Method for detecting leaks in objects to be tested and equipment

Abstract

A leak detection method (100) comprising: - a learning step (101) during which at least one reference measurement signal representative of the flow or concentration of tracer gas in a reference test object (A) or in an environment surrounding a reference test object (A) is measured during at least one leak test cycle (C), - a plurality of successive test steps (102) during which a measurement profile representative of the flow or concentration of tracer gas is measured using the leak detector (1) during at least one leak test cycle (C) and compared with the reference profile to provide, based on the result of the comparison, a similarity indicator allowing the presence of an anomaly to be deduced. Figure 1

Description

Title of the invention: Method for detecting leaks in objects to be tested and equipment. Technical field of the invention

[0001] The present invention relates to a method for detecting leaks in objects to be tested in equipment comprising a leak detector configured to provide a measurement signal representative of a flow or concentration of tracer gas. The present invention also relates to equipment implementing said leak detection method. Technical background

[0002] A known method for verifying the leak-tightness of an object under test consists of performing a leak test using a tracer gas, in particular helium. This method relies on the detection of helium passing through leaks more easily than other gases, due to the small size of the helium atom.

[0003] In production, in particular, that is, when leak testing is performed automatically and repeatedly on a very large number of items to be tested, the amplitude of the measurement signal representing the flow or concentration of tracer gas is generally compared with a rejection threshold. Depending on the result of the comparison, the item to be tested is either sent to the scrap yard or to the quality control department for analysis, or its leak-tightness is certified. The only criterion for determining whether an item to be tested is leak-tight or not is therefore whether the measured flow or concentration of tracer gas exceeds the rejection threshold.

[0004] However, it may happen that the object under test is not leak-proof even if the measured flow or concentration of tracer gas has not exceeded the discharge threshold. This can occur due to a failure to supply tracer gas to the object under test or to the test chamber, or if certain valves, particularly those of the leak detector, do not open or close correctly, or if the leak detector measurement has shifted, for example, due to drift.

[0005] To ensure the integrity of the leak test, particularly for test objects where the tracer gas flow or concentration measurement has not exceeded the discharge threshold, additional sensors can be used in the leak detection chain. For example, pressure sensors or flow controllers can be added to verify that tracer gas is indeed injected into or around the test object, thus preventing the detection of a leaking object due to the absence of tracer gas injection during the test. However, this solution can be relatively expensive and complicated to implement. Summary of the invention

[0006] One object of the present invention is to overcome these drawbacks at least partially by proposing an improved leak detection method.

[0007] To this end, the invention relates to a method for detecting leaks of objects to be tested in equipment, such as automated production equipment, comprising a leak detector including a gas analyzer configured to provide a measurement signal representative of a flow or concentration of tracer gas, characterized in that the leak detection method comprises: - a learning step during which at least one reference measurement signal representative of the flow or concentration of tracer gas in a reference test object placed in an environment exposed to a tracer gas or in an environment surrounding a reference test object filled with tracer gas is measured using the leak detector, during at least one leak test cycle, and a reference profile is determined from at least one reference measurement signal, - a plurality of successive test steps during which a measurement profile representative of the flow or concentration of tracer gas in an object to be tested placed in an environment exposed to a tracer gas or in an environment surrounding an object to be tested filled with tracer gas is measured using the leak detector, during at least one leak test cycle and is compared with the reference profile to, depending on the result of the comparison, provide a similarity indicator allowing the presence of an anomaly to be deduced, in particular a leak in the object to be tested or a defect in the leak detector or equipment.

[0008] A gas flow is a quantity of matter per unit of time. In a leak detector, this flow is measured in mbar.l / s (Pa.mVs in international units), i.e. a pressure P (in Pa), multiplied by the volume V of the gas (which corresponds to a quantity of matter since PV=nRT with n, the quantity of matter (mol), R the universal ideal gas constant and T, the absolute temperature) per unit of time.

[0009] The concentration of a gas is a ratio between the partial pressure of that gas and the total pressure. There is no notion of time. For example, in air, the concentration of nitrogen is 80%: at the seaside where the total pressure is 1000 mbar (approximately), the partial pressure of nitrogen is 800 mbar.

[0010] The result of comparing the measurement profile with the reference profile thus provides additional information to the user. This information allows the user to know if something did not happen as expected during the leak test cycle (if a leak detector test valve did not open or close correctly, if the gas injection (The tracer test was not performed or was performed with incorrect settings, in the event of a malfunction or drift of the leak detector). This method takes advantage of the fact that during repetitive tests, particularly in production, the measurement profile obtained during a leak test cycle under normal conditions, i.e., without anomalies, is always the same. Conversely, if something abnormal occurs, the measurement profile diverges from the reference profile, even if the maximum amplitude of the measurement profile does not exceed the rejection threshold. Furthermore, the degree of similarity provided by the indicator makes it possible to determine the extent of the deviation of the measurement profile from the reference profile and thus facilitates the associated decision-making. The information contained in the measurement signal is therefore better utilized, without additional cost for measurement equipment.

[0011] The leak detection method may further include one or more of the features described below, taken alone or in combination.

[0012] The reference profile can be obtained from a plurality of reference measurement signals, such as between twenty and forty reference measurement signals, such as thirty.

[0013] The reference profile can be determined by an average of the reference measurement signals, each reference measurement signal comprising a series of points of which a standard deviation is determined with the reference profile to which a weight is assigned, the similarity indicator taking into account a sum of the products of the deviations between the reference profile and the measurement profile for each point, with the weight assigned.

[0014] Depending on the value of the similarity indicator, an alert signal can be issued and / or a test step can be repeated with the same object to be tested, or the object to be tested can be sent to the scrap heap and / or a recalibration of the leak detector can be ordered, or the sealing of the object to be tested can be certified.

[0015] During a leak test cycle: - the internal atmosphere of the object to be tested or of the test chamber, initially at atmospheric pressure, is depressurized, - then, starting from a low threshold pressure measured by a pressure sensor on the leak detector, the fluidic communication of a gas analyzer on the leak detector with the object to be tested or the test chamber is controlled, - then after the passage of a predetermined duration, the isolation of the gas analyzer from the leak detector is controlled and the return to the air in the object to be tested or in the test chamber.

[0016] The invention also relates to equipment comprising a leak detector including a gas analyzer configured to provide a measurement signal representative of a flow or concentration of tracer gas, the leak detector comprising: - an input configured to be connected to the internal volume of an object to be tested, or to a sniffing probe, or to a test chamber containing an object to be tested, - a pumping device, the gas analyzer being connected to the pumping device to measure the flow or concentration of at least one gaseous species used as a tracer gas, - at least one test valve configured to isolate or connect the gas analyzer of the leak detector to the object under test or the test chamber, and - a control unit connected to the gas analyzer and at least one test valve, the control unit being configured to implement a leak detection process for objects to be tested as described above or the control unit being configured to communicate with a central unit of the equipment configured to implement a leak detection process for objects to be tested as described above. Brief description of the figures

[0017] Other features and advantages of the invention will become apparent from the following description, given by way of example, without limitation, with reference to the accompanying drawings in which:

[0018] [Fig-1] The [Fig.1] is a schematic view of a piece of equipment.

[0019] [Fig.2] Fig.2 is a schematic view of a leak detector of the equipment of the [Fig.l].

[0020] [Fig.3] Fig.3 is a graph showing several measurement signals of reference of a tracer gas flow (in mbar.l / s) in the internal volume of reference objects to be tested as a function of time (in seconds) during leak test cycles.

[0021] [Fig.4] Fig.4 schematically illustrates different stages of a leak detection process.

[0022] [Fig. 5] [Fig. 5] is a graph similar to that of [Fig. 3], on which are represented a reference profile S0 and six measurement profiles SI, S2, S3, S4, S5, S6 obtained during test steps.

[0023] [Fig.6] [Fig.6] is a graph similar to that of [Fig.3], on which are represented a reference profile S0 and three measurement profiles S7, S8, S9 obtained during test stages.

[0024] [Fig.7] [Fig.7] is a graph similar to that of [Fig.3] on which are represented a reference profile S0 and a measurement profile S10 obtained during a test step.

[0025] In these figures, identical elements bear the same reference numbers. Detailed description

[0026] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments, without departing from the scope of the invention as defined by the claims.

[0027] Fig. 1 represents an example of equipment 200, such as automatic equipment and in particular such as automatic production equipment, for the leak testing of objects to be tested A. An object to be tested is defined as an object whose leak testing is to be carried out.

[0028] The equipment 200 is intended to control several test objects A repeatedly and, for example, automatically. It includes, in particular, a central unit 201, such as an electronic board, a controller or computer or processor and memory, which can be configured to control, in particular, the reception of the test objects A in a test chamber of the equipment 200 or their connection to an input 3 of a leak detector 1 of said equipment 200.

[0029] As seen in [Fig.2], the leak detector 1 includes a gas analyzer 2 configured to provide a measurement signal representative of a flow or concentration of tracer gas in a test object A placed in an environment exposed to tracer gas or in the environment surrounding a test object A filled with tracer gas.

[0030] The tracer gas is, for example, helium.

[0031] According to a first method, the possible presence of tracer gas is sought in the internal volume of the object to be tested A connected to the leak detector 1 while the tracer gas is injected onto the object to be tested A. In this case, the inlet 3 of the leak detector 1 is connected to the internal volume of an object to be tested A.

[0032] The spraying of tracer gas onto the object to be tested A can be automated by a spray nozzle of the equipment 200 controlled by the central unit 201, particularly for testing certain specific areas of the object to be tested. According to another example, the object to be tested A is contained in a test chamber of the equipment 200 pressurized with tracer gas.

[0033] The central unit 201 can be configured to control the start-up and stop-down of the tracer gas supply in the test chamber or the spray gun.

[0034] According to a second method, the internal volume of the object to be tested A is filled with tracer gas and the possible presence of tracer gas in the environment of the object to be tested is sought using the leak detector 1.

[0035] In this case, the input 3 of the leak detector 1 can be connected to a sniffing probe of the equipment 200, which is moved around the object to be tested. The sniffing probe detection can be automated and controlled by the central unit 201 of the equipment 200, particularly for testing specific areas of the object to be tested. According to another example, the input 3 of the leak detector 1 is connected to a test chamber of the equipment 200 containing an object to be tested A, and the object to be tested A is filled with tracer gas, for example, beforehand (sealed product).

[0036] The leak detector 1 may include a pumping device 4, the gas analyzer 2 being connected to the pumping device 4 to measure the flow or concentration of at least one gaseous species used as a tracer gas, in particular in the gas taken from the inlet 3 of the leak detector 1.

[0037] The pumping device 4 includes for example a secondary vacuum pump 5, such as a turbomolecular pump, and a primary vacuum pump 6 mounted in series, the secondary vacuum pump 5 being arranged upstream of the primary vacuum pump 6 in the direction of gas flow (see arrows on [Fig.2]).

[0038] The gas analyzer 2 is, for example, connected to the suction of the secondary vacuum pump 5. The measuring cell of the gas analyzer 2 can thus be placed under a low pressure on the order of 10⁴ mbar. The gas analyzer 2 includes, for example, a mass spectrometer.

[0039] The leak detector 1 further comprises at least one controllable test valve 7a, 7b, such as a solenoid valve, configured to isolate or connect the gas analyzer 2 to the object under test A or the test chamber. At least one test valve 7a, 7b is, for example, fluidically interposed between the inlet 3 and the pumping device 4, for example at an intermediate compression stage of the secondary vacuum pump 5 and / or at the suction of the secondary vacuum pump 5 (depending on the level of leakage sought).

[0040] The leak detector 1 may include a pressure sensor 8, a controllable air release valve 9, such as a solenoid valve, fluidly connected to a pipe communicating with the inlet 3 of the leak detector 1.

[0041] The leak detector 1 may also include a controllable valve device lia, 11b allowing the primary vacuum pump 6 to be put into fluidic communication with the inlet 3 of the leak detector 1 in order to lower the pressure in the object to be tested or the test chamber, in particular by isolating the primary vacuum pump 6 from the secondary vacuum pump 5.

[0042] The leak detector 1 further comprises a control unit 10, such as an electronic board, including a controller, computer, or processor and memory. The control unit 10 may further include a display device such as a screen and / or an input / output interface, such as a keyboard or a touchscreen.

[0043] The control unit 10 is connected to the central unit 201 of the equipment 200 to communicate, in particular, measurements from the gas analyzer 2 to the central unit 201.

[0044] The control unit 10 or the central unit 201 is configured for the implementation of a leak detection method 100 of objects to be tested A in the equipment 200 as will be described later ([Fig.4]).

[0045] For this purpose in particular, the control unit 10 is connected to the gas analyzer 2 and the pressure sensor 8 to receive their respective measurement signals and to at least one test valve 7a, 7b and to the air release valve 9 to control their opening / closing piloting.

[0046] More specifically, the control unit 10 is configured to control the opening and closing of at least one test valve 7a, 7b as a function of the pressure measured by the pressure sensor 8 of the leak detector 1, the opening of at least one test valve 7a, 7b being programmed to be allowed during a leak test cycle when the measured pressure crosses a low pressure threshold.

[0047] Fig. 3 shows a graph of the tracer gas flow measured by the gas analyzer 2 of the leak detector 1 of the equipment 200, during an example of a leak test cycle C.

[0048] This leak test cycle C can be applied on the one hand, to the first method of testing in which the possible presence of tracer gas is sought in the internal volume of the object to be tested A connected to the leak detector 1 while the tracer gas is injected onto the object to be tested A and on the other hand, to the second method, in which the internal volume of the object to be tested A is filled with tracer gas and the possible presence of tracer gas is sought with the leak detector 1 in the environment of the object to be tested, the inlet 3 of the leak detector 1 being connected to a test chamber of the equipment 200 containing an object to be tested A and the object to be tested A is filled with tracer gas.

[0049] During the leak test cycle C, the internal atmosphere of the object under test A or the test chamber, initially at atmospheric pressure, is depressurized by the primary vacuum pump 6 of the pumping device alone or in parallel with an auxiliary pumping device. Then, starting from a low threshold pressure measured by the pressure sensor 8, the control unit 10 manages the fluidic communication of the gas analyzer 2 of the leak detector 1 with the object under test A or the test chamber, in particular by opening at least one test valve 7a, 7b.

[0050] The duration Tl on the graph corresponds to the time between the moment when the object to be tested A or the test chamber is depressurized and the moment when at least one test valve 7a, 7b opens. With at least one valve 7a, 7b closed, the analyzer gas 2 of leak detector 1 is isolated from input 3 and the tracer gas flow measurement signal provided by gas analyzer 2 is zero or negligible.

[0051] Once at least one test valve 7a, 7b is opened, a portion of the gases taken by the pumping device 4 of the leak detector 1, possibly containing the tracer gas, then propagates towards the gas analyzer 2 which provides a measurement of the tracer gas flow to the control unit 10 of the leak detector 1. In the example, this signal decreases over the duration T2 because the pumping device 4 continues to lower the pressure in the object to be tested A or in the test chamber.

[0052] Then, after the elapse of a predetermined time, here on the order of ten seconds, the control unit 10 controls the isolation of the gas analyzer 2 from the leak detector 1, in particular by closing at least one test valve 7a, 7b. Then, the control unit 10 controls the venting into the object to be tested or into the test chamber, in particular by controlling the opening of the venting valve 9. With the valves 7a, 7b closed, the measurement signal of the tracer gas flow obtained by the gas analyzer 2 is then zero or negligible (duration T3).

[0053] In the case where the input 3 of the leak detector 1 is connected to a sniffing probe of the equipment 200 which is moved around the object to be tested, the leak test cycle has, for example, a substantially constant pattern.

[0054] As schematically shown in [Fig.4], the leak detection method 100 includes a learning step 101 during which at least one reference measurement signal representative of the flow or concentration of tracer gas in a reference object A placed in an environment exposed to a tracer gas or in an environment surrounding a reference object A filled with tracer gas is measured using the leak detector 1 during at least one leak test cycle C and a reference profile is determined from at least one reference measurement signal.

[0055] The reference object to be tested A is an object similar to the objects to be tested A but certified leak-proof, a minimum condition of which is that the measurement of the tracer gas flow during a leak-test cycle C is less than a rejection threshold

[0056] The reference profile can be obtained from a plurality of reference measurement signals, such as between twenty and forty reference measurement signals, such as thirty.

[0057] Fig. 3 thus shows thirty reference measurement signals obtained for thirty reference objects to be tested A during the same leak test cycle C. It can be seen that the signals are almost superimposed.

[0058] The reference profile can be determined by the control unit 10 of the leak detector 1 or by the central unit 201 of the equipment communicating with the control unit 10 of the leak detector 1, in particular to receive the measurement signals reference profile. The reference profile is, for example, an average of the reference measurement signals.

[0059] The detection method 100 also includes a plurality of successive test steps 102 in which a measurement profile representative of the flow or concentration of tracer gas in a test object A placed in an environment exposed to a tracer gas or in an environment surrounding a test object A filled with tracer gas is measured using the leak detector 1 during at least one leak test cycle C and is compared with the reference profile to, depending on the result of the comparison, provide a similarity indicator allowing the presence of an anomaly to be deduced, in particular a leak of the test object A or a defect of the leak detector 1 or of the equipment 200.

[0060] Each reference measurement signal comprises a series of points, determined by sampling, for example separated by a predetermined measurement interval. For example, there are between ten points per second and one point per minute. The sampling duration is preferably the same for determining the reference profile and the measurement profile.

[0061] The comparison of the measurement profile with the reference profile can be carried out by the control unit 10 of the leak detector 1 or by the central unit 201 of the equipment 200 communicating with the control unit 10 of the leak detector 1.

[0062] According to one embodiment, a weight is calculated for each point of the reference profile. The more similar the points of the reference measurement signals are to each other, the greater the weight associated with the point of the reference profile.

[0063] For this purpose, for example, a mean and a standard deviation are determined for each point of the reference measurement signals. A weight is assigned to each point, for example, using a normal distribution, with the weight value being equal to 1 when the standard deviation is zero and the weight value being zero when the standard deviation is greater than 0.3. A weight is then obtained for each point of the reference profile.

[0064] During a test, a measurement profile representative of the flow or concentration of tracer gas in a test object A placed in an environment exposed to a tracer gas or in an environment surrounding a test object A filled with tracer gas is measured during at least one leak test cycle C and the deviations between the reference profile and the measurement profile are determined for each point.

[0065] The weight of each point of the reference profile is then multiplied by the deviations obtained and these weighted deviations are summed to obtain the similarity indicator.

[0066] The lower this sum, the closer the measurement profile is to the reference profile. The higher this sum, the further the measurement profile is from the reference profile.

[0067] The similarity indicator can be expressed as a percentage.

[0068] According to one embodiment, the similarity indicator is 100% when the sum obtained is less than the mean of the weighted standard deviations plus twice the standard deviation of the weighted standard deviations, and 0% when the sum obtained is greater than the mean of the weighted standard deviations plus one hundred times the standard deviation of the weighted standard deviations. The similarity indicator can vary linearly between these two points.

[0069] The closer the similarity indicator value is to 100%, the closer the measurement profile is to the reference profile.

[0070] It is possible to display the results, for example the result of the comparison of the measurement profile with the reference profile, for example in the form of a percentage of similarity.

[0071] At each test step 102, it is also possible to compare the amplitude of the measurement signal representing the flow or concentration of tracer gas with the rejection threshold in order to, depending on the result of the comparison, detect a leak in the object under test or certify the leak-tightness of the object under test A, as carried out in the prior art for double-checking purposes. This result can also be displayed along with the result of the comparison of the measurement profile with the reference profile.

[0072] Depending on the value of the similarity indicator, the control unit 10 of the leak detector 1 or the central unit 201 of the equipment 200 can issue an alert signal, in particular to the operators and / or order to repeat a test step 102 with the same object to be tested A or direct the object to be tested A to be scrapped and / or order a recalibration of the leak detector 1 or certify the leak tightness of the object to be tested A.

[0073] The learning step 101 can be repeated, for example after the completion of a predetermined number of C leak check cycles.

[0074] The leak detection method 100 can be better understood with reference to the graphs in Figures 5, 6 and 7 showing examples of measurement profiles obtained during test steps 102 following the learning step 101 illustrated in [Fig. 3]. The similarity indicators determined for these measurement profiles allow the presence of anomalies to be deduced.

[0075] The graph in [Fig.5] shows six measurement profiles SI, S2, S3, S4, S5, S6 obtained during test steps 102 according to the first search method, in the presence of a leak from an object to be tested, superimposed on the reference profile S0.

[0076] Three initial measurement profiles, S1, S2, and S3, are measured for a first leak value of the object under test. It is observed that the measured tracer gas flow is higher for measurement profiles S1, S2, and S3 than for the reference profile S0, which may indicate a leak in the object under test. For this first series of tests, the similarity indicator is between 40% and 60%. The value is understood to be The similarity indicator suggests an anomaly, and that this anomaly is reproduced across all three tests. Visualizing the individual measurement profiles can help deduce the presence of a leak in the object being tested.

[0077] Three second measurement profiles, S4, S5, and S6, are measured for a second leakage value of the object under test, higher than the first value. For this second series of tests, the similarity indicator is zero. The similarity indicator indicates that a more significant anomaly is reproduced in all three tests. Visualizing the measurement profiles can thus reveal the presence of a leak in the object under test.

[0078] The graph in [Fig.6] shows three measurement profiles S7, S8, S9 obtained during test steps 102 according to the first search method, in the presence of anomalies in the leak detector 1, superimposed on the reference profile S0.

[0079] Curve S7 is obtained for an example where cleaning alcohol is still present in the leak detector 1's pipes and a fitting is improperly adjusted, for example, following maintenance. For this curve S7, the similarity index is zero, which confirms the presence of a relatively significant anomaly.

[0080] Curves S8 and S9 are obtained for two successive test steps 102 following that of curve S7. The similarity indices obtained are 88% and 90%, respectively. Since the 90% similarity index was also previously obtained without alcohol present but with the connection defect, it is understood that a single leak test cycle is sufficient to completely eliminate the presence of cleaning alcohol from the pipes.

[0081] The graph in [Fig.7] shows a measurement profile S10 obtained during a test step 102 according to the first search method, in the presence of an anomaly of the leak detector 1, superimposed on the reference profile S0.

[0082] The S10 curve is obtained for an example where the air release valve 9 remained closed at the end of the previous leak test cycle. In this case, the similarity index is zero.

[0083] With a conventional prior art test comparing the tracer gas flow to a rejection threshold, only measurement profiles S4, S5, and S6 would have been associated with leaking test objects. Monitoring the amplitudes of the measurement profiles of signals S1, S2, S3, S7, S8, and S9 would not have revealed the deviation of these tests in a situation without anomalies.

[0084] The result of comparing the measurement profile with the reference profile thus provides additional information to the user. This information allows the user to know if something did not happen as expected during the leak testing cycle. This takes advantage of the fact that at During repetitive testing, particularly in production, the measurement profile obtained during a leak test cycle under normal conditions—that is, without anomalies—remains constant. However, if an anomaly occurs, the measurement profile deviates from the reference profile, even if the maximum amplitude of the measurement profile does not exceed the rejection threshold. Furthermore, the degree of similarity provided by the indicator allows for determining the extent of the deviation between the measurement profile and the reference profile, thus facilitating relevant decision-making. The information contained in the measurement signal is therefore better utilized without additional cost for measurement equipment.

Claims

Demands

1. A method for detecting leaks (100) of test objects (A) in equipment (200) comprising a leak detector (1) comprising a gas analyzer (2) configured to provide a measurement signal representative of a tracer gas flow or concentration, characterized in that the leak detection method (100) comprises: - a learning step (101) during which at least one reference measurement signal representative of the tracer gas flow or concentration in a reference test object (A) placed in an environment exposed to a tracer gas or in an environment surrounding a reference test object (A) filled with tracer gas is measured using the leak detector (1), during at least one leak test cycle (C), and a reference profile is determined from the at least one reference measurement signal,- a plurality of successive test steps (102) during which a measurement profile representative of the flow or concentration of tracer gas in an object to be tested (A) placed in an environment exposed to a tracer gas or in an environment surrounding an object to be tested filled with tracer gas is measured using the leak detector (1) during at least one leak test cycle (C) and compared with the reference profile to, depending on the result of the comparison, provide a similarity indicator allowing the presence of an anomaly to be deduced, in particular a leak in the object to be tested (A) or a defect in the leak detector (1) or the equipment (200).

2. Leak detection method (100) according to the preceding claim, characterized in that the reference profile is obtained from a plurality of reference measurement signals, such as between twenty and forty reference measurement signals, such as thirty.

3. Leak detection method (100) according to the preceding claim, characterized in that: - the reference profile is determined by an average of the reference measurement signals, each reference measurement signal comprising a series of points whose standard deviation is determined with the reference profile to which a weight is assigned, - the similarity indicator taking into account a sum of the products of the differences between the reference profile and the measurement profile for each point, with the weight assigned.

4. Leak detection method (100) according to any one of the preceding claims, characterized in that depending on the value of the similarity indicator, an alert signal is emitted and / or a test step (102) is ordered to be repeated with the same object to be tested (A) or the object to be tested (A) is directed to be scrapped and / or a recalibration of the leak detector (1) is ordered or the leak tightness of the object to be tested (A) is certified.

5. Leak detection method (100) according to any one of the preceding claims, characterized in that during a leak test cycle (C): - the internal atmosphere of the object to be tested (A) or of the test chamber initially at atmospheric pressure is depressurized, - then from a low threshold pressure measured by a pressure sensor (8) of the leak detector (1), the fluidic communication of a gas analyzer (2) of the leak detector (1) with the object to be tested (A) or the test chamber is controlled, - then after the flow of a predetermined duration, the isolation of the gas analyzer (2) from the leak detector (1) and the return to the air in the object to be tested (A) or in the test chamber are controlled.

6. Equipment (200) comprising a leak detector (1) including a gas analyzer (2) configured to provide a measurement signal representative of a flow or concentration of tracer gas, the leak detector (1) comprising: - an inlet (3) configured to be connected to the internal volume of an object to be tested (A) or to a sniffing probe or to a test chamber containing an object to be tested (A), - a pumping device (4), the gas analyzer (2) being connected to the pumping device (4) to measure the flow or concentration of at least one gaseous species used as a tracer gas, - at least one test valve (7a, 7b) configured to isolate or fluidically connect the gas analyzer (2) of the leak detector (1) with the object to be tested (A) or the test chamber, and - a control unit (10) connected to the gas analyzer (2) and to at least one test valve (7a, 7b), - the control unit (10) being configured for the implementation of a leak detection method (100) of objects to be tested (A) according to one of the preceding claims or the control unit (10) being configured to communicate with a central unit (201) of the equipment (200) configured for the implementation of a leak detection method (100) of objects to be tested (A) according to one of the preceding claims.

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