Leak detector

Abstract

Leak detection device for integral and local leak detection combination, comprising a test sample port (14), a sample high vacuum pump (16) whose inlet is connected to the test sample port (14), at least one pre-vacuum pump (20) whose inlet is connected to the outlet (19) of the sample high vacuum pump (16) through a test sample line (18), and a gas detector (32) connected to at least one pre-vacuum pump (20), the gas detector (32) being connected to the sample high vacuum pump (16), to the test sample line (18) and / or to the test sample port (14) through at least one first gas line (28) so that the gas from the test sample port (14) is supplied through the first gas line (28) to the gas detector (32) for gas analysis, characterized in that a gas manometric volume (22) connected to a gas pressure sensor is arranged in the test sample line (18) so that, when a gas measurement is performed using the gas detector (32), an integral leak detection can be performed by measuring the pressure curve in the gas manometric volume (22).

Description

[0001] This invention relates to a leak detection device and a leak detection method for a combination of overall and partial leak detection.

[0002] In the "rate of rise" method for detecting overall gas leaks, a vacuum pump is used to evacuate the sample, and then the total pressure curve of the evacuated sample is measured to infer gas leaks from the sample. If the pressure remains essentially constant, the sample can be assumed to be tight. If the total pressure curve increases, a leak is assumed to exist in the sample.

[0003] As an alternative to overall leak detection, local leak detection is performed with the aid of a spray gun or a sniffer leak detector to locate the leak in the sample. Traditional gas leak detection methods can only perform either overall or local leak detection. For pressure increase measurements, the volume to be measured must be completely isolated; that is, the volume cannot be further emptied during the measurement process to avoid pressure changes. However, in contrast, traditional leak detection equipment with a test gas spray gun requires continuous pumping of the gas to be measured from the test sample. Existing leak detection devices cannot simultaneously measure overall leak tightness and test gas spray leak detection.

[0004] In contrast, the object of the present invention is to provide an improved leak detection device and an improved leak detection method.

[0005] In a first variant of the leak detection device of the present invention, the test sample port connected to the test sample is connected to the inlet of the test sample high vacuum pump. The outlet of the test sample high vacuum pump is connected to the inlet of the pre-vacuum pump via a test sample line. Furthermore, the pre-vacuum pump is connected to a gas detector, which is connected to the test sample high vacuum pump, the test sample line, and / or the test sample port via at least a first gas line, such that the gas detector supplies gas for gas analysis from the test sample port via the first gas line. A feature of this first variant is that a gas pressure measurement volume connected to a gas pressure sensor is formed in the test sample line, so that when performing gas analysis using the gas detector, overall leak detection, such as total pressure, differential pressure, gas pressure, or partial pressure, can be performed by simultaneously measuring the pressure curve in the gas pressure measurement volume.

[0006] In a second variation of the leak detection device of the present invention, a test sample port is further provided for connection to the test sample. The inlet of the pre-vacuum pump is connected to the outlet of the detector high-vacuum pump via a detector pipeline. The gas detector is connected to the inlet of the detector high-vacuum pump and is connected to the test sample pipeline and / or the test sample port via at least one first gas pipeline, such that the gas detector receives gas from the test sample port via the gas pipeline. The second variation of the present invention is characterized by forming a gas pressure measurement volume connected to the gas pressure sensor in the detector pipeline, so that when the gas detector performs gas measurement, overall leak detection can be performed by measuring the pressure curve in the gas pressure measurement volume.

[0007] The gas detector may be a partial pressure sensor capable of detecting a gas in a gas-selective manner, such as a mass spectrometer.

[0008] The common feature of the two variants of this invention is that, during or after gas measurement using a gas detector, the gas pressure measurement volume connected to the gas pressure sensor is used to perform overall leak detection by measuring the pressure curve in the gas pressure measurement volume, thereby enabling local leak detection. The gas detector is used for local leak detection, and the gas pressure measurement volume and the gas pressure sensor connected to it can perform overall leak detection simultaneously with or rapidly alternate with local leak detection.

[0009] In the leak detection method combining overall and partial leak detection of this invention, the test sample is first connected to the test sample port, and then the test sample is evacuated. Gas from the test sample is delivered to a gas pressure measuring volume, where a pressure curve of the total pressure is measured over a period of time. Simultaneously, a test gas, such as hydrogen or helium, is sprayed onto the sample. A portion of the gas extracted from the test sample is supplied to a gas detector through a gas pipeline for analysis. Simultaneously, a high-vacuum pump can split the gas flow extracted from the test sample, allowing lighter gas components to be supplied to the gas detector through the gas pipeline, while most of the gas extracted from the test sample by the high-vacuum pump is compressed into the gas pressure measuring volume. This is typically air. The air compressed into the gas pressure measuring volume cannot pass through the high-vacuum pump of the test sample into the gas detector.

[0010] Here, it is advantageous to establish a selectively lockable shut-off valve between the gas pressure measurement volume and the pre-vacuum pump to separate the gas pressure measurement volume from the pre-vacuum pump during pressurization measurements. Therefore, during pressure-increase measurements, the pre-vacuum pump can be used to evacuate the gas detector and / or the detector high-vacuum pump connected to the gas detector. This is particularly advantageous for mass spectrometry gas detectors.

[0011] Therefore, a gas line can connect the intermediate gas port of the test sample high-vacuum pump to the gas detector, for example, through the intermediate gas port of the detector high-vacuum pump. Alternatively, a gas line can be provided to connect the test sample high-vacuum pump to the pre-vacuum pump and / or the test sample line between the gas pressure measurement volume and the gas detector, for example, through the intermediate gas port of the detector high-vacuum pump. Here, a throttling valve with a preset conductance can be installed in the intermediate gas line to provide a continuous gas flow from the gas pressure measurement volume to the gas detector. Considering the known conductance of the throttling valve and / or the pressure drop through the throttling valve, the total pressure increase of the gas pressure measurement volume can be determined.

[0012] Specifically, the high-vacuum pump for the test sample can be a booster pump that operates in conjunction with a conventional mass spectrometer countercurrent leak detector. Each intermediate gas line, if possible, should have a selectively shut-off valve on the connection line between the detector high-vacuum pump and the pre-vacuum pump.

[0013] A gas pressure sensor is installed on the gas pressure measuring volume to measure the pressure curve within the volume. The gas pressure sensor can be an airtight sensor or a pressure gauge used for total pressure measurement.

[0014] In the attached diagram:

[0015] Figure 1 A schematic block diagram of a first exemplary embodiment of the leak detection device is shown;

[0016] Figure 2 The first pressure curve is shown;

[0017] Figure 3 The second pressure curve is shown;

[0018] Figure 4 A schematic block diagram illustrating a second exemplary embodiment of the leak detection device is shown; and

[0019] Figure 5 A schematic block diagram of a third exemplary embodiment of the leak detection device is shown.

[0020] Figure 1The exemplary embodiment shown refers to a first variant of the present invention. Test sample 12 is connected to test sample port 14, which is connected to the input of test sample high vacuum pump 16 via a gas-conducting connection. Test sample high vacuum pump 16 is connected to pre-vacuum pump 20 via test sample line 18 and has a gas pressure measuring volume 22. This gas pressure measuring volume 22 is connected to the outlet 19 of test sample high vacuum pump 16 via a first portion of test sample line 18 and to the inlet of pre-vacuum pump 20 via a second portion of test sample line 18 via a gas-conducting connection. Gas pressure measuring volume 22 is connected to a gas pressure sensor 24, which measures the gas pressure p1 within gas pressure measuring volume 22.

[0021] The intermediate vacuum port 26 of the test sample high vacuum pump 16 is connected to the detector high vacuum pump 30 via the first gas line 28. Both the detector high vacuum pump 30 and the test sample high vacuum pump 16 are conventionally designed turbomolecular pumps. The inlet of the detector high vacuum pump 30 is connected to the gas detector 32. The gas detector 32 is a mass spectrometer evacuated by the detector high vacuum pump 30. The detector high vacuum pump 30 is connected to the pre-vacuum pump 20 via the connecting line 34. Figure 1 The component shown is a mass spectrometer gas leak detector based on the countercurrent principle, in which gas enters the gas leak detector 32 from the test sample 12 through the gas line 28 in the countercurrent.

[0022] The second gas line 36 connects the gas pressure measuring volume 22 to another intermediate gas port of the detector high vacuum pump 30. Here, the second gas line 36 has a throttle valve 38 with, for example, a preset adjustable gas conduction. Gas can continuously enter from the gas pressure measuring volume 22 in a countercurrent flow through the second gas line 36, and then enter the gas detector 32 via the detector high vacuum pump 30. Although in Figure 1 In the exemplary embodiment shown, the first gas line 28 and the second gas line 36 are displayed together, but other exemplary embodiments not shown in the figure are conceivable, in which the first gas line 28 is provided without the second intermediate gas line 36, or the second intermediate gas line 36 is provided without the first gas line 28.

[0023] A third gas line 40 is conceivable in all exemplary embodiments and is provided in the exemplary embodiment shown in the figures. The third gas line 40 connects the gas pressure measurement volume 22 to a further intermediate gas port of the gas detector high vacuum pump 30 in a gas-conducting manner and has a selective shut-off valve V3. The gas pressure measurement volume 22 can be discharged through the valve V3 and the third intermediate gas line 40.

[0024] The first gas line 28 has a selectively closable first shut-off valve V1. The second intermediate gas line 36 has a selectively closable second shut-off valve V2. The third intermediate gas line 40 has a selectively closable third shut-off valve V3. The second section of the test sample line 18, connecting the gas pressure measurement volume 22 and the pre-vacuum pump 20, has a selectively closable fourth shut-off valve V4. The connecting line 34, connecting the detection high vacuum pump 30 and the pre-vacuum pump 20, has a selectively closable fifth shut-off valve V5.

[0025] The first gas line 28 is equipped with a second pressure sensor 42, which measures the pressure at the intermediate gas outlet and the intermediate gas vacuum port 26 of the high vacuum pump 16 for the test sample.

[0026] A third pressure sensor 44 is located between the fifth valve V5 and the outlet of the detector high vacuum pump 30 in the connecting line 34. This third pressure sensor 44 measures the pressure at the outlet of the detector high vacuum pump 30.

[0027] The gas pressure sensor 24 is located at the pre-vacuum port of the test sample high-vacuum pump 16, and therefore is located to some extent at the inlet of the leak detector. In the method of the present invention, the pressure increment in the measured gas pressure volume 22 is located downstream of the test sample high-vacuum pump 16. The test sample high-vacuum pump 16 can also be referred to as a booster pump.

[0028] The test sample high-vacuum pump 16 separates the gas flow extracted from the test sample 12 into light components such as helium and / or hydrogen, primarily delivering this to the detector high-vacuum pump 30 for localized leak detection (spray leak detection). Most of the air extracted from the test sample 12 is delivered downstream of the test sample high-vacuum pump 16 to the gas pressure measurement volume 22. Due to the significant compression between the intermediate gas vacuum port 26 and the outlet of the test sample high-vacuum pump 16, the test sample high-vacuum pump 16 acts as a barrier to the air components. The gas pressure measurement volume 22 is cyclically closed by switching at least one valve (V2, V3, or V4) connected to the detector lines 18, 36, and 40 connected to the gas pressure measurement volume 22, preferably by switching the third valve V3. When air flows in and is compressed by the test sample high-vacuum pump 16, the pressure in the gas pressure measurement volume 22 increases and is measured by the pressure sensor 24. The pressure increase is proportional to the overall leakage of the test sample 12. In this regard, the intermediate gas vacuum port 26, also referred to as the intermediate gas outlet, is continuously open and connected to the gas detector 32, or more specifically, the first intermediate gas port of the detector's high vacuum pump 30. Therefore, local leak detection (in this example, spray leak detection) can be performed simultaneously with overall leak detection based on the mass spectrometry countercurrent principle.

[0029] As an alternative to completely closing the gas pressure measurement volume 22 via the fourth valve V4, the gas flow can be directed to the second or the same intermediate gas port of the detector high vacuum pump 30 via the throttle valve 38 of the second intermediate gas line 36. The gas compressed into the gas pressure measurement volume 22 by the test sample high vacuum pump 16 can flow through the throttle valve 38 and flow backward through the detector high vacuum pump 30 into the gas detector 32. The pressure drop through the throttle valve 38 can be determined, and like the pressure increase, this pressure drop is a measure of the overall leakage of the test sample 12. In this method, localized leak detection can also be performed in parallel with overall leak detection by opening the intermediate gas vacuum port 26 of the test sample high vacuum pump 16.

[0030] Next, using Figure 2 The pressure distribution curve is used to describe the measurement of pressure increase. During this process, the gas that leaks into the test sample 12 is drawn out of the test sample 12 by the test sample high-vacuum pump 16. Due to compression differences, lighter gases, such as helium, are mainly delivered to the detector high-vacuum pump 30. Therefore, helium is often used as the test gas. The remaining air is mainly delivered to the gas pressure measurement volume 22 downstream of the test sample high-vacuum pump 16. Because the compression between the intermediate gas vacuum port 26 of the test sample high-vacuum pump 16 and its outlet 19 for the air element is relatively large, gas accumulates in the gas pressure measurement volume 22, increasing the pressure within the pressure measurement volume 22. The pressure increase is proportional to the overall leakage rate of the sample.

[0031] Since all incoming gas is delivered via the test sample high-vacuum pump 16, the pressure increase in the gas pressure measurement volume 22 is independent of the volume of the test sample 12. The pressure is measured by a suitable total pressure sensor or airtightness sensor (e.g., pressure sensor 24) connected to the gas pressure measurement volume 22.

[0032] The pressure in the gas pressure measurement volume 22 should ideally be maintained within a range where the high vacuum pump 16 can still keep the test sample well compressed and where light gas backflow is low. Typically, the pressure range is between 0 and 5 mbar. In this respect, pressure p1 should be maintained between 0 and 5 mbar. If pressure p1 increases too much, gas can be vented by briefly opening at least one valve in the detector lines 18, 36, and 40 connected to the gas pressure measurement volume 22, namely, the second valve V2, the third valve V3, or the fourth valve V4, or any combination of these valves V2, V3, and V4.

[0033] The pressure increase within the gas pressure measurement volume 22 is measured within a preset time t, or the time required to reach a certain pressure increase is measured.

[0034] While performing overall leak measurement using the pressure increase method, local leak detection can also be performed using light gases (such as helium or hydrogen), as the light gas is primarily delivered to the gas detector 32 through the first valve V1. This allows for simultaneous local leak detection by spraying the test sample with a light test gas and measuring the overall seal of the entire test sample 12. The overall leak rate is the result of measuring the volume VA of the gas pressure measurement volume 22 and the pressure increment Δp / Δt, q=VA[I]*Δp[mbar] / t[s].

[0035] If the first valve V1, the second valve V2, and the fifth valve V5 are open, while the third valve V3 and the fourth valve V4 are closed, the overall sealing performance can be directly measured by differential pressure measurement. Here, contrary to the pressure increase measurement described above, the gas pressure measurement volume 22 is not completely sealed. Gas is delivered to the detector high-vacuum pump 30 via the throttling valve 38. This throttling causes an increase in pressure in the gas pressure measurement volume 22, which is measured by the first pressure sensor 24. The pressure increase is proportional to the amount of gas flowing into the test sample, and therefore proportional to the leakage. The resulting pressure stroke is as follows: Figure 3 As shown, this is used here for leak measurement. The final or equilibrium pressure of the unit can be determined by briefly opening the third valve V3 and / or the fourth valve V4. The pressure difference between the equilibrium pressure when the third valve V3 is open and the pressure when valve V3 is closed then generates the flow rate. Similar to the total pressure measurement method described above, both overall leak detection and localized helium or hydrogen leak detection can be performed simultaneously.

[0036] Figure 4 and Figure 5 The illustrated exemplary embodiments refer to two variations of the invention, wherein the pressure measurement volume is configured as part of the detector line 34 connecting the pre-vacuum pump 20 and the detector high-vacuum pump 30, i.e., between valve V5 and the detector high-vacuum pump 30. Here, pressure sensor 24 can measure the pressure in the pressure measurement volume 22 by cyclically closing and opening valve V5 to perform overall leak detection based on the pressure increase method. When valve V5 is closed, the pressure increment in the pressure measurement volume 22 is measured. The pressure increase is proportional to the overall leakage rate of the test specimen. Simultaneously with valve V1 opening, the gas detector can detect the test gas sprayed onto the test specimen 12 for local leak detection, thus performing local leak detection on the test specimen 12.

[0037] Alternatively or additionally, if air from the atmosphere surrounding test specimen 12 enters test specimen 12 through a leak and is supplied from there to gas detector 32, gas detector 32 can be used to determine a steady increase in the test gas signal, for example, in the form of the helium content in the air. In this way, overall leak detection can also be performed. Local detection can be performed immediately by spraying test specimen 12 with a test gas (such as helium) without modifying the equipment.

[0038] Considering the combination of these two possibilities, an internal leak in test specimen 12, such as a burst nitrogen pipe inside test specimen 12, can be distinguished from an external leak present in the outer casing of test specimen 12. An internal leak would cause a pressure rise, which pressure sensor 24 can measure, while the background signal of the test gas (e.g., helium) in gas detector 32 would not increase.

Claims

1. A leak detection device for a combination of overall and partial leak detection, comprising: Test sample port (14); A high vacuum pump for the sample (16) has its inlet connected to the test sample port (14); At least one pre-vacuum pump (20) has its inlet connected to the outlet (19) of the high-vacuum pump (16) of the sample via a test sample line (18); and A gas detector (32) is connected to the at least one pre-vacuum pump (20). The gas detector (32) is connected to the sample high vacuum pump (16), the test sample line (18) and / or the test sample port (14) via at least one first gas line (28), so that gas from the test sample port (14) is supplied to the gas detector (32) through the first gas line (28) for gas analysis. Its features are: A gas pressure measurement volume (22) connected to a gas pressure sensor (24) is configured in the test sample pipeline (18) so that when gas measurement is performed using the gas detector (32), overall leak detection can be performed by measuring the pressure curve in the gas pressure measurement volume (22); and An apparatus is provided for eliminating the influence of the pumping capacity of at least one pre-vacuum pump (20) on the gas pressure measurement volume (22) while measuring the pressure curve in the gas pressure measurement volume (22) using the gas pressure sensor (24).

2. A leak detection device for a combination of overall and partial leak detection, comprising: Test sample port (14); Detector high vacuum pump (30); At least one pre-vacuum pump (20) has its inlet connected to the outlet of the detector high-vacuum pump (30) via a detector line (34); and A gas detector (32) is connected to the inlet of the detector high vacuum pump (30). The gas detector (32) is connected to the test sample line (18) and / or the test sample port (14) through at least one first gas line (28), so that gas from the test sample port (14) is supplied to the gas detector (32) through the first gas line (28) for gas analysis. The outlet (19) of the sample high vacuum pump (16) is connected to the inlet of the at least one pre-vacuum pump (20) through the test sample line (18). The test sample port (14) is connected to the input of the sample high vacuum pump (16). Its features are: A gas pressure measurement volume (22) connected to a gas pressure sensor (24) is configured in the detector line (34) so ​​that when gas measurement is performed using the gas detector (32), overall leak detection can be performed by measuring the pressure curve in the gas pressure measurement volume (22), and An apparatus is provided for eliminating the influence of the pumping capacity of at least one pre-vacuum pump (20) on the gas pressure measurement volume (22) while measuring the pressure curve in the gas pressure measurement volume (22) using the gas pressure sensor (24).

3. The leakage detection device according to claim 2, characterized in that, A sample high vacuum pump (16) is provided, the inlet of which is connected to the test sample port (14), and the outlet (19) of which is connected to the at least one pre-vacuum pump (20) through the sample pipeline (18).

4. The leakage detection device according to claim 1 or 2, characterized in that, The device is provided in the form of a shut-off valve (V4, V5) or a cut-off device for the at least one pre-vacuum pump (20) to eliminate the effect of the pumping capacity of the at least one pre-vacuum pump on the gas pressure measurement volume (22).

5. The leakage detection device according to claim 1 or 2, characterized in that, The first gas line (28) is connected to the intermediate gas port of the sample high vacuum pump (16).

6. The leakage detection device according to claim 1 or 2, characterized in that, At least one of the test sample line (18) and other gas lines (36, 40) connected to the gas pressure measuring volume (22) is equipped with a throttle valve (38).

7. The leakage detection device according to claim 2, characterized in that, At least one throttle valve (38) is provided in the intermediate gas line (36, 40) connecting the gas pressure measuring volume (22) and the detector high vacuum pump (30).

8. The leakage detection device according to claim 1, 2, or 7, characterized in that, The gas line (28) and / or at least one intermediate gas line (36, 40) leads to a detector high vacuum pump (30) for purging the gas detector (32).

9. The leakage detection device according to claim 7, characterized in that, The outlet of the detector high vacuum pump (30) is connected to the pre-vacuum pump (20) so as to release the vacuum.

10. The leakage detection device according to claim 1 or 2, characterized in that, The gas detector (32) is a mass spectrometer.

11. The leakage detection device according to claim 1 or 2, characterized in that, The gas pressure sensor (24) is a pressure gauge that functions as a total pressure sensor, an airtightness sensor, or a differential pressure sensor.

12. The leakage detection device according to claim 1 or 2, characterized in that, At least one other gas line (36, 40) is provided with a selectively shut-off valve (V2, V3), and / or the first gas line (28) has a selectively shut-off valve (V1).

13. The leakage detection device according to claim 2, characterized in that, A selectively shut-off valve (V5) is provided in the detector line (34) connecting the detector high vacuum pump (30) and the at least one pre-vacuum pump (20).

14. The leakage detection device according to claim 13, characterized in that, The shut-off valve (V5) is formed in a portion of the detector line (34) that connects the pressure measuring volume (22) and the at least one pre-vacuum pump (20).

15. The leakage detection device according to claim 1 or 2, characterized in that, The test sample line (18) has a selectively shut-off valve (V4) between the gas pressure measurement volume (22) and the at least one pre-vacuum pump (20).

16. A leak detection method for a combination of overall and partial leak detection, comprising using the leak detection device according to claim 1 or claim 2, characterized in that... It includes the following steps: Connect the test specimen (12) to the test specimen port (14); The test sample (12) was evacuated. Gas is extracted from the test sample (12) into the gas pressure measuring volume (22), and the pressure curve in the gas pressure measuring volume (22) is measured; The test gas was sprayed onto the test sample (12); and A portion of the gas stream extracted from the test sample (12) is transported to the gas detector (32), and the pressure curve in the gas pressure measurement volume (22) is measured by the gas pressure sensor (24). At the same time, the gas is analyzed by the gas detector (32).

17. The leakage detection method according to claim 16, characterized in that, A portion of the gas flow is delivered at least via a first gas line (28) or via the first gas line (28) and an intermediate gas line (36), the intermediate gas line (36) connecting the gas pressure measurement volume (22) to the detector high vacuum pump (30) and having a known throttle valve (38).

18. The leakage detection method according to claim 17, characterized in that, The throttle valve (38) is taken into account when delivering the portion of the gas flow through the intermediate gas line (36) to determine the pressure curve in the gas pressure measurement volume (22).

19. The leakage detection method according to claim 16, characterized in that, When the pressure curve in the gas pressure measurement volume (22) is measured using the gas pressure sensor (24), the effect of the intake volume of the at least one pre-vacuum pump (20) on the gas pressure measurement volume (22) is eliminated.

20. The leakage detection method according to claim 16, characterized in that, The detector line (34) connecting the pre-vacuum pump (20) to the detector high-vacuum pump (30), the test sample line (18), or at least one intermediate gas line (36, 40) connecting the gas pressure measurement volume (22) to the at least one pre-vacuum pump (20) is closed and reopened cyclically according to the pressure measured in the gas pressure measurement volume (22). In the closed state, the leakage in the sample is inferred based on the increase in the measured pressure of the gas pressure measurement volume (22) based on the pressure increase method.

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