Carrier gas leak detection system, and carrier gas leak detection method for leak detection on a test piece
Patent Information
- Application Number
- EP2023783807
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-11
- Filing Date
- 2023-10-02
- Publication Date
- 2025-09-17
AI Technical Summary
Existing leak detection systems face challenges in efficiently adjusting the carrier gas flow and pressure in the test chamber and detector volume, requiring significant technical effort and affecting sensitivity, especially with quadrupole mass spectrometers, which demands a practical method to optimize these parameters for accurate leak detection.
A system with adjustable flow restrictors and valves allows for selective adjustment of carrier gas flow and pressure, using a flow divider configuration to direct partial flows through the test chamber vacuum pump and the gas detector, enabling precise control of pressure and flow rates to optimize sensitivity and efficiency.
This configuration allows for efficient leak detection by adjusting the carrier gas flow and pressure with minimal technical effort, enhancing sensitivity and reducing costs by optimizing the gas exchange rate and detector performance.
Smart Images
Figure 1.1
Abstract
Description
[0001] Träqerqas leak detection system and Träciercias leak detection method for
[0002] Leak detection on a test specimen
[0003] The invention relates to a system and a method for leak detection on a test object.
[0004] For integral leak testing with test gas, test specimens are tested in a test chamber using test gas vacuum leak detection. For this purpose, the test specimen filled with a test gas is placed in a test chamber, which is then evacuated. In the vacuum system, the test gas partial pressure is measured using a test gas detector. Test gas flowing from the test specimen into the test chamber through a leak can be actively guided to the test gas detector using a carrier gas. For this purpose, the carrier gas is continuously admitted into the test chamber and pumped out using the vacuum system so that an equilibrium working pressure is established in the test chamber. The resulting carrier gas flow transports any test gas escaping from the test specimen to the test gas detector. The presence or measured signal strength is a measure of the leak rate in the test specimen. Different detectors are used to detect the test gas, depending on the required detection limit.To achieve very high test gas sensitivity, a quadrupole mass spectrometer is used. The QMS exhibits both very high sensitivity and high selectivity.
[0005] In principle, the carrier gas method can also be used for other types of detectors that do not necessarily have to be operated in a vacuum or high vacuum, such as optical detectors or surface sensors.
[0006] Maximum sensitivity is achieved at an optimal total pressure of 1E-4 mbar in the ion source. A lower working pressure in the detection volume results in lower sensitivity due to the smaller number of molecules or atoms to be detected, while a higher working pressure results in a reduction in sensitivity due to charge carrier losses caused by space charge effects. An excessive density of electrically charged particles in the ion source volume results in excessive repulsion between the charge carriers.
[0007] This optimal working pressure is achieved with a fixed pumping speed at the QMS detection volume and a fixed conductance of the pressure transducer inlet (e.g., capillary) for a specific inlet pressure. A deviation from this optimal inlet pressure generally has a quadratic effect on the total pressure in the ion source. For example, halving the inlet pressure results in a reduction of the total pressure in high vacuum to a quarter of its original value. The sensitivity of the system scales with decreasing pressure in the ion source, i.e., a change in the pressure at the inlet to the mass spectrometer reduces the system's sensitivity disproportionately.
[0008] In the carrier gas method, the carrier gas flow rate should be adjusted to the gas quantity present in the test chamber. The aim is to exchange the gas quantity in the chamber approximately two to three times (2-3 Tau) in the shortest possible period of time in order to achieve a convergence value of the leak signal.
[0009] In principle, the pressure in the test chamber can be reduced to reduce the amount of gas to be exchanged. However, this requires additional time to evacuate the chamber and results in higher costs for the pumping system.
[0010] Accordingly, the carrier gas flow must be increased for larger test chambers (larger net chamber volume), and reduced for smaller net volumes.
[0011] As the carrier gas flow changes, the equilibrium pressure in the test chamber also changes.
[0012] It is desirable to adapt the working pressure at the gas detector, such as in the detector volume of the mass spectrometric gas detector, particularly in the case of a quadrupole mass spectrometer, to the changing working pressure in the test chamber. This also applies to other detector types. The working pressure in the test chamber depends on the amount of carrier gas supplied to the test chamber and the pumping speed of the pump used to evacuate the test chamber. This pump is referred to below as the test chamber vacuum pump. Adjusting the working pressure in the detector volume or at the detector via the pumping speed of the vacuum pump requires a high level of technical effort and is therefore not very practical. In the case of a vacuum detector, the vacuum pump that evacuates the detector volume is referred to below as the detector vacuum pump.
[0013] Against this background, the object of the invention is to provide a system and a method for leak detection on a test object by carrier gas leak detection, in which the flow strength of the carrier gas at the gas detector and the pressure in the test chamber can be adjusted with little technical effort.
[0014] The leak detection system according to the invention is defined by the features of patent claim 1. The leak detection method according to the invention is defined by the features of patent claim 13.
[0015] The carrier gas leak detection system according to the invention comprises a gas detector and a test chamber. The test chamber has a test chamber volume into which at least a first test chamber inlet and a test chamber outlet open. A test chamber vacuum pump that evacuates the test chamber volume is connected to the test chamber outlet. The test chamber outlet is connected to the gas detector and the test chamber vacuum pump via a first gas line to supply the gas to be analyzed from the test chamber to the detector.
[0016] The gas detector can have a detector volume inlet with a first flow restrictor for pressure conversion at the detector volume inlet. The first flow restrictor can, for example, be a suitable cross-sectional design of the detector volume inlet. Depending on the detector type, the first flow restrictor is not mandatory. A second flow restrictor is provided for supplying carrier gas into the test chamber volume at the test chamber inlet. The second flow restrictor can have an adjustable conductance for changing the carrier gas flow.
[0017] A second gas line connecting the test chamber outlet to the gas detector parallel to the first gas line is connected in a first connection point to the test chamber vacuum pump and to the first gas line. A third flow restrictor is provided in a detector section of the first gas line between the first connection point and the gas detector. A fourth flow restrictor is provided in the second gas line between the test chamber outlet and the first connection point. The third flow restrictor and the fourth flow restrictor, together with the first and second gas lines, therefore form a flow divider such that a first partial flow can be evacuated from the test chamber through the second gas line and a second partial flow through the first gas line using the test chamber vacuum pump.
[0018] The third flow restrictor is located in the first gas line between the first flow restrictor and the test chamber vacuum pump for adjusting the pressure in the first gas line. The third flow restrictor can have an adjustable conductance. The third flow restrictor can be used to set the pressure at the gas detector or to selectively adjust it manually or automatically using a pressure control device. The second flow restrictor can be used to set or change the carrier gas flow supplied to the test chamber.
[0019] The fourth flow restrictor is located in the second gas line between the test chamber outlet and the test chamber vacuum pump. The fourth flow restrictor can be used to specify or adjust the pumping speed with which the test chamber vacuum pump draws carrier gas into the test chamber volume. The test chamber vacuum pump is connected to the first and second gas lines between the third flow restrictor and the fourth flow restrictor at the first connection point, so that the main gas flow of the carrier gas flows through the second flow restrictor, through the test chamber inlet, through the test chamber volume, and out of the test chamber outlet through the fourth flow restrictor into the test chamber vacuum pump. The pumping speed at the test chamber specified via the fourth flow restrictor, together with the third flow restrictor, defines the pressure in the test chamber for a given carrier gas flow.
[0020] The fourth flow restrictor may also have an adjustable conductance to change the carrier gas flow and / or the pressure in the test chamber and / or to selectively adjust it, for example manually or automatically by a pressure control device.
[0021] The first, second, third and / or fourth flow restrictors each define the gas conductance of the respective line section and can be specified, for example, by an orifice plate, by a capillary or by the conductance, the cross-section or the diameter of the respective section of the gas line.
[0022] With the help of the third and fourth flow restrictors, the gas flow that is sucked in from the test chamber by the test chamber vacuum pump can be divided according to the invention. The third and fourth flow restrictors thus form a flow divider. One partial flow - referred to below as the first partial flow - goes directly along the first gas line to the test chamber vacuum pump, while the other part - referred to below as the second partial flow - goes along the first gas line past the gas detector to the test chamber vacuum pump. Carrier gas from the second partial flow, which contains test gas in the event of a leak in the test object, is fed to the detector and analyzed there. In the case of a vacuum or high-vacuum detector with an evacuated detector volume, such as in a mass spectrometer, the detector volume is typically continuously evacuated by a detector vacuum pump.The invention enables leak detection on a test specimen within a test chamber using an adjustable carrier gas flow, with which leak gas or test gas is continuously transported from the test chamber to the detector, while the required pressure conditions and gas quantities at the detector and in the test chamber can be selectively adjusted.
[0023] Accordingly, the carrier gas leak detection method according to the invention for leak detection on a test specimen is characterized by the following steps:
[0024] • Placing a test specimen into the test chamber,
[0025] • Evacuate the test chamber with the test chamber vacuum pump,
[0026] • Supplying carrier gas into the test chamber containing the test specimen through the second flow restrictor,
[0027] • Evacuate the first and second gas lines with the test chamber vacuum pump,
[0028] • Presetting or setting the conductances of the third flow restrictor and the fourth flow restrictor as a flow divider in such a way that a first partial flow is evacuated from the test chamber through the second gas line and a second partial flow through the first gas line using the test chamber vacuum pump and
[0029] • Analyze gas from the second partial stream using the gas detector.
[0030] Preferably, the gas flow along the first partial flow is larger, and in particular significantly larger, than along the second partial flow. The gas flows along the first and second partial flow are predetermined by the third and fourth flow restrictors and can be adjusted in the case of flow restrictors with variable conductance. The conductance S3 of the third restrictor is preferably lower, and in particular significantly lower, than the conductance S4 of the fourth restrictor. The conductances S3 and S4 can preferably be adjusted, e.g., manually or with the aid of an electronic control device.
[0031] Advantageously, a test chamber section of the first gas line between the test chamber outlet and the gas detector or the detector volume inlet is provided with a selectively closable first valve, while the detector section has a selectively closable second valve between the first flow restrictor and the third flow restrictor. With the help of the first valve and the second valve, the pressure conditions can be kept constant during the pumping down of the test chamber using the test chamber vacuum pump. When the first valve and the second valve are closed, the test chamber can be evacuated using a direct connection between the test chamber vacuum pump and the test chamber, without the pressure at the detector volume inlet being changed by the pumping down of the test chamber.
[0032] The test chamber inlet may be provided with a selectively closable third valve.
[0033] The test chamber may have at least one second test chamber inlet for venting or purging the test chamber or the test chamber volume, wherein the second test chamber inlet has a selectively closable fourth valve which is opened only for venting or purging.
[0034] The test chamber outlet can be connected directly to the test chamber vacuum pump, in particular via a third gas line. The third gas line preferably bridges the second gas line with the fourth flow restrictor and a possible sixth valve arranged upstream of the fourth flow restrictor. The third gas line can be provided with a selectively closable fifth valve. When the fifth valve is open, the test chamber is directly evacuated via the third gas line, for example, to bring it to the required test chamber vacuum pressure after a test specimen has been introduced into the test chamber. This test chamber vacuum pressure is advantageously in the range of a few millibars, for example, between 0.1 and 10 mbar.Subsequently, the fifth valve is closed and the sixth valve is opened, with the aid of the test chamber vacuum pump, to pump a continuous carrier gas flow through the test chamber volume into the second gas line while the third valve remains open. The sixth valve can also be opened beforehand, e.g., if the test chamber is evacuated via the third gas line, or it can be left out.
[0035] The second gas line, with the fourth flow restrictor and the sixth valve, runs parallel to the third gas line, with the fifth valve. With the first, second, third, and fourth valves closed and the fifth valve open, the test chamber can be evacuated directly via the third gas line using the test chamber vacuum pump. Once the required test chamber pressure is reached, the fifth valve is closed and the third valve is opened. This draws carrier gas into the test chamber volume through the first test chamber inlet and feeds it along the second gas line through the open sixth valve and through the fourth flow restrictor to the test chamber vacuum pump. Meanwhile, the gas detector can be evacuated using a gas detector vacuum pump.
[0036] At the start of the leakage measurement, the first and second valves are opened, allowing a partial flow of the carrier gas, referred to as the second partial flow, to flow along the first gas line past the gas detector and along the detector section of the test chamber vacuum pump. The third and fourth flow restrictors determine the flow split ratio. A first partial flow flows through the second gas line to the test chamber vacuum pump. From the second partial flow, which is routed along the first gas line past the gas detector, carrier gas containing any leakage gas from the test object reaches or enters the gas detector, where it can be detected.
[0037] The gas detector can be a vacuum gas detector or a mass spectrometric gas detector with a detector volume into which a detector volume inlet and a detector volume outlet open. A detector vacuum pump is connected to the detector volume outlet in order to evacuate the detector volume to the required vacuum pressure. Alternatively, the gas detector can be another type of detector, such as an optical detector, a radiation or radiation absorption detector, or a surface sensor past which the carrier gas stream is passed. In the case of a mass spectrometric gas detector, it can be a quadrupole mass spectrometer. Any type of detector that generally requires a vacuum for gas detection, such as a mass spectrometric gas detector, is referred to herein as a vacuum gas detector.To generate the required vacuum for the vacuum gas detector, a detector vacuum pump different from the test chamber vacuum pump may be provided, which may be a high vacuum pumping system with a high vacuum pump, e.g. in the form of a turbomolecular pump, which evacuates the detector volume, and with a forevacuum pump which evacuates the high vacuum pump.
[0038] A first pressure gauge can be connected between the first valve and the first flow restrictor to the test chamber section of the first gas line to measure the pressure in the test chamber section. A second pressure gauge can be connected between the first connection point and the third flow restrictor to the detector section of the first gas line to measure the pressure in the detector section. The flow restrictors D3, D4 and / or the valves V1, V2, V6 can be controlled depending on the measured pressures. The test chamber is preferably connected to a third pressure gauge for measuring the pressure in the test chamber, wherein the second restrictor D2, the fourth restrictor D4, the third valve V3, the fourth valve V4, the fifth valve V5, and / or the sixth valve V6 can be controlled depending on the measured pressure in the test chamber.
[0039] Two exemplary embodiments of the invention are explained in more detail below with reference to the figures. Each figure shows a schematic representation of a carrier gas leak detection system.
[0040] The carrier gas leak detection system 10 of the embodiment shown in Fig. 1 is a mass spectrometric carrier gas leak detection system with a mass spectrometric gas detector 12 in the form of a quadrupole mass spectrometer with a detector volume 14, a detector volume inlet 15 opening into the detector volume 14, and a detector volume outlet 16 opening into the detector volume 14. A detector vacuum pump 18 is connected to the detector volume outlet 16 to evacuate the detector volume 14. The detector vacuum pump 18 consists of a turbomolecular pump and a backing pump. In a known manner, the inlet of the turbomolecular pump is connected to the detector volume outlet 16, while the outlet of the turbomolecular pump is connected to the inlet of the backing pump. The outlet of the backing pump can be open to the atmosphere.
[0041] The detector volume inlet 15 is provided with a first flow restrictor D1 for pressure conversion at the detector volume inlet 15. The detector volume inlet 15 is connected to the test chamber outlet 26 by a first gas line 28.
[0042] The leak detection system 10 further includes a test chamber 20 with a test chamber volume 21, a first test chamber inlet 22 opening into the test chamber volume 21, a second test chamber inlet 24 opening into the test chamber volume 21, and a test chamber outlet 26 also opening into the test chamber volume 21. The test chamber outlet 26 is connected in a gas-conducting manner to the first flow restrictor D1 and the detector volume inlet 15 via the first gas line 28.
[0043] The section of the first gas line 28 connecting the test chamber outlet 26 to the detector volume inlet 15 is referred to herein as the test chamber section 34. The section of the first gas line 28 connecting the detector volume inlet 15 to the test chamber vacuum pump 27 is referred to herein as the detector section 40.
[0044] A second gas line 30 also connects the test chamber outlet 26 to the test chamber vacuum pump 27, with the second gas line 30 running parallel to the first gas line 28 and thus forming a bypass for the first gas line 28. The second gas line 30 is connected in a first connection point 38 to the first gas line 28 and to the gas inlet of the test chamber vacuum pump 27.
[0045] The first gas line 28 has a selectively closable first valve V1 in its test chamber section 34 and a selectively closable second valve V2 in its detector section 40. Between the second valve V2 and the first connection point 38, the first gas line 28 has a third flow restrictor D3 with a predetermined or adjustable conductance S3.
[0046] Between the test chamber outlet 26 and the first connection point 38, the second gas line 30 has a fourth flow restrictor D4 with a predetermined or adjustable conductance S4, wherein the second gas line 30 has a selectively closable sixth valve V6 between the fourth flow restrictor D4 and the test chamber outlet 26. The test chamber outlet 26 is also connected to the test chamber vacuum pump 27 via a third gas line 32, wherein the third gas line 32 is connected to the first gas line 28 and the second gas line 30 at a second connection point 42 at the test chamber outlet 26. The third gas line 32 bridges the first gas line 28 and the second gas line 30 between the first connection point 38 and the second connection point 42 and contains a selectively closable fifth valve V5.The first, second and third gas lines 28, 30, 32 are connected to each other and to the gas inlet of the test chamber vacuum pump 27 in the first connection point 38.
[0047] Between the first flow restrictor D1 and the first valve VI, the first gas line 30 is connected to a first pressure gauge PG1 in its test chamber section 34. The detector section 40 is connected to a second pressure gauge PG2 between the third flow restrictor D3 and the first connection point 38.
[0048] The test chamber 20 is connected in a gas-conducting manner to a third pressure gauge PG3 in the form of a total pressure sensor for measuring the pressure in the test chamber 20. The first test chamber inlet 22 has a second flow restrictor D2 with a predetermined or adjustable conductance S2 for the carrier gas supply, as well as a selectively closable third valve V3. The second test chamber inlet 24 has a selectively closable fourth valve V4 for purging and / or venting the test chamber volume 21.
[0049] The section of the first gas line 28 connecting the first connection point 38 to the gas inlet 15 and the first flow restrictor D1 is referred to as the detector section 40. The detector section 40 includes the second valve V2 and the third flow restrictor D3 and is connected to the second pressure gauge PG2. At the first connection point 38, the detector section 40 is connected in a gas-conducting manner to the second gas line 30, the third gas line 32, and the gas inlet of the test chamber vacuum pump 27. The detector volume 14 of the gas detector 12 is evacuated in a known manner by the detector vacuum pump 18, so that a suitable high vacuum pressure prevails inside the detector volume 14. In order to test a test specimen (not shown in the figure) for its leak tightness, the specimen contains a fluid test medium and is introduced into the test chamber 20. The test medium can be a test gas or a test liquid whose vapor phase serves to detect a leak.The test chamber 20 is then evacuated by the test chamber vacuum pump 27 with the valve V5 open. As soon as a suitable pressure is reached in the test chamber 20, the fifth valve V5 is closed.
[0050] By opening the sixth valve V6 and the third valve V3, the test chamber vacuum pump 27 draws carrier gas through the second flow restrictor D2 into the test chamber volume 21 and supplies it as a first partial flow through the test chamber outlet 26 along the second gas line 30 through the fourth flow restrictor D4 to the test chamber vacuum pump 27. A second partial flow of the carrier gas transported through the test chamber 20 is supplied, after opening the first valve V1 and the second valve V2, along the first gas line 28 past the detector inlet 15 and through the detector section 40 through the third flow restrictor D3 to the test chamber vacuum pump 27. By appropriately adjusting the conductances of the flow restrictors D3, D4, a flow division is effected such that the first partial flow is significantly larger than the second partial flow along the detector inlet 15.
[0051] From the second partial flow, carrier gas with possible leakage gas from the test specimen passes through the first flow restrictor D1 into the detector volume 14 for analysis. For this purpose, the first gas line 28 is connected to the gas detector 12 at a third connection point 44 connecting the test chamber section 34 to the detector section 40 via a short line section 46 of the detector volume gas inlet 15. Alternatively, in another embodiment not shown in the figures, the first gas line 28 can be connected to a gas detector 12 of a different type at the third connection point 44.
[0052] By adjusting the conductance of the second flow restrictor D2, the carrier gas flow is adapted to the test chamber volume 21 or the gas quantity in the test chamber 20. With a constant suction speed of the test chamber vacuum pump 27 and / or a constant suction speed acting effectively via the restrictors D3 and D4, a changed carrier gas flow leads to a changed equilibrium pressure within the test chamber 20. To prevent the changed test chamber pressure from also changing the pressure within the detector volume 14, the suction speed of the test chamber vacuum pump 27 is adjusted to the desired inlet pressure at the detector volume inlet 15 by adjusting the conductance of the fourth restrictor D4.The third flow restrictor D3 is then used to adjust the partial flow ratio of the two partial flows supplied to the test chamber vacuum pump 27 in such a way that a defined second partial flow is guided along the detector volume inlet 15, while the main portion of the carrier gas flow is guided as the first partial flow directly to the test chamber vacuum pump 27.
[0053] The detector volume 14 is continuously pumped via the detector vacuum pump 18.
[0054] Measurement procedure:
[0055]
[0056] (*) Point 3 can also be skipped
[0057] During measurement operation, the carrier gas flows through valve V3 into the test chamber 20. The strength of the carrier gas flow is defined by the throttle D2. Downstream of the test chamber 20, the carrier gas flow splits into two parts at the second connection point 42. The larger portion is directed via V6 and throttle D4 through the second gas line 30 directly to the test chamber vacuum pump 27. The second, smaller portion of the flow flows along the first gas line 28 through the first valve V1 and along the detector section 40 through the valve V2 and throttle D3 to the same test chamber vacuum pump 27. The flow through the throttle D1 into the detector volume 14 is negligibly small compared to the carrier gas flow.
[0058] The sum of the pumping speeds / conductances of the two flow throttles D3 and D4, whose partial flows are combined at the first connection point 38, are selected such that the desired equilibrium pressure in the test chamber 20 is achieved at the selected carrier gas flow (defined via the throttle D2).
[0059] The following applies:
[0060] P = Q / S with S = S3 + S4
[0061] Q: Carrier gas flow
[0062] S: Conductance of the throttles (equivalent to the suction capacity, which is limited by the throttles) S3: Conductance of the throttle D3
[0063] S4: Conductance of the choke D4
[0064] P: Equilibrium pressure in the test chamber.
[0065] The decision chain for the design of the parameters is as follows:
[0066] The carrier gas flow is determined. The flow is selected such that the gas quantity in the net volume of test chamber 20 is exchanged as completely as possible in the shortest possible time.
[0067] The carrier gas flow rate should not be chosen too large in order not to dilute the test gas too much.
[0068] For applications with a larger net volume of the test chamber 20, the pressure is reduced to a lower level to reduce the amount of gas to be exchanged with the carrier gas. The pressure is not selected too low to allow operation with a simple, inexpensive pump as a test chamber vacuum pump. The equilibrium pressure is adjusted via throttles D3 and D4.
[0069] The ratio of the conductances of the throttles D3 and D4 is selected such that a sufficiently rapid gas exchange in the first gas line 28 at the detector volume inlet 15 to the detection system of the gas detector 12 (path VI => V2 => D3) is ensured.
[0070] The embodiment illustrated in Fig. 2 differs from the embodiment illustrated in Fig. 1 essentially in the type and length of the routing of the first and second gas lines 28, 30, as well as in the fact that the gas detector 14 is not necessarily a mass spectrometric gas detector. Rather, the gas detector 14 can be any conceivable type of gas detector, in particular an optical gas analyzer, for example, based on the principle of radiation analysis or infrared adsorption, or a gas detector with a surface sensor, along the surface of which the second partial flow is guided.
[0071] The representation of the line routing in Fig. 2 illustrates that the first gas line 28 with the test chamber section 34 and the detector section 40 forms a common gas line path connecting the two connection points 42, 38, which runs between the two connection points 42, 38 parallel to the gas line path formed by the second gas line 30.
[0072] The line section 46 of the detector inlet 15 between the detector volume 14 and the third connection point 44 should be kept short. This ensures rapid gas exchange at the detector through the carrier gas flow passing through the third connection point 44. In particular, the line section 46 is shorter than the first gas line 28, the second gas line 30, the detector section 40, and the test chamber section 34.
[0073] A further difference between the embodiment according to Fig. 2 and the embodiment according to Fig. 1 is that the pressure gauges PG1, PG2, PG3, the second test chamber inlet 24 with the fourth valve V4, the third valve V3 and the flow restrictor D1 are not shown in Fig. 2. Nevertheless, one or more of these components can be provided in the embodiment shown in Fig. 2. Accordingly, it is also conceivable that in the embodiment in Fig. 2 the valves VI, V2, the second flow restrictor D2 and / or the third gas line path 32 with the fifth valve V5 are omitted. Depending on the type of application and detector type, it would also be conceivable that one or more of the valves VI, V2, V6 are omitted.
Claims
Patent claims Carrier gas leak detection system (10) for leak detection on a test specimen, with a gas detector (12) of a test chamber (20) with at least a first test chamber inlet (22), a test chamber outlet (26) and a test chamber vacuum pump (27) evacuating the test chamber outlet (26) and a first gas line (28) connecting the test chamber outlet (26) to the detector volume inlet (15) and the test chamber vacuum pump (27) in a gas-conducting manner, characterized by a second flow throttle (D2) for specifying the carrier gas flow through the first test chamber inlet (22), a second gas line (30) connecting the test chamber outlet (26) to the test chamber vacuum pump (27) parallel to the first gas line (28), wherein the first gas line (28) and the second gas line (30) are connected in a gas-conducting manner to the Test chamber vacuum pump (27) is connected,a third flow restrictor (D3) in a detector section (40) of the first gas line (28) between the first connection point (38) and the detector volume inlet (15) and, a fourth flow restrictor (D4) in the second gas line (30) between the test chamber outlet (26) and the first connection point (38), so that the third flow restrictor (D3) and the fourth flow restrictor (D4) form a flow divider such that a first partial flow through the first gas line (28) and a second partial flow through the second gas line (30) can be evacuated from the test chamber (20) using the test chamber vacuum pump (27). Carrier gas leak detection system (10) according to claim 1, characterized in that the conductance S3 of the third restrictor (D3) is lower than the conductance S4 of the fourth restrictor (D4).Carrier gas leak detection system (10) according to claim 1 or 2, characterized in that a test chamber section (34) of the first gas line (28) between the test chamber outlet (26) and the detector volume inlet (15) has a selectively closable first valve (V1), and the detector section (40) has a selectively closable second valve (V2) between the first flow restrictor (D1) and the third flow restrictor (D3). Carrier gas leak detection system (10) according to one of the preceding claims, characterized in that the first test chamber inlet (22) is provided with a selectively closable third valve (V3). Carrier gas leak detection system (10) according to one of the preceding claims, characterized in that the test chamber (20) has at least one second test chamber inlet (24) for venting or purging the test chamber (20) with a selectively closable fourth valve (V4). Carrier gas leak detection system (10) according to one of the preceding Claims, characterized in that the test chamber outlet (26) is connected to the test chamber vacuum pump (27) by a third gas line (32) via the first connection point (38), wherein the third gas line (32) is provided with a selectively closable fifth valve (V5) and is arranged parallel to the first and second gas lines (28, 30). Carrier gas leak detection system (10) according to one of the preceding claims, characterized in that the second gas line (30) has a selectively closable sixth valve (V6). Carrier gas leak detection system (10) according to one of the preceding Claims, characterized in that the gas detector (12) has a detector volume (14), a detector volume inlet (15) with a first flow restrictor (D1) for pressure conversion at the detector volume inlet (15), a detector volume outlet (16), and a detector vacuum pump (18) at the detector volume outlet (16). Carrier gas leak detection system (10) according to the preceding claim, characterized in that the gas detector (12) is a mass spectrometer, in particular a quadrupole mass spectrometer, and / or the detector vacuum pump (18) is a high-vacuum pump system with a turbomolecular pump and a forevacuum pump. Carrier gas leak detection system (10) according to one of the preceding Claims, characterized in that a first pressure gauge (PG1) is connected to the first gas line (28) between the first valve (VI) and the first flow restrictor (Dl) for measuring the pressure in the first gas line (28). Carrier gas leak detection system (10) according to one of the preceding Claims, characterized in that a second pressure gauge (PG2) is connected to the detector section (40) between the first connection point (38) and the third flow restrictor (D3) for measuring the pressure in the first gas line (28). Carrier gas leak detection system (10) according to one of the preceding Claims, characterized in that the test chamber (20) is connected to a third pressure gauge (PG3) for measuring the pressure in the test chamber (20). A carrier gas leak detection method for leak detection in a test specimen with a carrier gas leak detection system (10) according to one of the preceding claims, characterized by the steps: • Placing a test specimen into the test chamber (20), • Evacuating the test chamber (20) with the test chamber vacuum pump (27), • Supplying carrier gas into the test chamber (20) containing the test specimen through the second flow restrictor (D2), • Evacuating the second gas line (30) with the test chamber vacuum pump (27), • Presetting the conductance values of the third flow restrictor (D3) and the fourth flow restrictor (D4) as a flow divider such that a first partial flow is evacuated from the test chamber (20) through the second gas line (28) and a second partial flow through the first gas line (28) using the test chamber vacuum pump (27), and • Analyzing gas of the second partial flow with the gas detector Carrier gas leak detection method according to claim 13, characterized in that the gas detector (12) has a detector volume (14) and a detector Vacuum pump (18), wherein the detector vacuum pump (18) evacuates the detector volume (14) to a vacuum pressure required for gas detection. Carrier gas leak detection method according to claim 13 or 14, characterized in that the gas flow along the first partial flow is greater than along the second partial flow.