WO2016178009A1

WO2016178009A1 - A device for filtering a fluid

Info

Publication number: WO2016178009A1
Application number: PCT/GB2016/051257
Authority: WO
Inventors: Robert TALINTYRE; Alex DRIVER; Ian Riley; Andrew Whitwell
Original assignee: Labman Automation Limited
Priority date: 2015-05-04
Filing date: 2016-04-29
Publication date: 2016-11-10
Also published as: GB201507616D0

Abstract

The present invention relates to a device for filtering a fluid comprising: one or more filter positioning means on which at least a first and a second filter material are mountable, the filter positioning means being operable to move the at least first and second filter materials independently and parallel to a first direction; and at least one clamp head comprising: a first clamp portion having a first face, a second clamp portion having a second face, the first and second clamp portions being configured to receive one or more of the said filter materials between their faces, the first and second clamp portions being mounted on the clamp head such that their faces face one another and being operable such that they may be moved one relative to another between an open position in which their faces are spaced apart and a clamped position in which the faces are closer to each other than in the open position, and the first and second clamp portions each comprising a fluid flow channel to the face; wherein the device is configured to form a fluid flow pathway through the at least one clamp head, and thus in use through the first and the second filter materials in series, when the first and second clamp portions are in the clamped position. Also described is a method of filtering a fluid using the device.

Description

A device for filtering a fluid

Field of the invention The present invention relates to devices for filtering a fluid and methods of use thereof. Background

There is a need for devices to filter fluids that are capable of operating automatically or semi- automatically to complete a filtration process, for example to filter a series of samples of fluid or to complete the filtration of a single fluid volume, where the volume is either large, or the fluid is heavily contaminated, such that filters tend to block. Examples of applications are in filtration of fluids for analysis of small suspended or dissolved components where it is necessary to remove larger contaminants such as particulates and debris, and in preparation of beverages where there is often a need to remove suspended solids. Typically such processes are done manually using filter devices such as manual syringe filters, which have disadvantages of being slow to use, costly in terms of disposables, prone to error or misuse and which may cause health problems to operators, such as repetitive strain injury, owing to the large force that is sometimes needed to provide sufficient pressure to filter a sample, especially when a filter is becoming clogged. The present invention provides an improved device to achieve such filtration processes.

Description of the invention

According to a first aspect the invention provides a device for filtering a fluid comprising: one or more filter positioning means on which at least a first and a second filter material are mountable, the filter positioning means being operable to move the at least first and second filter materials independently and parallel to a first direction, and at least one clamp head comprising:

a first clamp portion having a first face,

a second clamp portion having a second face,

the first and second clamp portions being configured to receive one or more of the said filter materials between their faces,

the first and second clamp portions being mounted on the clamp head such that their faces face one another and being operable such that they may be moved one relative to another between an open position in which their faces are spaced apart and a clamped position in which the faces are closer to each other than in the open position, the first and second clamp portions each comprising a fluid flow channel to the face,

wherein the device is configured to form a fluid flow pathway through the at least one clamp head, and thus in use through the first and the second filter materials in series, when the first and second clamp portions are in the clamped position.

In use, the fluid flow pathway is through the clamp head and the two or more filter materials are received by said clamp head. As two filter materials are mountable on the system and the device in use provides a fluid flow pathway between the first and second filter materials this allows for both automation and improved filtration.

In some embodiments the clamp portions are configured to move parallel to a second direction orthogonal to the first direction. In some embodiments the one or more filter positioning means comprises a first filter positioning element on which the first filter material is mounted and a second filter positioning element on which the second filter material is mounted. The first and second filter positioning elements may be operable independently to move the first and second filter materials independently of each other. In some embodiments the device comprises a first and a second filter materials positioned between the first and second faces of the first and second clamp portions.

In some embodiments the device further comprises a support component between the first and second faces, the support component comprising at least one fluid flow channel therethrough. The first filter material may be positioned between the first face and the support component and the second filter material may be positioned between the second face and the support component. In this way the first and second filter materials may be clamped in place by a single operation of the clamp portions, both clamping together onto the support component. In some embodiments the device may further comprise a second clamp head and said filter positioning means comprises a first filter positioning element on which the first filter material is mounted and a second filter positioning element on which the second filter material is mounted, wherein the first filter positioning element is configured to support the first filter material between the clamp portions of the first clamp head, the second filter positioning element is configured to support the second filter material between the clamp portions of the second clamp head, and the device is configured to form a fluid flow pathway through the first and the second filter materials in series when all of the clamp portions are in the clamped position.

In this way the device comprises a first and a second filter material in series along the fluid flow pathway, such that the first filter material is upstream and the second filter material is downstream, and a fluid to be filtered passes through both filter materials. The first filter material may then act in use as a pre-filter, and the second filter material as a secondary filter, in order to ensure removal of contaminants from the fluid. The first filter material may have a larger pore size and the second filter material may have a smaller pore size.

The device is configured to move the first and the second filter materials in order to prevent the fluid flow pathway from becoming obstructed as a filter material becomes clogged. The device may be configured to move the two filter materials at the same time or at separate times. For example, with some samples having a higher proportion of larger contaminants, the first (coarse, upstream) filter material may be moved more often, as in use it is likely to become clogged more quickly than the fine filter. In other samples having a higher proportion of fine contaminants, the second (fine, downstream) filter material may be moved more often, as in use it is likely to become clogged more quickly than the first. In this way the device is operable to clamp the faces against the first and second filter materials to seal the filter materials between them. Fluid, such as liquid, may then be passed through the fluid flow pathway to achieve filtration of the fluid. In use the filter positioning means operates to move a filter material parallel to a first direction to position a portion of filter material between the faces. The faces then move parallel to a second direction, orthogonal to the first, to clamp against and seal against the filter material, which is then used in a filtration operation. The clamp portions then open to free the filter material, and the filter positioning means then operates again to move the filter material parallel to the first direction to position a new portion of filter material between the faces. The operations may be repeated until the filtration process is complete. A filter material may be in the form of a tape, and the filter positioning means may comprise a supply reel to hold a supply of tape and tape actuation means operable to move the tape from the supply reel between the faces. The tape actuation means may comprise a motor-driven pinch roller to bear on the tape to move it and may comprise a take-up reel to receive the tape, optionally being driven to pull the tape from the supply reel. The device may be configured to operate the filter positioning means to advance the tape following each filtration operation, positioning a new portion of the tape between the faces. The device may be adapted to move the filter material in steps, the movement step being typically greater than the dimension across the seal area of the faces of the clamp portions, such that a completely unused portion of the filter material is present between the faces after the movement. The device thereby provides a means to filter fluid samples through adjoining filter tape portions, each portion being unused before each filter operation.

In some embodiments the faces are provided in a vertical orientation or at an angle to vertical, the angle being in the range zero degrees to around 45 degrees. In this way the device provides the filter material in an orientation that is vertical or within the said range of angles to vertical. Such orientation may prevent, or reduce the likelihood, of liquid trapped by the faces during a filtration operation carrying-over in use to a new filter portion when this is positioned between the faces.

A clamp portion may have any appropriate form to apply a clamping force to seal the faces against the filter material, and to provide a fluid flow channel through it to the face.

A face is preferably configured to seal against a filter material, and may comprise a seal component such as an O-ring or a seal feature such as a raised ridge to apply compressing force to the filter material, to achieve sealing. The face may comprise a fluid flow region within the area of the seal component or seal feature. A first face may comprise a projection to define a seal area and the second face may comprise a matching recess to receive the projection when the clamp portions are in the clamped position.

A clamp portion may comprise a manifold opening to the face to allow an extended area of fluid flow through the filter material in use, the fluid flow region of the face being the opening of the manifold to the face. A clamp portion may comprise a plurality of apertures opening from the manifold to the face, such as an array of holes or a mesh, to provide a fluid flow pathway to the face and to support the filter material. The device may be configured to move one (such as the first) clamp portion while the other (such as the second) clamp portion is stationary. The second clamp portion may be mounted in a fixed position on the device.

The device may be configured to move both the first clamp portion and the second clamp portion towards one another.

The device may comprise a clamp actuator to move at least the first clamp portion. A clamp actuator may comprise a motor mounted on the clamp head, a pneumatic, hydraulic or magnetic drive means, or a spring to provide the clamping force and an actuation means to counteract the spring to open the clamp portions. A clamp portion may be mounted on a slide mechanism such that the clamp actuator may advance the clamp portion linearly along the slide towards the other clamp portion.

A fluid actuation means may be provided upstream or downstream of the clamp head, and may comprise a constant displacement actuation means such as a peristaltic or screw pump, a syringe or plunger-based pump, or a constant pressure actuation means such as gravity feed or feed from a pressurised reservoir, for example controlled by a valve.

The fluid may be an aqueous or non-aqueous liquid, a solution, an emulsion, a suspension, a paste or a gas. The filter material may be selected according to the fluid and the contaminants to be removed. In some embodiments the fluid is water and the device is adapted to remove contaminants such that species dissolved or suspended in the water may be analysed.

The filter material may be adapted to remove contaminants from the fluid so as to retain the contaminant on the filter material. The filter material may be adapted to physically retain the contaminant. According to the embodiment, contaminants may include: particulates such as solid particulates, flocculates or gelatinous masses, organisms such as bacteria, algae, multicellular organisms, debris such as organic matter, inorganic matter and waste. The filter material may be adapted to retain a contaminant by affinity, for example to bind a chemical or biological entity such as a molecule, a macromolecule, a protein, a virus, a cell by means of a chemical bond or association between the entity and a species provided on the filter. The first, upstream filter material may be adapted to physically retain a contaminant and the second, downstream filter material may be adapted to retain a contaminant by affinity. The filter material may be in the form of a tape and may comprise a single layer of a filter material continuous along the length of the tape, such that the tape consists of the filter material. The filter material may comprise a filter layer supported on a support material to form a two-layer structure. In this way the material of the filter layer is not limited to those materials or thicknesses that have sufficient mechanical strength to be self-supporting in a tape format. Typically a filter material may comprise a filter layer formed from a filter material known in the art, supported on a flexible polymer mesh, such as a nylon mesh. A filter layer may comprise polyvinyl difluoride) (PVDF) bonded to a nylon mesh. Other filter materials may comprise paper, glass fibre, a polymer filter formed for example from sintered material, woven or non-woven fibres, comprising for example polyethylene, polypropylene or polytetrafluoroethylene (PTFE), or a track-etched membrane, for example formed in polycarbonate. A filter material may comprise a single layer of a metal or polymer mesh, or two layers of mesh bonded together. In this way the pore size and material of the filter layer may be selected to suit the contaminants to be filtered from the fluid. The pore size of a filter layer may be selected in the range 0.1 micrometre (urn) to 1 mm, for example in the range 0.1 urn to 10um, 1 urn to 100um, 10um to 1 mm. The pore size of a support material may be selected to be greater than that of the filter layer, for example in the range 50um to 1 mm. In this way the pore size of a filter material may be that of the filter layer. A pore size suitable for the first, upstream, coarse filter material may be in the range 50um to 1 mm. A pore size suitable for the second, downstream, fine filter material may be in the range 0.1 urn to 50um. The filter material may comprise a plurality of portions of a filter material supported on a continuous support material, such that the filter material portions may be moved by movement of the support material. The portions may be separate and adjacent, and may be separated by a region of the support material such that the filter material comprises a series of panels of filter material supported on the support material. The portions may be joined together, and adapted so that the filter material may flex between the portions, such as by perforation or formation of a thin dividing region between the portions, to allow the filter tape to be moved around a curved pathway from the supply reel to the take-up reel. The filter layer may be flexible, semi-flexible or substantially rigid, in the form of a plurality of plates. In this way a filter layer may be used that does not have sufficient flexibility to be handled in a tape format without a support layer. The device may be adapted to move the filter material in steps, so as to position a portion or panel of the filter layer between the faces of the clamp portions, the movement step being typically equal to the distance between the centres of the portions or panels, and the portion or panel being sized such that the seal area is accommodated within the portion or panel. The device may comprise a controller to control operation of the clamp head, the filter positioning means and the fluid actuation means. The controller may be computer-implemented and may comprise a computing means, a data store and a control program as known in the art.

The controller may be configured to operate the filter positioning means to move a filter material at a constant time interval; to allow the interval to be pre-selected by a user; or to measure one of a pressure drop across a filter or a flow rate through the device in order to determine that a filter should be moved.

The device may comprise one or more pressure sensors to measure the pressure of the fluid in the pathway. The device may comprise a first pressure sensor to measure the pressure in the fluid flow pathway upstream of the first filter material, and may comprise a second pressure sensor to measure the pressure in the fluid flow pathway between the first and the second filter materials. The device may be configured such that the controller receives signals from a pressure sensor to determine the condition of a filter material, such as that the filter material is becoming blocked, or to move one or more of the filter materials.

The device may comprise one or more flow sensors to measure the flow rate of the fluid in the fluid flow pathway. The device may be configured such that the controller receives signals from a flow sensor to determine the condition of the filter material, such as that the filter material is becoming blocked, or to move one or more of the filter materials.

In one mode of operation a fluid sample is filtered through a fresh portion of filter material. The device may be configured to control the fluid actuation means to flow the sample through the device into a collection vessel and, once the whole sample has been filtered, to open the clamp head and to operate the filter positioning means to move a fresh portion of filter material between the faces, and to close the clamp head again so that the device is ready to filter a further sample.

In a further mode of operation, for example for a large or a highly contaminated sample, the device may be configured to, at intervals: stop the fluid flow, open the clamp head, move the filter material to provide a fresh portion of filter material between the faces, close the clamp head and restart the flow, and to continue this sequence of operations until all the sample has been filtered. The controller may control the operations in response to signals from a pressure or flow sensor as described above, the operations being carried out when the controller determines that a filter material is becoming blocked, when a pressure across a filter material exceeds a threshold amount, or when the flow rate falls below a threshold amount.

The device may comprise a fluid handling system configured to allow a sample to be filtered to be selected from a plurality of samples and the filtrate to be collected in a vessel. The device may comprise a sampling device configured to sample liquid from a sample vessel, for example using aspiration from the vessel. The device may comprise means to direct the filtrate to a selected filtrate vessel, for example by moving a liquid outlet relative to a plurality of empty vessels. Such liquid handling means are known in the art.

In this way the device provides an automatic means for filtering and collecting a sample under the control of the controller and a control program, for example being able to filter and collect a series of separate samples, or a single large or heavily contaminated sample in a series of separate filtration operations. The device may be configured to handle smaller (e.g. less than 1 litre) or larger (e.g. equal to or greater than 1 litre) sample sizes by choice of appropriate parameters such as the dimensions of the fluid flow pathway, the flow rate provided by the fluid actuator and the effective area of the filter in the fluid pathway. According to the embodiment the sample size may be in the range 1 ml to 1000 litres or more, such as in the range 1 ml to 1 litre, 10ml to 1 litre, 100ml to 10 litres, 1 litre to 1000 litres. Dimensions for an embodiment suited for sample sizes in the range around 10ml to around 1 litre will be given below. The controller may be provided as part of the device, or may be provided in a remote computer in data communication with the device.

In some embodiments the device is configured to clean the fluid flow pathway with a cleaning fluid, for example a wash liquid. The device may be configured to move the clamp head to the clamped position without a filter material in position between the faces to provide a fluid flow pathway through the clamp portions and between the faces, and to flow a cleaning fluid through the fluid flow pathway. The device may comprise a reservoir of cleaning fluid. The cleaning fluid may be a wash liquid such as water, a buffer, a solution of detergent, a sterilising liquid, or a gas, and may be flowed at higher flow rate than during a filtering operation to move residual particulates. The device may be configured to flow a wash liquid through the fluid flow pathway and then to flow as gas, such as air, in order to dry the fluid flow pathway.

In some embodiments the device is configured to move the clamp head, relative to a position in which the filter materials are held by the filter positioning means, between an operating position in which the first and second clamp portions may receive the filter materials between them and a wash position in which the clamp portions are clear of the said position of the filter materials.

In use, when the filter materials are mounted on the filter material positioning means, the clamp between an operating position in which a filter material is positioned between the first and second clamp portions and a wash position in which the clamp portions are clear of the filter material, so as to allow cleaning fluid to be passed through the clamp portions to clean the fluid flow pathway without passing through a filter material. In such embodiments the clamp head may be movable in a third direction, optionally orthogonal to the first and the second directions. The device may comprise a clamp head position actuator configured to move the clamp head in this way.

Accordingly, in some embodiments the filter positioning means is configured to move the filter material parallel to a first, substantially vertical direction, the device is configured to move the clamp portions parallel to a second, substantially horizontal direction, and the device is futher configured to move the clamp head parallel to a third substantially horizontal direction, orthogonal to the second direction.

In this way in a mode of use the clamp head may be moved to the wash position and the clamp portions may be clamped together to allow washing; the clamp portions may then be opened and the clamp head be moved to the operating position such that it may receive the filter material between the faces; the clamp portions may then be clamped together to seal to the filter materials, and the filtration operation may be carried out; the clamp portions may then be moved to the open position and the clamp head moved to the wash position to repeat the wash. Alternatively, or in addition, the filter positioning means may be moveable and the device may comprise a filter positioning means actuator configured to move the filter positioning means between an operating position in which the filter material is positioned between the first and second clamp portions and a wash position in which the clamp portions are clear of the filter material. In this way a similar mode of use may be achieved to that described above, now with the filter positioning means being actuated to move the filter material while the clamp head remains stationary. The filter positioning means may be configured to move the filter materials independently from between the clamp portions, such that a filter material may be taken out selectively from the fluid flow pathway, while a further filter material remains in the pathway. In use, the device thereby provides an effective filtration means having a pre-filter and a fine filter, each comprising a filter material that may be replaced by the device as needed in order to maintain efficient fluid flow and filtration. The device may be configured to move the first filter material at a first time interval and the second filter material at a second time interval. The time intervals may be selected to suit parameters including the type of fluid, the type of contaminants in the fluid and the desired flow rate through the filter. The device may be configured to move a filter material at a constant time interval, to allow the interval to be pre-selected by a user, or to measure one of a pressure drop across a filter or a flow rate through the device in order to determine that a filter material should be moved. The device may comprise a first pressure sensor upstream of the first filter material and a second pressure sensor to measure the pressure in the flow pathway between the first and second filter materials, so that the pressure drop across each filter material may be measured, the controller being configured to control the movement of the first and second filter materials independently in response to signals from the one or more pressure sensors.

The support component may have a first support component face facing the first face of the first clamp portion and a second support component face substantially parallel to the first facing the second face of the second clamp portion. The support component faces may be substantially flat or may comprise sealing features configured to interact with sealing features on the clamp portions. The support component may have a thickness and may comprise a plurality of apertures through the thickness, such as an array of holes, to provide the fluid flow pathway and to support the filter material.

The clamp head may be configured such that the second clamp portion remains stationary and the clamp actuator is configured to move the first clamp portion towards the first. The support component may be movable towards and away from the second clamp portion, and may be mounted on a sliding mount. The support component may be configured to move towards the second clamp portion driven by force from the first clamp portion when the clamp head is closing, and to move away from it while the clamp head is opening. The support component may be mounted on a shaft passing through clearance holes in the first and second clamp portion and may be actuated by movement of the shaft caused by movement of the first or second clamp portions, as will be described in more detail below with regard to an embodiment. The clamp head may comprise a spring to move the support component away from a clamp portion when the clamp portions move one relative to another to open the clamp head. In some embodiments the support component may be driven by the clamp actuator to move it towards and away from a clamp portion. In this way the support component may be centred between the first and second faces to allow the first and second filter materials to be moved, and to allow the clamp head to be withdrawn backwards from the position of the filter materials in order to carry out the washing operation.

The device may comprise a pressure sensor connected to the fluid flow pathway through the support component. The controller may be adapted to measure the pressure at the support component to control the movement of the first and the second filter material positioning means. In this way, the controller may measure the pressure drop across the first and the second filter materials separately, so may move each filter material independently to provide a fresh portion of filter material in the flow pathway as needed. According to a second aspect, the invention provides a method for filtering a fluid using a device as described herein.

The method may comprise:

providing a device as described herein comprising a first and a second filter material in which the first filter material is a coarse filter material and the second is a fine filter material,

measuring the pressure in the fluid flow pathway upstream of the first filter material during a filtration process,

comparing the measured pressure with a threshold pressure, and

controlling the clamp head and filter positioning means to move one or both of the first and the second filter materials if the pressure is above the said threshold pressure.

In some embodiments, the method may comprise:

measuring a second pressure in the flow pathway between the first and second filter materials during the filtration process,

comparing the measured second pressure with a threshold pressure, and

controlling the clamp head and filter positioning means to move the second filter material independently of the first if the measured second pressure is above the said threshold pressure.

In some embodiments the method comprises a wash operation comprising:

opening the clamp head,

moving the clamp head such that the clamp portions are clear of the position of the filter materials,

closing the clamp head,

flowing a cleaning fluid through the clamp head,

opening the clamp head,

moving the clamp head back to the operating position in which the first and second filter materials may be received between the clamp portions,

moving one or both filter materials, and

closing the clamp head ready for the next filtration operation.

The cleaning fluid may be wash liquid. In some embodiments the method comprises flowing a gas through the clamp head to dry the fluid flow pathway.

Preferred features of the second aspect of the invention are as for the first aspect mutatis mutandis. Brief description of the figures Figure 1 shows an isometric view of an embodiment of a device according to the invention.

Figure 2 shows a front elevation of the embodiment shown in figure 1 with the clamp head in the clamped position.

Figure 3 shows a front elevation as in figure 2 with the clamp head partially moved towards the clamped position.

Figure 4 shows a front elevation as in figure 2 with the clamp head in the open position.

Figure 5 shows a horizontal cross-section through the device at the mid-level of the clamp head. Figure 6 shows an isometric view of the clamp head of the embodiment shown in figure 1 .

Figure 7 shows a plan view of the clamp head in an open position.

Figure 8 shows an exploded view of the clamp head as shown in figure 6.

Figure 9 shows a cross-section through the clamp head in the clamped position with the filter materials in position, showing the fluid flow pathway through the clamp portions.

Figure 10 shows a front view of the clamp head in a further embodiment in which the first and second filter materials are in contact when the clamp portions are in the clamped position. The clamp head is shown in an open position.

Figure 1 1 shows a partial front view of a further embodiment comprising a first and a second clamp heads.

Figure 12 shows steps in a method of operation of an embodiment of the device.

Detailed description of an embodiment

Referring to figures 1 to 9, an embodiment 1 of a device according to the invention comprises: a first filter positioning means 10 and a second filter positioning means 12 on which a first 14 and a second 16 filter materials are mountable, the filter positioning means 10, 12 being operable to move the first and second filter materials independently and parallel to a first direction, the first direction being vertical in the orientation shown in figures 1 to 4 as indicated by axis 15; and

a clamp head 20 comprising:

a first clamp portion 22 having a first face 26,

a second clamp portion 24 having a second face 28,

the first and second clamp portions being configured to receive the said first and second filter materials between their faces,

the first and second clamp portions being mounted on the clamp head such that their faces 26, 28 face one another and being operable such that they may be moved one relative to another between an open position in which their faces are spaced apart (as shown in figure 4) and a clamped position (as shown in figure 2) in which the faces are closer to each other than in the open position, and the first and second clamp portions each comprising a fluid flow channel 30, 32 (see figure 9) to the face 26, 28, wherein the device is configured to form a fluid flow pathway 34 through the clamp head 20, and thus in use through the first and the second filter materials 14, 16 in series, when the first and second clamp portions are in the clamped position. In use, the fluid flow pathway 34 is through the clamp head 20 and the two filter materials 14, 16 are received by said clamp head. As two filter materials are mountable on the system and the device in use provides a fluid flow pathway between the first and second filter materials this allows for both automation and improved filtration. In this embodiment the clamp portion 22 is configured to move parallel to a second direction orthogonal to the first direction, the second direction being horizontal and left to right in the orientation as shown in figures 1 to 9, as indicated by axis 25, in order to move the clamp head from the open to the clamped position, while the second clamp portion 24 remains stationary and is mounted in a fixed position on the device.

In this embodiment the filter positioning means comprise a first filter positioning element 40 on which the first filter material 14 is mounted and a second filter positioning element 50 on which the second filter material 16 is mounted, the first and second filter positioning elements being operable independently to move the first and second filter materials independently of each other.

In this embodiment the device further comprises a support component 60 between the first and second faces, the support component comprising at least one fluid flow channel 62 therethrough. The first filter material 14 may be positioned between the first face 24 and the support component 60 and the second filter material may be positioned between the second face 28 and the support component. In this way the first and second filter materials may be clamped in place by a single operation of the clamp portions, both clamping together onto the support component.

The first and second filter materials 14, 16 are in the form of a first and second filter tapes, and the filter positioning means comprises a first and second filter positioning elements in the form of motor driven take-up reels 40, 50 to draw the filter tape from a supply reel provided in cassettes 42, 52. The filter positioning means comprise a set of features to position the first filter material, including the first take-up reel 40, a first supply cassette 42, and first tape guides 44a - 44d, and a corresponding set of features 50, 52, 54a - 54d to position the second filter material. In this embodiment typically the guides are positioned such that the portion of filter material to be clamped in the clamp head, 46, 56 is moved sideways relative to the straight line path between the guides 44b and 44c, 54b and 54c, as shown in figure 2, and so held in tension when the clamp portions are about to clamp onto the filter, to reduce the likelihood of creasing. The cassettes 42, 52 may comprise mounting features to fix them to the chassis 102, and may comprise indicators to indicate the amount of filter tape left on the supply reel. In this embodiment the faces 26, 28 are provided in a vertical orientation.

The faces 26, 28 are configured to seal against the filter material, and comprise a seal component 27, 29 in the form of an O-ring to achieve sealing. The face comprises a fluid flow region 31 , 33 within the area of the seal component or seal feature.

The support component 60 has a first support component face 66 facing the first face 26 of the first clamp portion and a second support component face 68 substantially parallel to the first facing the second face of the second clamp portion and seal components 67, 69 mounted on faces 66, 68. The support component comprises a plurality of apertures 62 through the thickness, such as an array of holes, to provide the fluid flow pathway and to support the filter material.

In use, while the clamp portions are in the open position as shown in figure 4, the filter positioning means 10, 12 operate to move the filter material parallel to the first (vertical) direction to position a portion of filter material between the faces. The faces then move in the second (horizontal) direction to clamp and seal against the filter material. A mid-way position of the clamp portions and the support component in the process of moving to the clamped position is shown in figure 3, in which the first clamp portion 22 has moved to the right towards the second clamp portion and the first filter material is in contact with the first face 26 and the first support component face 66. The first clamp portion then continues to move to the right towards the second clamp component, so moving the support component 60 to the right, and clamping the second filter material 16 between the second support component face 68 and the second face 28, as shown in figure 2. After the filtration process the operation of the clamp head is reversed to move to the configuration in figure 4 once more, to free the filter material, and the process may then repeat.

The support component is movable horizontally and is actuated by movement of the first clamp portion. The support component is mounted on the first and second clamp portions on an upper and lower shafts 64a, 64b that extend horizontally from the support component and pass through clearance holes in each clamp portion block 130, 134. Each end of each shaft has an oversize head 65a, 65b (e.g. the head of a bolt fixed into the shaft) that does not pass through the clearance holes. The support component is moved by the contact of the outer end of the clearance holes with the head. For example, in opening the clamp head, the first clamp portion moves away from the second towards the left. The left hand head 65a is pulled by the end of the clearance hole in the first clamp portion block 130, so moving the support component away from the second clamp portion. As shown in figure 9, the shaft has a length between the heads that is greater than the dimension over the two ends of the clearance holes when in the clamped position, so that the first clamp portion moves a distance before the first head 65a contacts the end of the clearance hole. In this way the first clamp portion moves away from the support component before it pulls the support component away from the second clamp portion, so centralising the support component between the faces when the clamp head is in the open position. In this embodiment the device is configured to clean the fluid flow pathway with a wash fluid and to move the clamp head in a third horizontal direction orthogonal to the first and the second directions, from the front to the back in the orientation shown in the figures and parallel to axis 35, between an operating position, as shown in figures 1 to 5, in which a filter material is positioned between the first and second clamp portions, and a wash position in which the clamp head is moved backwards from the filter materials along slides 70 by actuator 72 as is apparent in figures 5 and 6, such that the clamp portions are clear of the filter material. The clamp portions may then be moved to the clamped position, so as to allow cleaning fluid to be passed through the clamp portions to clean the fluid flow pathway without passing through a filter material.

Referring to figures 1 to 9, embodiment 1 comprises the following components and features: a housing 100, comprising a chassis 102 to support the components of the device, an inlet reservoir 104 for the liquid to be filtered, an inlet pre-filter 1 10 to remove debris, an inlet tube 1 12 and fluid actuation means in the form of a pump 1 14 to flow the liquid through the device, an outlet tube 108 and a collection vessel 106 for the filtrate, a first and second filter reel drives 1 16, 1 18 to drive the reels 40, 50, a clamp head subassembly 120 comprising slides 70 and clamp head positioning actuator 72, the clamp head being mounted on a clamp head mount 122 movable on the slides by the actuator to allow the clamp head to move in the third direction between the operating position as shown in the figures and the washing position, an upper and lower clamp portion slide 124a, 124b on which the first clamp portion 22 is movable on slide mounts 126 parallel to the second direction 25 towards the second clamp portion 24, which is mounted in a fixed position on the clamp head mount 122, a clamp actuator 128 comprising a motor mounted on the clamp head, a first clamp portion 22 comprising a clamp portion block 130 having a fluid flow channel 30 formed through it to a fluid flow region 31 defined within the area of the seal 27 on face 26, and a cover 132, a second clamp portion 24 having similar features formed within the second clamp portion block 134, and a cover 136, seals 27 and 67, 29 and 69 to seal the filter materials between the faces and the support component faces, a fluid flow pathway 34 through the device as shown in figure 9, comprising flow channel 30, fluid flow region 31 on the first clamp portion, apertures 62 through the support component 60, fluid flow region 33 on the second clamp portion and flow channel 32 - fluid connections from the inlet reservoir and pump to flow channel 30 and from flow channel 32 to the filtrate collection vessel may be made using conventional tubing and connectors (not shown), a controller 140 to control operation of the device, including the clamp head, the filter positioning means and the fluid actuation means. The controller may be computer-implemented and may comprise a computing means, a data store and a control program as known in the art.

The device may comprise one or more pressure sensors to measure the pressure of the fluid in the pathway, such as a first pressure sensor to measure the pressure upstream of the first filter material, such as in the flow channel 30, and a second pressure sensor to sense the pressure in fluid flow pathway 32 between the first and the second filter materials. The second pressure sensor may be mounted on the support component 60. The device may be configured such that the controller receives signals from a pressure sensor to control the filter positioning means.

In this way the embodiment provides an automatic means for filtering and collecting a sample under the control of the controller and a control program, for example being able to filter and collect a series of separate samples, or a single large or heavily contaminated sample in a series of separate filtration operations. The embodiment is suited for sample sizes in the range around 10ml to around 1 litre. It will be understood that by changing the inlet reservoir and filtrate collection vessel the embodiment may be used for volumes larger than this range, and that a scaled-down version of the component may be used for volumes in a smaller range, such as from around 1 ml to around 100ml. Referring to figure 10, a further embodiment 2 of the device comprises features and components as described for embodiment 1 , with the clamp head being different in that the support component 60 is omitted. In embodiment 2 the first and second filter materials both pass between the first and second faces 26, 28 on the first and second clamp portions 22, 24. The first and second filter materials 14, 16 may be moved independently.

Referring to figure 1 1 , in a further embodiment 3 the device comprises a second clamp head 220 and the filter positioning means comprises a first filter positioning element 40 on which the first filter material is mounted and a second filter positioning element 50 on which the second filter material is mounted, wherein the first filter positioning element 40 is configured to support the first filter material 14 between the clamp portions 22, 24 of the first clamp head, the second filter positioning element 50 is configured to support the second filter material 16 between the clamp portions 222, 224 of the second clamp head, and the device is configured to form a fluid flow pathway through the first and the second filter materials in series when all of the clamp portions are in the clamped position. The filter positioning means 12 comprising the filter positioning element in the form of the take-up reel 50, cassette 52 and guides 54a - 54d, as shown in figure 2, is positioned relative to the second clamp head 220 to position the second filter material 12 so that it may be received between the faces of the clamp portions 222, 224.

Figure 12 shows a flow diagram of operations that may be carried out by the device in a mode of operation in which the first filter material is a coarse filter material and the second is a fine filter material, wherein the device is configured, as part of a filtration operation, to:

measure the pressure P1 upstream of the first filter material during a filtration process, measure the pressure P2 in the flow pathway between the first and second filter materials, derive the pressure deltaP(1) across the first filter material as the difference between P1 and P2,

derive the pressure deltaP(2) across the second filter material as the value of P2, assuming that the outlet is at atmospheric pressure,

compare each measured pressure with a threshold pressure, and

control the clamp head and filter positioning means to move the first and the second filter materials independently if the respective measured pressure is above the threshold pressure.

and configured, as part of a wash operation, to:

open the clamp head, move the clamp head back from the filter materials so that the clamp portions are clear of the filter materials and close the clamp head,

flow wash liquid through the fluid flow pathway and optionally then a gas through the pathway to dry it,

open the clamp head and move the clamp head back to the operating position in which the first and second filter materials are received between the clamp portions,

advance both filter tapes to provide clean filter materials between the clamp portions, and close the clamp head ready for the next filtration operation.

The invention has been described by way of examples only and it will be appreciated that variation may be made to the above-mentioned embodiments without departing from the scope of invention. With respect to the above description then, it is to be realised that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as set out in the accompanying claims.

Claims

1 A device for filtering a fluid comprising: one or more filter positioning means on which at least a first and a second filter material are mountable, the filter positioning means being operable to move the at least first and second filter materials independently and parallel to a first direction, and at least one clamp head comprising:

a first clamp portion having a first face,

a second clamp portion having a second face,

the first and second clamp portions being mounted on the clamp head such that their faces face one another and being operable such that they may be moved one relative to another between an open position in which their faces are spaced apart and a clamped position in which the faces are closer to each other than in the open position, and

the first and second clamp portions each comprising a fluid flow channel to the face,

wherein the device is configured to form a fluid flow pathway through the at least one clamp head, and thus in use through the first and the second filter materials in series, when the first and second clamp portions are in the clamped position. 2 A device according to claim 1 wherein the one or more filter positioning means comprise a first filter positioning element on which the first filter material is mounted and a second filter positioning element on which the second filter material is mounted, the filter positioning elements being operable independently to move the first and second filter materials independently of each other.

3 A device according to any preceding claim comprising a first and a second filter materials positioned between the first and second faces of the first and second clamp portions.

4 A device according to any preceding claim comprising a support component between the first and second faces, the support component comprising at least one fluid flow channel therethrough.

5 A device according to any preceding claim further comprising a second clamp head. 6 A device according to claim 5 wherein the filter positioning means comprises a first filter positioning element on which the first filter material is mounted and a second filter positioning element on which the second filter material is mounted, wherein the first filter positioning element is configured to support the first filter material between the clamp portions of the first clamp head, the second filter positioning element is configured to support the second filter material between the clamp portions of the second clamp head, and the device is configured to form a fluid flow pathway through the first and the second filter materials in series when all of the clamp portions are in the clamped position. 7 A device according to any preceding claim wherein the filter material is in the form of a tape.

8 A device according to any preceding claim wherein the faces are provided in a vertical orientation or at an angle to vertical, the angle being in the range zero degrees to around 45 degrees.

9 A device according to any preceding claim comprising a pressure sensor to measure the pressure of the fluid in the flow pathway. 10 A device according to claim 9 comprising a first pressure sensor to measure the pressure in the flow pathway upstream of the first filter material and a second pressure sensor to measure the pressure in the flow pathway between the first and the second filter materials.

1 1 A device according to any preceding claim comprising a flow sensor to measure the flow rate of a fluid in the fluid flow pathway.

12 A device according to any preceding claim wherein the clamp head is movable relative to a position in which the filter materials are held by the filter positioning means, between an operating position in which the first and second clamp portions may receive the filter materials between them and a wash position in which the clamp portions are clear of the position of the filter materials.

13 A device according to any of claims 9 to 12 comprising a controller operable to receive a signal from a pressure or flow sensor and to control the operation of the clamp head and the filter positioning means.

14 A method of filtering a fluid using a device as described herein.

15 A method according to claim 14 comprising: providing a device as described herein comprising a first and a second filter material in which the first filter material is a coarse filter material and the second is a fine filter material,

comparing the measured pressure with a threshold pressure, and

A method according to claim 15 comprising:

comparing the measured second pressure with a threshold pressure, and

A method according to any of claims 14 to 16 comprising:

moving the clamp head such that the clamp portions are clear of the filter materials, moving the clamp portions to the clamped position, and

passing a cleaning fluid through the fluid flow pathway through the clamp head.