SYSTEM AND METHOD FOR DETERMINING THE INTEGRITY OF CONTAINERS

Abstract

The disclosure relates to system and method for determining the integrity of a container containing at least one gas. The disclosure relates to an environment with a lower absolute gas pressure than the pressure inside the container, a light source and a detector arranged to transmit a light signal to the detector through the environment, or a volume connected to the environment, but outside the container, and wherein a control unit for determining, based on said transmitted light signal being detected, if a level of the at least one gas inside the container is altered in the environment or the connected volume.

Claims

1. A system for determining the integrity of a container containing at least one gas, said system comprises: an environment with a lower absolute gas pressure than the pressure inside the container; a light source and a detector arranged to transmit a light signal to said detector through said environment, or a volume connected to said environment, but outside said container; wherein said light source and said detector is configured as an optical sensor being based on tunable diode laser absorption spectroscopy; a control unit for determining, based on said transmitted light signal being detected, if a level of said at least one gas inside said container is altered in said environment or said connected volume.

2. A method of determining the integrity of a container containing at least one gas, said method comprising: placing the container in an environment with a lower absolute gas pressure than the pressure inside the container; transmitting a light signal through a portion of said environment, or a volume connected to said environment outside said container using an optical transmitter and detecting at least a portion of the light using an optical detector being based on tunable diode laser absorption spectroscopy; wherein said optical transmitter and said detector forming an optical sensor sensitive to at least one gas present in said container; determining, based on said transmitted light signal being detected, if a level of said at least one gas inside said container is altered in said environment or said connected volume.

3. The method according to claim 2, where said environment is a closed chamber.

4. The method according to claim 3, where a partial vacuum is applied in said closed chamber.

5. The method according to claim 2, wherein a size of alternation of said level of said at least one gas gives information about the size of a leakage in said container.

6. The method according to claim 3, wherein: said light signal is transmitted as a light beam through a main compartment of said closed chamber; and said light beam can pass directly from said transmitter to said detector, or said light beam can be reflected in at least one mirror or other optical component, before reaching said detector.

7. The method according to claim 3, wherein said light signal is transmitted through a measurement volume, for example a pipe, connected to said closed chamber, and wherein a vacuum pumping device configured to extract the at least one gas from said closed chamber is placed in relation to said closed chamber so that the at least one gas extracted from said closed chamber passes through said connected measurement volume as a pressure within the closed chamber is decreased.

8. The method according to claim 3, wherein said light signal is transmitted through a measurement volume connected to said closed chamber, and wherein a circulation system circulates the gas through said closed chamber and said connected measurement volume.

9. The method according to claim 7, where a valve is placed in said closed chamber, so as to, at chosen time periods, allow gas to enter the closed chamber to create a flow through and from said closed chamber through said connected measurement volume.

10. The method according to claim 9, wherein said valve, alone or in combination with at least one more valve, is controlled to create a pressure cycle wherein a pressure of the closed chamber is first decreased to a fixed level with said valve closed, during which time a leakage in said container will increase the concentration of said at least one gas locally in said closed chamber; said valve is then fully or partially opened to allow a flow of the at least one gas from said closed chamber to and through said connected measurement volume.

11. The method according to claim 8, wherein an exact time when an altered concentration of said at least one gas is detected in said connected measurement volume, after said valve is opened, gives information about the position of a leakage in said container.

12. The method according to claim 10, wherein the pressure cycle is specially designed so that said leakage from said container is forced to reach the light beam.

13. The method according to claim 12, wherein the exact time when the altered concentration of said at least one gas is detected in said connected measurement volume, during the pressure cycle, gives information about the position of said leakage in said container.

14. The method according to claim 2, wherein multiple detectors are placed at different positions around said container, and wherein the multiple detectors are used in combination with at least one transmitter.

15. The method according to claim 14, wherein the at least one transmitter comprises a single transmitter and wherein said light beam is folded around said container using semi-transparent mirrors and a detector of the multiple detectors is placed behind at least one of said semi-transparent mirror and at the termination of said light beam.

16. The method according to claim 2, wherein a multi-pass cell is used to create a long optical path-length in a limited volume; and wherein a leakage from said container is allowed to pass into, or through, said multi-pass cell.

17. The method according to claim 2, wherein a porous medium is placed between said optical transmitter and said detector, to create a long optical path-length in a limited volume; and wherein a leakage from said container is allowed to pass into, or through, said porous medium.

18. The method according to claim 2, wherein a measurement is stopped as soon as a certain amount of an alternation of said level of said at least one gas is detected, to make the measurement time as short as possible.

19. The method according to claim 2, wherein said at least one gas is carbon dioxide.

20. The method according to claim 2 wherein said at least one gas is water vapor, methane, oxygen or carbon monoxide.

21. The method according to claim 2, wherein said container is a food package.

22. The method according to claim 2, wherein said container is a food package with a modified atmosphere (MAP packaging).

23. The method according to claim 2, wherein leak testing is performed inline.

24. The method according to claim 2, wherein the container is pressurized.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] These and other aspects, features and advantages of which examples of the disclosure are capable of will be apparent and elucidated from the following description of examples of the present disclosure, reference being made to the accompanying drawings, in which:

[0021] FIG. 1 is illustrating an example where a pressurized container placed in an open environment where a laser beam is transmitted around the container and folded using semi-transparent mirrors. Multiple detectors are used in order to detect where on the container a potential leak is present.

[0022] FIG. 2 is illustrating a container placed in a chamber through which a laser beam is transmitted. In this example a vacuum pump is connected to the chamber in order to decrease the pressure in the chamber to a partial vacuum.

[0023] FIG. 3 is illustrating a container placed in a chamber through which a laser beam is transmitted and folded around the container using semi-transparent mirrors. Multiple detectors are used to detect where on the container a potential leak is present.

[0024] FIG. 4 is illustrating an example where the container is placed in a chamber connected to a measurement volume through which the laser beam is transmitted. A vacuum pump is decreasing the pressure in the chamber and connected measurement volume.

[0025] FIG. 5 is illustrating an example of a pressure cycle that may be used to force gas leaking out of a container, for example as positioned as in FIG. 4, to reach the laser beam to be detected. Included is also an example of how the resulting detected alternation of the gas concentration may behave for a leaker.

[0026] FIG. 6 is illustrating an example where the container is placed in a chamber which is connected to a measurement volume. A circulation pump is circulating the gas through the chamber and connected measurement volume.

[0027] FIG. 7 is illustrating an example where the container is placed in a chamber which is connected to a measurement volume. A vacuum pump is decreasing the pressure in the chamber and measurement volume. In this example, a valve is placed in the chamber to allow a flow of gas from the chamber to the measurement volume.

[0028] FIG. 8 is illustrating an example where the container is placed in a chamber which also contains a multi-pass cell in which the light travels a long path, enabling a sensitive detection.

[0029] FIG. 9 is illustrating an example where the container is placed in a chamber which is connected to a measurement volume consisting of a multi-pass cell. A pump is circulating the gas through the chamber and measurement volume.

[0030] FIG. 10 is illustrating a flow-chart over an exemplary method.

DESCRIPTION OF EXAMPLES

[0031] Specific examples of the disclosure will now be described with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0032] The following disclosure focuses on examples of the present disclosure applicable to determining the integrity of containers by placing a container with at least one gas in an environment with a lower absolute pressure than that inside the container, and measuring an alternated level of the at least one gas in the environment. The environment may be a closed enclosure, such as a closed chamber or closed holder. In some examples, the environment may be an at least partial open enclosure, such as a chamber or a holder with at least one open side. In some further examples, the environment may be an open area. Additionally, in some examples, the container may be a pressurized container, such as a bottle, for example a bottle with carbonated beverage such as soda, or sparkling wine or beer. The container may also be a tray or a bag with at least one added gas with an absolute pressure higher than 1 atm. Alternatively, in some examples, the container may also be non-pressurized, for example a food tray, a non-pressurized beverage bottle or can, a bag, a carton-based container, a metal can, or a plastic based container etc. The container may even have an internal absolute gas pressure less than 1 atm. The headspace in the container contains the at least one gas detectable using an optical sensor. The optical sensor may be using spectroscopy technology, such as TDLAS, to detect the at least one gas. The at least one gas may be, for example carbon dioxide or oxygen. Both these gases are common in modified atmosphere packaging (MAP) which is used to prolong the shelf-life of, for example, food products. The at least one gas may also be, for example, water vapor, carbon monoxide or methanegases which are also suitable to detect using an optical sensor, such as TDLAS. The amount of alternation of the level of at least one gas in said environment may be used to determine the size of the leak in the container.

[0033] FIG. 1 is illustrating an example where a pressurized container is placed in an environment (2). In this example an optical transmitter (5) is transmitting a light beam (4) around the container (1). The light beam is reflected using semi-transparent mirrors (6) and is detected with several detectors (3). The use of several detectors enable information about the position of the leak on the container. In other examples the light beam may be transmitted directly from the transmitter to a detector. In other examples there may be more than one transmitter in combination with one or more detector. The light beam may also be shaped as, for example, a light sheet in order to cover a larger portion of the volume surrounding the container. The light beam may also be reflected around the container without the use of semi-transparent mirrors, but instead using a normal mirror, or another surfaces present in the environment of the container, or using reflections of the container material itself. Reflection geometries may also be used in order to allow better optical access or an increased detection sensitivity due to an elongated optical path.

[0034] The detected light may be analysed in a control unit for determining an alternated level of the at least one gas in the environment. The control unit may be a computer, a microprocessor or an electronic circuit that could run code or a software configured for analysing the light detected by the detector.

[0035] FIG. 2 shows another example where the container (1) is placed in an environment (2), here illustrated as an enclosure, such as a chamber, which has a lower absolute gas pressure than that inside the container (1). If the container (1) is pressurized, the environment (2) may be at ambient pressure or it may have a partial vacuum. In this example a vacuum pump (6) is connected to the environment (2) in order to create a partial vacuum. An optical transmitter (5) transmits a light beam (4) through the environment (2), and the light beam (4) is detected with a detector (3). The light is transmitted outside the container (1).

[0036] In this example the transmitter (5) and detector (3) are placed on the outside of the environment, but they may also be placed inside the environment or elsewhere. In some examples wave guides, such as optical fibers, may be used to guide the light from the transmitter (5) and/or to the detector (3). In this example the environment (2) contains a fan (7) which is used to create a circulation of the gas inside the environment (2) to ensure that the leaked gas from any position of the container (1) reaches the light beam (4). When using an enclosure such as a chamber, it may be advantageous to have an as small volume as possible of the enclosure to make the alternation of the level (concentration) of the at least one gas larger for a certain leak flow.

[0037] The detected light may be analysed in a control unit for determining an alternated level of the at least one gas in the environment. The control unit may be a computer, a microprocessor or an electronic circuit that could run code or a software configured for analysing the light detected by the detector.

[0038] FIG. 3 shows another example where the container (1) is placed inside an environment (2), here illustrated as an enclosure, such as a chamber, through which a light beam (4) is transmitted from an optical transmitter (5) to at least two optical detector (3) using at least one semi-transparent mirrors (7). The use of at least two detectors (3) allow for detection of the position of the leak on the container (1). A vacuum pump (6) is connected to the environment in order to create a partial vacuum. The detected light may be analysed by a control unit for determining an alternated level of the at least one gas in the environment. The control unit may be a computer, a microprocessor or an electronic circuit that could run code or a software configured for analysing the light detected by the detector.

[0039] FIG. 4 shows another example where the container (1) is placed in an environment (2), here illustrated as an enclosure, such as a chamber, which is connected to a separate measurement volume (6), in this case made as a conduit, such as a tube or a pipe. A transmitter (5) sends a light beam (4) through the measurement volume (6) to the detector (3). The light may be transmitted longitudinally through the measurement volume (6), such as along the length of a conduit, or transvers through the measurement volume (6). A vacuum pump (7) is in this example connected to the opposite side of the measurement volume (6) compared to the environment (2). In this way gas is flowing from the chamber (2) to and through the measurement volume (6) when the vacuum pump (7) is pumping. Special attention may be taken to the pressure cycle, i.e., how the pressure is varying in time during the leak testing, in order to ensure that the at least one gas leaking out from the container (1) is reaching the light beam (4) faster than it would through gas diffusion.

[0040] One example of such a pressure cycle is shown in FIG. 5. In this example the pressure is first quickly decreased (1a) to a certain level (2a) which is lower than that inside the container (1). The pressure is then kept constant for some time, for example one second, during which the at least one gas is leaking out from the container (1) and induces an increased concentration locally in the chamber (2). The pressure is then decreased further (3a) which creates a flow from the chamber (2) to the measurement volume (6). The exact time during the second pressure decrease (3a) may in some cases be used to determine where on the container (1) a leak is present.

[0041] The examples illustrated in FIGS. 4 and 6 may include a control unit for analysing the detected light for determining an alternated level of the at least one gas in the environment. The control unit may be a computer, a microprocessor or an electronic circuit that could run code or a software configured for analysing the light detected by the detector.

[0042] FIG. 6 shows another example where the container (1) is placed in an environment (2), here illustrated as an enclosure, such as a chamber, which is connected to a measurement volume (6) through which a transmitter (5) sends a light beam (4) to a detector (3). The light may be transmitted longitudinal through the measurement volume (6), such as along the length of a conduit, or transvers through the measurement volume (6).

[0043] In this example, a circulation through the measurement volume (6) and back into the environment (2) is made possible. A pump (7) which may be used for decreasing the pressure and/or circulating the gas is ensuring the gas leaking out from the container (1) reaches the light beam (4).

[0044] The detected light may be analysed using a control unit for determining an alternated level of the at least one gas in the environment. The control unit may be a computer, a microprocessor or an electronic circuit that could run code or a software configured for analysing the light detected by the detector.

[0045] FIG. 7 shows an example where a valve (8) is placed in the environment (2), here illustrated as an enclosure, such as a chamber, for example at the opposite side compared to the connected measurement volume (8). The valve (8), which may be controlled by various means, may be opened to chosen amounts at chosen times to create a desired flow through the environment (2) and the measurement volume (6) to ensure that gas leaking out from the container (1) reaches the light beam (4). As an example, the pressure may first be decreased with the vacuum pump (7) while the valve (8) is closed. The pressure may then be kept constant during some time while gas is leaking out from the container (1) into the chamber. The valve (8) may then be opened so that gas is flowing through the chamber into the measurement volume (6) so that the increased level of the at least one gas may be detected by the light beam (4).

[0046] The detected light may be analysed using a control unit for determining an alternated level of the at least one gas in the environment. The control unit may be a computer, a microprocessor or an electronic circuit that could run code or a software configured for analysing the light detected by the detector.

[0047] FIG. 8 shows an example where a multi-pass cell (8) is placed between the transmitter (5) and detector (3) to create a long optical path length in a small measurement volume in order to increase detection performance. In this example the transmitter (5) and detector (3) are placed inside the environment (2), here illustrated as an enclosure, such as a chamber, while in other examples the transmitter (5) and/or detector (3) may be placed on the outside of the chamber (2). In some examples the multi-pass cell may be mirror-based, for example of type Herriot, White or cavity, or of an integrating sphere type. In some examples the multi-pass cell may be a porous medium. A porous medium has the advantage of providing a long optical path-length while adding only a very small gas volume. In some examples optical fibers may be used to guide the light into, and/or out from the multi-pass cell.

[0048] FIG. 9 shows an example where a multi-pass cell is placed in a measurement volume outside of the main chamber (2).

[0049] The above described systems and methods may be implemented as a stand-alone unit for manual bench-top measurements on single containers. Alternatively, may the above described systems and methods be implemented in-line for example in a filling machine after the contained has been sealed. The machine may be configured so that all containers passes through the environment where the measurement is performed. Alternatively, in some examples samples are selected and measured on.

[0050] In the described systems and methods, the light source may be a white light source, for example transmitting a collimated light beam, or at least one laser source, such as a diode laser, a semiconductor laser. The wavelengths or wavelength range used for the light source is selected to match the absorption spectra of at least one species of the gas inside the container. The detector may be, for example, a photodiode, a photomultiplier, a CCD detector, a CMOS detector, a Si detector, an InGaAs detector, selected to be able to detect the wavelengths or wavelength range of the light source.

[0051] FIG. 10 is illustrating a method 1000 for determining the integrity of a closed container containing at least one gas. The method includes placing 1001 the container in an environment with a lower absolute gas pressure than the pressure inside the container. Transmitting 1002 a light signal through a portion of the environment, or a volume connected to the environment outside the container using an optical transmitter and detecting at least a portion of the light using an optical detector. The optical transmitter and the detector is forming an optical sensor. The optical sensor being sensitive to at least one gas present in the container. Determining 1003, based on said transmitted light signal being detected, if a level of said at least one gas inside said container is altered in said environment or said connected volume.

[0052] It should be noted that in the examples described above, it is not necessary to measure the gas concentration in absolute values. In some examples, it is sufficient to measure a signal that is related to the gas concentration. In some examples, the spectroscopic signal is related to the gas pressure.

[0053] The present invention has been described above with reference to specific examples. However, other examples than the above described are equally possible within the scope of the disclosure. Different method steps than those described above, performing the method by hardware or software, may be provided within the scope of the invention. The different features and steps of the invention may be combined in other combinations than those described. The scope of the disclosure is only limited by the appended patent claims.

[0054] The indefinite articles a and an, as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean at least one. The phrase and/or, as used herein in the specification and in the claims, should be understood to mean either or both of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases.