Leak detector

Abstract

A leak detection apparatus (10) comprising a gas analyzer (16), a vacuum pump (18), a first gas inlet (12) and a second gas inlet (20); provided with a first multi-way valve (14) connected to a first inlet (28) and at least a first outlet (34) and a second outlet (38), wherein said inlet (28) is connected to said first gas inlet (12); and a second multi-way valve (22) connected to a first inlet (32) and at least a first outlet (36) and a second outlet (40), wherein said inlet (32) is connected to said second gas inlet (20); wherein both first outlets of both multi-way valves (14, 22) are connected to said gas analyzer (16) and both second outlets of both multi-way valves (14, 22) are connected to said vacuum pump (18).

Description

[0001] This invention relates to a leak detection device, which includes a gas analyzer, a vacuum pump, a first gas inlet, and a second gas inlet; particularly for sniffing leak detection.

[0002] When a gas leak is detected, gas is drawn in through a gas inlet with the aid of a vacuum pump and supplied to a gas analyzer for analysis. In doing so, test gas flowing through the leak is detected. A specific variant of gas leak detection is sniffing leak detection, which draws in a constant gas flow through the gas inlet of a sniffing probe. While the drawn-in gas is being analyzed, the sniffing probe is directed to the test object. Therefore, leaks in the test object can not only be detected but also located. If the gas inlet of the sniffing probe is close to the gas leak point, the test gas escaping through the leak point is received along with the gas flow. To ensure the most reliable and complete absorption of the leaking gas, the largest possible sniffing gas flow is used. The sniffing gas flow refers to the gas flow drawn in through the gas inlet of the sniffing probe. Here, the flow rate is typically many times greater than the measured flow rate of the leaking test gas escaping from the leak.

[0003] The concentration of leaked gas in the gas stream drawn in through the gas inlet is the ratio of the leakage rate to the sniffing gas stream. Therefore, the concentration of leaked gas in the gas stream received by the sniffing probe is usually relatively low. Consequently, the sniffing gas stream cannot be selected as large as desired.

[0004] Typically, the atmosphere surrounding a test sample contains gaseous components that produce similar or identical measurement signals to the test gas in a gas detector or analyzer. These gaseous components are therefore referred to as interfering gases or subsurface gases. They generate interfering signals that are difficult to distinguish from the measurement signals of actual leaked gas.

[0005] A known method to suppress this interference signal is to alternately receive a measuring gas from the test area of ​​the sample under test and a reference gas from the atmosphere surrounding the sample. The reference gas serves as a reference (reference measurement) for determining the proportion of interfering gases in the inhaled gas mixture.

[0006] For example, such solutions are described in EP1342070B1 and EP1819998B1. The gas is drawn in by a compact sensor unit mounted on the handle of the sniffing probe in the form of an infrared absorption sensor. In WO2007 / 031386A1, a mass spectrometer is used as the gas analyzer. The drawn-in gas must be delivered to the analyzer through a sniffing line.

[0007] In other sniffing leak detection methods, several, typically two, separate sniffing probes are independently connected to the same gas analyzer and operate alternately to alternately evaluate signals from one sniffing probe and another. In this so-called multiplexing system, leak detection is performed via a gas detection system with several sniffing lines at multiple locations, switched serially from one line to another.

[0008] When the two gas inlets of the leak detection device connected to the same gas analyzer are switched off, pressure surge will occur in the sniffing line, affecting the measurement signal and causing signal fluctuations.

[0009] The purpose of this invention is to provide an improved leak detection device having two different gas inlets, each connected to the same gas analyzer, and a corresponding leak detection method.

[0010] The leak detection device of the present invention is defined by the features of claim 1. Accordingly, two multi-way valves are provided, each having a first inlet and at least a first outlet and a second outlet. The multi-way valves may be, for example, a 3 / 2-way valve body having one inlet and two outlets. Each first outlet of the two multi-way valves is connected to a first gas inlet of the leak detection device, and each second outlet of the two multi-way valves is connected to a separate vacuum pump. The two multi-way valves simplify the switching and distribution of the two gas inlets to the gas analyzer. Gas drawn in through the first gas inlet with one multi-way valve is supplied to the gas analyzer, while gas drawn in through the second gas inlet is drawn in by the vacuum pump and not supplied to the gas analyzer. By simply switching the multi-way valves, pressure fluctuations can be avoided or reduced because gas flows are drawn in through both gas inlets, and the gas analyzer can alternately analyze one or the other gas flow.

[0011] The two gas inlets can be located on different sniffing probes, each connected to two multi-way valves via a separate sniffing wire. Here, the vacuum pump may be a separate auxiliary pump, not connected to the gas analyzer. The gas analyzer may be a mass spectrometer leak detector with a multi-stage high-vacuum pump connected to the two second outlets, preferably open to the atmosphere.

[0012] Alternatively, the two gas inlets can be the measuring gas inlet and the reference gas inlet of the same sniffing probe. Here, the vacuum pump can form one stage of a multi-stage high-vacuum pump in the mass spectrometer gas analyzer, such as a pre-vacuum stage. In this case, the two first outlets of the multi-way valve are connected to the mass spectrometer, while the two second outlets of the multi-way valve are connected to a connecting branch via separate connecting lines. The connecting branch connects the vacuum pump to the other pump stages of the high-vacuum pump and the mass spectrometer. Throttling valves are provided on the two connecting lines to set the desired and expected gas flows, respectively. Alternatively, the connecting lines themselves can also be designed as throttling valves for the gas flow. The two first outlets can be connected to the two second outlets, thereby providing only a segmented portion of the flow to the gas analyzer, while the remainder of the gas flow is delivered to the atmosphere via the vacuum pump.

[0013] In the following sections, two exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings.

[0014] In the attached diagram:

[0015] Figure 1 A first exemplary embodiment is shown, and

[0016] Figure 2 A second exemplary embodiment is shown.

[0017] In the two leak detection devices 10 shown in the figure, the first gas inlet 12 is connected to the mass spectrometer gas analyzer 16 and the vacuum pump 18 in the form of a 3 / 2-way valve body via the first multi-way valve 14, while the second gas inlet 20 is also connected to the gas analyzer 16 and the vacuum pump 18 in the form of a 3 / 2-way valve body via the second multi-way valve 22.

[0018] According to Figure 1 In a first exemplary embodiment, two gas inlets 12, 20 are provided on the common sniffing probe 24 in such a way that the first gas inlet 12 points to the test area to be inspected, where a gas leak is suspected at the test sample, while the second gas inlet 20 forms a reference gas inlet through which gas can be drawn from the atmosphere surrounding the test sample.

[0019] The first gas inlet 12 is connected to the first inlet 28 of the first multi-way valve 14 via a first connecting line 26. The second gas inlet 20 is connected to the first inlet 32 ​​of the second multi-way valve 22 via a separate connecting line 30.

[0020] Furthermore, in two 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 the gas analyzer 16, while the second outlet 38 of the first multi-way valve 14 is connected in a gas-guiding manner to the second outlet 40 of the second multi-way valve 22 and the vacuum pump 18.

[0021] exist Figure 2 In the exemplary embodiment shown, two gas inlets 12, 20 are mounted on different sniffing probes, which are connected to two multi-way valves 14, 22 via separate connecting lines and can be guided and moved independently of each other.

[0022] According to Figure 1 In a first exemplary embodiment, two first outlets 34, 36 lead to a common connection line 42, which connects to a connection line 46 at a connector 44. The connection line 46 connects to a second exhaust port 38 of a first multi-way valve 14 and another connection line 48 connects to a second exhaust port 40 of a second multi-way valve 22. The common connection line 42 passes through the connector 44 and connects to a connection branch 50, which connects 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 sequentially connected to a gas analyzer 16 in the form of a mass spectrometer. Thus, vacuum pump 18 constitutes the first stage of a three-stage high vacuum pump system 56 consisting of vacuum pump 18, second vacuum pump 52, turbomolecular pump 54, and gas analyzer 16 (mass spectrometer). Thus, second vacuum pump 52 constitutes the second pump stage, and turbomolecular pump 54 constitutes the first pump stage of the multi-stage high vacuum pump 60.

[0023] Between the first two gas outlets 34 and 36 and the connector 44, a branch line 64, throttled by a throttle valve 62, branches off from the connecting line 42 and connects to the gas analyzer 16. A portion of the gas flow passing through the branch line 42 is diverted and supplied to the gas analyzer 16, while the remaining gas flow is supplied to the vacuum pump 18 via the connector 44 and then to the atmosphere. Here, the connecting line 42 includes a second throttle valve 66 between the connector 44 and the connecting branch 50, which blocks the gas flow. Because the flow is blocked, pressure fluctuations downstream of the throttle valve, such as those caused by the pump, do not have a disruptive effect as upstream pressure fluctuations.

[0024] Conversely, in the second exemplary embodiment, the connecting lines 42 from the two outlets 38, 40 to the vacuum pump 18 and the connecting lines 64 from the two outlets 34, 36 to the gas analyzer 16 are separate from each other and therefore not connected to each other in a gas-conducting manner.

[0025] In both exemplary embodiments, the vacuum pump 18 remains on during gas analysis by the gas analyzer 16 and is never connected to either of the two gas inlets 12, 20 of the gas analyzer 16 via the multi-way valves 14, 22 to deliver gas. Therefore, in Figure 2In the exemplary embodiment and on / off state shown, gas is supplied from the first gas inlet 12 through the first multi-way valve 14 from its first inlet 28 through its first outlet 34 and connecting line 64 to the gas analyzer 16 for gas analysis; simultaneously, gas flowing in through the second gas inlet 20 is supplied from its first inlet 32 ​​to its second outlet 40 through the second multi-way valve 22, and from there is pumped into the atmosphere through the connecting line 42 by the pump 18. Therefore, while the gas from the first gas inlet 12 is analyzed by the gas analyzer 16, the gas from the second gas inlet 20 is pumped into the atmosphere by the pump 18.

[0026] exist Figure 1 In the exemplary embodiment shown, the first gas inlet 12 forms a measuring gas inlet, and the second gas inlet 20 forms a reference gas inlet for the same sniffing probe 24. Gas from the first gas inlet 12 is supplied through line 26 to the first inlet 28 of the first multi-way valve 14, while the vacuum pump 18 draws in gas through the second gas inlet 20, which is then supplied through line 30 to the inlet 32 ​​of the second multi-way valve 22. In a first switching state, the first multi-way valve 14 connects the first inlet 28 to the first outlet 34, so that the gas drawn in through the first gas inlet 12 is supplied through the first outlet 34 of the connecting line 42. From this gas flow, a portion of the gas flow branches through the throttle tube 64 and is supplied to the mass spectrometer gas analyzer 16, while the remaining gas flow is added to the atmosphere through the second throttle tube 66 and the vacuum pump 18 through the connector 44. Simultaneously, the second multi-way valve 22 guides the gas drawn in from the second gas inlet 20 from inlet 32 ​​to the second outlet 40, from which the gas flows through line 48 and through the connector 44 into the common connecting line 42. From there, the gas is pumped into the atmosphere via vacuum pump 18.

[0027] Then, the two multi-way valves 14 and 22 are simultaneously switched from the first switching state to the second switching state. In the second switching state, the first multi-way valve 14 guides gas from the first gas inlet 12 through the second gas outlet 38 to the vacuum pump 18, without allowing the gas to enter the gas analyzer 16. At the same time, the second multi-way valve 22 guides gas from the second gas inlet 20 through the first gas outlet 36 to the common connection line 42, with a portion of the flow being guided to the gas analyzer 16 for analysis via the throttling line 64.

[0028] By simultaneously switching the two multi-way valves 14 and 22, gas enters the gas analyzer 16 for analysis from one of the two gas inlets 12 and 20, while gas from the other gas inlet is drawn into the atmosphere by the vacuum pump 18. Through the simultaneous switching of the two multi-way valves 14 and 22, the two gas inlets 12 and 20 can be alternately connected to the gas analyzer without significant delay and / or pressure fluctuations during the switching process. The continuously pumped flow rate through the two pipelines 26 and 30 maintains the pressure gradient in the pipelines, thereby avoiding pressure fluctuations at the detection system inlet during the switching process.

[0029] Another advantage of the continuous gas flow through the two lines 26 and 30 is that the gas received through the two inlet openings 12 and 20 also simultaneously reaches the switching valves 14 and 22. The transmission time of the gas through the front of the lines 26 and 30 may only be a few seconds. If the lines not connected to the gas analyzer 16 or leak detector 56 are no longer continuously pumped, the reaction time will be delayed by several seconds.

Claims

1. A leak detection device (10), comprising: Gas analyzer (16), vacuum pump (18), first gas inlet (12) and second gas inlet (20); Its features are: A first multi-way valve (14) has a first inlet (28) and at least a first outlet (34) and a second outlet (38), wherein the first inlet (28) of the first multi-way valve (14) is connected to the first gas inlet (12); A second multi-way valve (22) has a first inlet (32) and at least a first outlet (36) and a second outlet (40), wherein the first inlet (32) of the second multi-way valve (22) is connected to the second gas inlet (20); The first outlet (34) of the first multi-way valve (14) and the first outlet (36) of the second multi-way valve (22) are connected to the gas analyzer (16), and the second outlet (38) of the first multi-way valve (14) and the second outlet (40) of the second multi-way valve (22) are connected to the vacuum pump (18); and The first multi-way valve (14) and the second multi-way valve (22) are configured and controlled by a valve control device such that if the first inlet (32) of the second multi-way valve (22) is connected to the second outlet (40) and the first multi-way valve (14) and the second multi-way valve (22) are simultaneously turned on, the first inlet (28) of the first multi-way valve (14) is connected to the first outlet (34).

2. The leakage detection device (10) according to claim 1, characterized in that, The first gas inlet (12) and the second gas inlet (20) are located on different sniffing probes.

3. The leakage detection device (10) according to claim 1, characterized in that, The gas analyzer (16) is a mass spectrometer leak detector (56) with a multi-stage high vacuum pump (60).

4. The leakage detection device (10) according to claim 3, characterized in that, The vacuum pump (18) is an independent auxiliary pump and is not connected to the leak detector (56).

5. The leakage detection device (10) according to claim 3, characterized in that, The vacuum pump (18) forms the pump stage of the multi-stage high vacuum pump (60).

6. The leakage detection device (10) according to claim 1, characterized in that, The first outlet (34) and the first outlet (36) are connected to the gas analyzer (16) via a common connection branch (64), while the second outlet (38) and the second outlet (40) are connected to the vacuum pump (18) via a common connection line (42).

7. The leakage detection device (10) according to claim 1, characterized in that, The first outlet (34) and the first outlet (36) are connected to the second outlet (38) and the second outlet (40), and are connected to the gas analyzer (16) via a common connection branch (64), and are connected to the connection branch that connects the vacuum pump (18) to the multi-stage high vacuum pump (60) via a common connection line (42).

8. A method for sniffing leak detection, using the leak detection device (10) according to any one of claims 1-7, characterized in that: It includes the following steps: Turn on the vacuum pump (18); Connect the first inlet (28) of the first multi-way valve (14) to its first outlet (34), and connect the first inlet (32) of the second multi-way valve (22) to its second outlet (40); The gas drawn in through the first gas inlet (12) is analyzed by the gas analyzer (16), and the gas drawn in through the second gas inlet (20) is analyzed by the vacuum pump (18); The first multi-way valve (14) and the second multi-way valve (22) are switched synchronously, while the vacuum pump (18) remains on; and The gas drawn in through the second gas inlet (20) is analyzed by the gas analyzer (16), and the gas drawn in through the first gas inlet (12) is also analyzed by the vacuum pump (18).

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