Leak Detection Device

Abstract

A sniffer-type leak detection device and method using the same eliminates the effects of pressure surges. [Solution] A leak detection device (10) having a gas analyzer (16), a vacuum pump (18), a first intake port (12), and a second intake port (20), a first multi-way valve (14) having a first inlet (28) connected to the first intake (12) and at least first and second outlets (34, 38); a first inlet (32) connected to the second intake (20), and a second multi-way valve (22) connected to at least first and second outlets (36, 40); The first outlets (34, 36) of the two multi-way valves (14, 22) are connected to a gas analyzer (16), and the second outlets (38, 40) are connected to a vacuum pump (18).

Description

[Technical field]

[0001] The present invention relates to a leak detection device including a gas analyzer, a vacuum pump, a first inlet, and a second inlet, and particularly to a leak detection device for sniffer-type leak detection. [Background technology]

[0002] When detecting a gas leak, gas is sucked through the inlet by a vacuum pump and fed to a gas analyzer for analysis. In this case, the test gas flows through the leak and is detected. A specific example of gas leak detection is sniffer leak detection, in which a constant air flow is sucked through the inlet of a sniffer probe. While analyzing the sucked gas, the sniffer probe is guided over the object being examined. This not only detects the leak in the object, but also allows the leak point to be located. If the inlet of the sniffer probe is close to the gas leak, the test gas leaking through the leak is sucked in together with the air flow. In order to suck in the leak gas as reliably and completely as possible, a sniffer gas flow as large as possible is used. The sniffer gas flow is the flow rate of the gas flow sucked through the inlet of the sniffer probe. Here, the flow rate of the air flow is usually many times larger than the flow rate of the leak gas to be measured, that of the test gas leaking from the leak.

[0003] The concentration of the leakage gas in the gas flow drawn through the inlet is the ratio of the leakage rate to the sniffer gas flow. Thus, the concentration of the leakage gas in the gas flow drawn by the sniffer probe is usually relatively low. As a result, the sniffer gas flow cannot be selected as large as desired.

[0004] In many cases, the atmosphere surrounding the test object contains gas components that generate similar or identical measurement signals to the test gas in the gas detector or gas analyzer. These gas components are therefore called interference gases or background gases. They produce interference signals that are not easily distinguishable from the measurement signal of the actual leak gas.

[0005] In a known method for suppressing such interference signals, a measurement gas from a test area of ​​the object being examined and a reference gas from the atmosphere surrounding the object are alternately aspirated, the reference gas serving as a reference for determining the proportion of the interference gas in the aspirated gas mixture (reference measurement).

[0006] Such solutions are described, for example, in EP 1 342 070 and EP 1 819 998. The gas is drawn in by a small sensor unit in the form of an infrared absorption sensor mounted in the handle of a sniffer probe. In WO 2007 / 031386 a mass spectrometer is used as gas analyzer. The drawn in gas must be fed to the analyzer via a sniffer line. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent No. 1342070 [Patent Document 2] European Patent No. 1819998 [Patent Document 3] International Publication No. 2007 / 031386 Summary of the Invention [Problem to be solved by the invention]

[0008] In other sniffer-based leak detection methods, several, typically two, separate sniffer probes are independently connected to the same gas analyzer and operated alternately to evaluate the signal from one sniffer probe and then the signal from the other sniffer probe. In such so-called multiplexer systems, leak detection is performed at multiple locations by a gas detection system with several sniffer lines, switching from line to line in sequence.

[0009] When switching between two inlets of a leak detection device connected to the same gas analyzer, a pressure surge occurs in the sniffer line, which affects the measurement signal and leads to signal fluctuations. [Means for solving the problem]

[0010] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide an improved leak detection apparatus having two different gas inlets, each connected to the same gas analyzer, and a corresponding leak detection method.

[0011] The leak detection device of the present invention is defined by the features of claim 1. Two multi-way valves are provided, each having a first inlet and at least a first and a second outlet. The multi-way valves may for example be 3 / 2-way valves with one inlet and two outlets. The first outlet of each of the two multi-way valves is connected to a first inlet of the leak detection device, while the second outlet of each of the two multi-way valves is connected to a separate vacuum pump. The two multi-way valves simplify the switching and allocation of the two inlets to the gas analyzer. With one multi-way valve, the gas sucked through the first inlet is supplied to the gas analyzer, while the gas sucked through the second inlet is sucked by the vacuum pump without being supplied to the gas analyzer. By simply switching the multi-way valve, pressure surges can be avoided or reduced, since the gas flow is sucked through both inlets, while one gas flow and the other gas flow can be analyzed by the gas analyzer alternately.

[0012] The two inlets may be located on different sniffer probes, each connected to two multi-way valves by separate sniffer lines. Here, the vacuum pump may be a separate auxiliary pump not connected to the gas analyzer. The gas analyzer may be a mass spectrometry type leak detector with a multi-stage high vacuum pump. The vacuum pump connected to the two second outlets is preferably open to the atmosphere.

[0013] Alternatively, the two inlets may be the measurement gas inlet and the reference gas inlet of the same sniffer probe. Here, the vacuum pump may form a pump stage, for example a pre-vacuum stage, of a multi-stage high vacuum pump of a mass spectrometric gas analyzer. In this case, the two first outlets of the multi-way valve are connected to the mass spectrometer, and the two second outlets of the multi-way valve are connected via another connecting line to a connecting branch connecting the vacuum pump to the other pump stage of the high vacuum pump and to the mass spectrometer. Throttles are provided in the two connecting lines for respectively setting the necessary and desired gas flows. Alternatively, the connecting lines themselves may be designed to act as throttles for the gas flows. The two first outlets may be connected to the two second outlets, so that only a part of the branched flow is supplied to the gas analyzer, while the remainder of the gas flow is conveyed to the atmosphere via the vacuum pump.

[0014] In the following, two exemplary embodiments of the invention are explained in more detail with reference to the drawings. [Brief description of the drawings]

[0015] [Figure 1] 1 illustrates a first exemplary embodiment. [Diagram 2] 2 illustrates a second exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In both of the leak detection devices 10 shown in the drawings, the first inlet 12 is connected to a mass spectrometry type gas analyzer 16 and a vacuum pump 18 via a first multi-way valve 14 in the form of a 3 / 2 way valve, and the second inlet 20 is also connected to the gas analyzer 16 and the vacuum pump 18 via a second multi-way valve 22 in the form of a 3 / 2 way valve.

[0017] In a first exemplary embodiment shown in FIG. 1, two inlets 12, 20 are provided on a common sniffer probe 24, with the first inlet 12 directed toward a test area of ​​the subject suspected of gas leakage, and the second inlet 20 forming a reference inlet, which allows gas to be drawn from the atmosphere surrounding the subject.

[0018] The first intake 12 is connected to a first inlet 28 of the first multi-way valve 14 via a first connecting line 26. The second intake 20 is connected to a first inlet 32 ​​of the second multi-way valve 22 via another connecting line 30.

[0019] Further, in both exemplary embodiments, the first outlet 34 of the first multi-way valve 14 is connected to the first outlet 36 of the second multi-way valve 22 and to the gas analyzer 16, and the second outlet 38 of the first multi-way valve 14 is connected to the second outlet 40 of the second multi-way valve 22 and to the vacuum pump 18 for gas transport.

[0020] In the exemplary embodiment shown in FIG. 2, the two inlets 12, 20 are provided with separate sniffer probes that can be individually guided, and which are connected to two multi-way valves 14, 22 via separate connection lines.

[0021] In the first exemplary embodiment shown in Fig. 1, the two first outlets 34, 36 are connected to a common connection line 42, which is connected at a junction 44 to a connection line 46 connected to the second gas outlet 38 of the first multi-way valve 14 and to a further connection line 48 connected to the second outlet 40 of the second multi-way valve 22. Beyond the junction 44, the common connection line 42 is connected to a connection branch 50 connecting the vacuum pump 18 to a second vacuum pump 52. The second vacuum pump 52 is connected to a turbomolecular pump 54, the inlet of which is in turn connected to a gas analyzer 16 in the form of a mass spectrometer. The vacuum pump 18 thus forms the first pump stage of a three-stage high vacuum pump of a mass spectrometer type leak detector 56 consisting of the vacuum pump 18, the second vacuum pump 52, the turbomolecular pump 54 and the gas analyzer 16 (mass spectrometer). The second vacuum pump 52 then forms the second pump stage, and the turbomolecular pump 54 forms the third pump stage of a multi-stage high vacuum pump 60 .

[0022] Between the first two gas outlets 34, 36 and the junction 44, a line 64, which is throttled by a throttle 62, branches off from the connecting line 42 and connects to the gas analyzer 16. The line 64 branches off a part of the gas flow flowing through the line 42 and supplies it to the gas analyzer 16, while the remaining gas flow is supplied to the vacuum pump 18 via the junction 44 and is discharged to the atmosphere by the vacuum pump 18. Here, the connecting line 42 is provided with a second throttle 66 between the junction 44 and the connecting branch 50, which is used to block the gas flow. By blocking the flow, pressure surges downstream of the throttle, for example caused by a pump, do not have a disturbing effect in the form of pressure fluctuations upstream.

[0023] However, in the second exemplary embodiment, the connection line 42 from the two outlets 38, 40 to the vacuum pump 18 and the connection line 64 from the two outlets 34, 36 to the gas analyzer 16 are separate from each other and therefore not connected in a manner that allows gas to flow therethrough.

[0024] In both exemplary embodiments, the vacuum pump 18 remains in an operating state during the gas analysis using the gas analyzer 16, transporting gas from the one of the two inlets 12, 20 that is not connected to the gas analyzer 16 via the multi-way valves 14, 22. Thus, in the exemplary embodiment and in the switching state shown in FIG. 2, gas from the first inlet 12 is supplied to the gas analyzer 16 via the first inlet 28 and the first outlet 34 of the first multi-way valve 14 and the connecting line 64 for gas analysis, while at the same time gas entering from the second inlet 20 is conveyed via the second multi-way valve 22 from its first inlet 32 ​​to its second outlet 40, from where it is discharged to the atmosphere via the connecting line 42 and the pump 18. Thus, while gas from the first inlet 12 is being analyzed by the gas analyzer 16, gas from the second inlet 20 is being discharged to the atmosphere by the pump 18.

[0025] In the exemplary embodiment shown in Fig. 1, the first inlet 12 of the same sniffer probe forms the measurement gas inlet and the second inlet 20 forms the reference gas inlet, the gas from the first inlet 12 is fed via line 26 to the first inlet 28 of the first multi-way valve 14, while the vacuum pump 18 draws gas through the second inlet 20 and feeds it via line 30 to the inlet 32 ​​of the second multi-way valve 22. In the first switching state, the first multi-way valve 14 connects the first inlet 28 to the first outlet 34, and the gas drawn through the first inlet 12 is fed from the first outlet 34 to the connecting line 42. From this gas flow, a part of the flow branches off via the throttled line 64 and is fed to the mass spectrometric gas analyzer 16, while the remaining gas flow passes beyond the junction 44 and is added to the outside air through the second throttle 66 and the vacuum pump 18. At the same time, the second multi-way valve 22 directs gas drawn from the second intake 20 through the inlet 32 ​​to the second outlet 40, from where it is directed through line 48 and junction 44 to the shared connecting line 42. From there, the gas is conveyed via the vacuum pump 18 to the outside atmosphere.

[0026] Then, both multi-way valves 14, 22 are switched synchronously from the first switching state to the second switching state, in which the first multi-way valve 14 directs gas from the first inlet 12 through the gas outlet 38 to the second vacuum pump 18 without the gas entering the analyzer 16, while the second multi-way valve 22 directs gas from the second inlet 20 through the first gas outlet 36 to the common connecting line 42, from which a portion of the flow is directed through the throttled line 64 to the gas analyzer 16 for analysis.

[0027] By switching the two multi-way valves 14, 22 simultaneously in a synchronized manner, gas from only one of the two inlets 12, 20 can enter and be analyzed by the gas analyzer 16, while gas from the other inlet is exhausted to the atmosphere via the vacuum pump 18. By switching the two multi-way valves 14, 22 simultaneously in a synchronized manner, the two inlets 12, 20 can be alternately connected to the gas analyzer without significant delays and / or pressure surges during switching. The continuously pumped flow through both lines 26, 30 maintains a pressure gradient in the lines and pressure surges at the inlet to the detection system are avoided during switching.

[0028] A further advantage of the continuous gas flow through the two lines 26, 30 is that the gas drawn through the two inlet openings 12, 20 also arrives at the switching valves 14, 22 simultaneously. The transit time of the gas front through the lines 26, 30 can be several seconds. If the lines that are not connected to the gas analyzer 16 or leak detector 56 are not continuously evacuated or pumped, the reaction time is delayed by several seconds. [Explanation of symbols]

[0029] 10 Leak detection device 12 First air intake 14 First multi-way valve 28 Entrance 34 Exit 1 38 2nd Exit 16 Gas Analyzer 18 Vacuum Pump 20 Secondary air intake 22 Second multi-way valve 32 Entrance 36 Exit 1 40 2nd Exit 24 Sniffer Probe 52 Second Vacuum Pump 56 Turbomolecular Pump 60 Multi-stage high vacuum pump

Claims

1. A leak detection device (10) having a gas analyzer (16), a vacuum pump (18), a first inlet (12), and a second inlet (20), a first multi-way valve (14) having a first inlet (28) and at least a first outlet (34) and a second outlet (38), said inlet (28) being connected to said first air intake (12); a second multi-way valve (22) having a first inlet (32) and at least a first outlet (36) and a second outlet (40), said inlet (32) being connected to said second intake port (20); the two first outlets (34, 36) of the two multi-way valves (14, 22) are connected to the gas analyzer (16), and the two second outlets (38, 40) of the two multi-way valves (14, 22) are connected to the vacuum pump (18); A leak detection device (10).

2. The leak detection device (10) of claim 1, The multi-way valve (14, 22) is When the inlet (32) of the second multi-way valve (22) is connected to its second outlet (40), the inlet (28) of the first multi-way valve (14) is connected to its first outlet (34), and the switching of the two multi-way valves (14, 22) is configured to be performed synchronously and is controlled by a valve control device. A leak detection device (10).

3. The leak detection device (10) according to claim 2, The two intakes (12, 20) are located on separate sniffer probes; A leak detection device (10).

4. The leak detection device (10) of claim 1, The gas analyzer (16) is a mass spectrometry type leak detector (56) having a multi-stage high vacuum pump (60). A leak detection device (10).

5. The leak detection device (10) according to claim 4, the vacuum pump (18) is a separate auxiliary pump that is not connected to the leak detector (56); A leak detection device (10).

6. The leak detection device (10) according to claim 4, The leak detection device (10) according to claim 1, characterized in that the vacuum pump (18) forms a pump stage of the multi-stage high vacuum pump (60).

7. The leak detection device (10) of claim 1, The two first outlets (34, 36) are connected to the gas analyzer (16) via a common connecting branch (64), and the two second outlets (38, 40) are connected to the vacuum pump (18) via a common connecting line (42). A leak detection device (10).

8. The leak detection device (10) of claim 1, the two first outlets are connected to the two second outlets and are connected via a throttled line (64) to the gas analyzer (16) and via another throttled line (42) to a connecting branch connecting the vacuum pump (18) to a high vacuum pump (60).

9. A sniffer-type leak detection method using a leak detection device (10) according to any one of claims 1 to 8, comprising the steps of: starting the vacuum pump (18); connecting the inlet (28) of the first multi-way valve (14) to its first outlet (34) and the inlet (32) of the second multi-way valve (22) to its second outlet (40); analyzing the gas drawn through the first inlet (12) with the gas analyzer (16) while drawing gas through the second inlet (20) with the vacuum pump (18); synchronously switching the two multi-way valves (14, 22) while driving the vacuum pump (18); and analyzing the gas drawn through the second inlet (20) with the gas analyzer (16) while drawing the gas through the first inlet (12) with the vacuum pump (18). A method comprising:

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