WO2005052550A1

WO2005052550A1 - Apparatus for collecting fluid borne particles

Info

Publication number: WO2005052550A1
Application number: PCT/GB2004/004757
Authority: WO
Inventors: Ian Michael Black; Kevin Steven Black; Peter Andrew Wilson; Sam Athey
Original assignee: Partrac Limited
Priority date: 2003-11-15
Filing date: 2004-11-11
Publication date: 2005-06-09
Also published as: GB0326669D0

Abstract

There is disclosed apparatus for collecting fluid borne particles, the apparatus of a type including a chamber for the particles and an inlet for flow of particle bearing fluid into the chamber. In one embodiment, apparatus in the form of a particle trap (10) is disclosed, the trap (10) including a housing (12) defining a chamber (14) for the particles, and at least one inlet (16) for flow of particles into the chamber (14). The trap (10) also includes at least one indicator member, in the form of a disc (18), which is adapted to be located in the chamber (14) to define an indicator layer in the particles collected in the chamber.

Description

APPARATUS FOR COLLECTING FLUID BORNE PARTICLES

The present invention relates to apparatus for collecting fluid borne particles. In particular, but not exclusively, the present invention relates to apparatus for collecting fluid borne particles, the apparatus of a type including a chamber for the particles and an inlet for flow of particles into the chamber. Various types of apparatus for collecting fluid borne particles are known. These are often referred to as particle traps, and are used principally for capturing air or water borne particles in the environment. The most basic types of particle traps originally developed were simple devices, consisting of a hollow tube which is sealed at both ends and which has holes at the sides of the tube close to the top. Used in a fluid medium such as a river or sea, particles suspended in the water pass into the trap via the holes, stall in the tube and fall down through the tube to become trapped. These particles may be fine sediments, or biological matter such as small organisms, seeds, cellular material, waste material and the like. The captured particles are then typically removed from the trap at a later date for analysis . The particles collected by the traps accumulate from the base of the tube upwards over a period of time and, whilst traps of this type provide a useful means of collecting particles, it is largely impossible to determine when a particular particle arrived and settled in the tube. This deficiency lead to the development of more advanced particle traps, such as the aquatic sediment and pollution monitors disclosed in US patent nos. 3,715,913 and 4,321,823 (Anderson). These particle monitors include a collecting tube for collecting sediment, and a dispensing device for dispensing a granular marking material at regular intervals into the collected sediment. This provides layers of marking material between layers of sediment, giving an indication of the quantity of sediment accumulated in the collecting tube during such intervals. However, the marker material is released into the stream of sediment entering the monitor, and is affected by flow currents generated within the collecting tube, leading to traces of the marker material becoming mixed in with the collected sediment layers, which causes problems in later analysis of the sediment. Furthermore, the marker material cannot be easily separated from the collected sediment for future reuse. US patent no. 5,085,085 (Anderson) discloses an alternative sediment and pollution monitor, which includes a magnifying cone and a number of collecting tubes located below the cone. The cone is arranged to feed into a single tube, and the collecting tubes are cycled at short time intervals, providing for the collection of a number of samples over an extended interval of time. However, the monitor is relatively bulky and comparatively complex, requiring a dedicated mechanism for rotating, aligning and sealing the collecting tubes relative to the cone. It is amongst the objects of embodiments of the present invention to obviate or mitigate at least one of the foregoing disadvantages . According to a first aspect of the present invention, there is provided apparatus for collecting fluid borne particles, the apparatus comprising: a housing defining a chamber for the particles; at least one inlet for flow of particles into the chamber; and at least one indicator member adapted to be located in the chamber to define an indicator layer in the particles collected in the chamber. The invention provides apparatus for collecting fluid borne particles which offers advantages over prior apparatus. In particular, the indicator member provides clearly defined layers within the collected particles and thus improved determination of results; is easily removed without contaminating the collected particles; and can readily be reused. Furthermore, the apparatus is of relatively simple construction. The particles typically comprise granular materials, sediments or the like, such as soil, rock or clay based materials; biological matter such as relatively small organisms, seeds, cellular material, waste material; and/or solid chemical waste/by-product materials, combustion by-products and the like, as may be found in an aqueous environment, or indeed in the air. As will be described, embodiments of the invention are designed to collect fluid borne particles falling out of suspension from a carrying fluid. Other embodiments of the invention are designed such that particle bearing fluid flows into the chamber or other parts of the apparatus, whereupon the particles stall and fall out of the fluid and collect within the chamber. The apparatus may be adapted to be located in an aquatic/marine medium/environment, and may therefore take the form of an aquatic apparatus for collecting waterborne particles. The apparatus may be adapted to be located in a fluid flow or generally static fluid environment, such as in a river, sea or ocean, or in a lake or reservoir. However, it will be understood that the apparatus may equally be used to collect particles in alternative environments, such as in alternative liquids, or indeed to collect airborne particles. The indicator member may be adapted to fall under gravity within the chamber to rest upon collected particles present in the chamber, to thereby define an indicator layer. It will therefore be understood that further particles collected within the chamber may rest upon the indicator member such that the member defines a clear indicator layer between adjacent layers of collected particles. Preferably, the indicator member is initially located outside the chamber and is adapted to be moved into the chamber. The indicator member may be initially located laterally spaced relative to the chamber. The chamber may include an opening adapted to receive the indicator member, and the indicator member may be adapted to be moved to a position adjacent the opening, and/or through the opening, for location in the chamber. Alternatively, the indicator member may be initially located at least partly, optionally entirely within the chamber and may be adapted to be moved within the chamber to a location defining the indicator layer. For example, the indicator member may be stored at or towards an upper end of the chamber, and may be adapted to be moved or released to move down the chamber to a location defining an indicator layer. The indicator member may be shaped to correspond to an internal shape of the chamber. Thus when the indicator member is located in the chamber to define an indicator layer, the indicator member may form a close fit within the chamber. Accordingly, the indicator member may be of the same or a similar shape to an internal shape of the chamber, but of smaller dimensions. In a preferred embodiment of the invention, the chamber and the indicator member may be circular in cross section, which may facilitate location of the indicator member in. the chamber. Preferably, the apparatus comprises a plurality of indicator members. The indicator members may be mounted in a magazine or store coupled to or provided integrally with the housing. The indicator members may be adapted to be located in the chamber at spaced time intervals, and the apparatus may include a controller for controlling location of the indicator members in the chamber. The indicator members may be adapted to be located in the chamber at predetermined time intervals. Additionally or alternatively, the indicator members may be adapted to be located in the chamber in response to detection of at least one parameter, or a change in said at least one parameter. This parameter/change in parameter: may be measured by the controller, which may be adapted to generate a corresponding control signal to locate an indicator member in the chamber. For example, the at least one parameter may be selected from the group comprising a measured temperature, pressure, flow rate of fluid past or through the apparatus/fluid turbidity, rotational orientation or tilt of the apparatus, fluid salinity and depth within a body of fluid. The apparatus may include at least one sensor for measuring said parameter of the fluid and/or of the apparatus. The apparatus may also include a processor for storing data relating to the measured parameter. The apparatus may further comprise an actuating mechanism for locating the indicator member in the chamber. The actuating mechanism may include an actuating member for controlling location of the indicator member in the chamber. The actuating mechanism may be adapted to exert a force on the indicator member to locate the indicator member in the chamber. The actuating member may take the form of an arm, leg, finger or the like. Where the chamber includes an opening adapted to receive the indicator member, the actuating mechanism may be adapted to transport the indicator member to a position adjacent the opening and/or through the opening, to locate the indicator member within the chamber. The actuating mechanism may be located laterally spaced from the chamber, and the actuating member may be adapted to translate or otherwise move the indicator member relative to the chamber to locate the indicator member in the chamber. Alternatively, where the indicator member is initially located within the chamber, the actuating member may be adapted to restrain the indicator member, and may be movable between a restraint position and a release position, to release the indicator member and allow movement of the indicator member within the chamber to a location defining an indicator layer. Thus the actuating member may be arranged to release the indicator member, allowing the indicator member to fall within the chamber. The actuating mechanism may include a driver for moving the actuating member, to locate the indicator member within the chamber. The driver may be adapted to generate a rotational drive force, and the actuating mechanism may include a drive link coupling the driver to the actuating member, for converting the generated rotational drive force of the driver into a translation or other force for translating/moving the indicator member relative to the chamber. The driver may comprise a motor, such as an electric motor, or any other suitable driver capable of generating a rotational drive force. Preferably, the apparatus comprises an inlet assembly defining the inlet and a flow passage for flow of particles into the chamber. In one embodiment, the inlet assembly comprises a generally conical or other divergent particle collector which defines the inlet (the collector diverging towards the inlet) , for collecting particles and directing said particles into the chamber. A particle collector of this type may have a utility for collecting particles falling vertically (or substantially vertically) out of suspension from a particle bearing fluid. Particle collectors of this type may be of particular use in relatively low fluid flow rate environments, such as lakes or low tidal flow areas. It will be understood that making the particle collector conical/divergent may optimise particle collection in such environments. In another embodiment, the inlet assembly comprises a particle collector having a collector housing defining the inlet, the housing converging towards the inlet. The velocity of particle bearing fluid flowing into the collector through the inlet may reduce, causing the fluid to stall such that particles fall out of suspension from the fluid and collect in the chamber. The inlet may be aligned with a direction of flow of fluid through/past the apparatus, and may be directed substantially horizontally/parallel to a surface of the fluid. A particle collector of this type may have a particular utility for collecting particles in high fluid flow rate environments, such as in a river or high tidal flow area. The diameter/area of the inlet may be selected according to parameters including anticipated fluid flow rate through the inlet. For example, for a relatively high fluid flow rate, a collector having a relatively small diameter/area inlet may be selected. This may assist in preventing the chamber from filling with particles in a short time period. The inlet assembly may be releasably couplable to the housing;, for example, in a push or screw fit. This may facilitate provision of an inlet assembly suited to a particular fluid environment. The apparatus may include an outlet for flow of fluid out of the apparatus. The inlet assembly, in particular the particle collector, may define the outlet. Alternatively, the inlet and/or outlet may be defined by a wall of the chamber. The inlet may thus open directly into the chamber. Preferably, the inlet and the outlet are offset/staggered, and may be at least partly misaligned relative to a direction of flow of fluid past or through the apparatus. Where the inlet and outlet are defined by the chamber wall, this may facilitate collection of particles in the chamber by ensuring that there is no direct flow path for fluid through the apparatus. Thus particle bearing fluid entering the chamber through the inlet will tend to impinge upon an opposite wall of the chamber, enhancing the effect of particles falling out of suspension from the fluid. The inlet and the outlet may be spaced along a length/height direction of the chamber and/or rotationally spaced. The apparatus may include a plurality of inlets and/or outlets. In alternative embodiments, the apparatus may comprise an inlet tube or the like defining the inlet, the inlet tube adapted to define a flow passage for flow of particle bearing fluid into the chamber. The apparatus may include a flow restrictor, baffle or the like, such as a plate or disc, which may be located in a flow path extending from the inlet, such that fluid entering the inlet impinges on the baffle. This may facilitate particle collection by slowing the fluid. The baffle may be movable between a position where the baffle causes a minimal obstruction to fluid flow and a position where the baffle causes maximal obstruction. The baffle may be located in a position suited to a particular fluid flow environment. For example, in a high fluid flow rate environment, the baffle may be located in a position causing a relatively large obstruction, to slow the fluid and assist particle collection. In a lower fluid flow rate environment, it may not be necessary to slow the fluid to such a degree, and the baffle may be located in a position causing a relatively small obstruction. The baffle may be mounted in the chamber or provided as part of the inlet assembly. The apparatus may be adapted to rotate about an axis of the apparatus to face a direction of fluid flow, and thus to position the inlet facing towards, and thus in the path of fluid flow towards the apparatus. The apparatus may include a positioning member such as a fin, vane or the like for positioning the apparatus relative to a direction of fluid flow. This facilitates use of the apparatus in fluid flow environments, where the direction of fluid flow relative to the apparatus varies over time, for example, due to variations in weather conditions or tidal flow. The positioning member may be coupled to or may form part of the housing. The apparatus and/or the positioning member may be streamlined, which may reduce drag forces exerted on the apparatus. The positioning member may be releasable, and may be releasably coupled to the housing. This may allow the positioning member to be released, to reduce weight, if not required. The apparatus may be adapted to be at least partly located below ground level, for example, below sea, river or lake-bed level . This may facilitate collection of particles at or near said bed level. At least part of the housing may be buried. The chamber may be at least partly filled with a fluid comprising a biological material preservative and/or a biological material marker. The preservative may be Formaldehyde and the marker may be ROSE BENGAL

(TM) , which may label collected biological particles.

The density of the preservative/marker may be greater than that of the particle bearing fluid. This may avoid the preservative/marker being washed out of the chamber. According to a second aspect of the present invention, there is provided apparatus for collecting fluid borne particles, the apparatus comprising: a housing defining a chamber for the particles; at least one inlet for flow of particles into the chamber; and at least one outlet for flow of fluid out of the chamber, the inlet and the outlet being misaligned relative to a direction of fluid flow past the apparatus. According to a third aspect of the present invention, there is provided a method of collecting fluid borne particles, the method comprising the steps of: locating an apparatus for collecting fluid borne particles in a fluid environment such that particles enter an inlet of the apparatus and fall into a chamber of the apparatus; and locating an indicator member in the chamber to define an indicator layer in the collected particles. Preferably, the method further comprises locating a plurality of indicator members in the chamber and may comprise locating members in the chamber at defined time intervals or in response to measurement or detection of a selected at least one parameter, or a change in said parameter. According to a fourth aspect of the present invention, there is provided apparatus for collecting fluid borne particles, the apparatus comprising: a housing defining a chamber for the particles; at least one inlet for flow of particle bearing fluid into the chamber; and at least one indicator member adapted to be located in the chamber to define an indicator layer in the particles collected in the chamber. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of apparatus for collecting fluid borne particles, in accordance with an embodiment of the present invention; Fig. 2 is a perspective view of an indicator member forming part of the apparatus of Fig. 1; Fig. 3 is a side view of a stack of the indicator members of Fig. 2; Fig. 4 is a schematic cross-sectional side view of part of the apparatus of Fig. 1 in use, during collection of particles; Figs. 5 and 6 are top and side views, respectively, of a lower housing portion forming part of the apparatus of Fig. 1; Figs. 7 and 8 are side and bottom views of a lower cap forming part of the apparatus of Fig. 1; Figs. 9 and 10 are top and side views, respectively, of part of an upper housing portion forming part of the apparatus of Fig. 1; Fig. 11 is a view of a motor case of said part of the upper housing portion of Figs. 9 and 10; Figs. 12 and 13 are top and side views, respectively, of an upper cap forming part of the apparatus of Fig. 1; Figs. 14 and 15 are top and side views, respectively, of a further part of an upper housing portion forming part of the apparatus of Fig. 1; Fig. 16 is a schematic cross-sectional view of a pressure compensator forming part of the apparatus of Fig. 1; Fig. 17 is a view of part of a vane forming part of the apparatus of Fig. 1; Fig. 18 is a view of the apparatus of Fig. 1, drawn to a smaller scale and showing a mooring/anchoring assembly for the apparatus; Fig. 19 is a perspective view of apparatus for collecting fluid borne particles, in accordance with a preferred embodiment of the present invention; Figs. 20 and 21 are top and side views, respectively, of a lower housing portion forming part of the apparatus of Fig. 19; Figs. 22 and 23 are top and side views, respectively, of part of an upper housing portion forming part of the apparatus of Fig. 19; Figs. 24 and 25 are top and side views, respectively, of a further part of an upper housing portion forming part of the apparatus of Fig. 19; Fig. 26 is a schematic side view of an inlet assembly forming part of the apparatus of Fig. 19; Fig. 27 is a schematic side view of an alternative inlet assembly, forming part of the apparatus of Fig. 19; Fig. 28 is a perspective view of apparatus for collecting fluid borne particles, in accordance with an alternative embodiment of the present invention; and Fig. 29 is a schematic cross-sectional side view of part of the apparatus of Fig. 28 in use, during collection of particles. Turning firstly to Fig. 1, there is shown apparatus for collecting fluid borne particles in accordance with an embodiment of the invention, the apparatus indicated generally by reference numeral 10. The apparatus 10 is suitable for use in collecting any fluid borne particles, whether liquid or airborne, but has a particular utility in collecting waterborne particles. Such particles may be found in rivers, seas, lakes, oceans and the like, and typically comprise granular materials, sediments or the like (such as soil, rock or clay based materials) , biological matter such as relatively small organisms, seeds, cellular material, waste material, and solid chemical waste/by—product materials, combustion byproducts and the like. The apparatus 10 is used to collect the particles in order, for example, to determine levels of pollutants present by measuring quantities of a particular contaminant such as waste (animal or human) ; levels of sediment deposited into a river course; or to track flow of particles into a sensitive area released from an off site location. The apparatus 10 takes the form of a particle trap and includes a housing 12 defining a chamber 14 for the particles, and at least one inlet 16 for flow of particles into the chamber 14. The apparatus also includes at least one indicator member 18, shown in the perspective view of Fig. 2, which is adapted to be located in the chamber 14 to define an indicator layer in the particles collected in the chamber. A stack of the indicator members 18 is also shown in the side view of Fig. 3. Fig. 4 is a cross-sectional schematic view of the chamber 14 of the apparatus 10 in use, during collection of particles 20, and illustrates a number of the indicator members 18 defining indicator layers 22 within the collected particles 20. The particle trap 10 and its method of operation will now be described in more detail. The housing 12 of the trap 10 includes a tube 24 which defines the chamber 14. The length and diameter of the tube 24 is set according to anticipated conditions of use of the trap 10, such as deployment depth within a body of water, duration of deployment, and anticipated volumes of collected particles. The tube 24 includes four spaced inlets 16 for flow of particle bearing fluid into the chamber 14, and an outlet 26 spaced around the circumference of the tube 24 from the inlets 16, positioned generally opposite to the inlets. The inlets 16 and the outlet 26 are relatively spaced along a length of the tube 24 and thus offset, such that there is no direct flow path for fluid through the chamber 14, as shown in the schematic view of Fig. 4. Accordingly, particles entering from one side of the tube 24 through the inlets 16 cannot pass out through the outlet 26 on the other side of the tube. This assists in causing the fluid flowing into the chamber 14 to stall, such that particles 20 in the fluid fall out of suspension, as indicated by the arrow A. The chamber 14 optionally contains a preservative such as formaldehyde, and a biological material marker such as ROSE BENGAL (TM) . The preservative assists in preventing deterioration of collected biological particles, whilst the marker serves for labelling the particles. The preservative/marker mixture is typically of a greater density than the particle bearing fluid. The tube 24 is coupled at a lower end to a lower housing portion 28, and at an upper end to an upper housing portion indicated generally by reference numeral 30. The tube 24 includes an upper opening 32, through which the indicator members 18, which take the form of discs, enter the chamber 14. The lower housing portion 28 is shown in more detail in the top and side views of Figs. 5 and 6, respectively, and includes a sealed battery case 34 containing a permanent rechargeable battery pack 36, which supplies all onboard power requirements for the trap 10. A cap 42, shown in the side and plan views of Figs. 7 and 8, is provided at a lower end of the tube 24 for closing the tube, and the cap 42 is fixed to the bottom 44 of the lower housing portion 28 by releasable catches 46. The cap 42 serves for clamping the tube 24 in the housing 12, and allows removal of the tube to gain access to the collected particles 20, as will be described below. The upper housing portion 30 comprises a disc actuator casing 48, which is shown in more detail in the top and side views of Figs. 9 and 10. The casing 48 carries an actuating mechanism 50 for locating the discs 18 in the chamber 14, which includes an actuating arm or blade 52, a driver in the form of a motor 54, a drive wheel 56 and a drive link arm 58. The motor 54 is located in a sealed motor case 60, shown in more detail in Fig. 11, and which is mounted on the top 62 of the actuator casing 48. The link arm 58 is connected off- centre to the drive wheel 56 at one end, and at the other end to the arm 52. When the motor 54 is activated, the drive wheel 56 rotates, translating the actuating arm 52 back and forth in a reciprocating fashion, in the direction of the arrows B-C. The actuator casing 48 also carries a magazine 64, which stores a number of the discs 18, stacked as shown in Fig. 3, which is closed by a cap 38 shown in the top and side views of Figs. 12 and 13, coupled to the magazine 64 by bolts/screw 40. The cap 38 allows for resupply of additional discs 18 to the magazine 64. A lowermost disc 18 initially rests on the actuator arm 52. When the motor 54 is activated, the arm 52 is retracted clear of the magazine 64 such that the disc drops down and rests against a bottom lip 66 of the actuator casing 48. When the arm 52 travels forward again to the position of Fig. 10, the lowermost disc 18 is pushed forwards and falls under gravity into the passage 68. The actuator casing 48 is coupled to an electronics casing 70, shown in the top and side views of Figs. 14 and 15, respectively. The electronics casing 70 houses an electro compass board 72 which measures rotational and tilt orientation of the trap 10, and a cpu 74, which stores directional and tilt angle data measured by the compass board 72 throughout a deployment period of the trap 10. This allows the facing direction of the trap 10 and thus the direction of current flow to be determined. The cpu 74 controls operation of the actuating mechanism 50, and includes a serial interface port (not shown) for connection to a personal computer, both for downloading stored data, and for uploading appropriate software to the cpu. The compass board 72 and cpu 74 are provided in a sealed, oil filled unit 76, which is coupled via oil line 78 to a pressure compensator 80 shown in Fig. 1, and also in more detail in Fig. 16. The battery case 34 and motor case 60 are also sealed, oil filled and coupled to the compensator 80 through the line 78, and thus sealed. The compensator 80 includes a smpply of oil 82, which is pressurised by a compensator piston 84 through a spring 86, and by opening a chamber 87 to external fluid pressure by a one-way valve 88. The oil 82 in the battery case 34, motor case 60 and the unit 76 is thus pressurised to above external water pressure. Thus, in the event of failure of any seals, there would be a positive flow of oil, thereby preventing water ingress. To allow for this, the compensator 80 contains a sufficient supply of oil to account for any leaks of oil from the case 34, motor case 60 or unit 76. The disc passage 68 continues through the casing 70, which receives the end of the tube 24, and thus allows the disc 18 to fall into the tube 24 and therefore the chamber 14, as will be described below. Also, as will be noted from Fig. 1, the trap 10 is generally streamlined to reduce drag on the trap due to current flow. However, in addition, the housing 12 includes a positioning member in the form of a fin or vane 90, shown also in Fig. 17, which assists in rotating the trap 10 to face towards the flowing fluid, thus facing the inlets 16 towards the oncoming fluid, ensuring particle bearing fluid enters the trap 10. As shown in Fig. 18, the trap 10 is suspended in the water between a buoy at surface and an anchor on the seabed (not shown) via lines 92 and 94, respectively. The trap 10 includes front and back connecting rods 96 and 98 which bear the forces exerted by the buoy and anchor, ensuring that the loads are not transmitted to the trap housing 12. The rod 98 also acts as a support for the vane 90 and acts as a carry handle. To allow the trap 10 to rotate in the water, the rods 96 and 98 carry shackle eyes 100 which are connected to swivels 102, 104 and thus to the respective lines 92, 94. The trap 10 can thus rotate relative to the lines 92, 94 by the swivels 102, 104. In use, the trap 10 is deployed in an aqueous environment, such as the sea, suspended and anchored as described above. The trap 10 rotates in the flow of water to direct the inlets 16 towards the oncoming water. Water enters the trap 10 through the inlets 16 and particles 20 in the water fall out of suspension and collect in the chamber 14, as shown in Fig. 4. At a predetermined time interval, the cpu 74 activates the motor 54 to retract and extend the actuating arm 52, pushing a first disc 18a (Fig. 4) into the passage 68, and the disc 18 falls under gravity into the chamber 14, settling on the collected particles 20. Further particles 20 then settle on top of the first disc 18a. The first disc 18a thus defines a first indicator layer 22a in the particles, separating the particles into first and second particle layers 106a, 106b. After a further predetermined time interval, the cpu 74 again activates the motor 54 to release a further disc 18b, which settles on the particles 20 to define a further indicator layer 22b, and the process is repeated by locating further discs 18c, d and e over further time intervals. It will be understood that any suitable number of discs 18 may be dropped into the chamber 14 according to the requirements of a particular collection procedure. At the end of the procedure, the trap 10 is recovered, and the tube 24 is released from the housing portions 28, 30 by releasing the catches 46 and removing the base cap 42. The collected particle sample core then either simply slides out of the bottom of the tube 24 onto a collecting platform, or is pushed out from the top of the tube 24 using a plunger. Alternatively, the entire volume of collected particles 20 can be pushed into a second tube of the same diameter and length. The time interval between release of the discs may be a period of anything from minutes up to a year or more, depending upon the requirements of the procedure. It will therefore be understood that the indicator layers 22 formed in the collected particles 20 provide a clear indication of the time period when specific particle layers 106 collected in the chamber 14. For example, the time intervals between release of the discs 18 may be one day. Thus the particles 20 in the first layer 106a are collected during the first day, those in the second layer 106b during the second day, and so on. This provides an accurate picture of the time periods when the particles were collected to an operator. Turning now to Fig. 19, there is shown a perspective view of apparatus for collecting fluid borne particles, in accordance with a preferred embodiment of the present invention. The apparatus takes the form of a particle trap and is indicated generally by reference numeral 10' . Like components of the trap 10' with the trap 10 of Figs. 1-18 share the same reference numerals, with the addition of the suffix ' . Only trie differences between the trap 10' and the trap 10 will be described in detail herein. The trap 10' is also shown in Figs. 20-25, in which:

Figs. 20 and 21 are top and side views, respectively, of a lower housing portion 28' (similar to the views of the trap 10 in Figs. 5 and 6); Figs. 22 and 23 are top and side views, respectively, of part of an upper housing portion 30' (similar to the views of the trap 10 in Figs. 9 and 10); and Figs. 22 and 23 are top and side views, respectively, of a further part 70' of an upper housing portion (similar to the views of the trap 10 in Figs. 14 and 15) . The trap 10' includes a magazine 64' for the discs 18 which is further spaced from the chamber 14' . This enables coupling of an indicator assembly, such as the assembly 108 shown in Fig. 26, to an uppermost opening 32' . The indicator assembly 108 includes a particle collector 110 in the form of a divergent cone. The cone 110 includes an opening which defines the trap inlet 16' , and a flow path for flow of particles into the chamber 14' . The particle collector 110 includes a screw- threaded connector 112 which mates with the aperture 32' , for connecting the collector to an upper plate 114 of the trap 10' . The particle collector 110 has a particular utility for collecting particles 20 falling vertically into the trap 10' . The collector 110 thus has a particular use in relatively low fluid flow rate environments, such as in a lake or in a relatively low tidal force area of a sea or ocean. The trap 10' may optionally include an outlet (not shown) , however, this may not be required when collecting particles using the collector 110. An alternative inlet assembly 116 is shown in Fig. 27, which includes a particle collector 118. The particle collector 118 has a screw-threaded connector 120, similar to the connector 112. However, the collector 118 comprises a housing which includes an opening defining the trap inlet 16', and the housing has a generally conical portion 121, which diverges from the opening 16' towards an inner area 122. The housing 118 also includes an opening forming an outlet 26' of the trap 10' . In use, particle bearing fluid entering the inlet 16' slows as it enters the conical portion 121 and stalls in the area 122, such that particles 20 fall down through the housing 118 and into the chamber 14' . Fluid exits the collector housing 118 through the outlet 26' , which is misaligned with the inlet 16' . The inlet assembly 116 has a particular utility in areas of relatively high fluid flow rate, such as in a river or high tidal flow rate area of a sea or ocean, and is intended for collecting horizontally transported particles. The collector 118 is provided with an outlet 16' of a diameter or area suited to a particular fluid flow environment. For example, in a relatively high fluid flow rate (high turbity) environment, the diameter or area of the inlet 16'- is made relatively small, such that the particle chamber 14' does not fill over a relatively small time period. Conversely, in environments of a lower fluid flow rate, a collector 118 having an inlet 16' of a larger diameter or area may be provided. It will be noted that the inlet assemblies 108, 116 are interchangeable such that the trap 10' may be provided with an inlet assembly suited to a particular fluid flow environment. Indeed, a trap including a number of collectors may be provided and may, for example, include both of the collectors 110, 118. Also, the particle collectors 110, 118 may optionally be designed to push-fit into the opening 32' . The trap 10' also includes a cap 115, which closes an aperture 117 in the upper plate 114, to facilitate reloading of the magazine 64' with further discs 18, and is secured by a strap 119. Turning now to Fig. 28, there is shown a perspective view of apparatus for collecting fluid borne particles in accordance with an alternative embodiment of the present invention. The apparatus takes the form of a trap and is indicated generally, by reference numeral 10' ' . Like components of the trap 10'' with the trap 10 of Figs. 1- 18 share the same reference numerals, with the addition of the suffix ". However, it will be noted that the trap 10'' has a structure similar to the trap 10' of Figs. 19-27. Only the differences between the apparatus 10'' and the apparatus 10' will be described herein. In place of the inlet assembly of the trap 10' , the trap 10'' includes an inlet 16'' and an outlet 26'' in the wall of an upper part of the chamber 14'', similar to the trap 10 of Figs. 1-18. The trap 10" includes a flow restrictor or baffle 124 which is mounted in the upper portion of the chamber 14''. The baffle 124 includes a disc 126 which is mounted via a shaft 128 to the chamber 14' wall, which permits rotation of the disc between a position defining a minimal obstruction to fluid flow, and a position defining a maximal obstruction to fluid flow through the inlet 16''. The disc 126 is shown in the maximal obstruction position in Fig. 28, where a surface of the disc 126 is located with its circular surface facing the inlet 16' ' . It will be understood that in the minimal flow restriction position, the disc 126 is tilted such that an edge 130 faces the inlet 16''. In Fig. 29, the disc 126 is shown in a position between said minimal and maximal flow restriction positions. It will be noted that fluid flowing into the chamber 14' impinges upon the plate 126, stalling and causing particles 20 to fall out of suspension, as indicated by the arrow B. The trap 10' ' includes a cap 132 located in the aperture 32'' and secured by the strap 119, to close the upper end of the chamber 14''. Various modifications may be made to the foregoing without departing from the spirit or scope of the invention. For example, the apparatus may include attachment points for attaching a number of other complimentary instruments to measure other environmental parameters, both in aqueous and terrestrial environments. The apparatus may equally be used to collect particles in alternative environments, such as in alternative liquids, or indeed to collect airborne particles . The indicator member may be initially located at least partly, optionally entirely within the chamber and may be adapted to be moved within the chamber to a location defining the indicator layer. For example, the indicator member may be stored at or towards an upper end of the chamber, and may be adapted to be moved or released to move down the chamber^' to a location defining an indicator layer. The indicator member may be of any suitable alternative shape/dimensions other than circular. The indicator members may be adapted to be located in the chamber in response to detection of at least one parameter, or a change in said at least one parameter. This parameter/change in parameter may be measured by the controller, which may be adapted to generate a corresponding control signal to locate an indicator member in the chamber. For example, the at least one parameter may be selected from the group comprising a measured temperature, pressure, flow rate of fluid past or through the apparatus, rotational orientation or tilt of the apparatus, depth within a body of fluid, Ph and a level of dissolved oxygen present within the fluid. The apparatus may include at least one sensor for measuring said parameter of the fluid and/or of the apparatus. The apparatus may also include a processor for storing data relating to the measured parameter. Where the indicator member is initially located within the chamber, the actuating member may be adapted to restrain the indicator member, and may be movable between a restraint position and a release position, to release the indicator member and allow movement of the indicator member within the chamber to a location defining an indicator layer. Thus the actuating member may be arranged to release the indicator member, allowing the indicator member to fall within the chamber. The apparatus may comprise an inlet tube or the like defining the inlet, the inlet tube adapted to define a flow passage for flow of particle bearing fluid into the chamber . The apparatus may be adapted to be at least partly located below ground level, for example, below sea, river or lake-bed level. This may facilitate collection of particles at or near said bed level. At least part of the housing may be buried to facilitate location of said part of the apparatus below ground^' level .

Claims

1. Apparatus for collecting fluid borne particles, the apparatus comprising: a housing defining a chamber for the particles; at least one inlet for flow of particles into the chamber; and at least one indicator member adapted to be located in the chamber to define an indicator layer in the particles collected in the chamber.

2. Apparatus as claimed in claim 1, wherein the indicator member is adapted to fall under gravity within the chamber to rest upon collected particles, to thereby define an indicator layer.

3. Apparatus as claimed in either of claims 1 or 2, wherein the indicator member is initially located outside the chamber and is adapted to be moved into the chamber.

4. Apparatus as claimed in claim 3, wherein the indicator member is initially located laterally spaced relative to the chamber.

5. Apparatus as claimed in any preceding claim, wherein the chamber includes an opening adapted to receive the indicator member, and wherein the indicator member is adapted to be moved through the opening, for location in the chamber.

6. Apparatus as claimed in either of claims 1 or 2, wherein the indicator member is initially located at least partly within the chamber and is adapted to be moved within the chamber to a location defining the indicator layer.

7. Apparatus as claimed in claim 6, wherein the indicator member is stored at an upper end of the chamber, and is adapted to be fall down the chamber to a location defining an indicator layer.

8. Apparatus as claimed in any preceding claim, wherein the indicator member is shaped to correspond to an internal shape of the chamber.

9. Apparatus as claimed in any preceding claim, comprising a plurality of indicator members.

10 . Apparatus as claimed in claim 9 , wherein the indicator members are stored in a magazine coupled to the housing .

11 . Apparatus as claimed in either of claims 9 or 10 , wherein the indicator members are adapted to be located in the chamber at spaced time intervals .

12 . Apparatus as claimed in any one of claims 9 to 11, wherein the indicator members are adapted to be located in the chamber in response to detection of at least one parameter .

13. Apparatus as claimed in any one of claims 9 to 13, wherein the indicator members are adapted to be located in the chamber in response to detection of a change in at least one parameter .

14. Apparatus as claimed in either of claims 12 or 13, wherein said parameter is selected from the group comprising a measured temperature; pressure; flow rate of particle bearing fluid; rotational orientation of the apparatus; particle bearing fluid salinity; depth of the apparatus within a body of fluid; Ph; and dissolved oxygen.

15. Apparatus as claimed in any one of claims 12 to 14, comprising at least one sensor for measuring said parameter.

16. Apparatus as claimed in any one of claims 12 to 15, comprising a processor for storing data relating to the measured parameter.

17. Apparatus as claimed in any preceding claim, comprising a controller for controlling location of the indicator members in the chamber.

18. Apparatus as claimed in claim 17, when dependent upon claim 12 or 13, wherein said parameter is detected by the controller, and wherein the controller is adapted to generate a corresponding control signal to cause an indicator member to be located in the chamber.

19. Apparatus as claimed in any preceding claim, comprising an actuating mechanism for locating the indicator member in the chamber.

20. Apparatus as claimed in claim 19, wherein the actuating mechanism includes an actuating member adapted to exert a force on the indicator member to locate the indicator member in the chamber.

21. Apparatus as claimed in either of claims 19 or 20, comprising an opening adapted to receive the indicator member, and wherein the actuating mechanism is adapted to transport the indicator member to a position adjacent the opening, to locate the indicator member within the chamber.

22. Apparatus as claimed in any one of claims 1 to 18, wherein the indicator member is initially located within the chamber, and wherein the apparatus comprises an actuating member adapted to restrain the indicator member, the actuating member movable between a restraint position where the actuating member restrains the indicator member, and a release position where the indicator member is released to facilitate movement of the indicator member within the chamber to a location defining an indicator layer.

23. Apparatus as claimed in any one of claims 20 to 22, wherein the actuating mechanism includes a driver for moving the actuating member, to locate the indicator member within the chamber.

24. Apparatus as claimed in claim 23, wherein the driver is adapted to generate a rotational drive force, and the actuating mechanism includes a drive link coupling the driver to the actuating member, for converting the generated rotational drive force of the driver into a translation of the actuating member.

25. Apparatus as claimed in any preceding claim, comprising an inlet assembly defining the inlet and a flow passage for flow of particles into the chamber.

26. Apparatus as claimed in claim 25, wherein the inlet assembly comprises a generally conical particle collector which defines the inlet, for collecting particles and directing said particles into the chamber.

27. Apparatus as claimed in any one of claims 1 to 25, wherein the inlet assembly comprises a particle collector having a collector housing defining the inlet, the housing converging towards the inlet.

28. Apparatus as claimed in claim 27, wherein the inlet is aligned with a direction of flow of fluid past the apparatus .

29. Apparatus as claimed in either of claims 27 or 28, wherein the area of the inlet is selected according to the anticipated flow rate of fluid therethrough.

30. Apparatus as claimed in any one of claims 25 to 29, wherein the inlet assembly is releasably couplable to the housing.

31. Apparatus as claimed in any preceding claim, comprising an outlet for flow of fluid out of the apparatus.

32. Apparatus as claimed in claim 31, wherein the inlet and the outlet are at least partly misaligned relative to a direction of flow of fluid past the apparatus.

33. Apparatus as claimed in either of claims 31 or 32, when dependent on claim 25, wherein the inlet assembly defines the outlet.

34. Apparatus as claimed in either of claims 31 or 32, wherein the inlet and the outlet are defined by a wall of the chamber, such that particle bearing fluid entering the chamber through the inlet impinges upon an opposite surface of the chamber.

35. Apparatus as claimed in any one of claims 31, 32 or 33, wherein the inlet and the outlet are spaced along a length of the chamber.

36. Apparatus as claimed in any one of claims 31, 32, 33, or 35, wherein the chamber is cylindrical, and wherein the inlet and the outlet are rotationally spaced around the chamber.

37. Apparatus as claimed in any preceding claim, comprising a flow restrictor located in a flow path extending from the inlet, such that fluid entering the inlet impinges on the flow restrictor.

38. Apparatus as claimed in claim 37, wherein the baffle is movable between a position where the flow restrictor causes a minimal obstruction to fluid flow and a position where the flow restrictor causes a maximal obstruction to fluid flow.

39. Apparatus as claimed in either of claims 37 or 38, where the flow restrictor is mounted in the chamber.

40. Apparatus as claimed in either of claims 37 or 38, when dependent upon claim 25, where the flow restrictor is provided as part of the inlet assembly.

41. Apparatus as claimed in any preceding claim, wherein the apparatus is adapted to rotate to face a direction of fluid flow, to position the inlet facing towards and thus in the path of fluid flow towards the apparatus.

42. Apparatus as claimed in claim 41, comprising a vane for positioning the apparatus relative to a direction of fluid flow.

43. Apparatus as claimed in any preceding claim, wherein the apparatus is adapted to be at least partly located below ground level, to facilitate collection of particles at or near said ground level.

44. . Apparatus as claimed in any preceding claim, wherein the chamber is at least partly filled with a fluid comprising a biological material preservative.

45. Apparatus as claimed in any preceding claim, wherein the chamber is at least partly filled with a biological material marker.

46. Apparatus as claimed in either of claims 44 or 45, wherein the density of said fluid is greater than that of the particle bearing fluid.

47. Apparatus as claimed in any preceding claim, wherein the apparatus is adapted to be located in an aquatic environment for collecting waterborne particles.

48. Apparatus as claimed in any one of claim 1 to 46, wherein the apparatus is adapted to collect airborne particles .

49. Apparatus for collecting fluid borne particles, the apparatus comprising: a housing defining a chamber for the particles; at least one inlet for flow of particles into the chamber; and at least one outlet for flow of fluid out of the chamber, the inlet and the outlet being misaligned relative to a direction of fluid flow past the apparatus.

50. A method of collecting fluid borne particles, the method comprising the steps of: locating an apparatus for collecting fluid borne particles in a fluid environment such that particles enter an inlet of the apparatus and fall into a chamber of the apparatus; and locating an indicator member in the chamber to define an indicator layer in the collected particles.

51. A method as claimed in claim 50, comprising locating indicator members in the chamber at defined time intervals .

52. A method as claimed in claim 50, comprising locating indicator members in the chamber in response to measurement or detection of a selected at least one parameter, or a change in said parameter.

53. Apparatus for collecting fluid borne particles, the apparatus comprising: a housing defining a chamber for the particles; at least one inlet for flow of particle bearing fluid into the chamber; and at least one indicator member adapted to be located in the chamber to define an indicator layer in the particles collected in the chamber.