This invention relates to a method and to apparatus for distributing a liquid. It is particularly, but not exclusively, concerned with the distribution of samples of waste waters so as to obtain representative portions of liquid from which its average composition can be determined.

When sampling a flowing liquid, such as waste waters from a drain, a common requirement is to establish its average composition over a specific period of time, such as over a twenty four hour period. This is normally achieved by aggregating a set of individual sub-samples taken with sufficient frequency to include all the effect of changes in composition of the flow over the period of the sample. The more frequent the taking of the samples the more representative the eventual composite sample will be.

Individual sub-samples can be passed into a sequence of separate containers to store discrete samples of the flow from hour to hour.

When sampling waste waters it is important to include solid wastes carried by the waters so that the, or each, sample is representative of the material flowing or conveyed at the time of sampling.

According to a first aspect of the present invention there is provided a method of distribution of liquid samples from a bulk reservoir thereof to at least two receiving stations by way of a transfer passage characterised by the steps of:

1 locating an inlet to each receiving station on a path located beneath a bulk reservoir;

2 causing an outlet from the transfer passage to follow a path by way of the extremity of an articulated arm, fixed relative to the path at its datum end, there being adapted to rotate about an essentially vertical datum-axis, the arm incorporating an elbow to articulate a fore-arm component of the arm about an elbow-axis parallel to the datum-axis ;

3 by rotation of the arm and its fore-arm component about the datum and elbow-axes respectively, to cause the extremity of the arm to follow the said path between the inlets to each station; and

4 discharging a sample from the reservoir into the transfer passage at an upper part thereof whereby the sample passes along the transfer passage and out of the outlet to pass into a receiving station.

According to a first preferred version of the first aspect of the present invention the step of causing the outlet to follow a path is characterised by the use of a transfer passage in the form of a flexible duct linked to the articulated arm at the extremity thereof.

According to a second aspect of the present invention there is provided apparatus for the distribution a liquid sample from a reservoir characterised by:

1 at least two receiving stations to which liquid from the reservoir is to be distributed;

2 a transfer passage located beneath the reservoir having an inlet end adapted to receive liquid from the reservoir and an outlet end whereby liquid conveyed along the transfer passage can be discharged therefrom at a receiving station ;

3 an articulated arm comprising first and second longitudinal sections each having an inner and an outer end; the inner end of the first section being pivoted for rotation by a first drive shaft about a first substantially vertical axis relative to the housing; the outer end of the inner section being pivotably attached to the inner end of the second longitudinal section to enable the second section to pivot about a second substantially vertical axis parallel to the first; the inner end incorporating a second drive shaft concentric with the second axis; the outer end of the second section serving to locate the outlet end of the transfer passage;

4 a first motor for regulating the rotation of the first section about the first axis by way of the first drive shaft;

5 a second motor for regulating the rotation of the second drive shaft about the second axis; and

6 a programmable control means whereby the first and /or the second motors can be powered to cause rotation about the first and second axis so as to cause the outlet end to follow a pre-determined path on which the receiving stations are located

According to a first preferred version of the second aspect of the present invention the transfer passage is in the form of two rigid closed tubes which also form the first and second longitudinal sections of the articulated arm, the tubes communicate one with another through a swivel coupling with swivel axis concentric with the second axis.

According to a second preferred version of the second aspect of the present invention the transfer passage comprises two open channels, the first supported by the first longitudinal section and having an inlet region coincident with the inner end of the first longitudinal member and having also an outlet end in the region of the second axis, discharging, by free fall, into the second open channel which is supported by the second longitudinal section, the second channel having an outlet end coincident with the outer end of the second section;

According to a third preferred version of the second aspect of the present invention or the first preferred version thereof the transfer passage is in the form of a flexible duct the outlet end of which is located at the outer end of the second section of the arm.

According to a fourth preferred version of the second aspect of the present invention or the first, second or third preferred versions thereof the first motor is characterised by a geared motor powering the first drive shaft.

According to a fifth preferred version of the second aspect of the present invention or of any preceding preferred versions thereof characterised in that the second motor is a geared motor mounted adjacent to the first motor and driving the second drive shaft by way of a toothed belt or other transmission system which provides for the second drive shaft to be powered by way of the transmission system regardless of the relative positions of the first and second longitudinal sections of the duct.

Accord ng to a sixth preferred version of the second aspect of the present invention or of any preceding preferred version thereof the apparatus is characterised by at least one rotary potentiometer incorporated for driving by the first and /or second motors so that changes in the angular position of the first and second longitudinal sections result in changes in the resistance of the

or each potentiometer to vary in a predetermined manner so that control means can monitor the angular position of the first and second longitudinal sections.

According to a seventh preferred version of the second aspect of the present invention or any preceding preferred version thereof the apparatus is characterised in that the first and/or second motors are of the stepping type.

According to an eighth preferred version of the second aspect of the present invention or any preceding preferred version thereof the apparatus is characterised by receiving stations comprising an array of open topped containers within the housing and disposed about the first axis.

According to a ninth preferred version of the second aspect of the present invention or any preceding preferred version thereof the volume occupied the array of open topped containers characterised by being mounted on a carrier for the containers which can be readily located at, and removed from, a datum location within the housing relative to the first axis.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings of a first and second embodiments of liquid distribution unit for a water sampler of which:

Figure 1 is a sectional elevation of a first embodiment;

Figure 2 is an enlargement of the central portion of Figure 1 showing in more detail the sample distribution module;

Figure 3 is a sectional view on section III-III of Figure 1; and

Figure 4 is an alternative sample distribution arrangement for a second embodiment representing an alternative to that shown in Figure 2.

Items appearing in more than one figure are identified by the same reference throughout.

Figure 1 shows a sampler housing 11 made up of a body 12, with an integral carrying handle 13, and a hinged door 14. Both the body 12 and the door 14 are of double skinned foam filled plastics material. A resilient seal 15 is positioned in slot 16 in front flange 17 of the body to provide for a weathertight seal between body and door when closed together and retained in

place by over centre clips (not shown) .

The housing 11 serves to retain a number of modular assemblies which can be readily accessed and, where necessary, removed. Within the housing from the top down these include : a sample taking module T ; a sample distribution module D; and a sample bottle module B . In addition there are miscellaneous items providing service and other support for the modules.

SAMPLE TAKING MODULE T

This is not described in detail since it does not as such form part of the present invention but merely serves as a way of providing a liquid sample for distribution by apparatus described hereafter. In applicants co-pending application number there is described a suitable sampling device for use in conjunction with the present application. For the purposes of the present description the module T contains a bulk liquid reservoir R from which a delivery duct 23 extends downwardly by way of a control valve 25 to duct outlet end 26 located above a sample bottle B' .

SAMPLE DISTRIBUTION MODULE D

Downstream end 26 of the flexible outlet pipe 23 is located above a sample bottle duct by means of the distribution module shown broadly in Figure 1 and in more detail in Figure 2. The necessary motion is conveyed to the end 26 by way of an articulated arm arrangement comprising an inner arm 60 and an outer arm 61.

Inner end 62 of arm 60 is secured to drive shaft 63 for rotation about axis Al by way of a stepper motor/ gearbox assembly 64 mounted on a chassis plate 65. Outer end 66 of arm 60 incorporates a shaft 67 on which is pivotably mounted inner end 68 of outer arm 61 for rotation about axis A2.

Outer end 69 of outer arm 61 incorporates a locating ring 70 for retaining downstream end 26 of the flexible outlet pipe 23.

The chassis plate 65 is secured to horizontally spaced projections (projections 100, Figure 6,7) integral with the rear part of the housing body 12.

The shaft 67 is driven by a second stepper motor/gearbox assembly 72 secured to chassis plate 65. Drive is transmitted from the assembly 72 to toothed wheel 73, locked to shaft 74. From the assembly 72 drive is transmitted firstly by way of a first toothed belt 73 which extends from output shaft 74 of assembly 72 to the lower part of an idler pulley 75 on shaft 63. A further toothed belt 76 extends from the upper part of the pulley 75 to pulley 73. The pair of belts 73, 76 and the idler pulley 75 provide a constant length transmission drive for the outer arm 61 which consequently can be aligned regardless of the alignment of the inner arm 60 established by way of the first drive assembly 64.

In order to provide for the monitoring of the angular position of the shaft 63, and so of the inner arm 60, a first rotary potentiometer 77 is coupled to shaft 63 by way of gear train 78.

Likewise the position of outer arm 61 is identified by way of a second rotary potentiometer 79 driven by way of idler pulley 80 and toothed belt 73.

SAMPLE BOTTLE MODULE B

Figures 3 shows a U-shaped array B ^τ of sample bottles. Void 90 represents volume bounded by projections 100 (Figure 1) within the housing 11 in which the service items for the sampler as will be referred to hereafter.

The array B' is contained within a carrier 91 which can be readily inserted into the housing (with empty samples bottles) to locate at a predetermined datum position and readily removed to enable the contents of sample bottles containing sample material to be analysed. In this case the open tops of the bottles are laid out at constant pitch (at a receiving station -typically station 104) on a path 92 shown in double chain dotted outline.

The articulated arms 60, 61 and the driving system for them described in connection with Figure 2 enable the outlet end 26 of the pipe 23 to follow any desired path (such as path 92 described in connection with Figure 3) so as to include the required number of sample bottles and to dwell for a suitable period over each bottle opening to allow for the passage of sample into the selected bottle.

An adaptable microprocessor program is used to control operation of the distribution system . In particular it provides that the arms 60, 61 are caused to move relative to each other so that the outlet end 26 avoids contact with the walls of the housing regardless of the path and order of bottles chosen.

The use of an articulated arm arrangement in the distribution system enables the outlet end 26 to follow a predetermined path over a number of stations at which sample bottles are located. Since the path can be configured, and programmed, at will (in particular it need not be circular as would be the case with an un-articulated duct) it is consequently possible to provide a housing 11 which while providing a compact overall envelope for the sampler can nevertheless enable the filling of a relatively large number of bottles in any order and for any period. The use of stepper motors in the distribution system also enables the axial angular alignment of the arms to be established with considerable accuracy without the need for a continuous monitoring. Thus having pulsed a given number of steps the angular displacement of the arm is established. The potentiometers serve to confirm whether or not the stepped operation has resulted in the expected displacement.

Figure 4 shows an alternative transfer passage D made up of two rigid longitudinal sections : upper section 30 and lower section 31. Liquid for distribution is fed into upstream end 33 which is pivotably attached to block 32 on the upper end of upper section 30. Block 32 is mounted on a drive shaft by way of a square section recess 32A. The drive shaft is used to rotate block 32 about axis Al by way of a first stepper motor/ gearbox assembly corresponding to that described in connection with Figure 2.

Lower end 35 of upper section 30 terminates in a block 36 which is pivotably linked to block 38 which forms the upper end of lower section 31. Block 38 contains a square section recess 38 A whereby a stepper motor /gear box combination corresponding to the second such combination described in connection with Figure 2 can rotate the block 38.

Downstream end 42 of lower section 31 provides a spout whereby samples in the transfer passage are directed into a particular sample bottle as described in connection with the first embodiment.

The present description refers to a transportable sampler. However the sample taking module can be used as an independent unit in a situation where the question of portability does not arise.

Both embodiments provide a 'one path to many' arrangement wherein a liquid sample from a given source can be directed to one of any number of possible end locations. However it is readily seen that a modified version of the articulated arm sample distribution module can be used in a 'many path to one' arrangement . It could for example be used in a laboratory unit for recovering samples from sample bottles in a tray withdrawn from the sampler. Typically in a testing laboratory where recovered samples are to be analysed a complimentary program can be used in a decanting unit with a similar articulated arm arrangement which incorporates a pipette or other extracting device at the outer end of the arm so that the samples in the bottles can be withdrawn in sequence for analysis.

MISCELLANEOUS ITEMS

The void 90 serves to contain, amongst other things, battery 93 for powering the sampler, and a detector unit 94 in the form of a linear potentiometer which senses the type of array B' loaded into the bottle compartment.

A printed circuit board and a microprocessor are located in the upper part of the casing 11. The processor is programmed to regulate the operation of sample distribution module . By making use of a suitable program and sensors it is possible, for example, to identify by way of the detector 94 the characteristics of the bottles in the array B ¹ contained in the drawer such as the number of sample bottles installed; what optimum path the outlet 26 should follow to ensure the appropriate filling of the installed bottles; that the duct aligning signals fed to drive assemblies 64, 72 (Figure 5) are in fact resulting in a correct alignment by monitoring the output of the potentiometer; the type of sampling program to be followed (simple time periodic, flow proportional) .

Typically for the array B' (Figure 3) the location of the centre of each bottle opening in the array will be logged in a call up table stored in a memory of the

micro processor which will be suitably programmed to cause the motor assemblies 64, 72 (Figure 2) to align the outlet 26 appropriately for a given period over each bottle in the chosen path to allow the collected sample to be appropriately stored for the chosen sampling routine.

A key pad and a display are mounted for access within the housing 11 with the door 13 open typically to check equipment operation, to add, remove or modify operational or other programs or to recover recorded material.

The location of the various components within the housing 11 provides for a compact assembly which is readily lifted in contrast top existing known samplers. The embodiment is concerned with providing a distribution system wherein the heavier components, such as the battery 93, and bottle array B' are located in the lower part of the sampler so as to contribute to a stable structure having as low a centre of gravity as is practicable.