WO2002059568A1

WO2002059568A1 - Sample collection

Info

Publication number: WO2002059568A1
Application number: PCT/AU2002/000032
Authority: WO
Inventors: Timothy Clarke
Original assignee: Agriculture Victoria Services Pty Ltd
Priority date: 2001-01-25
Filing date: 2002-01-14
Publication date: 2002-08-01
Also published as: AUPR270901A0

Abstract

A liquid sampler assembly 1 comprising, a collection vessel 3 having a mouth 4, a sub-sampler vessel 11 having a mouth 12, a cap 5 for sealing both mouths against ingress of air, an entry duct 7 for supplying liquid to the collection vessel 3, a transfer passage 21 for permitting transfer of liquid from the collection vessel 3 to the sub-sampler vessel 11, and an exhaust tube 15 having one end 16 terminating at a level within the sub-sampler vessel, wherein the arrangement is such that tilting of the liquid sampler assembly 1 and its vessels causes liquid to flow through the transfer passage 2 from the collection vessel 3 to the sub-sampler vessel 11 and the exhaust tube 15 causes liquid in the tilted sub-sampler vessel to be expelled down to the level of the one end 16 when air is admitted into the liquid sampler assembly.

Description

SAMPLE COLLECTION

Field of the Invention

This invention relates to methods and devices for the sampling of liquid flow. In a particular non-limiting form, the invention relates to a means of obtaining representative samples of small, and roughly fixed volumes of samples from liquid flows which vary widely in relation to flow rates and flow duration.

Background of the Invention

Liquid sampling devices are needed in a range of industrial and agricultural applications, and particularly in relation to measuring performance of lactating animals such as cows. When sampling from a flow of liquid such as milk from a milking machine, the liquid flow quantity will vary greatly. Other factors which will vary will include flow rate, the chemical composition and the proportion of mixing of entrained air and milk.

For performance testing of lactating animals a representative sample of milk from one or more milkings is usually required for laboratory analysis. Any excess milk taken is discarded after testing. The sample must have enough volume for the amount of testing required, while at the same time the volume of the sample must not be so great as to require a sampling container of excessive capacity ie. the amount of sample taken should not be so large as to have a significant impact on the total amount of milk collected during the milking procedure bearing in mind that the excess may be discarded.

Samplers that have a fixed sampling rate to meet these requirements will often collect samples that are much larger than is required for laboratory analysis or for efficient handling and transport. Thus there is a need for a device which can collect a representative sample of milk obtained from an animal throughout a milking operation, the sample being of roughly fixed and controlled volume notwithstanding variations in milking parameters and the animals being milked.

Disclosure of the Invention

In one aspect the invention provides a liquid sampler assembly comprising, a collection vessel having a mouth, a sub-sampler vessel having a mouth, a cap for sealing both mouths against ingress of air, an entry duct for supplying liquid to the collection vessel, a transfer passage for permitting transfer of liquid from the collection vessel to the sub-sampler vessel, and an exhaust tube having one end terminating at a level within the sub-sampler vessel, wherein the arrangement is such that tilting of the liquid sampler assembly and its vessels causes liquid to flow through the transfer passage from the collection vessel to the sub- sampler vessel and the exhaust tube causes liquid in the tilted sub-sampler vessel to be expelled down to the level of the one end when air is admitted into the liquid sampler assembly.

The collection vessel and the sub-sampler vessel are suitably designed so that they may snap fit into the cap. Similarly, they may be removable from the cap by simply pulling them away from the cap.

Alternatively, the cap and/or vessels may include fixing means such as screw threads which may be provided to connect the collection vessel and/or sub-sampler vessel to the cap.

The cap may be made from a resilient material. Most suitably, it may be made from a rubbery material which assists with snap fitting and sealing.

The cap may be designed so that the collection vessel and the sub-sampler vessel are held at an angle to each other. Typically, the axes of the collection vessel and sub-sampler vessel may make an angle of 10° to 70° with each other. More preferably the angle will be 20° to 55°.

The entry duct may be provided with a valve for controlling the exit of liquid and air from the collection vessels. Most suitably it may take the form of a one-way valve. The oneway valve may operate so as to permit entry of liquid into the collection vessel through an outlet of the entry duct and may prevent return of liquid and air through that outlet.

A second valve may also be provided in association with the liquid sampler assembly. The second valve may be operable to admit air into the liquid sampler assembly when it is opened. The second valve may be provided in the cap. A mixing tube may connect with the second valve. The mixing tube may extend into the collection vessel. The valve may be opened to admit air to bubble through the liquid in the collection vessel to mix it.

In a particular embodiment, the exhaust tube may have a second end terminating within the entry duct in order to allow liquid being exhausted from the sub-sampler vessel to be directed into the entry duct.

In a typical milking operation, the entry duct may be in communication with means for diverting a proportion of milk from a milking machine into the entry duct. Such diversion means are known in the art. They may for example comprise a gate which directs a proportion of milk from a milk flow into the entry duct.

The exhaust tube is suitably arranged so that liquid being exhausted from the sub-sampler vessel is automatically returned to the milk flow from which it has been diverted.

The liquid sampler assembly may be operated by arranging it to collect a proportion of milk from the milking line of a system used to milk an animal for the entire milking period. After milking has been completed, the second valve may be opened to mix the milk by allowing ingress of air through the mixing tube and the liquid sampler assembly may be tilted to allow milk to flow into the sub-sampler vessel. The interior of the assembly may be under a partial vacuum or sub-atmospheric pressure by virtue of the fact that it may be connected by the entry duct to a milking line of a milking operation and the milking line will itself operate under partial vacuum. This causes an inflow of air through the second valve when it is opened and has the effect of pushing excess liquid flowing into the sub-sampler assembly out the one end of the exhaust tube and back into the milking line from whence it was diverted. Thus the one end of the exhaust tube sets the level at which milk will be left in the sub-sampler vessel.

As the sub-sampler vessel can be designed so that it only retains a desired quantity of milk, it is possible to provide roughly constant volumes of samples even though a large volume may have been diverted into the collection vessel. This is because the assembly can be configured so that any excess milk is automatically returned to the milking line through the exhaust tube when the assembly is tilted and the second valve opened.

The invention will now be further explained and illustrated by reference to the accompanying drawings.

Description of the Drawings

Figure 1 is an elevational view of a cross-section through a liquid sampler assembly according to the invention,

Figure 1 A is an upside down plan view of the cap used in the liquid sampler assembly of Figure 1, and

Figure 2 is an elevational view of a cross-section through an alternative form of liquid sampler assembly according to the invention.

The following integer list lists the various elements identified by numerals in the drawings.

Integer List

1 liquid sampler assembly

3 collection vessel 4 mouth

5 cap

7 entry duct

8 outlet

9 side walls

11 sub-sampler vessel

12 mouth

13 one way valve

15 exhaust tube

16 bottom end

17 second valve

19 angle

21 transfer passage

25 milking mixing tube

Detailed Description of the Preferred Embodiments

Referring to Figures 1 and 1 A, there is shown a liquid sampler assembly 1 which includes a collection vessel 3 and a sub-sampler vessel 11.

The two vessels may be formed of any suitable material. As it is anticipated that they will be used for the collection of milk, they should be designed so that they can be readily cleaned and cannot easily be broken when handled roughly as would be expected in the environment of a milking shed.

Collection vessels made of impact resistant transparent plastics are particularly suitable. Furthermore, because of the variability of flow encountered during milking operations, the collection vessel may be relatively large compared to the sub-sampler vessel. For instance, it is anticipated that the collection vessel will have at least four times, more preferably ten to forty times the capacity of the sub-sampler vessel. A cap 5 is constructed so that it can receive the mouths 4 and 12 of the collection vessel and sub-sampler vessels respectively in a snap or friction fit. Thus it is preferred that the cap is formed of a rubbery material. However for greater security means to assist the securement of the vessels to the cap, such as screw threads or the like, may also be used.

The cap also includes downwardly directed side walls 9 forming a pair of circular sections for surrounding the circular mouths 4 and 12 of the vessels.

The cap includes an entry duct 7 whose outlet 8 is arranged to direct milk into the collection vessel.

A one-way valve 13 in the form of a flap is located in the region of the outlet. It allows entry of milk to the collection vessel. It prevents return of milk and air from the collection vessel through the outlet when the liquid sampler assembly is tilted and the valve 17 is open. By preventing exit of air via the entry duct 7 it causes the pressure to exhaust the excess milk quickly when valve 17 is open. It also prevents gross air admission to the milking system bearing in mind that gross air admission compromises the milking vacuum for cows still milking. The valve 13 also acts in concert with the exhaust tube 15 described in more detail below, to prevent major vacuum loss when either the sub sample or collection vessels are removed.

A second valve 17 is also provided in the cap. The second valve 17 is arranged so that air at atmospheric pressure can be injected through the valve to mix the milk sample via mixing tube 25.

A conduit (not shown) may be arranged to deliver the proportion of milk diverted from a milking line into the entry duct of the liquid sampler assembly.

The exhaust tube 15 extends through the cap and has a bottom end 16 extending into the sub-sampler vessel. The extent to which the bottom end extends into the sub sampler vessel can be adjusted to vary the volume of sub-samples taken by the assembly. The other end of the exhaust tube can be arranged to return excess milk to the milking line from which it is initially diverted or to some suitable part of the milk collection system that is at the same partial vacuum level. The inside cross sectional area of the exhaust tube should be small enough to restrict air entry to the milking system but be large enough to allow rapid expulsion of excess milk. Tubes of 2 to 5mm diameter will work but a diameter of 3 to 4mm is preferred.

The configuration of the assembly is such that the sub-sampler vessel makes an acute angle across the gap 19 between the two. Typically this angle will be about 45°.

Referring to Figure 2 the assembly shown therein is substantially the same as that described with reference to Figure 1, the major feature of difference between the two being the provision of an alternative exhaust tube 15 which directs milk exhausted from the sub- sampler vessel back into the entry duct. Where such a configuration is preferred, the exhaust tube protrudes into the lumen of the entry duct 7 so that milk moving down the duct does not enter this tube.

During a normal milking operation, a proportion of milk is diverted from a milking line using conventional techniques, such as a gate provided with knife edges. This diverted milk is fed through the entry duct into the collection vessel 3 shown in Figure 1. Diversion of milk from an individual animal continues for the entire period of the milking operation.

When milking is complete, valve 17 is opened to mix the sample and the assembly is tilted to allow milk to flow from the collection vessel through the transfer passage 21 into the sub-sampler vessel 11. The assembly is tilted sufficiently to permit all of the milk in the collection vessel to transfer through the transfer passage into the smaller sub-sampler vessel without leaving any in the collection vessel.

As the opening of valve 17 allows air to be injected into the assembly by the mixing tube 25, the pressure of the air pushes excess milk up the bottom end of the exhaust tube to be returned to another part of the milking line. Thus the bottom end of the exhaust tube defines the level at which milk will be collected in the sub-sampler vessel. After the drainage of the collection vessel and exhausting of the excess milk, the assembly may be returned to its untilted position, where the sample from the next cow can be collected while the sub sample from the previous cow is held in its respective vessel, waiting for a convenient time in the operator's work routine for its removal.

When this operation is completed, the sub-sampler vessel may simply be removed and capped ready for testing. Alternatively if a large sample is required the collection vessel may be removed with the large sample and replaced with a fresh one and the operation repeated for the next cow. The valve 13 prevents air returning through the entry duct when the vessels are removed. Furthermore, the narrow diameter of the exhaust tube 15 limits the amount of air bleeding into the milking system through the exhaust tube to a level which does not unduly disrupt the milking vacuum for other cows on the same system.

It is to be understood that the word comprising as used throughout the specification is to be interpreted in its inclusive form ie. use of the word comprising does not exclude the addition of other elements.

It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. These modifications and/or additions are therefore considered to fall within the scope of the invention.

Claims

1. A liquid sampler assembly comprising, a collection vessel having a mouth, a sub-sampler vessel having a mouth, a cap for sealing both mouths against ingress of air, an entry duct for supplying liquid to the collection vessel, a transfer passage for permitting transfer of liquid from the collection vessel to the sub-sampler vessel, and an exhaust tube having one end terminating at a level within the sub-sampler vessel, wherein the arrangement is such that tilting of the liquid sampler assembly and its vessels causes liquid to flow through the transfer passage from the collection vessel to the sub- sampler vessel and the exhaust tube causes liquid in the tilted sub-sampler vessel to be expelled down to the level of the one end when air is admitted into the liquid sampler assembly.

2. A liquid sampler assembly according to claim 1 wherein the cap, collection vessel and sub-sampler vessel are constructed so that the collection vessel and sub-sampler vessel may be snap fitted or screw fitted onto the cap.

3. A liquid sampler assembly according to claim 2 wherein the cap comprises a rubbery material which facilitates snap fitting and sealing with the vessels.

4. A liquid sampler assembly according to claim 1 wherein the collection vessel and sub-sampler vessel are elongate vessels each extending from the cap generally along axial directions which make an angle of 10° to 70° with each other.

5. A liquid sampler assembly according to claim 4 wherein the angle falls within the range 20° to 55°.

6. A liquid sampler assembly according to claim 1 wherein the entry duct is provided with a one way valve operable so as to permit entry of liquid into the collection vessel through an outlet of the entry duct.

7. A liquid sampler assembly according to claim 6 comprising a second valve operable to admit air into the liquid sampler assembly when the second valve is opened.

8. A liquid sampler assembly according to claim 7 comprising a mixing tube extending from communication with the second valve into the collection vessel.

9. A liquid sampler assembly according to claim 1 wherein a second end of the exhaust tube terminates within the entry duct to allow liquid being exhausted from the sub- sampler vessel to be directed into the entry duct.

10. A method of sampling milk from a milk line of a milking machine maintained under at least a partial vacuum using a liquid sampler assembly according to claim 7 comprising the steps of, diverting a proportion of milk from the milking machine into the entry duct over a period to provide a sample of milk in the collection vessel representative of the milk passing through the milk line over the period, at the end of the period, tilting the liquid sampler assembly from an initial orientation to cause milk to flow from the collection vessel through the transfer passage into the sub-sampler vessel, and opening the second valve to admit air into the sub-assembly to drive excess milk out of the sub-sampler vessel leaving milk in the sub-sampler vessel at the level of the one end of the exhaust tube.

11. A method according to claim 10 wherein collection of milk in the collection vessel is continued after tilting and after the liquid sampler assembly has been returned to its initial orientation for further collection of milk.