet and allow the vortex to be properly established. Furthermore, this portion of the cavity allows the high pressure of the water flow from the inlet to reduce before the water reaches the filter element. The reduction in water pressure means there is less force pushing the 10 limescale particulates through the filter element, which increases the filtering efficiency. Advantageously, the inlet is formed in a wall on the side of the cavity relative to the direction in which the annular filter element extends from the outlet. This location for the inlet enhances the advantages of the inlet opening into the portion of 15 the cavity beyond the end of the filter element, as just described, because the water flow from the inlet does not impinge directly on the water filter. Thus the limescale particulates are not forced through the filter element by the high pressure flow from the inlet.
Similar advantages can be achieved with other arrangements where the inlet 20 is arranged to prevent the water flow from the inlet from impinging indirectly onto the filter element.
Advantageously, the annular filter element and the annular wall are both cylindrical with a uniform, circular cross-section perpendicular to the cylindrical axis, because this best promotes the generation of the desired vortex. However, other 25 shapes for the annular filter element and the internal annular wall are equally possible. Preferably, the filter element comprises at least one sheet of filter material, for example a mesh. By providing the filter material as a sheet, it is relatively thin, which reduces the negative effect of the filter element on the flow rate through the 30 filter assembly.
Preferably, the at least one sheet of filter material is flexible, for example by being nylon, and supported by a rigid fra''ne.
It has been found that a particularly suitable filter element is an element of the] type known for use as a strainer in a paint spray gun. In this use, the filter element 5 strains particulates from the paint. However, the particulates collect on the filter element which must be removed for cleaning or replacement. Also, no vortex is! generated because of the arrangement of the filter assembly and the relatively high viscosity of paint as compared to water.
Advantageously, the inlet and outlet have external fittings of a standard size 10 for coupling in a domestic water system. i This allows the filter assembly to be easily fitted into a domestic water system. For example, the fittings may be screw fittings of a standard size for the [ hose and the outlet of a domestic electric shower. This allows the filter assembly to be close coupled between the domestic shower unit and the hose to filter the heated 15 water supplied by the shower unit before it passes through a shower head on the end of the hose. Alternatively, the fittings may be of a standard size for coupling to domestic water pipes to allow use of the filter in pipework of a domestic water system. To allow better understanding, an embodiment of the present invention will 20 now be described by way of non-limitative example, with reference to the accompanying drawings, in which: Fig. 1 is a side view of a filter assembly with the internal structure being shown in dotted outline;: Fig. 2 is a plan view of the filter assembly with the internal construction 25 being sown in dotted outline; Fig. 3 is an end view of the water assembly taken from the end on the left hand side of Figs. 1 and 2 with the internal construction shown in dotted outline; Fig. 4 is a perspective view of a cylindrical filter element used in the filter assembly; 30Fig. 5 is a side view ofthe filter element;
-5 Fig. 6 is a cross-sectional view of the filter element, the crosssection being taken along line VI-VI in Fig. S.; and Fig. 7 is a crosssection view of the filter assembly coupled to an intermediate member, the cross-section being taken in a plane extending along the cylindrical axis 5 of the filter element.
A filter assembly I which is an embodiment of the present invention is illustrated in Figs. 1 to 3 in which the internal construction of the filter assembly 1 is shown in dotted outline.
The filter assembly I has a housing 2 comprising a cylindrical body 3 and an 10 end cap 4 which together define an internal cavity 5. The cylindrical body 3 has a cylindrical wall 6 closed at one end, on the right hand side in Figs. 1 and 2, by an end wall 7. At the other end of the cylindrical wall 6, on the left hand side of Figs. 1 and 2, the cavity 5 is closed by the end cap 4.
The cylindrical body 3 of the housing 2 has a neck portion 9 extending 15 radially outwardly from the cylindrical side wall 6. The neck portion 9 has an internal bore 10 which opens into the cavity 5 to define an inlet 11 for the cavity 5.
A collar 12 extends around the neck portion 9. The collar 12 is retained by an outwardly protruding flange 13 formed on the end of the neck portion 9 engaging with a corresponding ledge 14 formed in an internal bore 15 in the collar 12. The 20 bore 15 is formed with an internal screw thread 16 at its external end beyond the end of the neck portion 9. The collar 12 is freely rotatable around the neck portion 9 to connect the screw thread 16 to a corresponding external screw thread on a further pipe (not shown). The bore 15 and screw thread 16 are of a standard size to be coupled to the outlet of a domestic electric shower.
25 The end cap 4 is formed with an outwardly protruding extension 18 having an external screw thread 19. The extension 18 and the screw thread 19 are of a standard size for coupling to the female collar of a hose (not shown) of a domestic electric shower. The end cap 4 has an internal bore 31 extending through the extension 18 and 30 through a pipe 21 protruding from the end cap 4 into the cavity 5. The bore 31 open
-6 into the cavity 5 to define an outlet 21 for the cavity 5.
All the parts of the housing 2 described above are constructed of acrylonitrile butalienne styrene (ABS), although any other suitable material may be used. I Disposed within the cavity 5 is an annular filter element 8 which is illustrated 5 in isolation in Figs. 4 to 6.
The filter element 8 is cylindrical and comprises four sheets 22 of flexible filter material forming respective portions around the circumference of the cylindrical shape of the filter element 8 by a frame 23. The frame 23 comprises an open, annular end piece 24 at one end of the cylindrical filter element and a closed annular end 10 piece 25 at the opposite end of the cylindrical filter element 8. The closed end piece i 25 is closed by a planar sheet 26 of filter material extending across the annular end piece 25 supported by struts 27 protruding radially inwardly from the closed Granular end piece 25. Alternatively, the closed end piece 25 could be solid without any filter material. Between the end pieces 24 and 25, the filter element 8 has struts 28 15 extending parallel to the cylindrical axis of the filter element 8. The respective sheets 22 of filter material are held between the struts 28 and between the end pieces 25.
The sheet 22 and 26 of filter material has pores which are sized to filter limescale from water flowing through the filter element. Preferably, the area of the pores is at least 2500 1lm2 or more preferably at least 5000 1lm2. Preferably, the area 20 of the pores is at most 25000 imp or more preferably at most 20000,um2 orl 5000 imp. Most preferably, the area of the pores is 10000 imp 2000 rums. Such pore sizes have been found to provide effective removal of limescale when the filter element 8 is used in a vortex, as in the present invention.
Preferably, the filter material of the sheet 22, 26 is nylon, but any other 25 suitable material may be used. The preferred form of filter material is a mesh of filaments, for example a nylon 6.6 monofilament weave having the following specification:
Pore Size: 100 micron Thread diameter: 75 micron 30 Variation of pore size: Woven to din 4197 with 10% tolerance on pore size
Open area: 33% Pore shape: Square Aperture per cm: 56 Aperture per SO cm: 3,136 S The material of the frame 23 is preferably polypropylene, but again any other suitable material may be used. The Darne 23 is formed by moulding, the sheets 22, 26 of filter material being moulded into the material of the frame 23.
The filter element 8 may be of the type used as a strainer in a paint spray gun.
The filter element 8 is coupled to the end cap 4 of the housing 2 by an I O intermediate member 30 preferably formed of polyethylene although any other suitable material may be used. The intermediate member 30 comprises a circular disc 32 having a central aperture 33 sized to have an interference fit around the pipe 21 protruding from the end gap 4. Around the periphery ofthe disc 32, the member 30 has an annular lip 34 sized to have an interference fit around the open end piece 15 24 of the filter element 8. By fitting the filter element 8 inside the lip 34 and the pipe 21 inside the aperture 33, the cylindrical filter element 8 is coupled, at one end, around the outlet 21, via the intermediate member 30. Thus, the outlet 21 communicates with the space inside the cylindrical filter element 8.
The cylindrical filter element 8 is held coaxially with the cylindrical wall 6 of 20 the cavity 5. The relative sizes of the cylindrical filter element 8 and the portion of the internal cylindrical wall 6 extending around the filter element 8 are chosen to define an annular gap 29 therebetween. Both the filter element 8 and the portion of the cylindrical wall 6 around the filter element 8 have a unifonn, circular cross section perpendicular to the cylindrical axis.
25 The cavity 5 is longer than the filter element 8 which therefore extends only part way across the cavity 5, leaving a portion 30 of the cavity 5 beyond the closed end piece 25 of the cylindrical filter element 8. The inlet 11 opens into this portion 30 of the cavity 5 beyond the closed end piece 25 of the filter element 8.
The filter assembly 1 is used as follows.
30 The filter assembly 1 is intended to be closed coupled between a domestic
-8 electric shower (not shown) and its hose (not shown). The collar 12 is used as a fitting to couple the filter assembly I to the outlet of the shower unit. As the outlet of the shower unit is usually formed on the underside of the shower unit, the filter assembly 1 is used in the orientation shown in Figs. 1 and 3. The hose of the shower 5 unit is coupled to the extension 18.
When the shower unit is switched on, water is supplied under pressure through the inlet 11. A domestic electric shower unit supplies water at substantially the pressure of the domestic supply, although perhaps with a small pressure drop.
The water pressure forces the water through the filter assembly 1 and hence through 10 the shower hose to a shower head which may then be used in the normal manner.
The internal shape of the cavity 5, and in particular the cylindrical shape of the cylindrical wall 6, under the pressure of water supplied through the inlet 11, generates a flow between the inlet 11 and the outlet 2t in a vortex around the outlet 21. Hence the flow of the vortex is also around the annular gap 29. Such a flow in a 15 vortex is generated merely by the combination of the pressure of water supplied through the inlet 21 and the shape of the cavity 5. Optionally, the cavity 5 may additionally be provided with fins or other formations to promote the generation of the vortex.
As the water flows through the filter assembly, the filter element 8 filters out 20 limescale particulates. However, the filter element 8 does not receive significant deposits of limescale which would otherwise cause blockage and increase the water pressure drop through the filter assembly 1 over time. Instead, the filtered limescale collects as a deposit in the bottom of the cavity, that is in the lowermost portion of the cavity 5 in Fig. 1.
25 The reason why the limescale particulates do not collect on the filter element 8 is thought to be that the generated vortex entrains the filtered limescale particulates in the annular gap 29 around the filter element 8 whilst water is supplied under pressure. The vortex does not allow the limescale particulates to settle on the filter element 8. Subsequently, when the water pressure is removed by the shower unit 30 being switched off, the limescale particulates simply fall under gravity to the bottom
-9- of the cavity 5 (the lowermost portion of the cavity in Figs. I and 3) , where they collect as a deposit. As the limescale collects predominantly at the bottom of the cavity 5, it does not cause blockage of the filter element 8 which would increase the pressure drop through the filter assembly 1 over time. Thus the filter element 8 does 5 not need to be periodically replaced. The limescale deposited at the bottom of the cavity 5 may be removed by backwashing the filter assembly 1, for example by reverse fitting it to the shower unit. Under normal usage, such backwashing typically needs to be performed every six months.
The cylindrical body 3 and the end cap 4 are manufactured as separate parts 10 to allow fitting ofthe filter element 8 inside the cavity 5, but the cylindrical body 3 and the end cap 4 are sealed together during manufacture so that the filter assembly 1 cannot be dismantled, because the filter assembly I does not need to be replaced or serviced. Furthermore, the filter assembly 1 provides a minimal reduction in flow rate l 5 between the inlet 11 and the outlet 21. In some test situations, it has been found that the flow from the outlet 21 is smoother than the flow at the inlet 1 1, presumably because the vortex smooths turbulence in the flow.
Significantly, the filter assembly 1 is also cheap and easy to manufacture.
It will be noted that the inlet 1 1 opens into the portion 30 of the cavity 5 20 beyond the end piece 25 of the filter element 8. Furthermore, as the inlet 11 is formed in the cylindrical wall 6 which is on the side of the cavity 5 relative to the cylindrical axis of the cylindrical filter element 8 along which the filter element 8 extends from the outlet 21, the water flow from the inlet 11 does not impinge directly onto the filter element 8. These two features have been found to improve the 25 filtering efficiency of the filter assembly I. It is thought that this advantage is achieved because the portion 30 of the cavity 5, being wider than the inlet 11, allows the water pressure at the inlet 11 to drop before the flow reaches the filter element 8.
This allows the vortex to be properly generated, without the relatively high pressure flow from the inlet 11 forcing limescale particulates through the filter element 8. It is 30 anticipated that the same advantages could be achieved with other arrangements
-10 where the inlet is arranged to prevent water flow from the inlet from impinging directly onto the filter element.
In the filter assembly 1, the filter element 8 is around 4cm in length and 2.5cm in diameter and the annular gap 29 is around 0.5cm in diameter. However, the 5 exact dimensions of the cavity 5 and the filter element 8 are not critical and may be varied. In practice, the minimum size of the annular gap 29 is selected to provide sufficient space that the deposit deposited at the bottom of the cavity 5 does not block the flow in a vortex around the annular gap 29. The smaller the annular gap 29, the more frequently the filter assembly 1 needs backwashing to remove the 10 deposit. The diameter of the cylindrical wall 6 must be sufficiently small for the cavity 5 to generate a vortex for a desired range of water pressures at the inlet 11.
Typically the filter assembly 1 is designed to generate a vortex at the expected pressure of a domestic water supply, for example at pressures of at least 0.5 bar and/or less than 10 bar.
15 The formation of a vortex may be easily tested by arranging a filter unit 8 in a transparent tube, for example glass, which has the generation of a vortex to be observed. In practice, there has been found to be considerable leeway in the size of the cavity 5. The filter assembly 1 has been tested at inlet water pressures between 0.4 bar and 10 bar and has in all cases generated the necessary vortex.
20 Various modifications to the filter assembly 1 will be apparent, for example as follows.
While the cylindrical shape for the filter element 8 and the portion of the cylindrical wall 6 around the filter element 8 are preferred to be cylindrical, various other shapes are possible, provided that an annular gap is provided therebetween to 25 accommodate the vortex flow. For example, either or both of the filter element 8 or the internal wall 6 may be varied to have a cross-section perpendicular to the cylindrical axis which is not circular and/or which is not uniform Alternatively, the annular gap 29 may have a different annular shape instead of being cylindrical.
30 Similarly, the nature of the filter material of the filter element may be varied
- t 1 provided the required pore size is maintained.
The portion 30 of the cavity 5 beyond the filter element 8 need not have the same shape as portion of the cavity in which the filter element 8 is located.
Another possible variation is to replace the collar 12 and the extension 18 by S other external fittings of a standard size for coupling in a domestic water system. For example, instead of providing fittings with screw threads, the fittings may be of a standard size to be coupled to pipework. In this case the filter assembly I may be used at other locations in a domestic water system.
Claims (19)
- -12 ClaimsI. A filter assembly for filtering limescale from a water supply, the filter assembly comprising: 5 a housing defining a cavity having an inlet and an outlet; and an annular filter element disposed within the cavity and having an internal space communicating with the outlet, wherein the cavity has an armular wall extending around the annular filter element and spaced from the annular filter element to define an annular gap between 10 the wall and the filter element, the housing being arranged to generate, when water is supplied under pressure to the inlet, flow in a vortex around the annular gap.
- 2. A filter assembly according to claim 1, wherein the filter element has pores of area at least 2500 1lm2 and at most 25000 1lm2.
- 3. A filter assembly according to claim 1 or 2, wherein the annular filter element is coupled at one end around the outlet, from which end the annular filter element extends part way across the cavity to leave a portion of the cavity beyond the opposite end of the annular filter element, the inlet opening into said portion of the 20 cavity.
- 4. A filter assembly according to claim 3, wherein the inlet is formed in a wall on the side of the cavity relative to the direction in which the annular filter element extends from the outlet.
- 5. A filter assembly according to any one of the preceding claims, wherein the inlet is arranged to prevent the water flow from the inlet from impinging directly onto the filter element.30
- 6. A filter assembly according to any one of the preceding claims, wherein the- 1 3 annular filter element is cylindncal.
- 7. A filter assembly according to claim 6, wherein the filter element has a circular cross-section perpendicular to the cylindrical axis.
- 8. A filter assembly according to claim 6 or 7, wherein the filter element has a uniform cross-section perpendicular to the cylindrical axis.
- 9. A filter assembly according to any one of the preceding claims, wherein the
- 10 annular wall is cylindrical.l O. A filter assembly according to claim 9, wherein the annular wall has a circular internal cross-section perpendicular to the cylindrical axis.15
- 1 1. A filter assembly according to claim 9 or 10, wherein the annular wall has a uniform, internal cross-section perpendicular to the cylindrical axis.
- 12. A filter assembly according to any one of the preceding claims, wherein the filter element comprises at least one sheet of filter material.
- 13. A filter assembly according to claim 12, wherein the at least one sheet of filter material is a mesh.
- 14. A filter assembly according to claim 12 or 13, wherein the at least one sheet 25 of filter material is flexible and supported by a rigid frame.
- 15. A filter assembly according to any one of claims 12 to 14, wherein the filter material is nylon.30
- 16. A filter assembly according to any one of the preceding claims, wherein the-14 in1et and outlet have external fittings of a standard size for coupling in a domestic water system.
- 17. A filter assembly according to any one of the preceding claims, wherein the 5 filter element is coupled to the housing by an intermediate member.
- 18. A filter assembly according to claim 17, wherein the intermediate member has an interference fit with the filter element and has an interference fit with the housing.
- 19. A filter assembly for filtering limescale from a water supply, the filter assembly being constructed and arranged to operate substantially as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0217763A GB2391493A (en) | 2002-07-31 | 2002-07-31 | Filter assembly with vortex flow generation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0217763A GB2391493A (en) | 2002-07-31 | 2002-07-31 | Filter assembly with vortex flow generation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0217763D0 GB0217763D0 (en) | 2002-09-11 |
| GB2391493A true GB2391493A (en) | 2004-02-11 |
Family
ID=9941468
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0217763A Withdrawn GB2391493A (en) | 2002-07-31 | 2002-07-31 | Filter assembly with vortex flow generation |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2391493A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2507728A (en) * | 2012-11-02 | 2014-05-14 | Rigdeluge Global Ltd | A trap for collecting debris |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4597871A (en) * | 1979-05-25 | 1986-07-01 | Hitachi, Ltd. | Apparatus for removing foreign matters |
| US6125826A (en) * | 1997-12-18 | 2000-10-03 | Societe Nationale D'etude Et De Construction De Moteurs D'aviation | Self-washing device for separating and filtering solid particles from a flow of liquid, and use of the device in a fuel injection circuit |
-
2002
- 2002-07-31 GB GB0217763A patent/GB2391493A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4597871A (en) * | 1979-05-25 | 1986-07-01 | Hitachi, Ltd. | Apparatus for removing foreign matters |
| US6125826A (en) * | 1997-12-18 | 2000-10-03 | Societe Nationale D'etude Et De Construction De Moteurs D'aviation | Self-washing device for separating and filtering solid particles from a flow of liquid, and use of the device in a fuel injection circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2507728A (en) * | 2012-11-02 | 2014-05-14 | Rigdeluge Global Ltd | A trap for collecting debris |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0217763D0 (en) | 2002-09-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |