WO2001027578A1

WO2001027578A1 - Data logger

Info

Publication number: WO2001027578A1
Application number: PCT/IE2000/000125
Authority: WO
Inventors: David Reynolds Gray
Original assignee: Logpro Limited
Priority date: 1999-10-11
Filing date: 2000-10-11
Publication date: 2001-04-19
Also published as: AU7681800A

Abstract

A data logger in the form of a temperature sensing device (10) having three temperature sensors (1, 2, 3) and a data port is mounted in a milk storage vessel (11) of double skinned construction for cool water and housing a stirrer or mixer (4). The temperature sensing device (10) is used to track the temperature of the milk and ambient air at various heights in the vessel. The temperature profiles and heat retention of the milk is monitored to ensure no bacterial contamination due to malfunction of the milk condition such as stirring, cooling and so on.

Description

"Data Logger"

introduction

The present invention relates to a data logger and in particular to a temperature tracking device.

It is known to provide data loggers which data loggers can, for example, record temperatures over time. For example, one such data logger sold under the Trade Mark Logger iButton is capable of recording over 2,000 consecutive temperatures at intervals between 1 and 255 minutes and storing these readings of _^temperature in read only memory before it starts to delete previously recorded temperatures as new temperatures are recorded. These are programmable data loggers which can record temperature to an accuracy of 1°C and can have a battery life of over ten years. Further they are relatively small devices having a bulk greater than common coinage in use in many countries.

French Patent Specification No. 2577043 (Mesure Automatisme Electronique - MAE. et al) describes such a sensor which can be used to record the temperature, for example, of pasteurising milk. It essentially comprises a data logger which includes an interface which subsequently can be connected, for example, to an external computer or the like, for downloading of the data previously sensed.

Many industries are becoming more concerned with the accurate logging of temperatures of products and processes. This has become of particular importance in the food industry where the HCAP regulations are becoming more stringent. In Ireland for example the HCAP regulations have been enforced since September 2000. This is largely concerned with the datatracking of food from production to consumer.

One of the major problems in relation to food is to ensure that the temperature of the food is always maintained within defined limits. This is particularly the case for chilled and frozen foods but equally well applies to fresh food. The importance of temperature control for the former has long been appreciated by everybody and everybody is aware that if frozen food is trucked or transported from factory to supermarket that it is relatively easy for the food to thaw and then to be refrozen without this being immediately apparent. Elaborate sensing devices have been developed which for example permanently change colour if the temperature exceeds a defined limit. However, similar and equally important considerations apply to fresh food which is often transported chilled. To name but two examples it will appreciated that it is vital that fish from the time it has been taken out of the water be stored under the correct temperature conditions until it is either processed or sold as raw fish to the consumer. A similar and indeed more difficult problem arises in the handling of milk. Generally, creameries collect the milk by means of bulk tankers from a number of locations where the primary producer stores the milk in vessels which vessels are usually provided with some form of refrigeration and a mixer to ensure that the contents of the stored milk is both gently agitated and chilled to the desired temperature. Bacterial growth in milk is directly temperature dependent and the longer the milk stays at a high temperature, the greater the bacterial growth and thus the more effect it has on the quality of milk. Unfortunately, when the milk is being collected by a bulk storage tanker, there is nothing to indicate to the person collecting the milk that for example the temperatures of milk in the vessel or tanker has increased beyond an acceptable level, the mixer wasn't operating or indeed there had been some form of power failure. Thus, when the bulk storage tanker returns to it's depot and the milk is tested the whole load may have to be rejected. It is impossible for the collector to ascertain exactly where the problem arose. It is difficult to identify the source of the contaminated milk and thus very little can be done about it. This problem will be exacerbated as the regulations in relation to the storage and transport of milk are made more stringent. In some ways, a more serious problem is that midway through collection, for example, a milk tanker could stop operating correctly and thus would continue to collect milk when it should cease collection. Thus, in many instances, a full load of milk is rejected when a more adequate warning would have ensured that possibly little or no milk would be rejected in that the collection operation would be stopped immediately malfunction was detected. One method of attempting to solve this problem is described and claimed in US Patent Specification No. 6006615 (Uttinger). Unfortunately, it is not a complete solution to the problem. There is thus a need in the food and in many other industries to be able to ascertain very clearly the conditions under which the product has been handled throughout the production cycle and particularly during storage and transport.

While in situ temperature and other probes may be provided in storage vessels and the like as is conventional they do not address the problems experienced for example by a producer who does not have control of the product throughout the production cycle whether it be fresh food producer who has to entrust the food to third parties to transport and store or where as is the case as mentioned above creameries, there are a large number of producers delivering or having collected as in the case of raw milk product for further processing by the producer.

In many situations particularly in storage vessels it is not just simply enough to obtain the average temperature of the particular product but it is often of vital necessity to have a vertical temperature tracking analysis.

There is also a need for a temperature tracking device that can be a separate instrument that for example can be placed into vessels or containers of food and other products to record the temperature over a period of time and then removed for subsequent analysis. Particularly it is necessary to have a tamper-proof system.

The present invention is directed towards providing such a temperature tracking device.

Statements of Invention

According to the invention, there is provided a method of tracking the temperature of a liquid stored in a storage vessel comprising:-

recording the temperature at preset time intervals at at least two locations in the vessel;

storing the recorded temperatures; comparing the recorded temperatures with preset limit temperatures; and

preparing a report detailing temperatures outside the preset limit temperatures.

It will be appreciated that the great advantage is that a producer will be able to put his or her own temperature tracking devices into something that they are entrusting to a third party while at the same time obtaining full control over the data. It will also be appreciated if possible to encrypt the data so that a third party can not interfere with it.

Ideally, the duration of the time period over which the temperatures were outside the preset limit temperatures is recorded.

Preferably, the locations correspond to different heights within the storage vessel representing potentially different depths of liquid.

In one method according to the invention, when liquids are added at time intervals to mix with previously stored liquids, said liquids being introduced at temperatures at variance with the storage temperature liquids in which the initial steps are performed of:

preparing a base sample of known base volume;

storing the base sample in the vessel with liquid within a desired temperature range;

recording the temperature of the base sample;

adding a test sample of recorded added volume and temperature to the base sample;

preparing a profile over time of the resultant temperature of the mixture as a control profile; preparing a database of control profiles for sets of base and added volumes; and

subsequently, on adding a known volume of liquid to a vessel containing an existing known volume of liquid, the steps are performed of:

preparing a profile of the resultant actual temperature over time as a recorded profile for the liquid stored;

comparing the recorded profile against the control profile in the database for the appropriate set of base and added volumes to determine the operation of the storage vessel; and

rejecting or accepting the liquid consequent on the result.

In this latter method, when the vessel contains a liquid conditioning apparatus the test is carried out for various operating conditions of the liquid conditioning apparatus to obtain a control profile and the control profile is used to detect possible subsequent malfunction of the conditioning apparatus. Such liquid conditioning apparatus could be, for example, a pump circulating cooling water, a refrigeration unit and coils within or surrounding the vessel, a mixer paddle, or the like.

Since malfunction will usually lead to temperature stratification, the arrangement according to the present invention is particular suitable for detecting this. Thus, ideally, the malfunction is detected by observing the stratification of the temperature profile within the storage vessel.

In addition to recording to the temperature of the liquid, the ambient temperature above the liquid is recorded.

In one embodiment of the invention, the control profile is based on the total heat retention of the liquid over the storage period. It will be appreciated that it is the total heat retained by the liquid that will cause the biological damage and therefore this is very important. Ideally, the total heat retention is measured by integrating the temperature profile over time to produce a control profile number. This integration is one of the easiest and most efficient ways of obtaining a useful control factor to determine when malfunction occurs or is about to occur since the warning can take place prior to malfunction. Ideally, therefore, the report is prepared in real time and a warning device is provided whereby on the total heat of the liquid over a storage period exceeding a preset limit, the warning device is activated.

It will be appreciated that the method according to the present invention is particularly directed towards the storage or transportation of milk.

According to the invention, there is further provided a liquid storage vessel including a data logger of the type comprising a sensor, an analogue to digital converter, a memory and data port characterised in that the data logger comprises a plurality of temperature sensors at different heights within the storage vessel representing potentially different depths of liquid. In this latter liquid vessel, one location one location is close to the bottom of the vessel and the other the top and ideally, the uppermost sensor is positioned to be above the maximum liquid level in use.

Preferably, the data logger is housed in a sealed tube and is provided with releasable mounting means for releasably mounting the data logger within the vessel.

In one embodiment of the invention, the data logger comprises:-

a plurality of separate lengths of tubing, each containing a temperature sensor;

means to interconnect the tubing and sensors;

a pair of end caps; and

a data port included in one of the end caps. The data logger preferably includes a telecommunications device for the downloading of data to a remote location.

Further, the invention provides a temperature tracking device of the type comprising a temperature sensor, an analogue to digital converter, a memory clock and data port contained within a sealed enclosure characterised in that the enclosure is an elongate enclosure and comprises:-

means to interconnect the tubing and sensors;

a pair of end caps; and

a data port included in one of the end caps.

Ideally, this latter temperature tracking device includes a telecommunications device for the downloading of data to a remote location.

Detailed Description of the Invention

The invention will be more clearly understood from the following description of an embodiment thereof given by way of example only with reference to the accompanying drawings in which:

Fig. 1 is a side diagrammatic view of a storage vessel according to the invention,

Fig. 2 is a sectional elevation of a temperature tracking device according to the invention,

Fig. 3 is a sectional plan view on an enlarged scale of the device of Fig. 2, Figs. 4 to 6 show various temperature profiles achieved in one test according to the invention,

Figs. 9 to 12 show various temperature profiles achieved with another test according to the invention,

Figs. 13 to 15 show various temperature profiles achieved with another test according to the invention,

Figs. 16 to 21 show temperature profiles achieved in a test when partial mixer failure occurred,

Figs. 22 to 24 show temperature profiles achieved in another test when partial mixer failure occurred,

Fig. 25 is a sectional view of an alternative construction of temperature tracking device according to the invention, and

Fig. 26 is an exploded sectional view of the device of Fig. 25.

Referring to the drawings and initially to Fig. 1 , there is provided a milk storage vessel, indicated generally by the reference numeral 1 , having a vessel wall 2 of double-skin construction through which cooling water is pumped during the storage operation. The vessel includes a milk inlet port 3 and a stirrer mixer 4, together with a data logger, in this case, a temperature tracking device, indicated generally by the reference numeral 10. Suitable mounting means, in this case a sleeve-like connector 5, secures the temperature tracking device 10 in the vessel 1.

Referring to Figs. 2 and 3, the temperature tracking device 10 comprises an enclosed stainless steel tube 12 having a sealed end 13 at one end and a dataport 14 at it's other end. The tube 12 carries three data loggers, in this case, temperature sensors 15, 16 and 17 urged against the interior bore of the tube 12 by a packing device 18 which is simply a strip of plastic packaging material arcuate in cross-section as can be seen in Fig. 3. The packing device 18 is a tight fit within the tube 12 and thus bears against each temperature sensor 15, 16 and 17 forcing them into intimate contact with the interior of the bore of the tube 12. Each temperature sensor 15, 16 and 17 is connected by internal cable 19 to the dataport 14. The dataport 14 can be connected directly by cabling to a suitable processor.

Referring now specifically to Fig. 4 to 6, there is illustrated the filling of a milking tank over a period of one day. The first fill of the tank occurs mid-morning and immediately the temperature of the hot milk has been sensed at the bottom temperature sensor 17 which causes the temperature recorded to rise sharply (Fig. 4). While the temperature sensors 15 and 16 are above the level of the milk, the ambient temperature above the milk will obviously be increased and this is clearly shown by the slight rise in temperature at the temperature sensors 15 and 16 (Figs. 5 and 6). The second filling of the tank which occurs later will now cause the hot milk initially to be sensed by the data logger, namely, the temperature sensor 16, which causes the temperature to rise most sharply in the temperature sensor 16 (Fig. 5) and less sharply in the data logger 17 (Fig. 4), while in the data logger 15 which is still above the level of the milk, there is a slight rise in temperature and then quickly in each case the temperature drops to its correct level. "Thus, it will be easily seen that the mixer is working correctly and that the temperatures are being reduced sufficiently rapidly. For example, if the mixer was not in operation, or if the mixer was not working efficiently then there would be a temperature gradient throughout the milk tank which would be readily easily detected. Similarly the shutting off of coolers and the like will be readily easily detected. All this is shown in further tests described below.

It is relatively easy to download through the dataport 14 the information to a hand held computer or other storage device for subsequent processing.

Referring now to Figs. 7 to 15 inclusive, there is illustrated a test carried out on two different days and again, it can be seen, with a normal cooling function and the vessel operating correctly, how the temperature changed.

Referring now to Figs. 16 to 24, there is shown various tests carried out with partial mixer failure. The mixing paddle was not operating effectively, that is to say, some of the liquid conditioning apparatus was not operating.

Dealing firstly with Figs. 16 to 18, it will be seen that when, at the first fill in the early morning milking, while the temperature rose as one would normally expect, the effect was relatively little because there was little milk within the vessel 1 and secondly, the data logger 3, that is to say, the bottom temperature sensor, is relatively close to the bottom of the tank and thus would tend to sense, even with partial reduction in agitation of the cooling water, relatively cool temperatures. In other words, the milk close to the bottom of the tank, with partial mixer failure, would continue to show little malfunction. Thus, it is envisaged, having regard to this test, that additional sensors may need to be provided to detect such failure. However, the failure is partial failure and has not yet caused any great problems in relation to the quantity of milk within the tank, that is to say, the milk is still being stored relatively efficiently. However, referring now to Figs. 19 to 21 , the position changes radically when, during the afternoon on the same day, additional milk was added to the vessel. It will be seen that while there was some increase at the bottom sensor, at the middle temperature sensor, there was a huge increase in temperature and this temperature did not decay quickly but quite clearly, a considerable amount of milk now being stored at an unacceptable temperature. Again, the top temperature sensor does not display any great rise in temperature because it was not covered by milk.

In the test carried out on the next day, as can be seen from Figs. 22 to 24 inclusive, when the milk was filled up to the level of the top temperature sensor, even a more unacceptable gradient of milk was detected.

Referring now to Figs. 25 and 26, there is illustrated an alternative construction of temperature tracking device, indicated generally by the reference numeral 20. In this embodiment, the data logger comprises a plurality of separate lengths of tubing 21 , each containing a temperature sensor 22, and each length of tubing 21 has means for connecting to another length of tubing comprising a male end 23 with appropriate electrical connections and a female end 24, again with appropriate electrical connections. These are threaded parts. A pair of end caps, namely, a top end cap 25 and a bottom end cap 26 having a data port 27 is also provided. This particular construction is relatively efficient because it will allow the appropriate size of data logger to be used. Additional lengths of tubing can be added.

It will be appreciated that when, for example, any of the milk conditioning apparatus fails such as, for example, the water chilling refrigerator, the water pump recirculating the chilled water around the walls of the vessel, the mixer paddle or indeed any other conditioning apparatus, that there is a clearly identified temperature stratification within the liquid as well as an increased temperature.

It will be noticed that the upper temperature sensors indicate a much lower rate of cooling and that further, the upper temperature sensors show a faster than normal temperature rise. It has been found that one of the ideal ways of measuring, for example, the heat retention of the milk, is to integrate the temperature over time because this indicates the total amount of heat imparted to the milk. In other words, it measures the heat retention of the milk which is what causes the biological degradation. Thus, the control profile is based on the total heat of the liquid over the storage period and this total heat can be measured by integrating the temperature profile over time to produce a control profile number.

Because the device, according to the present invention, will be used in tankers and the like, collecting milk, it is envisaged that a warning device will be provided whereby with the total heat retention of the liquid over a storage period exceeding a preset limit, the warning device is activated.

Essentially, what will be done in practice is that various base tests will be made to calibrate the equipment and then the profiles of situations where the vessel is operating correctly and incorrectly, will be prepared. However, it is felt that the use of the integration, as mentioned already, will be particularly useful. Similarly, malfunction will be detected by stratification within the vessel. It is also envisaged that, prior to actual malfunction occurring, the warning device may be provided whereby the total heat of the liquid over a storage period exceeding a preset limit, the warning device is activated.

It is also envisaged that a telecommunications device may be incorporated in the data logger for advance warning to, for example, a central unit or to, for example, the cab of a trailer unit transporting the storage vessel.

It should be appreciated that certain failures will be more easily detected than others. For example, cooler failure will be readily easily be detectable as reduced cooling would be seen globally in the liquid volume, however, mixer or paddle failure is hardest of all problems to detect.

While in all the embodiments described above, only three temperature sensors have been used, it will be appreciated that many more temperature sensors can be used and indeed, since the temperature sensors are relatively inexpensive, there is no great difficulty in providing additional sensors.

In the specification the terms "comprise, comprises, comprised and comprising" or any variation thereof and the terms "include, includes, included and including" or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

The invention is not limited to the embodiments hereinbefore described but may be varied in both construction and detail.

Claims

1. A method of tracking the temperature of a liquid stored in a storage vessel comprising:-

storing the recorded temperatures;

comparing the recorded temperatures with preset limit temperatures; and

2. A method as claimed in claim 1 , in which the duration of the time period over which the temperatures were outside the preset limit temperatures is recorded.

3. A method as claimed in claim 1 or 2, in which the locations correspond to different heights within the storage vessel representing potentially different depths of liquid.

4. A method as claimed in any preceding claim, in which, when liquids are added at time intervals to mix with previously stored liquids, said liquids being introduced at temperatures at variance with the storage temperature liquids in which the initial steps are performed of:

preparing a base sample of known base volume;

storing the base sample in the vessel with liquid within a desired temperature range; recording the temperature of the base sample;

preparing a profile over time of the resultant temperature of the mixture as a control profile;

preparing a database of control profiles for sets of base and added volumes; and

rejecting or accepting the liquid consequent on the result.

5. A method as claimed in any preceding claim, in which, when the vessel contains a liquid conditioning apparatus, the test is carried out for various operating conditions of the liquid conditioning apparatus to obtain a control profile and the control profile is used to detect possible subsequent malfunction of the conditioning apparatus.

6. A method as claimed in claim 5, in which the malfunction is detected by observing the stratification of the temperature profile within the storage vessel.

7. A method as claimed in any preceding claim, in which, in addition to recording the temperature of the liquid, the ambient temperature above the liquid is recorded.

8. A method as claimed in any preceding claim, in which the control profile is based on the total heat retention of the liquid over the storage period.

9. A method as claimed in claim 8, in which the total heat retention is measured by integrating the temperature profile over time to produce a control profile number.

10. A method as claimed in any preceding claim, in which the report is prepared in real time.

11. A method as claimed in claim 9, in which a warning device is provided whereby on the total heat retention of the liquid over a storage period exceeding a preset limit, the warning device is activated.

12. A method as claimed in any preceding claim, in which the liquid is milk.

13. A liquid storage vessel (1) including a data logger (10) of the type comprising a sensor, an analogue to digital converter, a memory and data port (14) characterised in that the data logger (10) comprises a plurality of temperature sensors (15, 16, 17) at different heights within the storage vessel (1) representing potentially different depths of liquid.

14. A liquid storage vessel (1) as claimed in claim 13, in which one location is close to the bottom of the vessel (1) and the other the top.

15. A liquid storage vessel (1) as claimed in claim 13 or 14, in which the uppermost sensor (1) is positioned to be above the maximum liquid level in use.

16. A liquid storage vessel (1) as claimed in any of claims 13 to 15, in which the data logger (10) is housed in a sealed tube (12).

17. A liquid storage vessel (1) as claimed in claim 16, in which means (5) are provided for releasably mounting the data logger (10) within the vessel (1).

18. A liquid storage vessel (1) as claimed in claim 17, in which the data logger (10) comprises:-

a plurality of separate lengths of tubing (21), each containing a temperature sensor (22);

means (23, 24) to interconnect the tubing (21) and sensors (22);

a pair of end caps (25, 26); and

a data port (27) included in one of the end caps (26).

19. A liquid storage vessel (1) as claimed in any of claims 13 to 18, in which the data logger (10) includes a telecommunications device for the downloading of data to a remote location.

20. A temperature tracking device of the type comprising a temperature sensor, an analogue to digital converter, a memory clock and data port contained within a sealed enclosure characterised in that the enclosure is an elongate enclosure and comprises:-

means (23, 24) to interconnect the tubing (21) and sensors (22);

a pair of end caps (25, 26); and

a data port (27) included in one of the end caps (26).

1. A temperature tracking device as claimed in claim 20, in which there is included a telecommunications device for the downloading of data to a remote location.