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`Digital Access Service
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`WIPO
`WORLD
`INTELLECTUAL PROPERTY
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`CERTIFICATE OF AVAILABILITY OF A CERTIFIED PATENT DOCUMENT INA
`DIGITAL LIBRARY
`
`The International Bureau certifies that a copy of the patent application indicated
`below has been available to the WIPO Digital Access Service since the date of
`availability indicated, and that the patent application has been available to the
`indicated Office(s) as of the date specified following the relevant Office code:
`
`Documentdetails:
`
`Country/Office: SE
`
`Filing date:
`
`O06 Jul 2021 (06.07.2021)
`
`Application number: 21508908
`
`Date of availability of document:
`
`09 Aug 2022 (09.08.2022)
`
`The following Offices can retrieve this document by using the access code:
`AR, AT, AU, BE, BR, CA, CL, CN, CO, DK, EA, EE, EP, ES, Fl, GB,
`GE, IB, IE, IL, IN, JP, KR, LV, MA, MX, NL, NO, NZ, PL, SE, US
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`Date of issue ofthis certificate:
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`03 Oct 2022 (03.10.2022)
`
`34, chemin des Colombettes
`1211 Geneva 20, Switzerland
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`

`Multipass Water Filger
`
`TECHNICAL FIELD
`
`8604] The present invention relates to filters for water. In particular, the present invention relates to
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`portable filter devices for filtering water using multiple passes througha filter.
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`BACKGROUND
`
`(#802) Conventional waterfiltration systems involve passing water through a filter once.
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`improvements in filtration are therefore dependent on the design of said filter and, thas, highly
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`purified water can be complex and costly to achieve.
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`16603] Furthermore, typical water filtration systems distinguish between unfiltered water reservoirs
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`and filtered water reservoirs, whereby water is taken fromthe unfiltered water reservoir and passed
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`through a filter so as to be deposited into the filtered water reservoir.
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`(8004) Common houschold water filter devices use the gravitational pull of water in an upper
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`reservoirto pall it through a through a filter so as to be deposited mto a lower reservoir.
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`[#008] These reservoirs can be particularly configured for integration into such filter devices. That is,
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`the reservoirs form part of the filtration systemsuch that the filter arrangement and/or upper reservoirs
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`can be shaped te complement the shape of the lower reservoir. This can lead to a wasted space in such
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`filter devices, as the upper reservoir is not used for storage of filtered water,
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`16606] Moreover, although the use of gravity to move water through the filter can simplifythe
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`constraction ofa filter device, such systems are slow and thus cannot provide filtered water on larger
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`scales.
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`[8007] Some filtration systems cniploy a pump to recirculate filtered water from the filtered water
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`reservoir back ite the unfiltered water reservoir so as to further purify the water. Typically, only the
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`water in the filtered water reservoir will be made available for consumption. Thos, if the total volume
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`of water is desired for consumption, a user will be required to wait for the water in the unfiltered water
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`reservair to be passed through the filter and inte the filtered water reservoir,
`
`SUMMARYOF THE INVENTION
`
`(8808) The present disclosure provides an improved filter device overcommgs one or more of the
`
`aforementioned problems m cxisting filter devices.
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`{8009} According to a first aspect, there is provided a filter device for filtering water, comprising a
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`housing configured for submersion in a water reservoir, comprising an intake aperture arranged for
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`intake of water from the water reservoir and a return aperture arranged for returning water to the water
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`reservoir. The housing extends along an axis. The filter device further comprises a pump, housed in
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`the housing, arranged on the axis to direct floid from the intake aperture to the return aperture, and a
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`

`

`3
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`filter arrangement, housed in the housing, arranged along the axis from the pump im a flaid path
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`between the intake aperture and the return aperture.
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`10026] According to this aspect, there is provided a quick and ergonomic filter device forfiltering
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`water that has a simple construction. The filter device does not require particular configuration for
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`integration tnfo a specific reservoir, so if can be easily applicd to any water reservoir, such as a
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`household water jug, saucepan, or other such water reservoirs, without modifying the filter device or
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`reservomfer mutual compatibility.
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`{#033) Furthermore, the configuration of the filter device as a nultipass filter device allows forthe
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`filters used in the filter arrangement to have a lesser degree of separation. For example, if the degree of
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`separation/filtration provided by a particular filter is, for example, 50%of contamimants on average,
`
`then it would not Hkely be considered for use in the aforementioned single-pass filter devices.
`
`However, using the presently described multipass filter device, two passes through such a filter would
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`lead to 78%of contaminants removed, then 87.5%after three passes, 93.75% after four passes, and so
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`on. Hence, smaller and/or inexpensive filters may be used, thus further improving the compactness of
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`the filter arrangement and simplifying tts construction.
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`(8032) The housing maybe formed ofa rigid matenal with mechanical longevity, so that a first end
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`ofthe housing may be used for manipulating the filter device (e.g. lifted into a reservoir, removed
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`therefrom, moved therein, directed, ctc.). The shape of the housing may take any form that extends
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`along an axis, such as a cylinder or a prism, such that the length of the housing is defined along the
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`axis, Although some examples may have constant cross-sectional profile, the cross-section of the
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`housing may instead vary along at least some of the length the housing. For example, the housing may
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`taper toward the first end so that a user may more casily grip the first end of the housing. Additionally
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`or alternatively, the housing may be provided with a handle for case of manipulating the filter device.
`
`{6013} In some examples, the housing maybe spherical, spheroidal, or ellipsoidal, ¢.g. extending
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`along a diameter, semi-major axis, or semi-niimor axis,
`
`(#034) The mtake aperture may be one or more apertures (openings, through-holes, perforations, etc.)
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`that allowfor a flow of water therethrough, ic. from an outside of the housing to an inside of the
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`housing. The intake aperture(s) may take any shape but may preferably be large enough to allowfor
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`the pump to operate at full power without being timited by viscous behaviour at the mtake aperture.
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`However, the intake aperture may also be advantageously small enough and/or shaped so as to
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`advantagcously create a directional flow throughthe intake aperiure. For example, a substantially
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`smooth-edged circular aperture having a suitable diameter may create a jet-like flowtherethrough,
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`Thus, an intake aperture maybe arranged and shaped in such a wayas to assist in directing water
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`towards the filter arrangement forfiltration.
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`{GG35] The housing may further comprise one or more spacers extending from a second end, the
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`second end bemg opposed to the first end, wherein the one or more spacers are configured for spacing
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`the intake aperture from a surface of a water reservoir whilst allowimg a passage of water into the
`
`

`

`Led
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`intake aperture. The spacers maytake any form thet provides a spacing between the housing anda
`
`surface of a water reservoir. For example, ifthe intake aperture were disposed on a botiomsurface of
`
`the filter device, the placement of the filter device vertically onto a flat bottom surface of a water
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`reservoir may cause the intake aperture to be obstructed, thus lumiting the water flowinto the filter
`
`device. Thus, the spacers may allow for an increased water flowinto the intake aperture of the
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`housing. In some examples, the spacers may be arranged so as to have a direction and/or low-drag
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`profile for water flowing towards the intake aperture. For exanyple, the spaces maytake the form of
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`fins, splines, ridges, or similar that are radially arranged around the intake aperture so as to direct
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`water towards the intake aperture.
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`jG036] The return aperture maysimilarly be one or more apertures (openings, through-hales,
`
`perforations, ctc.) that allows for a flow of water therethrough, ic, from an inside of the housing to an
`
`outside (c.g. returning water back into a water reservoir). The return aperture(s) may take any shape
`
`but may preferably be large enough not to excessively impede the flow of water. The return
`
`aperture(s} may be shapedor sized so as ta encourage recirculation in a water reservoir. Additionally
`
`or alternatively, the return aperture(s) may be shaped or sized to maxinusc a surface of the filter
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`arrangement that is proximate to a return aperture, thus helping to ensure that filtered wateris not
`
`unnecessarily retained in the filter device.
`
`(627) The housing may further comprise an access aperture for allowing access to internal
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`components of the filter device (c.g. the pump and/or the filter arrangement). The access aperture may
`
`be at the first end or the second end of the filter device, aor somewhere in between, for example taking
`
`the form of a side panel or an entire side wall
`
`[6038] The access aperture is removably sealed by a sealing clement whichselectively allows access
`
`to the access aperture. The sealing cloment may form an entirely waterproof seal or may have the
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`intake aperture and/or return aperture arranged therein. In use, a user may remove the scaling element
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`to open the access aperture and access internal components so that the mternal components may be
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`maintained or replaced.
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`{G839] The filter device may further comprise a sub-housing housed in the housing for containing
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`liquid-sensitive components, Liquid-sensitive components may include clectronics, iquid-solubic
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`components and/or other components that are sensitive to guid.
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`[0028] The sub-housing may preferably be openable for access to components stored therein. In such
`
`cases, the sub-housing may be sealable closed by a waterproof seal. For exnampic, a part of the sub-
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`housing may be comprised of the scaling clement such that the scaling of the housing by the scaling
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`element also seais the sub-housing. Alternatively, the sealing clement may comprise the sub-housing
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`as part of it. For example, the sub-housing may take the form ofa plug, conforming to the size and
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`shape of the access aperture, such that placement of the sub-housing into the access aperture
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`removeable seals the access aperture. When removing the sub-housing from the access aperture, the
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`opening may then be on a side of the sub-housing that was spaced towards an Inside of the housing
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`

`

`4
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`such that the outer-facing portion of the sub-housing forms the sealing element for the housing and can
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`be formed without scams, thus improving the waterproofseal.
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`10021] The pump maybe an ciectric pump or a mechanically powered pump. For example, the pump
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`may comprise an electric motor and an impeller driven bythe electric motor.
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`16622]
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`In some examples, the electric motor may be arranged spaced along the axis of the housing
`
`from the impeller. The electric motor may be powered bya battery housed inside or outside the
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`housing, or by a mains connection. in some examples, the filter may further comprise a power cable
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`for communicating power from outside the housing to internal electronic components of the filter
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`device.
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`HMIZ3] Alternatively, the pump may comprise an impeller (or propeller} mechanically engaging a
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`gearing assemblythat is driven through actuation of the filter device, c.g. against a surface of a water
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`reservolr, Thatis, in some examples, the second end of the filter device may comprise a driving screw
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`and actuation of the filter device may cause the driving screwto rotate and, via the gearmeg assembly,
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`drive the impeller of the pump. A biasing means such as a spring may be provided to return the driving
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`screw to is original extended position. Such a mechanical arrangement may advantagcously reduce
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`the clectricity required to operate the filter device.
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`[8024] The pump may be shaped similarly as the housing, thus optimising the utilisation of space
`
`within the housing and allowing for a more compact device. For example, ane or both of the motor
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`and the impeller may be shaped so as to have a similar cross-section to the housing: ¢.g., ifthe housing
`
`were cylindrical, the motor and/or the impcHer may be shaped so as to alsa be substantially
`
`cylindrical. Furthermore, the pump may be arranged concentrically with the shape of the housing.
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`[6025] Similarly, the filter arrangement may be shaped similarly as the housing, o.g. a cylindrical
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`filter arrangement arranged concentrically with a cylindrical housing. The pump and/orthe housing
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`may alternatively be shaped as a prism, extending along an axis,
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`{O026) The pump may comprise an intake and an outlet, wherein the pumpis configured to take water
`
`in at itslet and eject water from its outlet. The miet may be arranged proximate to the mtake aperture
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`such that water is drawn directly into the inlet of the pump from the intake aperture. Alternatively, the
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`pump infect may be arranged remote from the intake aperture, for example at an opposite end thereto.
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`in this latter arrangement, itis still possible for the pump to generate a flow such that fuid is directed
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`from the intake aperture to the retarn aperture.
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`(8027) The intake and/or outlet of the pump may be configured such that the pump directs fhuid along
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`the axis. The return aperture may then advantagcously be arranged perpendicular to the axis such that,
`
`for example, water exiting the return aperture can encourage greater circulation in the water reservoir.
`
`{#028] The filter arrangement may enclose a space that is in fluid communication with the outlet of
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`the punip, so that the pump directs water into said enclosed space. Water within the enclosed space
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`maythen be filtered through the filter arrangement before it can oxit through the return aperture. In
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`

`

`&2
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`this way, it may be better ensured that more water passes through the filter arrangement as it is
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`circulated throughthe multipass filter device.
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`10029] The filter arrangement may comprise one filter or a plurality of different filters, for example,
`
`each having different filtration characteristics. Examples of filters inchide paper filters, adsorption
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`fihers sech as activated carbonfilters, ion exchangers (for improving the hardness qualities of water),
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`amongst others. In some exanmples, the filter arrangement comprises a UV light source arranged to
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`direct LV hight towards water m the fhaid path. The use of sucha UVlight has the further advantage
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`that bacteria and other organic contammeants im the water maybe destroyed.
`
`(630) The filter device may further comprise a backflow prevention valve configuredta prevent a
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`backflow of water out trom the intake aperture. The backflow prevention valve may, for example, be
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`fitted as part of the housing or the pump, and may enforce a unidirectional flow of water through the
`
`filter device. Thus, it is possible to prevent water from flowing in an opposite direction to that
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`mtended, e.g. from the return aperture to the mtake aperture, or an ‘meorrect’ progression throughthe
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`fier arrangement, honce preventing sediment or other impurities from being returned into the water
`
`reservol.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`(6342) One or more embodiments will be described, by way of cxarmpic only, and with reference to
`
`the following figures, in which:
`
`100321 Figure | schematically shows a filter device according to an embodiment:
`
`[8035] Figure 2 shows a cross-section of a filter device in a water reservoir, according to an
`
`embodiment:
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`[6034] Figure 3 shows a side viewofa filter device, according to an embodiment;
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`(6035] Figure 4 shows a perspective viewof a filter device according to an embodunent,tilted to
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`show an ond surface;
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`{036} Figure S shows a cross-section through a filter device according to an embodiment; and
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`{G037] Figure 6 shows a perspective view of a portion ofa filter device, according to an embodiment,
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`with the housing made transparent to showinternal components of the filter device.
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`16038) Whilst the invention is susceptible to various modifications and alternative forms, specific
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`embodiments are shown by way of example imthe drawings as herem described mdetail. It should be
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`understoad, however, that the detailed description herein and the drawings attached hereto are not
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`mtconded to limit the invention to the particular form disclosed. Rather, the intention is to cover all
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`modifications, squivalents, and alternatives falling within the scope of the appended clams.
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`(8039) For example, although ‘water’ has been referred to throughout the application, it will be
`
`appreciated that any suitable liqntid in need of filtration could be substituted without departing from
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`the scope of the appended claims.
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`

`

`[#048] Any reference to prior art documents or comparative examples in this specification is not to be
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`considered as an admission that such prior art is widely knownor forms part of the common general
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`6
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`knowledge in the field.
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`180449] As used im this specification, the words “comprise”, “comprising”, and similar words are not
`
`to be interpreted in the exclusive or exhaustive sense. In other words, they are intended to mean
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`“Gnchading, but not limited to”.
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`DETAILED DESCRIPTION
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`ff842] The present invention is described in the following by way of a mumberof thistrative
`
`examples. It will be appreciated that these cxamples are provided for illustration and explanation only
`
`and are not intended to be lumiting on the scope of the present invention. Instead, the scope of the
`
`present inventionis to be defined by the appended claims. Furthermore, although the examples may be
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`presented in the form of individual embodiments, it will be recognised that the invention also covers
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`combinations of the embodiments described herein,
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`(8043) Figure 1 schematically shows a filter device 100, according to an embodiment.
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`(8044) Tn the ithistrated embodiment, the filter device 100 has a housing 102 configured for
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`submersion ia water reservoir. The housing 102 may be any waterresistant or waterproof material
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`having suitable rigidity so as to hold its shape when submerged in a water reservoir. For cxample, the
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`housing 102 may be made of plastic, non-corroding metal such as stainless steel, silicon rubber, or the
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`ike.
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`16645] The housing 102 has an intake aperture 104 and a return aperture 106. In the illustrated
`
`embodiment, these are arranged at opposing ends of the housing 102, although they may be arranged
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`m any suitable position that allows for a placement of a filter arrangement 112 ima fluid path there
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`between.
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`[846] Housed imthe housing, there is a pump 110 anda filter arrangement 112. The pamp 110 may
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`be an electric or mechanically powered pumpand is arranged to direct thud tromthe intake aperture
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`104 to the return aperture 106. Although the pump 110 is illustrated as being in the fluid path between
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`the intake aperture 104 and the return aperture 106 (the fluid path being shown as dotted arrows), it
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`mayalso be arranged m any suitable position m or awayfrom the fluid path where the pump has
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`sufficient fhid communication with the intake aperture 104 and/or return aperture 106 to promote the
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`flowof flid therethrough.
`
`(0047) The filter arrangement 112 maybe formed of one or more filters and/or, for cxanyple, a UV
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`light. The filter arrangement 112 is arranged m the fluid path between the make aperture 104 and the
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`return aperture 106 so as to remove contaminants (particulates, bacteria, sediment, etc.) from the water
`
`passing therethrough.
`
`10048]
`
`it may be preferable te prioritise fluid flow through the filter arrangement 112 aver superior
`
`filtration characteristics of the filter arrangement 112, so as to allowfor improvedcirculation of water
`
`

`

`4
`
`through the water reservoir and increase the rate at which multiple passes through the filter
`
`arrangement may be achieved.
`
`10049] The housing 102 is extended along an axis 108, shown as a dotted linc. Thus, the filter device
`
`100 has en ergonomic configuration such that a user may easily place the filter device 100 into a water
`
`reservoly, remove it therefrom, and/or direct it therein. For example, a user may wish to move the filter
`
`device 106 around in the water reservoir so as to target particular areas where sediment may be visibic,
`
`or simply to expedite the circulation of most/all of the water through the filter device 100.
`
`{8080) The pumyp 110 and the 112 are arranged along the axis 108. Thus, the extended shape of the
`
`housing 102 (delimiting the overall shape of the filter device 100) may remain compact and
`
`ergonomic.
`
`10051] As illustrated in figure 1, there may be one or more fluid paths from the intake aperture 104 to
`
`the return apertarc 106 that do not pass throughthe filter arrangement 112. This may be preferable so
`
`as to encourage greater circulation through the water reservoir G.c. without slowing/impeding thid
`
`flow by forcing it through the filter arrangement 112}, which may allowforafaster filtration of all of
`
`the water in the water reservoir using multiple passes,
`
`(8082) The pump 110 and the filter arrangement 112 as shown m figure i are arranged centrally in
`
`the housing 102. However, their placement may instead be more towards one side than another, if
`
`particular fluid flows are desired or ifany other mechanical constraints cxist when arranging the
`
`internal components inside the housing 102.
`
`{G053] Figure 2 shows a cross-section of a filter device 100 in a water reservoir 120, according to an
`
`embodiment. Components having reference mimerals that are also used in figure 1 maybe the same or
`
`similar components as those with correspondimg reference minerals in figure 1.
`
`[0054] The filter device 100 shown in figure Z has an intake aperture arrangedat the bottom of the
`
`filter device (as illustrated), as with figure 1, howeverthe return aperture in the filter device 100
`
`shown in figure 2 is arranged at a side of the filter device 100, i.e. perpendicular to the axis 108.
`
`[HOSS] The pump 110 is formed of two sub-components: an electric motor 1 10a and an impeller 110b
`
`arranged proximate to the intake aperture 104. The electric motor 11a may be battery powered or
`
`mains powered. ifthe electric motor 110a is mains powered, for example, the filter device 100 may
`
`further comprise power connection cables extending through the housing 102 (e.g. through the access
`
`aperture or some other opening) for connecting the electric motor 110a to a mains power supply.
`
`(8056) When operated, the tmpeller 110b draws water through the intake aperture 104 and into the
`
`housing 102. The portion of the housing 102 that houses the pump 110 is connected to the portion that
`
`houses the filter arrangement 112 in such a waythat the outlet of the impeller 110b is in floid
`
`communication with the filter arrangement 112.
`
`iG057]
`
`In particular, the filter arrangement 112 can be seen in figure 2? as enclosing a space 126 and
`
`the outlet of the impeller 110b is m flaid communication with this space 126. Thus, water cannot
`
`escape the space 126 through the return aperture 106 without passing through the filter arrangement
`
`

`

`8
`
`112. In the llustrated embodiment, the space 126 is formed as a central core of the filter arrangement
`
`112 however, other arrangements are possible.
`
`10058] The filter device 100 has a first ond (indicated generally as 114) and a second end (indicated
`
`generally as 118) being opposed along the axis 108.
`
`16659] The first end 114 may be configured for manipulation by a user. That is, in the iastrated
`
`examplo, the filter device 100 is shown as being in a water reservoir 120, for example a jug of water
`
`(water not shown). It can be seen that the first end Lid is appropriately proportioned for a hand ofa
`
`user to ergonomically grasp such that the filter device 100 may be moved within the water reservoir
`
`120 or removedtherefrom. In some examples, the first endl 114 may further comprise a handle for
`
`further ease of manipulation by a user.
`
`10060] The second end 118 maybe configured to be spaced from a surface of the water reservoir 120
`
`(e.g. the bottom surface 120s, as in figure 2). In the ilhustrated example, this spacing is achieved by
`
`one or more spacers 116 which space the intake aperture 104 from the bottom surface 120a of the
`
`water reservoir 120, thus allowmg a flow of water io the intake aperture 104.
`
`{80G1] The filter device 100 further comprises a sub-housing 122 housed in the housing 102. [n the
`
`illustrated cxample, the sub-housing 122 is arranged at the first ond 114 of the filter device 100 and is
`
`sealed by a sealing element 124.
`
`18662] The sub-housing 122 may be compleicly or substantially waterproof so as to be configured for
`
`contaming Hiquid-sensitive components (not shown). Liquid-sensitive components may be electronics,
`
`soluble components, or other components that are mot well suited for submersion in water (or other
`
`higuids}. In the illustrated example, the sub-housing 122 is removeablysealed by a sealing clement
`
`124, taking the form of a Hd (cap, topper, etc.). The sealing element 124 may be attached with a
`
`threaded attachment, a push-in attachments, a bayonet attachment, or some other moans that allows for
`
`the creation of a substantially waterproofseal.
`
`{8863] As shownin figure 2, the scaling element 124 also scals the housing 102 at the firat ond 114.
`
`if the sealmg element 124 were removed, the housmg 102 would have its access aperture (blocked in
`
`this view) openedfor access ta the internal components, such as the sub-housing 122 Gneluding the
`
`liguid-scnsitive components contained therein), the filter arrangement 112, and/or the pump 110.
`
`16064)
`
`in some alternative arrangements, the sub-housing 122 may have an openable sealing on its
`
`other end G.c. towards the second end 118) and the sub-housing 122 may take the form ofa phig,
`
`conforming to the size and shape of the access aperture of the housing 102 such that, when the sub-
`
`housing 122 is pushed inte the access aperturc at the first end 114, the sub-housing 122 scais the
`
`housing 102 in a substantially waterproof manner.
`
`[G065] Ht will be appreciated that, if the first end 114 ofthe filter device 100 is not intended to be
`
`fully submersed in water, the sub-housing 122 and/or the sealing element 124 may not necessarily be
`
`required te be entirely waterproof.
`
`

`

`go
`
`[3066] Figure 3 shows a side view ofa filter device 100, according to an embodiment. The internal
`
`components such as the pemp 110 and the filter arrangement 112are not visible in this view.
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`10067) The illustrated housing 102 is cylindrical in shape, having a circular sealing clement 124
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`arranged to seal the housing 102 at the first end 114, and a plurality of spacers 116 arranged at the
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`second end 118 for spacing the filter device 100 from a surface of a water reservoir (as discussed
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`above).
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`i@0G6R] As shown m figure 3, the return apertures 106 of the housing 102, according to the illustrated
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`example, extend across a length of the housing 102 and are arranged perpendicular to the axis 108 of
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`housing 102. The return apertures 106 are evenly arranged around a circumference of the cylindrical
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`housing 102 so as to provide a large area for returning water into the water reservoir. The retum
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`apertures 106 may have a grid or mesh thereacross so as to prevent an entry of debris, contaminants,
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`ete. from the water reservoir.
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`18669} The housing 102, spacers 116, and sealing element may be formedfrom a same material (e.g.
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`plastic, stainless steel, silhcon rubber, or the like} or different materials.
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`(8070) Figure 4 shows a perspective viewof a filter device 100 according to an embodiment, tilted to
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`showan cond surface of the second end 118. Elements having like reference numerals as in figure 3
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`may be the same or similar to those discussed in figure 3.
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`i671] The intake aperture 104 and the spacers 116 are more clearly shown in the viewoffigure 4. In
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`the ilhistrated example, there are four spacers 116 taking the form of fins protruding fromthe circular
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`lower surface of the cylindrical housing 102 and extending along a radial direction.
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`16672] The spacers 116 preferably have a substantially even or flat construction on their lowerside,
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`so as to allow for the filter device 100 to be stable when placed on a bottom surface of a water
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`reservoir. To this ond, the spacers 116 may preferably extend in a radial direction enough to
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`collectively provide a stable surface.
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`(8073) Furthermore, the spacers 116 preferably have a low-drag profile viewed from the intake
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`aperture 104 and may be arranged for directing water towards the intake aperture 104. Thus, water
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`being drawn in by the pump 110 (e.g. by an impeller such as the impeller 110a shown in figure 2) docs
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`not excessively drag against the spacers 116, which may cause the filter device 100 to move or tip
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`over in the water reservoir,
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`[0074] Although only four spacers 116 are shown, it will be appreciated that there may be more or
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`fower spacers 116, and these may have a different shape or configuration, although the aforementioned
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`considerations of stability and fhaid drag profile may still apply.
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`{807S| The mtake aperture 104 is shown as bemg a circular aperture concentrically arranged at a
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`centre of the circular lower face of the cylindrical housing 102. The spacers 116 are arranged at a
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`radius beyond the intake aperture 104, although in some cxamples these may radially overlap (c.g. the
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`spacers 116 may form a cross shape across the intake aperture 104). It will also be appreciated that the
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`intake aperture 104 may take any shape that is suitable for allowimg sufficient fluid flowtherethrough.
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`[#076] The imtake aperture 104 may have a backflow prevention valve (not shown) arranged
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`proximate thereto, for cxamplo nmmediately at its entry. The backflow prevention valve may censure
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`that water flowing in through the intake aperture 104 cannot flowback out, for example ifthe pump
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`110 is tamed off, or if there is a malfunction. Thus, it is possible to prevent contammants that have
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`been filtered oat from the water from being returned to the water reservoir. The intake aperture 104
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`mayfurther comprise a mesh, screen, or grid arranged thereacross for preventing solids of a particular
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`size from entering the filter device 100 and potentially damaging the internal components.
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`(0077) Figure S shows a cross-section through a filter device 100 according to an embodiment.
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`fG878] As with the filter devices 100 shown in figures 3 and 4, the illustrated example has a circular
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`cross-section. However, the housing 102 (and/or pump 110, filter arrangement 112, or other internal
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`components) mayinstead have a different cross-section, such as a triangular or rectangular cross-
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`section.
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`18078} The cylindrical housing 102 has a plorality of retumapertures 106 extending through the
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`thickness of the housing 102 and arranged evenly around its circumferences. In some examples, the
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`retura apertures 106 may be unevenly distributed about a perimeter of the housing 102, for exampic
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`dircetionally distributed so as to encourage circulation m a water reservoir m a particular dircetion.
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`[#086] As shown tmfigure 5, the filter arrangement 112 has a circular cross section and is arranged
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`concentrically with the housing 102. The filter arrangement 112 is shown having a homogencous
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`construction, although the filter arrangement 112 may instead have a plurality of layers therein, such
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`ag a sequence of different filters having different filter characteristics. For example, an ranermost layer
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`maybe a coarse sponge filter, whilst an outermost layer may be a fine activated carbon filter. The
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`filter arrangement 112 is configured to enclose a space 126, which is shown as a concentric circle at a
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`radial centre of the cross-section. Water may be directed, by the pump 110, into this space 126,
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`wherefrom it flows through the filter arrangement 112 and out through the return apertures 106