System for the detection of a tracer gas

Abstract

The present invention relates to a system (1) for the detection of a tracer gas (2), comprising: a test chamber (3) adapted to receive at least one item (4) inside it, a first gas source (5) arranged upstream of said test chamber (3) and configured to send a first gas (3a) inside the test chamber (3), a gas sensor (6) arranged downstream of said test chamber (3) and configured to detect said tracer gas (2) fed into the test chamber (3) by the item (4), a first duct (7) positioned between said first gas source (5) and said test chamber (3), a second duct (8) positioned between said test chamber (3) and said gas sensor (6X a third duct (9) positioned between said first gas source (5) and said gas sensor (6X flow adjusting means (10) associated with at least one of said ducts (7, 8, 9) adapted to allow / prevent the flow towards said test chamber (3) and / or said gas sensor (6) through the first duct (7) and / or the third duct (9).

Description

[0001] SYSTEM FOR THE DETECTION OF A TRACER GAS

[0002] Technical Field

[0003] The present invention relates to a system for the detection of a tracer gas, particularly carbon dioxide, inside a test chamber adapted to receive an item to be inspected. In particular, the system allows a leak test to be carried out on an item, e.g., the casing or an internal cavity of the item, in order to check for the presence of any gas leak / escape.

[0004] Background Art

[0005] Systems for carrying out leak tests on items and products of various types are known in the prior art. In particular, the known systems allow the airtightness of one or more cavities of items to be checked. The items subjected to leak tests may be, e.g., car batteries, containers, pharmaceutical product packaging or food product packaging.

[0006] A well-known and very advantageous system for leak testing uses helium as a tracer gas, as its molecule is very small (approximately 5 ppm) and easily detectable in the atmosphere and allows background noise to be reduced during analysis. Another molecule used in the state of the art is hydrogen.

[0007] The inspection is generally carried out by placing the item within the test chamber, connecting it to a duct to receive helium and bringing it into overpressure with respect to the surrounding chamber. The chamber is then isolated from the external environment for a predefined period of time to allow helium to escape from the item towards the chamber through any holes in the casing of the item itself. Finally, the volume of gas inside the chamber is sent via a pump to a helium sensor that determines the presence of helium and, therefore, the airtightness of the item.

[0008] Although known helium inspections can effectively identify non-conformities in the cavities of items, the aforementioned systems do have several limitations. First of all, helium is a rare and expensive molecule and the sensors used to identify it are slow to respond, meaning that these systems can actually only be used on items of high or very high value.

[0009] Secondly, helium inspections require time to carry out leak tests that are not compatible with high-productivity processes. To speed up measurements, it is therefore necessary to analyze several samples at a time, sizing the test chambers ad hoc which, on the other hand, causes a significant number of false rejects that must be remeasured.

[0010] Description of the Invention

[0011] In view of the aforementioned problems, the Applicant has decided to develop a system that does not require the use of helium as a tracer gas.

[0012] One object of the present invention is therefore to provide a system for the detection of a tracer gas that is efficient, versatile and economical.

[0013] A further object of the present invention is to create a system for the detection of a gas which allows the use of different types of tracer gas.

[0014] A further object of the present invention is to provide a system for the detection of leaks and micro-leaks very quickly.

[0015] A further object of the present invention is to provide a system that allows naturally occurring and / or item-generated tracer gases to be detected, for example, those produced by natural or endogenous chemical reactions, such as gases from food products derived from wine-making, such as wine and beer, or from the dairy sector.

[0016] Yet a further object of the present invention is to provide a system for the detection of a gas that allows leak tests to be carried out on a plurality of items simultaneously. To this end, the Applicant has developed a system for the detection of tracer gas with two separate ducts connecting a gas sensor to the test chamber and to a gas source respectively, thus allowing the time required for leak testing of an item placed inside the chamber to be reduced without reducing the effectiveness and reliability of the test itself. The main aim of the present invention is therefore to devise a system for the detection of a tracer gas which allows the aforementioned drawbacks of the prior art to be overcome in a simple, rational, easy and effective to use as well as inexpensive solution.

[0017] The above objects are achieved by the system for the detection of a tracer gas according to claim 1.

[0018] Brief Description of the Drawings

[0019] Some embodiments and aspects of the invention will be described below with reference to the accompanying drawings, which are provided for illustrative purposes only and are therefore not limiting, in which:

[0020] - Figures 1-5 show examples of block diagrams of the system in accordance with the present invention.

[0021] Embodiments of the Invention

[0022] This description relates to a system 1 for the detection of a gas. In particular, the system 1 is adapted to detect the presence of a gas inside a test chamber 3 in which an item 4 is placed. In detail, the gas may be released from the item itself or conveyed through the item, as will be explained in more detail below.

[0023] According to one embodiment, the system 1 of the invention is adapted to detect the presence of a tracer gas 2 inside a test chamber 3 in which an item 4 is placed. According to one aspect, the tracer gas 2 is carbon dioxide or a mixture of gases comprising carbon dioxide.

[0024] The system 1 comprises a test chamber 3 adapted to receive at least one item 4 inside it. The test chamber 3 is configured to be airtight at least in one condition of use. As will be described below, the test chamber 3 is configured to be open in a first configuration of the system 1 and to be airtight in a second configuration of the system 1. In detail, the test chamber 3 is made so as to accommodate the item 4 in its interior 3 a and to surround it.

[0025] In one aspect, the test chamber 3 is made based on the item 4 to be inspected. In detail, the test chamber 3 has an internal volume adapted to contain the item in such a way that the item occupies most of this internal volume.

[0026] Advantageously, the test chamber 3 is sized so that it is occupied for the most part by the item. In this way, the free volume between the chamber and the item is minimized, thus facilitating the detection of the tracer gas fed by the item into this free volume.

[0027] In one embodiment, the test chamber 3 is configured to surround only one portion to be analyzed of the item 4. For example, the test chamber 3 may be defined by a probe adapted to contact the portion to be analyzed of the item 4. The portion to be analyzed may be, e.g., a portion of the item 4 in which it is necessary to check for holes and / or leakage of the tracer gas.

[0028] The item 4 may be an item for which it is necessary to check the airtightness of a portion thereof, such as the casing thereof, or an internal cavity in order to check for the presence of any gas leak / escape. In further versions, the item 4 may be a food product from which to detect the presence of any endogenous / natural gases.

[0029] Preferably, the item 4 can be selected from the group comprising: containers, industrial containers (such as those used for aerosols), bottles, single-dose packaging, protective packaging, electronic components, batteries, applications in the aerospace or automotive sector, chemical product containers, pharmaceutical product packaging, food product packaging, food products, microorganism samples, absorbent materials, etc. Furthermore, the item may be e.g. an industrial plant adapted to carry / store the gas, and the system is used to detect gas leaks from this plant through a test chamber defined by a probe.

[0030] With reference to the example shown in Figure 1, the system 1 comprises a first gas source 5 arranged upstream of the test chamber 3. The first gas source 5 is configured to send a first gas in the interior 3a of the test chamber. The first gas source 5 can then be set in fluidic communication with the test chamber 3 to feed and convey the first gas to the test chamber 3.

[0031] According to one aspect, the first gas is air and / or nitrogen. The first gas source 5 is configured to convey air inside the test chamber 3. The system 1 can be configured to use air as carrier gas for the tracer gas. For example, in the case where the item conveys the tracer gas inside the test chamber, air can be used to carry this tracer gas out of the test chamber 3.

[0032] The system 1 also comprises a gas sensor 6 arranged downstream of the test chamber 3. The gas sensor 6 is configured to detect the tracer gas 2 fed into the test chamber 3 by the item 4. The gas sensor 6 is set in fluidic communication with the interior 3a of the test chamber 3 to receive a flow from the test chamber 3 and detect the concentration of the tracer gas 2 within such a flow. The gas sensor 6 is configured to detect the concentration of carbon dioxide within the flow received from the test chamber 3.

[0033] In use, the first gas source 5 is configured to feed the first gas to the test chamber so that the first gas can convey the tracer gas towards the gas sensor 6. In other words, any tracer gas present in the test chamber is mixed with the first gas and conveyed or pushed towards the gas sensor 6 so that the latter can determine the concentration thereof. By detecting the concentration of carbon dioxide in the gas flow leaving the test chamber, the system is able to determine whether an item has released carbon dioxide into the test chamber.

[0034] For example, if the gas sensor detects a carbon dioxide concentration equal to or less than 350-400 ppm in the flow leaving the test chamber, then the item has not released carbon dioxide into the test chamber. Conversely, if the gas sensor detects a carbon dioxide concentration greater than 400 ppm, then the item has released carbon dioxide into the test chamber. What is observed is an initial increase in the carbon dioxide concentration, followed by a rapid decrease, due to the rapid dilution of the carbon dioxide fed into the test chamber with the first gas. In one embodiment, the gas sensor 6 may be configured to implement digital filters or moving average filters for the detection and measurement of the concentration of the tracer gas in the gas flow. For example, the gas sensor 6 may be configured to detect the tracer gas only when that tracer gas is present in the flow in a concentration greater than 300 ppm, or 350 ppm or 400 ppm.

[0035] Preferably, the gas sensor 6 is of the type of a non-dispersive infrared (NDIR) sensor. The gas sensor 6 may also be of the non-dispersive infrared and / or tunable laser diode absorption spectroscopy (TDLAS) and / or photoacoustic and / or electrochemical type. In detail, the gas sensor 6 is configured to determine the concentration of carbon dioxide using detection techniques (e.g., spectrometry and / or spectroscopy) with a sensitivity of the order of a few ppm of carbon dioxide.

[0036] The gas sensor 6 is configured to detect the concentration of tracer gas on a continuous and / or dynamic basis. In detail, the gas sensor is configured to detect the concentration of tracer gas with a measurement frequency equal to or greater than 1 kHz. Advantageously, performing tracer gas concentration measurements at a frequency equal to or greater than 1 kHz allows changes in the concentration of tracer gas to be detected quickly and reliably.

[0037] The system 1 comprises a first duct 7 positioned between the first gas source 5 and the test chamber 3. In detail, the first gas source 5 is set in fluidic communication with the test chamber 3 by means of the first duct 7. The first gas source 5 is configured to feed the first gas to the test chamber 3 through the first duct 7.

[0038] The system 1 also has a second duct 8 positioned between the test chamber 3 and the gas sensor 6. In other words, the second duct 8 connects the test chamber 3 to the gas sensor 6 in fluidic communication. The gas sensor 6 is configured to receive the gas flow from the test chamber 3 by means of the second duct 8. In detail, the test chamber 3 is positioned between the first gas source and the gas sensor, and therefore between the first duct 7 and the second duct 8.

[0039] In use, any tracer gas present in the test chamber 3 is mixed with the first gas sent from the first source through the first duct and conveyed out of the test chamber towards the sensor through the second duct. In other words, the tracer gas is pushed by the first gas from the test chamber 3 into the second duct 8 towards the gas sensor 6.

[0040] In addition, the system 1 comprises a third duct 9 positioned between the first gas source 5 and the gas sensor 6. In detail, the third duct 9 connects the first gas source 5 to the gas sensor 6 in fluidic communication. In other words, the gas sensor 6 is configured to receive a flow of gas, particularly of first gas, from the first gas source without this flow passing through the test chamber 3. The gas sensor can be in direct fluidic communication with the first gas source through the third duct 9. The first gas source is therefore configured to feed the first gas to the first duct and to the third duct simultaneously or alternately.

[0041] The system 1 comprises flow adjusting means 10 associated with at least one of the ducts. The adjusting means 10 are adapted to allow and prevent the flow from the first gas source towards the test chamber 3 through the first duct 7. In detail, the flow adjusting means 10 are associated with each of the ducts.

[0042] The flow adjusting means 10 may also be adapted to allow and prevent the flow from the first gas source to the gas sensor 6 through the third duct 9. In detail, the flow adjusting means 10 allow the feeding of the first gas to be controlled so that the latter is conveyed alternately or simultaneously to the first duct and to the third duct.

[0043] The flow adjusting means 10 are also configured to ensure an even flow during the passage of gas between the test chamber 3 and the third duct 9. This is necessary to avoid turbulence or instantaneous variations in the flow towards the gas sensor 6 that could alter the measurement thereof. A variation in flow, even for a few moments, can cause accumulations or small variations in carbon dioxide that could cause fluctuations in the background of the measurement, negatively affecting the accuracy of the measurement. To significantly improve the sensitivity of the measurement, the flow is kept as uniform and constant as possible in order to correctly detect carbon dioxide, regardless of the type of sensor used.

[0044] In detail, the flow adjusting means 10 are adapted to allow and interrupt the fluidic communication between the first gas source and the test chamber 3 by opening / closing the first duct 7 and / or the second duct 8 and the fluid communication between the first gas source 5 and the gas sensor 6 by opening / closing the third duct 9.

[0045] In one embodiment, the system 1 is switchable between a first configuration and a second configuration.

[0046] In the first configuration, the gas sensor 6 and the first gas source 5 are in fluidic communication with each other by means of the third duct 9. In particular, in the first configuration of the system 1, the test chamber 3 is hermetically closed.

[0047] In the second configuration, the adjusting means 10 prevent the flow of the first gas from the first gas source 5 towards the gas sensor 6 through the third duct 9. Furthermore, in the second configuration, the gas sensor 6 is in fluidic communication with the test chamber 3 through the second duct 8.

[0048] The gas sensor 6 is configured to detect the concentration of tracer gas in both system configurations. In the first configuration, the gas sensor 6 determines the concentration of tracer gas in the gas flow received from the first gas source, then the gas sensor 6 determines the concentration of tracer gas in the first gas. In the second configuration, the gas sensor 6 determines the concentration of tracer gas in the gas flow received from the test chamber.

[0049] In one embodiment, the system 1 is configured to alternate the first configuration and the second configuration according to a predefined sequence. In particular, the system 1 is configured to maintain the first configuration for a predefined time. The predefined time is determined depending on one or more of the item, the tracer gas, the gas sensor and the process parameters in such a way that the tracer gas can migrate from the item 4 to the test chamber 3, e.g. in the case of an item 4 with a non-airtight cavity. In detail, as the predefined time increases, the sensitivity of the system 1 in identifying the non-airtightness of the item increases. In particular, a longer predefined time allows the system 1 to check for the presence of smaller holes in the item.

[0050] In accordance with the example shown in Figure 2, according to one aspect, the system 1 may comprise a second gas source 11 arranged upstream of the test chamber 3. The second gas source 11 is configured to send the tracer gas 2 to the item 4. In detail, the second gas source 11 is set in fluidic communication with an internal cavity of the item 4 to send the tracer gas to that cavity. The second source is configured to send carbon dioxide to the item 4, which the item will release into the test chamber 3 in the event of non-airtightness in the cavity. In other words, if the cavity of the item 4 is not airtight, the latter will release an amount of tracer gas detectable by the gas sensor 6 into the interior 3a of the test chamber 3.

[0051] The second gas source 11 can be configured to cause an overpressure of the cavity of the item with respect to the test chamber 3. The second gas source can be configured to feed the tracer gas to the item in both the first configuration of the system and the second configuration of the system or in only one of them. For example, the second gas source 11 may be set in fluidic communication with the interior of a vehicle battery to send carbon dioxide to that battery in order to check for the presence of holes in the battery casing.

[0052] The system 1 has a fourth duct 12 positioned between the second gas source 11 and the item 4. The second gas source 11 can be set in fluidic communication with the item by means of this fourth duct 12. In particular, the adjusting means 10 are configured to allow and / or prevent the passage of flow from the second gas source 11 to the item 4 through the fourth duct 12. The flow adjusting means 10 are configured to open and close the fourth duct 12 to allow or prevent the second gas source 11 from sending carbon dioxide to said item 4.

[0053] In one embodiment, the flow adjusting means 10 comprise a first valve 10a coupled to the first duct 7 to allow and / or prevent the flow from passing from the first gas source 5 towards the test chamber 3.

[0054] In addition, the flow adjusting means 10 comprise a second valve 10b coupled to the second duct 8 to allow / prevent the flow from passing from the test chamber 3 towards the gas sensor 6.

[0055] The flow adjusting means 10 may also comprise a third valve 10c and a fourth valve lOd coupled to the third duct 9 to allow / prevent the flow from passing from the first gas source 5 towards the gas sensor 6 and to the fourth duct 12 to prevent / allow the flow from passing from the second gas source 11 towards the item respectively.

[0056] According to one aspect, in the first configuration of the system, the first valve 10a and the second valve 10b are closed, and the third valve 10c and the fourth valve lOd are open. In the second configuration of the system 1, the first valve 10a, the second valve 10b and the fourth valve lOd are open while the third valve 10c is closed.

[0057] In one embodiment, for example shown in Figure 3, the system 1 comprises evacuation means 13 in fluidic communication with the test chamber 3. The evacuation means 13 are configured to control an internal pressure of the test chamber 3. In particular, the evacuation means 13 allow an overpressure situation to be created in the item inside the test chamber 3. In other words, the evacuation means 13 allow the internal pressure in the test chamber 3 to be reduced below the internal pressure of the item 4 in order to facilitate the escape of tracer gas from the item 4.

[0058] In particular, the evacuation means 13 comprise one or more pumps adapted to reduce the internal pressure of the test chamber. In particular, in the first configuration of the system, the one or more pumps are activated for a time less than the predefined time of the system remaining in the first configuration so as to reduce the internal pressure of the test chamber.

[0059] According to one aspect, the system 1 comprises a control unit 14 configured to switch the system 1 between the first configuration and the second configuration.

[0060] The control unit 14 is in signal communication with the flow adjusting means 10. In particular, the control unit 14 is configured to command the adjusting means 10 to allow and / or prevent the flow from passing in at least one of the first, second, third or fourth ducts. The control unit is configured to control one or more of the first valve 10a, the second valve 10b, the third valve 10c and the fourth valve lOd so as to open and close the respective ducts.

[0061] The control unit 14 is also set in signal communication with the gas sensor 6 and configured to receive the tracer gas concentration data from said gas sensor 6.

[0062] The control unit 14 is specifically configured to generate an alarm signal representative of the possible presence of a hole in the item 4 depending on the concentration data. In particular, the alarm signal indicates that the item 4 is not airtight.

[0063] In detail, the control unit 14 is configured to compare the concentration data received from the gas sensor when the system is in the second configuration with the concentration data received from the gas sensor 6 when the system is in the first configuration. In other words, the control unit is configured to identify an increase in the concentration of tracer gas in the switch between the first configuration and the second configuration. The control unit 14 is configured to generate the alarm signal if the concentration of tracer gas increases when the system switches from the first configuration to the second configuration. In other words, the control unit is configured to generate the alarm signal when the concentration of carbon dioxide in the flow exceeds the concentration of carbon dioxide in the air received from the first gas source in the first configuration of the system 1.

[0064] The control unit 14 can be set in signal communication with the evacuation means 13 and configured to control these evacuation means depending on a desired pressure inside the test chamber. In particular, the control unit is configured to activate the evacuation means to reduce the internal pressure in the test chamber 3 and to deactivate such evacuation means when the desired pressure is achieved.

[0065] According to one aspect, the control unit 14 may be configured to implement algorithms for analyzing the concentration data received from the gas sensor 6. Such algorithms may comprise machine learning algorithms and / or spectrum analysis algorithms.

[0066] The system 1 may comprise interface means in signal communication with the control unit 14. The interface means are configured to receive the concentration data and / or the alarm signal and to display such concentration data and / or alarm signal to a user. In other words, a user can display the concentration data through the interface means, particularly through a screen, a computer, a smartphone or a tablet defining at least part of the interface means.

[0067] In one embodiment such as that shown in Figure 4, the system 1 comprises at least one additional gas sensor 15. The additional gas sensor 15 is arranged in series downstream of the gas sensor 6. Furthermore, the additional gas sensor 15 is configured to detect the concentration of the tracer gas 2 and to receive a flow from the second duct 8 and from the third duct 9.

[0068] The additional gas sensor 15 and its operation are entirely similar to the gas sensor 6 as described above and will not be described further on.

[0069] The control unit 14 can be set in fluidic communication with the additional gas sensor 15 and configured to compare the concentration data received from the gas sensor 6 with the concentration data received from the additional gas sensor 15 in order to refine and improve the measurement of the tracer gas concentration.

[0070] According to one aspect, the gas sensor 6 and the additional gas sensor 15 are calibrated and / or synchronized to measure the concentration of the tracer gas in the same maimer.

[0071] Advantageously, arranging two or more gas sensors in series with each other allows the reliability of the measurement and of the system to be increased. In fact, if one of the sensors does not measure the concentration of the tracer gas correctly, the other sensor could effectively offset this deficiency. Usefully, the responses of two or more sensors in series can be combined, taking into account possible delays in detecting the increase in carbon dioxide. Combining the measurements obtained from multiple signals received by two or more sensors in series allows substantially increasing the overall sensitivity of the measurement, as the received (or intrinsic) noise by an individual sensor increases at a lower rate than the increase in the amount of detected / measured carbon dioxide. The use of multiple sensors in series allows substantially increasing the overall sensitivity of carbon dioxide measurement. In actual facts, by combining signals from multiple sensors, it is possible to better distinguish the real changes in carbon dioxide concentration from background noise, thus making the measurement more reliable.

[0072] With reference to the example shown in Figure 5, in one embodiment, the system comprises two or more test chambers 3, 3’, each adapted to receive a respective item 4, 4’ within it. Each of the test chambers is entirely similar to the test chamber described in this description and will therefore not be discussed in detail.

[0073] In particular, each test chamber is configured for the parallel connection to the other test chambers. Each test chamber of the system is arranged downstream of the same first gas source 5 and is configured to receive from the latter the first gas. In other words, the system 1 comprises an individual first source that sends the first gas to two or more test chambers 3, 3’.

[0074] In detail, the system 1 comprises two or more first ducts 7, 7’ for connecting the test chambers to the first gas source 5. Each of the first ducts is positioned between the first gas source and a respective test chamber. The first gas source is configured to send the first gas to each first duct simultaneously or individually. In other words, the first gas source can supply the first gas to all the first ducts or only to some of them.

[0075] In addition, the system 1 comprises two or more gas sensors associated with the test chambers. Each gas sensor 6, 6’ is arranged downstream of a respective test chamber and is configured to detect the tracer gas fed into the respective test chamber by the respective item. Each gas sensor is configured to receive a flow of gas from the respective test chamber to determine the presence of tracer gas. In particular, each test chamber may be associated with a gas sensor and with an additional gas sensor arranged in series with each other.

[0076] In detail, the system comprises two or more second ducts 8, 8’ for connecting each test chamber to a respective gas sensor 6, 6’. Each gas sensor 6, 6’ is in fact positioned between a respective chamber of said test chambers and a respective gas sensor 6, 6’.

[0077] In addition, the system 1 comprises two or more third ducts 9, 9’ for connecting the first gas source 5 to each of such gas sensors 6, 6’. Each third duct 9, 9’ is positioned between the first gas source 5 and a respective gas sensor 6, 6’. Each gas sensor is configured to receive a flow of gas from the first gas source by means of a respective third duct. According to one aspect, the flow adjusting means 10 are associated with the first ducts, and / or with the second ducts and / or with the third ducts and are adapted to allow and prevent the flow towards each test chamber and / or each gas sensor through such ducts. The adjusting means 10 may comprise first valves 10a, 10a’, second valves 10b, 10b’ and / or third valves 10c, 10c’ coupled to the first ducts, second ducts and third ducts respectively to open and close such ducts.

[0078] The system can detect the presence of tracer gas in a plurality of test chambers 3, 3’ simultaneously. It is therefore possible to check for the airtightness of a plurality of items simultaneously.

Claims

1.CLAIMS1) System (1) for the detection of a tracer gas (2), comprising: a test chamber (3) adapted to receive at least one item (4) inside it, a first gas source (5) arranged upstream of said test chamber (3) and configured to send a first gas (3a) inside the test chamber (3), a gas sensor (6) arranged downstream of said test chamber (3) and configured to detect said tracer gas (2) fed into the test chamber (3) by the item (4), a first duct (7) positioned between said first gas source (5) and said test chamber (3), a second duct (8) positioned between said test chamber (3) and said gas sensor (6), a third duct (9) positioned between said first gas source (5) and said gas sensor (6), flow adjusting means (10) associated with at least one of said ducts (7, 8, 9) adapted to allow / prevent the flow towards said test chamber (3) and / or said gas sensor (6) through the first duct (7) and / or the third duct (9).2) System (1) according to the preceding claim, wherein the system is switchable between: a first configuration, wherein the gas sensor (6) and the first gas source (5) are in fluidic communication with each other by means of the third duct (9) and the test chamber (3) is hermetically closed, and a second configuration, wherein the adjusting means (10) prevent the flow from the first gas source (5) towards the gas sensor (6) through the third duct (9) and wherein the gas sensor (6) is in fluidic communication with said test chamber(3) through the second duct (8).3) System (1) according to any one of the preceding claims, comprising: a second gas source (11) arranged upstream of said test chamber (3) and configured to send said tracer gas (2) to said item (4), a fourth duct (12) positioned between the second gas source (11) and the item(4), the adjusting means (10) being configured to allow / prevent the passage of flow from the second gas source (11) to said item (4) through said fourth duct4) System (1) according to any one of the preceding claims, wherein the adjusting means (10) comprise one or more of: a first valve (10a) coupled to the first duct (7) to allow / prevent the flow from passing from the first gas source (5) towards the test chamber (3), a second valve (10b) coupled to the second duct (8) to allow / prevent the flow from passing from the test chamber (3) towards the gas sensor (6), a third valve (10c) coupled to the third duct (9) to allow / prevent the flow from passing from the first gas source (5) towards the gas sensor (6), a fourth valve (lOd) coupled to the fourth duct (12) to prevent / allow the flow from passing from the second gas source (11) towards the item (4).5) System (1) according to the preceding claim, wherein: in the first configuration of the system:- the first valve (10a) and the second valve (10b) are closed, and- the third valve (10c) is open,- optionally, the fourth valve ( lOd) is open; in the second configuration:- the first and the second valves (10a, 10b) are open,- the third valve (10c) is closed,- optionally, the fourth valve ( lOd) is open.6) System (1) according to any one of the preceding claims, comprising evacuation means (13) in fluidic communication with the test chamber (3) and configured to control an internal pressure of the test chamber (3).7) System (1) according to any one of the preceding claims, comprising a control unit (14) in signal communication with said adjusting means (10) and / or with said gas sensor (6), wherein the control unit (14) is configured to:- command said adjusting means (10) to allow / prevent the flow from passing in at least one of the first, second, third and fourth ducts (7, 8, 9, 12), and / or- receive from said gas sensor (6) concentration data of said tracer gas, and- generate an alarm signal representative of the possible presence of a hole in said item (4) depending on said concentration data.8) System (1) according to any one of the preceding claims, wherein:- the gas sensor (6) is of the type of a non-dispersive infrared (NDIR) sensor, a TDLAS sensor, an electrochemical sensor, a photoacoustic sensor, and / or- the tracer gas (2) is carbon dioxide, and / or- the first gas is air and / or nitrogen.9) System (1) according to any one of the preceding claims, comprising at least one additional gas sensor (15) arranged in series downstream of the gas sensor (6) and configured to detect the concentration of the tracer gas (2) and to receive a flow from said second duct (8) and third duct (9).10) System (1) for the detection of a tracer gas (2), comprising: at least two test chambers (3, 3’), each adapted to receive within it at least one respective item (4, 4’), a first gas source (5) arranged upstream of said test chambers (3, 3’) and configured to send a first gas within each of said test chambers (3, 3’), at least one gas sensor (6, 6’) arranged downstream of each of said test chambers (3, 3’) configured to detect said tracer gas fed into each test chamber (3, 3’) by the respective item (4, 4’), at least two first ducts (7, 7’), each positioned between said first gas source (5) and a respective test chamber (3, 3’), at least two second ducts (8, 8’), each positioned between the respective test chamber (3, 4’) and the respective gas sensor (6), at least two third ducts (9, 9’), each positioned between said first gas source (5) and the respective gas sensor (6, 6’), flow adjusting means (10) associated with said first ducts (7, 7’) and / or second ducts (8, 8’) and / or third ducts (9, 9’) and adapted to allow / prevent the flow towards said test chambers (3, 3’) and / or towards said gas sensors (6, 6’) through the two first ducts (7, 7’) and / or the two third ducts (9, 9’).

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