CA2424629A1 - On-line sampling device for ir milk analysis - Google Patents

Abstract

A proportion liquid sampling on-line device uses a frustroconically-shaped deflector positioned in a sampling chamber. The deflector reverses twice the main flow incidence by 180° and generates a film of flowing liquid substantially bubble-free. A secondary flow containing a predetermined quantity of liquid is diverted from the main flow and compacted in a measurement attachment to create slabs of liquid with no entrained air. Advantageously, these slabs of liquid are similar to a microscope slide and provide for an optimal IR sensing. It is an inexpensive tester, easy to position/use in any parlor and with any farm milking machine. The tester provides complete milk information for efficient herd management.

Description

ON-LINE SAMPLING DEVICE FOR IR MILK ANALYSIS
Background of the invention Field of invention This invention is generally concerned with liquid analysis and in particular with a sampling device for spectrometric analysis of emulsions and suspensions.
Related art Spectrophotometry is largely used for electro-optical analysis of emulsions and suspensions as it is economical in manufacture and accurate in results.
Spectrophotometric analysis is generally used for measurement of fat, protein, lactose, or solids present in milk, as well as bacteria (e.g. e-coli) or somatic cells.
Typically, a representative analysis sample, which normally should not comprise more than 50 ml of milk, is flown into an optical measurement cell and irradiated with a reference beam and a measurement beam at differing wavelengths. The received signals are indicative of uncorrected concentrations. Sampling results are compared with stored data taken through calibration runs under similar conditions.
Scaling and correction circuits are then used for compensating the effects on each reading caused by other constituents. The corrected signals are finally provided in percentage by weight, or weight over volume.
Miik analysis can be carried out by infrared (IR) spectroscopy using for example a through-flow type detector connected to a IR spectrometer analyzer.
Light emitted by the IR radiation unit goes to a representative analysis sample, or probe and comes back from the probe. The reflected beam is analyzed and converted in numeric data. IR spectroscopy can gather data on a continuous basis and can perform a complete multi component analysis in a matter of seconds.
The quality of milk is dictated by its constituents, in particular the fat content.
Obtaining a representative analysis sample and determining the fat content require long and exact procedures, especially when the milk has been standing for a period of time, since a large portion of fat separates and deposits on the upper surface of the milk.

It is to be noted that, performing the IR analysis in the main flow using an on-line sampling device, may provide inaccurate results and adverse effects. For example, expected values for total production of a cow differ between around 5kg and 30 kg. During milking, the flow can fluctuate between around 0.1 and 1.2 kg/minute, and this adds to the difficulty of extracting a proportion sample for volume calculations. Similarly, the fat content in milk increases towards the end of milking, and obtaining a representative analysis sample becomes problematic. An adverse effect of using measurements in the main flow (during milking), is due to the under pressure prevailing at the milking unit placed on the udder which is influenced by the measuring apparatus creating a vacuum drop. This results in an incomplete milk extraction causing udder irritation and/or inflamation.
On the other hand, the information contained in a representative analysis sample may lead to inaccurate readings if the sample is not homogenous, or "flowing". Air pockets, concentration gradients, or turbulence have a direct impact on readings. Such gas inclusion may be due to turbulence when air is mixed with liquid, or to small drop in pressure when some liquid sample is vaporized to create bubbles. The changes in milk concentration and the presence of bubbles in milk is one of the problems associated with liquid chromatography, as the injection of a probe containing bubbles or gas into the chromatographic column is conducive to erroneous results, as it provides for inaccurate flow measurement and/or noise generation in the IR measuring unit.
Freshly milked milk is a foaming liquid which does not have a clearly defined surface. Particularly during milking, the air content of the fresh milk produces a significant foam volume and thus, variations in flow density.
Circulation systems such as agitators, have to be provided to increase the quality and the accuracy of the on-line sampling devices.
To determine the correction factors, the content of the entrained air has to be constantly measured, e.g. using gas chromatography, for subsequently weighing the samples according to a predetermined formula. This is a time consuming method and also generally inaccurate due to fluctuations in the air bubble content during milking.

The quality of milk is constantly monitored by state agencies. Diary control agents request samples from farmers tanks which are labeled and sent to a district laboratory. Typically, the results are returned from the laboratory about one week after the analysis and evaluated by the diary control agent about two weeks following sample collection at the farm. The above procedure provides for undesirable delays as the dairymen need at the cowsite results for efficient herd management.
It is a need for a sampling device which is easy to manufacture and operate, and provides suitable sampling for a spectroscopic measuring unit performing in-flow testing of emulsions and suspensions.
Summary of the Invention It is an object of the present invention to overcome the disadvantages of the prior art associated with spectrometric analysis of emulsions and suspensions.
The invention provides an on-line sampling device capable of extracting a proportion sample of substantially bubble-free liquid suitable for IR
spectrometry analysis.
According to one aspect of the invention, a proportion sampling device is provided. The sampling device comprises a sampling chamber with a vertical axis including a dome-shaped upper section with an intake conduit arranged along the vertical axis for receiving a main flow of liquid, a funnel-shaped lower section for discharging by gravity liquid from the sampling chamber, and connecting means for joining the upper section and the lower section together and forming the sampling chamber. A frustroconical deflector is attached to the upper section and has a ?5 bottom wall defined in a horizontal plane and an inclined wall connecting the bottom wall with a rim, such that the main flow is first reversed about 180°
when contacting the bottom wall and uniformly redirected upwards along the inclined wall.
Further on, the main flow is again reversed about 180° after leaving the rim due to gravity.
Collecting means are formed on the inside wall of the lower section including a sampling conduit with one exterior end extending downwardly outside the lower section and having a collecting spout at the opposite end protruding upwardly inside the upper section. The spout has a slot defined in a plane located under the plane of the rim and radially extending towards the inside wall of the upper section for' diverting a proportion flow from the main flow of liquid.
The main flow of liquid exiting the rim is a flowing liquid film of constant thickness and substantially bubble-free. A measurement attachment may be connected to the sampling conduit for receiving the proportion flow. The attachment has an indentation for compacting the proportion flow into a slab of liquid with no entrained air and suitable for accurate spectrometric measurements.
The sampling device of the invention is an inexpensive tester, easy to position and use in any parlor and with any farm milking machine. It provides at the cowsite complete milk information extremely valuable for herd management.
Advantageously, the slabs of liquid flown through the indentation of the measurement attachment, are similar to a microscope slide and provide for an optimal IR sensing. A representative analysis sample containing homogenous liquid may be extracted as well.
The sampling device is described more particularly in its application to fresh milk, but it can be used with any other foaming liquids (beer, petroleum, etc.), non-foaming liquids, emulsions, or suspensions. As well, any light source may be used for spectrometric analysis.
The "Summary of the Invention" does not necessarily disclose all the features essential for defining the invention. The invention may reside in a sub-combination of the disclosed features.
Brief Description of the Drawings The invention will be now explained by way of example only and with reference to the following drawings.
Figure 1 is a perspective view of the sampling device of the invention;
Figure 2 is an illustration of the upper section of the sampling device of Figure 0 1 as viewed from the inside;

Figure 3 is an illustration of the deflector as viewed from the direction of the flow;
Figure 4 is a top perspective view of the lower section of the sampling device of Figure 1 with the deflector illustrated in a working position:
Figure 5 is a top view of the lower section of the sampling device of Figure 1;
Figure 6 is a longitudinal cross section along line 6-6' of Figure 4;
Figure 7 is a perspective view of the IR measurement attachment;
Figure 8 is a longitudinal cross section of the sampling device of Figure 1 connected to a sample flask meter; and Figure 9 is a longitudinal cross section of the sampling device of Figure 1 connected to a somatic cell count (SCC) flowcell and to an IR sensing unit for performing on-line multi-component milk analysis.
Similar references are used in different figures to denote similar components.
l5 Detailed Description of the Preferred Embodiment The following description is of a preferred embodiment by way of example only and without limitation to combination of features necessary for carrying the invention into effect.
The invention will be now described with reference to Figures 1 to 6. Figure 1 is a perspective view of an on-line sampling device 10 according to the invention.
Sampling device 10 comprises a dome-shaped upper section 15, also illustrated in Figure 2, for receiving liquid (arrow A) through conduit 14 and input port 12, and a funnel-shaped lower section 17, also illustrated in Figures 4 to 6, for collecting the liquid and discharging same through conduit 14' having an output port 18 (arrow B).
The upper section 15 is joined to the lower section 17 along a mating plane substantially perpendicular to the AB direction of flow. An upper ring 25 is formed in section 15 in a plane perpendicular to the direction of flow. Similarly, funnel 17 has a lower ring, shown at 35 in Figure 5, which is formed in a plane perpendicular to the direction of flow. Both upper and lower rings 25, 35, have an annular form and are of the same size which is substantially the thickness of the material used to manufacture the sampling device 10.
Two identical reinforcing collars, 26, 36, are provided around both the upper and the lower rings 25, 35. Three screws and corresponding paired ears 13, 13', defined at 120° around the circumference of the upper and the lower reinforcing collars 26, 36, are used for connecting the upper section 15 with the lower section 17.
Paired ears 13, 13', may be larger than the thickness of the reinforcing rings 26, 36, in order to increase their mechanical resistance. In such a case, a plurality of indentations 29 will be provided on the perimeter of the upper collar 26 to match with the lower collar 36. Indentations 29 and corresponding grooves co-operate for allowing upper ring 25 to be in contact and flush with lower ring 35. One or two indentations 29 may be of a larger size and when matched with corresponding notches (not shown) defined on the perimeter of the opposite ring provides for easy assembling. An O-ring (not shown) may be provided along the mating plane in-between sections 15 and 17 for sealing the sampling device 10. When connected, the upper section 15 and the lower section 17 define a sampling chamber 30.
Sampling chamber 30 is surrounded by a substantially continuous inside wall including the inside wall 37 of the upper section 15, and the inside wall 37' of the lower section 17.
A cylinder, or proportion collector 16 is formed in sampling chamber 30.
Proportion collector 16 is attached tangent to the inside wall 37' of funnel 17 for diverting a secondary flow of a known proportion from the main flow, as it will be explained later.
?5 Figure 2 is an illustration of the upper section 15 of the sampling device of Figure 1 as viewed from the sampling chamber 30. A deflector 20 is centered inside the upper section 15 and attached to the upper section 15 by screws 11 threaded in ears 24. Preferably, ears 24 are of the same length "L".
In operation, the sampling device 10 is vertically connected to the milking pipes 50 (see Figure 7), and the liquid flows from the input port 12 to the output port 18 by gravity, as shown by arrows A and B. The secondary flow diverted by cylinder 16 inside the sampling chamber 30 is discharged through an output sample port (arrow C).
Throughout the description the words "upper" and "lower" are used with respect to the vertical position of the sampling device 10, when in operation.
All parts forming the sampling device 10, may be manufactured by injection molding from polysulphone plastic made by Amoco Corp. No silicone based mold release shall be used. The parts shall be free of flash, grease, and other contaminants. It is also understood, all conduits are slightly conical for easy coupling.
Figure 3 is an illustration of the deflector 20 as viewed from the direction of the flow, or the upper side. Figure 6 includes a longitudinal cross section of the deflector 20 and of the lower section 17 of Figure 4 along line 6-6'.
Deflector 20 has a frustroconical shape with a circular bottom wall 23 for receiving the main stream of milk along direction "A", an inclined wall 22, and a rim 21. The bottom wall 23 is defined in a horizontal plane which is parallel to the plane of rim 21. Bottom wall 23 is positioned substantially perpendicular to the direction of the incoming main flow and has a diameter substantially equal to the interior diameter of conduit 14. Inclined wall 22 has a predetermined inclination (~i°) for placing rim 21 in a plane positioned above the proportion collector 16 inside the sampling chamber 30.
Deflector 20 is used for re-directing a portion of the main flow (the secondary flow) into the proportion collecting elements 16, 28. The main flow arriving in the sampling chamber 30 through input port 12, hits first the bottom wall 23 where the flow is reversed about 180°, then flows upwardly along the inclined wall 22, and is ?5 reversed about 180° for a second time due to gravity, when leaving the rim 21.
It is known that the main flow contains air pockets and turbulence areas. It has been discovered that by twice-reversing (Z x 180°) the main flow, a radially flowing milk film of constant thickness and substantially bubble-free is generated.
Accordingly, the proportion collecting elements 16, 28, can divert a probe containing 0 homogenous liquid.

As illustrated in Figures 5 and 6, proportion collecting elements include proportion collector 16 and a collecting spout 28. Collecting spout 28 includes in the example of Fig. 5 a rectangular crater 38 with a rectangular slot 39. In this example, slot 39 is rectangular but any shape like circular, oval, square, rhomboidal, trapezoidal, may be considered. Crater 38 is carved at the upper end of spout along a radial direction and extending above the mating plane inside upper section 15. Collecting spout 28 projects above the mating plane with a protrusion length "h".
In the example of Figures 5 and 6, slot 39 is positioned in a plane substantially parallel to and slightly under the plane of rim 21, radially extending between rim 21 and inside wall 37. Rim 21 is closely spaced and above slot 39 allowing a secondary flow representing a known portion of the twice-reversed main flow, to be diverted. The liquid by-passed by proportion collecting elements 16, 28, (the secondary flow) is discharged through output sample port 19 and may be later returned to the main flow.
The inclination (~3°) of the inclined wall 22, the length "L" of ears 24, and the protrusion length "h", are so chosen so as to provide a known proportion secondary flow since it is extracted from a radially flowing liquid film of constant thickness and substantially bubble-free. The dimensions of the slot 39 are selected so as to divert always a given amount of liquid, e.g. 1.5% of the main flow, irrespective of the main flow velocity or accelerations.
Figure 7 is a perspective view of a measurement attachment 45 according to the invention. Attachment 45 is a cylinder having an inlet 46 which fits into the output sample port 19 of the proportion collector 16, and an outlet 48 coupled to the main pipe 50 to redirect the secondary flow into the main flow. As mentioned before, the homogenous and substantially bubble-free secondary flow entering attachment 45, is forced through indentation 47, 47', formed in a middle region of the measurement attachment 45. Indentations 47, 47', are formed on diametrically opposite sides of attachment 45. Indentation 47, 47', provides throughout its passage of length "d", a constant and uniform flow of homogenous liquid suitable for IR analysis.

Indentation 47, 47', may be so formed so as to define a bore-like passage.
Preferably, indentation 47, 47', defines a passage having parallel walls for outputting slabs of liquid.
As milking an intermittent process, segments, or slabs of liquid similar to a microscope slide are irregularly flown through attachment 45. The slabs allow for optimal optical analysis since they have well defined dimensions, uniform flowing velocity, and thickness. In this way, the liquid is analyzed in a standardized fashion.
Indentation 47, 47', may include connectors for attaching a pair of emitter-detector and fiber optic cables for exposing the slab of liquid to light of a specific wavelength, and to provide the modulated light signal to electronics for interpretation, as it is known in the art. A continuous beam of light can detect time of flowing and the interruptions due to slabs of liquid irregularly flown through attachment 45, the analyzed data (volume, milk components) may be recorded such that the contribution each slab may be accounted for. At the end of the milking process, a composite value for each analyzed component contained in the liquid may be generated. Real time values for these components may be also supplied during milking as interval, readings.
One or more attachments 45 having one or more pairs of emitters-detectors may be also used if necessary. As mentioned before, conduits 14, 14', 16, as well as inlet 46 and outlet 48 are slightly conical for easy coupling, as known in the art.
Figure 8 is a longitudinal cross section of the on-line sampling device 10 of Figure 1 used as a flask type meter 51. A flask 55 is coupled to the output sample port 19. "Flask type" means that the measure of the total flow of liquid can be determined on-line by capturing a known portion of the main stream in the calibrated flask 55. This sample collection technique may provide for a quick in-line measurement of the main flow volume, mass velocity, and accelerations. A valve may be provided in proportion collector 16 for controlling the collection time.
Alternatively, the flask may be used to provide a representative sample of homogenized liquid as required by the DHI (dairy herd improvement) standards.
>0 The total volume of the liquid examined, the mass velocity and flow accelerations during milking may be calculated as well, Figure 9 is a longitudinal cross section of the on-line sampling device 10 of Figure 1 connected to a somatic cell count (SCC) flowcell 60, and to the IR
measurement unit 10 for multi-component milk analysis. Multi-component testing device 52 includes IR port 57, positioned along the length "d" of indentation 47, 47', of the measurement attachment 45. An IR source (62) and an IR receiver (64) are connected to IR port (57). A central processing unit (65) with interface (IF) 68, receive IR modulated signal from IR receiver (64) and the output of a spectrometer (65) for processing and outputting results of display (70). In this way, in-flow, continuous IR monitoring is provided and real time data are obtained from a homogeneous, substantially bubble-free proportion flow. By incorporating the spectrometer 65, milk components and flow rates may be measured as well.
In the example of Figure 9, the milk is flown through SCC flowcell 60 for counting the somatic cell and to generate a complete milk analysis. SCC
flowcell 60 is disclosed in US Patent No. 6,031,367 issued on February 29, 2,000 to the same applicant and incorporated herein by reference. Flowcell 60 may be used upstream or downstream sampling device 10.
The sampling device 10 may be used on-line, during milking and can fit any farm milking machine. As mentioned before, optimal IR sensing can not be achieved by performing the analysis in the main stream due to the entrained air bubble content . The sampling device according to the invention, uses a deflector positioned in such way so as reverse twice the main flow incidence by 180° and to generate a film of flowing liquid substantially bubble-free. A secondary flow having a predetermined quantity of liquid is diverted from the main flow and compacted in a measurement device to create slabs of liquid with no entrained air.
Advantageously, these slabs of liquid are similar to a microscope slide and provide for an optimal iR sensing. Accurate and complete information is provided by the in-flow testing device 10 at a reduced time and an affordable price. In addition, testing device 52 can provide end of milking information and precise milk temperature values.

The complete milk information provided at the cowsite is extremely valuable for herd management purposes. Representative analysis samples containing homogenous liquid according to laboratory standards may be easily obtained.
No adverse effects like rancid milk are caused by mechanically forcing the milk in conduits, nor the milk chemistry is modified as the device prevents the air to mix with milk, nor vacuum drops are generated as the device uses gravity for diverting the proportion flow of liquid.
Numerous modifications, variations, and adaptations may be made to the particular embodiments of the invention without departing from the scope of the invention which is defined in the claims.

Claims (11)

1. A proportion sampling device, comprising:
a sampling chamber with a vertical axis including, a dome-shaped upper section with an intake conduit arranged along said vertical axis for receiving a main flow of liquid, a funnel-shaped lower section for discharging by gravity liquid from said sampling chamber, and connecting means for joining said upper section and said lower section together and forming said sampling chamber, a frustroconical deflector attached to said upper section and having a bottom wall defined in a horizontal plane and an inclined wall connecting said bottom wall with a rim, such that said main flow is first reversed about 180° when contacting said bottom wall and uniformly redirected upwards along said inclined wall, and said main flow is again reversed about 180° after leaving said rim, and collecting means formed on the inside wall of said lower section including a sampling conduit with one end extending downwardly outside said lower section and having a collecting spout at the opposite end protruding upwardly in said upper section, said spout having a slot defined in a plane located under the plane of said rim and radially extending towards the inside wall of said upper section for diverting a proportion flow from said main flow of liquid.

2. The proportion sampling device of claim 1, wherein said rim and said slot are defined in two horizontal planes.

3. The proportion sampling device of claim 2, wherein said main flow of liquid exiting said rim is a homogenous liquid film.

4. The proportion sampling device of claim 1, wherein said slot is rectangular.

5. The proportion sampling device of claim 1, wherein said proportion flow is about 1.5% from said main flow.

6. The proportion sampling device of claim 1, wherein said sampling conduit is defined along a longitudinal axis parallel to said vertical axis.

7. The proportion sampling device of claim 1, further comprising a measurement attachment connected to said sampling conduit for receiving said proportion flow, said attachment having an indentation for compacting said proportion flow into a slab of liquid with no entrained air.

8. The proportion sampling device of claim 7, wherein said indentation for receiving a pair of emitter-detector for performing spectrometric analysis of said slab of liquid and to provide interval readings.

9. The proportion sampling device of claim 8, wherein said spectrometric analysis including IR spectroscopy.

10. The proportion sampling device of claim 9, wherein said liquid is milk.

11. The proportion sampling device of claim 10, wherein said interval readings comprising a percentage of milk components in the overall volume of milk delivered.