Leak detection method and detector
The method addresses the scarcity and cost issues of helium by using nitrogen or argon as a tracer gas, enhancing leak detection efficacy through existing equipment without additional setup, thus offering a cost-effective and safer alternative.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PFEIFFER VACUUM SAS
- Filing Date
- 2025-10-16
- Publication Date
- 2026-05-15
AI Technical Summary
The use of helium as a tracer gas for leak detection is problematic due to its scarcity and rising costs, while using hydrogen in nitrogen mixtures reduces measurement sensitivity, and there are risks associated with flammable gases.
A leak detection method using a readily available tracer gas, such as nitrogen or argon, by monitoring a decrease in the measurement signal of a tracer gas within the object under test, which can be implemented with existing equipment without additional setup.
This method avoids the use of rare and expensive gases like helium and reduces risks associated with flammable gases, providing a simple and effective leak detection process that can be easily integrated into existing installations.
Smart Images
Figure EP2025079943_15052026_PF_FP_ABST
Abstract
Description
Description Title: Leak detection method and detector Technical field of the invention
[0001] The present invention relates to a method for detecting leaks in an object under test using a tracer gas and a leak detector comprising a gas analyzer connected to the object under test or to a sniffing probe. The present invention also relates to a leak detector implementing said leak detection method. Technical background
[0002] A well-known method for verifying the airtightness of an object under test involves performing a leak test using a tracer gas, particularly 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] A leak detector connected to a sniffing probe is used to search for the possible presence of tracer gas around an object to be tested, which is filled with the tracer gas and usually pressurized. Alternatively, the object to be tested is exposed to the tracer gas, with its internal volume depressurized and connected to a leak detector. An increase in the amplitude of the measurement signal, representing the flow or concentration of tracer gas, indicates the presence of a leak.
[0004] One drawback of this method is that the use of helium becomes problematic. Helium is a scarce resource with numerous applications in various sectors, making it increasingly difficult to supply and driving up costs.
[0005] It is also known to use hydrogen as a tracer gas in a small proportion of a nitrogen-based mixture. The hydrogen is diluted to reduce the risks associated with its use due to its flammability. However, the low concentration of hydrogen used reduces the measurement sensitivity. Summary of the invention
[0006] One aim of the present invention is to overcome these drawbacks at least partially by providing an improved leak detection method and detector.
[0007] To this end, the invention relates to a method for detecting leaks in an object to be tested by means of a tracer gas with a leak detector comprising a gas analyzer connected to the object to be tested, in which: the pressure inside the object to be tested is lowered with a pumping device of the leak detector connected to the object to be tested and / or with an auxiliary pumping device connected to the object to be tested; a measurement signal of a tracer gas, representative of the flow or concentration of a gaseous species present in the environment surrounding the object to be tested, is monitored inside the object to be tested with the gas analyzer; the environment surrounding the object to be tested is exposed to a filling gas, and a decrease in the measurement signal of the tracer gas is sought to detect the presence of a leak in the object to be tested.
[0008] The leak detection method based on detecting the decrease in the tracer gas measurement signal allows, using an existing gas analyzer but operated differently, the use of a readily available tracer gas, such as a gaseous species present in the air. This avoids the use of rare and / or expensive gases like helium, or certain risks associated with the use of flammable or greenhouse gases. The leak detection method is simple because it requires no additional equipment compared to the prior art tracer gas method and can easily be implemented on existing installations.
[0009] The leak detection method may also include one or more of the characteristics described below, taken alone or in combination.
[0010] According to one example of an embodiment, the object to be tested is placed in a chamber into which the filling gas is introduced.
[0011] According to another embodiment, the filling gas is supplied into the environment surrounding the object to be tested by spraying.
[0012] The filling gas can be a gas or a gaseous mixture not comprising the gaseous species of the tracer gas being measured.
[0013] The filling gas may be a gaseous mixture comprising the gaseous species of the tracer gas with a concentration lower than the concentration of the gaseous species in the initial gaseous mixture surrounding the object to be tested.
[0014] The gaseous species of the tracer gas can be a component of air such as nitrogen, argon, oxygen, a volatile organic compound, helium or hydrogen or any other gaseous species.
[0015] The filling gas can be argon or nitrogen or a mixture based on argon or nitrogen.
[0016] The invention also relates to a method for detecting leaks from an object to be tested by tracer gas with a leak detector comprising a gas analyzer connected to a sniffing probe, characterized in that: a measurement signal of the tracer gas, representative of the flow or concentration of a gaseous species present in the environment surrounding the object to be tested, is monitored with the gas analyzer connected to the sniffing probe, a filling gas is supplied to the object to be tested, the sniffing probe is moved around the object to be tested, and a decrease in the measurement signal of the tracer gas is sought to detect the presence of a leak from the object to be tested.
[0017] The leak detection method based on detecting the decrease in the tracer gas measurement signal allows, using an existing gas analyzer but operated differently, the use of a readily available tracer gas, such as a gaseous species present in the air. This avoids the use of rare and / or expensive gases like helium, or certain risks associated with the use of flammable or greenhouse gases. The leak detection method is simple because it requires no additional equipment compared to the prior art tracer gas method and can easily be implemented on existing installations.
[0018] The leak detection method may also include one or more of the characteristics described below, taken alone or in combination.
[0019] The filling gas can be a gas or a gaseous mixture not comprising the gaseous species of the tracer gas being measured.
[0020] The filling gas may be a gaseous mixture comprising the gaseous species of the tracer gas with a concentration lower than the concentration of the gaseous species in the initial gaseous mixture surrounding the object to be tested.
[0021] The gaseous species of the tracer gas can be a component of air such as nitrogen, argon, oxygen, a volatile organic compound, helium or hydrogen.
[0022] The filling gas can be argon or nitrogen or a mixture based on argon or nitrogen.
[0023] The invention further relates to a leak detector comprising a gas analyzer configured to provide a measurement signal representative of a flow or concentration of tracer gas present in the environment of the object to be tested or inside the object to be tested, characterized in that the leak detector comprises a control unit configured for the implementation of a method for detecting leaks of objects to be tested such as those described above. Brief description of the figures
[0024] Other features and advantages of the invention will become apparent from the following description, given by way of example and without limitation, with reference to the accompanying drawings in which:
[0025] [Fig. 1] Figure 1 is a schematic view of an object to be tested connected to a leak detector and an auxiliary pumping device and placed in an enclosure, during a leak detection process according to a first example of embodiment.
[0026] [Fig. 2] Figure 2 is a schematic view similar to Figure 1 in the case of an object to be tested exhibiting a leak during a first step of the leak detection process.
[0027] [Fig. 3] Figure 3 is a schematic view similar to Figure 2 during a step of the leak detection process successive to the first step.
[0028] [Fig. 4] Figure 4 is a graph of a tracer gas measurement signal (in arbitrary units) as a function of time (curve B) and a filling gas measurement signal (in arbitrary units) as a function of time (curve C).
[0029] [Fig. 5] Figure 5 is a schematic view of an object to be tested connected to a leak detector and an auxiliary pumping device during a leak detection process according to a second embodiment.
[0030] [Fig. 6] Figure 6 is a schematic view similar to Figure 5 in the case of an object to be tested exhibiting a leak during a first step of the leak detection process.
[0031] [Fig. 7] Figure 7 is a schematic view similar to Figure 6 during a step of the leak detection process successive to the first step.
[0032] [Fig. 8] Figure 8 is a schematic view of an object to be tested connected to a filling gas cylinder and a leak detector equipped with a probe sniffing during a leak detection process according to a third embodiment example.
[0033] [Fig. 9] Figure 9 is a schematic view similar to Figure 8 in the case of an object to be tested exhibiting a leak during a first step of the leak detection process.
[0034] [Fig. 10] Figure 10 is a schematic view similar to Figure 9 during a step of the leak detection process successive to the first step.
[0035] In these figures, identical elements bear the same reference numbers. Detailed description
[0036] 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.
[0037] Figure 1 shows a schematic view of an object to be tested A connected to a leak detector 1 and an auxiliary pumping device 4 and placed in an enclosure 3. The term "object to be tested" is defined as a closed and hollow object whose leak tightness we wish to check.
[0038] The leak detector 1 includes a gas analyzer 2 configured to provide a measurement signal representative of a flow or concentration of a gaseous species of a tracer gas.
[0039] The leak detector 1 may include a pumping device 5, the gas analyzer 2 being connected to the pumping device 5 to measure the flow or concentration of at least one gaseous species used as a tracer gas, in particular in the gas taken at the inlet of the leak detector 1.
[0040] The pumping device 4 and / or 5 includes, for example, a secondary vacuum pump, such as a turbomolecular pump, and a primary vacuum pump mounted in series, the secondary vacuum pump being arranged upstream of the primary vacuum pump in the direction of gas flow.
[0041] The gas analyzer 2 is, for example, connected to the suction of the secondary vacuum pump of the pumping device 5 of the leak detector 1. The measuring cell of the gas analyzer 2 can thus be placed under a low pressure of less than or equal to 10' 3 mbars (10' 1 Pa). Gas analyzer 2 includes, for example, a mass spectrometer.
[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 also include a display device such as a screen and / or an input / output interface, such as a keyboard or a touchscreen. The control unit 10 is configured to implement a method for detecting leaks from a test object A. In particular, the control unit 10 is connected to the gas analyzer 2 to receive measurement signals.
[0043] In the first embodiment of the method for detecting leaks of an object to be tested A by tracer gas with the leak detector 1 illustrated in figures 1 to 3, the gas analyzer 2 of the leak detector 1 is connected inside the object to be tested A.
[0044] Initially, we consider that the inside of the object to be tested A may be at ambient initial pressure (atmospheric pressure), in particular ambient air pressure.
[0045] During the leak detection process, the pressure inside the object to be tested A is lowered with the pumping device 5 of the leak detector 1 connected to the object to be tested A and / or with the auxiliary pumping device 4 connected to the object to be tested A (Figure 1).
[0046] The interior of the object to be tested A can be depressurized by the pumping device 5 of the leak detector 1 alone or in parallel or alternatively, of the auxiliary pumping device 4.
[0047] This depressurization, for example of at least 100mbars (10 OOOPa) below the initial pressure (atmospheric pressure or 100 OOOPa), allows the tracer gas to enter the object to be tested A through the possible leak (figure 2).
[0048] Then, when gas analyzer 2 requires it, from a low pressure compatible with gas analyzer 2 (high vacuum if gas analyzer 2 is a mass spectrometer for example, such as 10' 3 mbars (10 -1 Pa)), the gas analyzer 2 of the leak detector 1 can be put into fluidic communication with the object to be tested A.
[0049] And, we monitor a measurement signal of a tracer gas, representative of the flux or concentration of a gaseous species (or molecule) present in the environment surrounding the object to be tested A, inside the object to be tested A, with the gas analyzer 2.
[0050] The gaseous species of the tracer gas can be a component of air such as nitrogen, argon, oxygen, a volatile organic compound, helium or hydrogen.
[0051] The tracer gas can also be any other gaseous species present in the environment surrounding the object to be tested A, but may require a prior conditioning step of the enclosure 3 by prior filling with this other gas which is not present in the ambient air.
[0052] Then, the environment surrounding the object to be tested A is exposed to a filling gas (figure 3).
[0053] The filling gas can be a gas or a gaseous mixture not comprising the gaseous species of the tracer gas.
[0054] According to another example, the filling gas is a gaseous mixture comprising the gaseous species of the tracer gas with a lower concentration, such as at least 10% lower, than the concentration of the gaseous species in the initial gaseous mixture surrounding the object to be tested A.
[0055] The filling gas is, for example, argon or an argon-based mixture, such as a mixture of argon and oxygen. Argon is present in small amounts in air (<1%). The argon-oxygen mixture helps reduce the risk of hypoxia.
[0056] In another example, the filling gas is nitrogen or a nitrogen-based mixture.
[0057] Nitrogen and argon are readily available, inexpensive, and chemically neutral gases.
[0058] In the first embodiment, the filling gas is introduced into the enclosure 3 in which the object to be tested A has been placed, for example by means of a filling gas cylinder 6 connected to the enclosure 3.
[0059] The initial gas mixture contained in the object to be tested A can be replaced in whole or only partially by the filling gas.
[0060] For example, the filling gas is introduced into chamber 3 until it differs by at least 10% from the concentration of the initial gas mixture. The filling gas can also completely replace the concentration of the initial gas mixture (100% difference).
[0061] And, we are looking for a decrease in the measurement signal of the tracer gas to detect and possibly quantify the presence of a leak from the object to be tested A.
[0062] As soon as the measurement signal of the tracer gas decreases, we can consider that the object to be tested A is leaking.
[0063] We can consider that there is a significant decrease in the measurement signal of a leak when the measurement signal decreases by a value greater than at least twice the standard deviation of the noise of the measurement signal.
[0064] It is possible to quantify the level of leaks by the level of reduction of the measurement signal of the tracer gas if the measurement signal has been calibrated beforehand.
[0065] In the absence of leaks (Figure 1), the vacuum gas mixture remains the same inside the object under test A regardless of the nature of the gas around the object under test A. No change in the measurement signal of the tracer gas is observed with the gas analyzer 2 measuring inside the object under test A except for background noise.
[0066] In the event of a leak, the tracer gas present in the external environment enters through the leak and is also present inside the object to be tested A. The measurement signal of the tracer gas is therefore higher in the event of leaks than in the absence of leaks.
[0067] This can be better understood by reference to the graph in Figure 4, showing a tracer gas measurement signal (curve B) as a function of time.
[0068] The tracer gas measurement signal curve B is non-zero over the range [0-To]. In the prior art, it is this amplitude of the measurement signal that allows the presence of a leak to be identified. In the invention, when the test object A is exposed to the filling gas (To in Figure 4), the filling gas present in the external environment also enters the test object A through the leak, simultaneously lowering the partial pressure of the tracer gas species initially present in the test object A.
[0069] The measurement signal of the filling gas is indicated by curve C in Figure 4, which increases from To.
[0070] In fact, in the event of a leak, a drop in the measurement signal of the tracer gas is observed beyond To on curve B in figure 4.
[0071] Thus, it is understood that the leak detection process by searching for a decrease in the tracer gas measurement signal allows, by means of an analyzer, The existing gas 2 method, but used differently, involves using a readily available tracer gas such as a gaseous species present in the air. This avoids the use of rare and / or expensive gases like helium, or certain risks associated with the use of flammable or greenhouse gases. The leak detection process is simple because it requires no additional equipment compared to the prior art tracer gas method and can easily be implemented on existing installations.
[0072] Figures 5, 6 and 7 illustrate a second variant of the embodiment.
[0073] In this variant, instead of placing the object to be tested A in the enclosure 3 into which the filling gas is introduced, the filling gas is supplied into the environment surrounding the object to be tested by spraying, for example by means of a spray gun 7 or a blow gun (figure 7).
[0074] The spraying of tracer gas on the object to be tested A can be automated, in particular to test the tightness of certain specific areas of the object to be tested A.
[0075] The other characteristics of this variant embodiment are similar to those of the previous example embodiment.
[0076] Thus, in the absence of leaks (Figure 5), no change in the tracer gas measurement signal is observed with the gas analyzer 2 measuring inside the object to be tested A, with the exception of background noise.
[0077] In the event of a leak (figure 6), the tracer gas present in the external environment is also present inside the object to be tested A because it can pass through the leak to enter the object to be tested A.
[0078] At the time of exposure of the object to be tested A to the filling gas by spraying (figure 7), the filling gas also enters the object to be tested A through the leak, at the same time lowering the measurement signal of the tracer gas, which makes it possible to locate the leak in the vicinity of the location of the end of the spray gun 7.
[0079] Figures 8, 9 and 10 illustrate another embodiment in which the gas analyzer 2 of the leak detector 1 is connected to a sniffing probe 8.
[0080] During the leak detection process, a measurement signal of the tracer gas, representative of the flow or concentration of a gaseous species present in the environment surrounding the object to be tested A, is monitored with the gas analyzer 2 connected to the sniffing probe 8.
[0081] The gaseous species of the tracer gas can be a component of air such as nitrogen, argon, oxygen, a volatile organic compound, helium or hydrogen.
[0082] Then, a filling gas is supplied (in particular under overpressure) to the object to be tested A (figure 8).
[0083] The filling gas may be a gas or gas mixture not comprising the gaseous species of the tracer gas or a gas mixture comprising the gaseous species of the tracer gas with a lower concentration, such as at least 10% lower, than the concentration of the gaseous species in the initial gas mixture surrounding the object to be tested A.
[0084] The filling gas is, for example, argon or an argon-based mixture, or nitrogen or a nitrogen-based mixture.
[0085] Then, the sniffing probe 8 is moved around the object to be tested A and a decrease in the measurement signal of the tracer gas is sought in order to detect, locate, and possibly quantify the presence of a leak from the object to be tested A.
[0086] The movement of the sniffing probe 8 around the object to be tested A can be automated, in particular to test the sealing of certain specific areas of the object to be tested A.
[0087] In the absence of leaks (Figure 8) the gas mixture around the object to be tested A remains the same regardless of what is injected inside the object to be tested A. No change in the measurement signal of the tracer gas is observed with the gas analyzer 2 connected to the sniffing probe 8 measuring outside the object to be tested A except for background noise.
[0088] In the event of a leak (figure 9), the tracer gas present in the object to be tested A is also present in the external environment because it can pass through the leak.
[0089] If the sniffing probe 8 is too far from the leak, no change in the tracer gas measurement signal is observed with the gas analyzer 2 connected to the sniffing probe 8 (Figure 9). When the sniffing probe 8 is moved closer to the leak, the filling gas supplied to the test object A and escaping into the external environment through the leak simultaneously lowers the partial pressure of the tracer gas species initially surrounding the test object A (Figure 10). Therefore, in the presence of a leak, a decrease in the tracer gas measurement signal is observed.
Claims
DEMANDS
1. A method for detecting leaks in an object under test (A) by means of a tracer gas with a leak detector (1) comprising a gas analyzer (2) connected to the object under test (A), characterized in that: the pressure inside the object under test (A) is lowered with a pumping device (5) of the leak detector (1) connected to the object under test (A) and / or with an auxiliary pumping device (4) connected to the object under test (A), a measurement signal of a tracer gas, representative of the flux or concentration of a gaseous species present in the environment surrounding the object under test (A), is monitored inside the object under test (A) with the gas analyzer (2), the environment surrounding the object under test (A) is exposed to a filling gas, and a decrease in the measurement signal of the tracer gas is sought to detect the presence of a leak in the object under test (A).
2. Leak detection method according to claim 1, wherein the object to be tested (A) is placed in an enclosure (3) into which the filling gas is introduced.
3. Leak detection method according to claim 1, wherein the filling gas is supplied into the environment surrounding the object to be tested (A) by spraying.
4. Method for detecting leaks from an object to be tested (A) by tracer gas with a leak detector (1) comprising a gas analyzer (2) connected to a sniffing probe (8), characterized in that: a measurement signal of the tracer gas, representative of the flux or concentration of a gaseous species present in the environment surrounding the object to be tested (A), is monitored with the gas analyzer (2) connected to the sniffing probe (8), a filling gas is supplied to the object to be tested (A), the sniffing probe (8) is moved around the object to be tested (A), and a decrease in the measurement signal of the tracer gas is sought to detect the presence of a leak from the object to be tested (A).
5. A leak detection method according to any one of the preceding claims, wherein the filling gas is a gas or gaseous mixture not comprising the gaseous species of the tracer gas being measured.
6. Leak detection method according to any one of claims 1 to 4, characterized in that the filling gas is a gaseous mixture comprising the gaseous species of the tracer gas with a concentration lower than the concentration of the gaseous species in the initial gaseous mixture surrounding the object to be tested (A).
7. A leak detection method according to any one of the preceding claims, characterized in that the gaseous species of the tracer gas is a component of air such as nitrogen, argon, oxygen, a volatile organic compound, helium or hydrogen.
8. Leak detection method according to any one of the preceding claims, characterized in that the filling gas is argon or nitrogen or a mixture based on argon or nitrogen.
9. Leak detector (1) comprising a gas analyzer (2) configured to provide a measurement signal representative of a flow or concentration of tracer gas present in the environment of the object to be tested (A) or inside the object to be tested (A), characterized in that the leak detector (1) comprises a control unit (10) configured for the implementation of a method for detecting leaks of objects to be tested (A) according to any one of the preceding claims.