GAS LEAK DETECTION DEVICE AND GAS LEAK DETECTION METHOD FOR DETECTING A GAS LEAK IN A TEST ITEM

Description

[0001] The invention relates to a gas leak detection device for detecting a gas leak in a test object and a corresponding method.

[0002] There are two basic methods for detecting a gas leak: integral detection and localization. Integral detection offers two possibilities. First, the test object can be contained in a test chamber connected to a gas detector, where the test object is pressurized with test gas while the test chamber is evacuated. Second, alternatively, the test object, contained in a test chamber or enclosure, can be connected to the gas detector and evacuated while the test chamber or enclosure is pressurized with test gas, such as ambient air. Integral leak detection can only detect a leak, but not pinpoint its location.

[0003] To locate a leak, localization detection is performed without a test chamber using either the sniffing or spraying principle. In the sniffing principle, the test object is pressurized with test gas, and its exterior is sniffed with a sniffing probe connected to a vacuum pump and a gas detector. In the spraying principle, the test object is sprayed externally with test gas using a spray gun while it remains connected to the vacuum pump and gas detector.

[0004] Gas leak detection devices using helium or hydrogen as the test gas typically employ a mass spectrometer as the gas detector, while the vacuum pump is a high-vacuum pump, such as a turbomolecular pump in combination with a backing pump. For localized detection, the test specimen is evacuated using the vacuum pump and sprayed externally with a test gas (spray principle). For integral leak testing, the test specimen is pressurized with the test gas and placed in a test chamber. The test chamber is evacuated using the backing pump, and the test gas fraction is measured under vacuum using the mass spectrometer. The test gas fraction is a measure of the leak rate of a leak in the test specimen.

[0005] Such vacuum leak detectors are marketed, for example, under the designations UL3000 and UL5000 by INFICON®. With these systems, to confirm the tightness of a system, an integral pressure rise measurement is performed using a test chamber following the localization measurement by spraying or sniffing the test specimen. The test specimen is placed in a test chamber connected to the vacuum leak detector, which is then evacuated while the test specimen is pressurized with the test gas. Alternatively, the test specimen is connected to the vacuum leak detector and evacuated while the test chamber surrounding the test specimen is pressurized with the test gas.

[0006] German patent DE 16 48 648 C3 describes mass spectrometric leak detection using the countercurrent principle. A test vessel is connected to the inlet of a turbomolecular pump. The test vessel contains the object being tested for leaks. The object is filled with a test gas, such as helium. The inlet side of the turbomolecular pump is connected to a backing pump. The pressure side of another turbomolecular pump is connected to an intermediate gas inlet between the turbomolecular pump and the backing pump. This second turbomolecular pump evacuates the gas detector, which is a mass spectrometer. The two turbomolecular pumps are operated such that test gas extracted from the test vessel is supplied to the mass spectrometer, while the test vessel and the mass spectrometer are evacuated using the backing pump.

[0007] EP 1 620 706 B1 describes an arrangement for countercurrent leak detection in which the high-vacuum pump evacuating the test container is connected directly, without throttling or a valve, to the inlet of the leak detector and the test container connected to the inlet. This increases the pumping speed for helium at the inlet and reduces the response time for the test gas, even when connecting large-volume test specimens.

[0008] In DE 101 56 206 A and DE 10 2014 223 841 A, arrangements of vacuum leak detectors with a booster pump are described. The booster pump is positioned in the inlet area of ​​the vacuum leak detector in the form of an additional turbomolecular pump to improve the pumping speed and thus the response time of the vacuum leak detector.

[0009] US 6,286,362 B1 discloses a leak detector with at least two partial pressure analyzers.

[0010] The invention is based on the objective of creating an improved gas leak detection device that enables both localizing gas leak detection on a test object and integral measurement, as well as providing a corresponding method.

[0011] The gas leak detection device according to the invention is defined by the features of patent claim 1. The method according to the invention is defined by the features of patent claim 6.

[0012] According to the invention, in addition to the vacuum pump and the gas detector connected to the vacuum pump, a gas pressure sensor is provided. This sensor is designed for integral measurement of the total pressure rise within the test chamber or within the test specimen (pressure rise method) as a total pressure sensor and / or as a gas-selective partial pressure sensor for measuring the partial pressure rise of at least one second test gas, different from the first, within the test specimen or the test chamber (partial pressure rise method). The partial pressure sensor can, for example, determine the partial pressure of the second or further test gas by optical spectral analysis of the gas. A locking device is provided and designed to isolate the gas pressure sensor and the connection for the test specimen or the test chamber from the vacuum pump when the test specimen or the test chamber is being examined with the gas pressure sensor.

[0013] This enables particularly fast measurements using the pressure rise method or the accumulation principle, while the vacuum pump continues to run. For integral or localized measurements with the gas detector, the first test gas is used, while for integral pressure rise measurements with the gas pressure sensor, at least a second test gas is used. Switching off or interrupting the operation of the vacuum pump for integral measurements using the pressure rise method or the accumulation principle is then no longer necessary, because the barrier device isolates the gas pressure sensor and the test specimen or test chamber from the vacuum pump during the measurement.

[0014] The vacuum pump can be a single vacuum pump or a vacuum pump of a vacuum pumping system consisting of several vacuum pumps. In particular, the claimed vacuum pump can be a high-vacuum pump of a vacuum pumping system consisting of at least one backing pump and at least one high-vacuum pump.

[0015] The gas detector can be a mass spectrometer with a high-vacuum pump or an ultra-high-vacuum pump, such as a turbomolecular pump, which uses the vacuum pump that evacuates the test specimen or test chamber as a backing pump and evacuates the mass spectrometer to the atmosphere via the backing pump. The backing pump and the high-vacuum pump can thus be referred to as a vacuum pumping system. Alternatively, the gas detector can be a gas-specific optical gas detector or a semiconductor sensor.

[0016] The gas pressure sensor can be a pressure sensor for measuring the total pressure increase within the test chamber or within the test specimen using the pressure rise method. Alternatively or additionally, the gas pressure sensor can be designed as a gas-selective partial pressure sensor for measuring the partial pressure increase of the test gas. Partial pressure, in this context, refers to the relative proportion of the test gas in the gas mixture under investigation. The measurement of the partial pressure increase can be performed using the accumulation method, in which the partial pressure increase of the gas accumulating in the measuring area is measured with the vacuum pump shut off.

[0017] The gas pressure sensor can be, in particular, a membrane window sensor, an absorption spectroscopic sensor (e.g., an infrared absorption sensor), an emission spectroscopic sensor (e.g., an OES sensor), or a semiconductor gas sensor, chemical gas sensor, or optical gas detector. Specifically, the gas pressure sensor is not necessarily a pressure gauge. In the case of the total pressure rise method, the gas pressure sensor measures the increase in the total pressure of a gas mixture containing the second test gas. In the case of the partial pressure rise method, the gas pressure sensor measures the increase in the partial pressure of at least the second test gas.

[0018] The optical spectral analysis carried out in one embodiment of the gas pressure sensor enables a particularly fast evaluation according to the pressure increase method or the accumulation principle of the total pressure and / or the partial pressure.

[0019] The gas-selective partial pressure sensor is advantageously an OES sensor designed for optical emission spectroscopy.

[0020] Advantageously, the pressure sensor is contained in or connected to a gas line path that connects the connection for the test specimen or test chamber to the vacuum pump or gas detector.

[0021] The shut-off device can be a selectively controllable device that shuts off manually, electronically, and / or pneumatically. Selectively actuated or controllable valves can be used in the gas pipelines to be shut off. Alternatively, the shut-off device can, for example, include gate valves, butterfly valves, or bellows shut-off valves to achieve vacuum isolation of the gas pipelines.

[0022] Advantageously, the booster pump pumps during the measurement, so that the gas escaping from a leak in the test volume is compressed into the volume on the downstream side of the turbomolecular pump. Typically, the volume of the test chamber or test specimen is several times larger than the volume in the area behind the compressing turbomolecular pump, so the pressure increase in this compressed gas volume is amplified by a factor of approximately the volume ratio.

[0023] The following section provides a more detailed explanation of embodiments of the invention with reference to the figures. They show: Figure 1 is a schematic representation of an embodiment without a booster pump, and Figure 2 is a schematic representation of a corresponding embodiment with a booster pump.

[0024] Both figures show a gas leak detection device with the following components: a gas detector 12; a connection 20 for the test specimen or a test chamber receiving the test specimen; a vacuum pump 16 for evacuating a test specimen connected to the connection 20 and the gas detector 12.

[0025] A gas line 22 connects the connection 20 with the vacuum pump 14.

[0026] The gas detector 12 of the illustrated embodiments is a mass spectrometer that is evacuated by a turbomolecular pump 18. The gas detector 12 and the turbomolecular pump 18 can be referred to as a detector system. The outlet of the turbomolecular pump 18 is connected to the inlet of the vacuum pump 16 and uses it as a backing pump. Thus, the vacuum pump 16 and the turbomolecular pump 18 form a vacuum pumping system 14. The outlet of the vacuum pump 16 is open to the atmosphere.

[0027] According to the invention, a gas pressure sensor 24, which can be a total pressure sensor and / or a gas-selective partial pressure sensor 24, e.g., in the form of an OES (optical emission spectroscopy) sensor, is connected to the gas line 22. For this purpose, a locking device 26 is provided upstream of the gas pressure sensor 24, i.e., between the gas pressure sensor 24 and the gas line 22, via which the gas pressure sensor 24 is connected to the gas line 22. The locking device 26 is configured to establish a gas-conducting connection between the port 20 and the gas pressure sensor 24, while the connection between the port 20 and the other components, i.e., in particular the gas detector 12 and the vacuum pump 16, is disconnected.In the simplest case, the blocking device 26 can be a switch that either opens the gas line 22 between the connection 20 and the vacuum pump 16 and closes the connection to the gas pressure sensor 24, or vice versa. The switch can be a changeover valve or a 3-2-way valve.

[0028] For the sake of simplicity, the blocking device 26 is depicted in the figures as a box extending over the gas lines 22 and 28, thereby indicating that the blocking device can block the gas lines 22 and 28. This can be achieved by a controllable valve 27 in the gas line 22 to block the connection between the port 20, the gas pressure sensor 24, and the vacuum pump 26. Additionally, the blocking device of the illustrated embodiments includes a controllable valve 25 for blocking the gas line 28, which connects the mass spectrometric high-vacuum pump 18 (i.e., the pump connected to the gas detector 12) to the port 20 and the gas pressure sensor 24. Thus, in the embodiments shown in the figures, at least part of the blocking device 26 is contained within the gas line 22 to enable it to be blocked.

[0029] Another possible arrangement of the gas pressure sensor 24 is in Fig. 1The line is shown with a dashed line. The gas pressure sensor 24 can be connected to the connecting branch 30, which connects the backing pump 16 to the turbomolecular pump 18. In this case, the blocking device 26 is formed by the controllable valve 29 in the gas line 30.

[0030] Corresponding arrangements of the locking device 26 and the gas pressure sensor 24 are also found in the one described in Figure 2 The illustrated embodiment is conceivable without being shown separately.

[0031] In Fig. 2An additional booster pump 32 in the form of a turbomolecular pump is included in the gas line 22 to evacuate the port 20 via the vacuum pump 16. Advantageously, the gas pressure sensor 24 and the shut-off device 26 are connected to the gas line 22 downstream of the booster pump 32 and upstream of the backing pump 16, i.e., connected to the section of the gas line 22 that connects the booster pump 32 to the backing pump 16.

Claims

1. A gas leak detection device for identifying a gas leak in a test object, comprising a connector (20) for the test object or for a test chamber accommodating the test object; a vacuum pump (16, 18) connected to the connector (20) for evacuating the test object or test chamber; a gas detector (12) connected to the vacuum pump (16, 18) and to the connector (20) and configured for detection of a first test gas and for integral leak detection or for localizing leak detection of a gas leak in the test object according to the spraying principle during continuous operation of the vacuum pump (16, 18), a gas pressure sensor (24) connected to the vacuum pump (16, 18) and to the connector (20) and configured for integral measurement of the total pressure increase according to the pressure increase method and / or the partial pressure increase of at least one second test gas different from the first test gas according to the partial pressure increase method, and a blocking device (26) configured for separating, in terms of vacuum, the gas pressure sensor (24) and the connector (20) from the vacuum pump (16, 18) when the test object is examined by means of the gas pressure sensor (24), characterized in that a gas conducting path (22) connecting the connector (20) to the vacuum pump (16, 18) comprises a booster pump (32), and the gas pressure sensor (24) is arranged in the gas conducting path (22) between the booster pump (32) and the vacuum pump (16, 18) and thus downstream of the booster pump (32) and upstream of the vacuum pump (16, 18) so as to measure, with the blocking device closed, the total pressure increase and / or the partial pressure increase of the second test gas in the gas conducting path (22) downstream of the booster pump (32) and upstream of the vacuum pump (16, 18) and / or of the gas detector (12), using the gas pressure sensor (24).

2. The gas leak detection device according to claim 1, characterized in that the gas pressure sensor (24) is connected to a gas conducting path (22) which connects the connector (20) to the vacuum pump (16, 18) and / or to the gas detector (12) such that the gas pressure sensor (24) measures the gas upstream of the vacuum pump (16, 18) and the gas detector (12), respectively.

3. The gas leak detection device according to any one of the preceding claims, characterized in that the gas pressure sensor (24) is configured for an optical spectral analysis of the second test gas.

4. The gas leak detection device according to any one of the preceding claims, characterized in that the gas detector (12) is a mass spectrometer having a high-vacuum pump (18), in particular an ultrahigh-vacuum pump, in the gas conducting path (30) connecting the gas detector (12) to the vacuum pump (16, 18), and the blocking device (26) is configured for separating, in terms of vacuum, the gas pressure sensor (24) and the connector (20) from the high-vacuum pump (18) when the test object is examined by means of the gas pressure sensor (24).

5. The gas leak detection device according to any one of the preceding claims, characterized in that the gas pressure sensor (24) is configured for integral measurement of the partial pressure increase of the second test gas at the connector (20) according to the accumulation principle.

6. A gas leak detection method for identifying a gas leak in a test object, comprising the following steps in any order: determining a gas leak in the test object by supplying a first test gas to the test object or to a test chamber surrounding the test object and detecting the first test gas on the basis of integral leak detection or on the basis of localizing leak detection according to the spraying principle during continuous evacuation of the test object or of the test chamber by means of a vacuum pump (16, 18), and identifying a gas leak in the test object by supplying at least one second test gas different from the first test gas to the test object or to the test chamber, and by integral measurement of the total pressure increase in the test object or the test chamber according to the pressure increase method and / or the partial pressure increase of the second test gas inside the test object or the test chamber according to the partial pressure increase method, while the test object or the test chamber and the gas pressure sensor (24) are disconnected from the vacuum pump (16, 18) and thus the test object or the test chamber is not evacuated, characterized in that using the gas pressure sensor (24), the total pressure increase and / or the partial pressure increase of the second test gas are measured in a gas conducting path (22) which connects the outlet of a booster pump (32), whose inlet is connected to the connector (20) for the test object or the test chamber, to the vacuum pump (16, 18) and / or to the gas detector (12), such that the total pressure increase and / or the partial pressure increase are measured downstream of the booster pump (32) and upstream of the vacuum pump (16, 18) and / or the gas detector (12).

7. The gas leak detection method according to claim 6, characterized in that the total pressure increase and / or the partial pressure increase of the second test gas are measured in a gas conducting path (22) which connects a connector (20) for the test object or the test chamber accommodating the test object to the vacuum pump (16, 18) and / or to the gas detector (12), or in an increased or decreased measuring volume connected thereto.

8. The gas leak detection method according to any one of claims 6 to 7, characterized in that the partial pressure increase of one or a plurality of different components of air is measured.

9. The gas leak detection method according to any one of claims 6 to 8, characterized in that the partial pressure increase of the test gas is measured by analyzing the optical spectrum of the test gas.

10. The gas leak detection method according to any one of claims 6 to 9, characterized in that the total pressure increase and / or the partial pressure increase of the second test gas are measured in a gas conducting path (28) which connects a high-vacuum pump (18) of the gas detector (12) to the connector (20) and to the gas pressure sensor (24), or in an increased or decreased measuring volume connected thereto.