Vacuum Helium Leak Detector and Method without Helium Gas Source

Abstract

The present invention relates to a vacuum helium leak hole detection device without a helium gas source, which includes a first standard vacuum helium leak hole, a second standard vacuum helium leak hole, a vacuum helium leak hole to be calibrated, a pressure gauge, a mechanical pump, and a helium gas cylinder; wherein, the leak rate value of the first standard vacuum helium leak hole is less than that of the vacuum helium leak hole to be calibrated, and the leak rate value of the second standard vacuum helium leak hole is greater than that of the vacuum helium leak hole to be calibrated; the first standard vacuum helium leak hole, the second standard vacuum helium leak hole, and the vacuum helium leak hole to be calibrated are connected in parallel to a helium mass spectrometer detector, and valves are provided at the front ends of each of them; a digital pressure gauge is provided at the rear end of the vacuum helium leak hole to be calibrated, and it is divided into two paths and connected to the mechanical pump and the helium gas cylinder respectively; valves are provided at the front ends of the mechanical pump and the helium gas cylinder respectively.

Description

Technical Field

[0001] The present invention relates to a vacuum helium leak hole detection device, and particularly to a vacuum helium leak hole detection device and method without a helium gas source. Background Art

[0002] A vacuum helium leak hole refers to a leak hole calibrated and used under the condition that the outlet pressure is less than 1 kPa using helium gas as a tracer gas. Vacuum helium leak holes are divided into two types: leak holes with a helium gas source and leak holes without a helium gas source. The calibration methods for vacuum helium leak holes include the flowmeter method, the quantitative gas method, and the relative comparison method, among which the relative comparison method is the most convenient to operate. The relative comparison method is to select a standard leak hole with a leak rate value in the same order of magnitude or similar leak rate to the leak rate of the leak hole to be calibrated, install the two leak holes on the leak detector at the same time, and use the leak detector to compare the leak rate value of the standard leak hole with the leak rate value of the leak hole to be calibrated, so as to obtain the leak rate value of the vacuum helium leak hole to be calibrated. If the indication value of the leak detector for the leak rate of the standard leak hole is Q 标准漏孔示值 and the indication value of the leak detector for the leak rate of the leak hole to be calibrated is Q 被校漏孔示值 and the leak rate value of the standard leak hole is Q 标准漏孔漏率值 , then the actual leak rate value of the vacuum helium leak hole to be calibrated is:

[0003] The technical problems existing in the prior art are:

[0004] 1. The leak hole with a helium gas source can be directly connected to a helium mass spectrometer leak detector for detection. For the leak hole without a helium gas source, the detection personnel need to externally provide high-purity helium gas, but how to quickly and effectively provide high-purity helium gas with a certain pressure has not been explored in the prior art.

[0005] 2. Since the helium mass spectrometer leak detector is not linear, when calibrating the leak hole to be detected with a single standard leak hole, the introduced error is relatively large. Summary of the Invention

[0006] The purpose of the present invention is to provide a new vacuum helium leak hole detection device and method without a helium gas source, which are used to solve the problem that the vacuum helium leak hole without a helium gas source cannot be calibrated at present, and the problem of relatively large error when calibrating the leak rate with a traditional single standard leak hole.

[0007] A vacuum helium leak detector without a helium gas source, comprising a first standard vacuum helium leak 5, a second standard vacuum helium leak 6, a to-be-calibrated vacuum helium leak 7, a pressure gauge, a mechanical pump 12, and a helium gas cylinder 10; wherein, the leak rate value of the first standard vacuum helium leak 5 is less than that of the to-be-calibrated vacuum helium leak 7, and the leak rate value of the second standard vacuum helium leak 6 is greater than that of the to-be-calibrated vacuum helium leak 7; the first standard vacuum helium leak 5, the second standard vacuum helium leak 6, and the to-be-calibrated vacuum helium leak 7 are connected in parallel to a helium mass spectrometer 1, and valves are provided at their respective fronts; a digital pressure gauge 11 is provided at the rear end of the to-be-calibrated vacuum helium leak 7, and it is divided into two paths and connected to the mechanical pump 12 and the helium gas cylinder 10 respectively; valves are provided at the fronts of the mechanical pump 12 and the helium gas cylinder 10 respectively.

[0008] Preferably, the valves are all pneumatic valves.

[0009] Preferably, the pressure gauge is the digital pressure gauge 11.

[0010] Preferably, the leak rate value of the first standard vacuum helium leak 5 is less than and close to that of the to-be-calibrated vacuum helium leak 7, and the leak rate value of the second standard vacuum helium leak 6 is greater than and close to that of the to-be-calibrated vacuum helium leak 7.

[0011] A vacuum helium leak detection method without a helium gas source, using the vacuum helium leak detection device described in any one of the above; the leak rate value Q of the leak of the first standard vacuum helium leak 5 标准漏孔漏率值1 is less than and close to the leak rate value of the to-be-calibrated leak, and the leak rate value Q of the second standard vacuum helium leak 6 标准漏孔漏率值2 is greater than and close to the leak rate value of the to-be-calibrated leak. They are respectively connected to a helium mass spectrometer leak detector, and the display values of the helium mass spectrometer leak detector are Q 标准漏孔示值1 and Q 标准漏孔示值2 , then the leak rate value of the to-be-calibrated leak is the average value of the two measurements, that is:

[0012] Furthermore, it includes the following steps:

[0013] S1. Place the first standard vacuum helium leak 5, the second standard vacuum helium leak 6, and the to-be-calibrated vacuum helium leak 7 in the same environment for no less than 24 hours. After the helium mass spectrometer leak detector is started, preheat it for a set time first;

[0014] S2. Connect the to-be-calibrated vacuum helium leak 7 to the helium mass spectrometer leak detector. Prepare a four-way gas pipe, one end is connected to the to-be-calibrated vacuum helium leak 7, one end is connected to the digital pressure gauge 11, one end is connected to the mechanical pump 12 through a first pneumatic valve 9, and one end is connected to a helium gas source through a needle valve 8;

[0015] S3. Close the second pneumatic valve 4 at the front end of the to-be-calibrated vacuum helium leak 7, start the helium mass spectrometer leak detector to measure the background, and the background is less than 1×10 -12Pa·m 3 / s;

[0016] S4. Start the mechanical pump 12, open the first pneumatic valve 9 to evacuate the gas inside the four-way gas pipe; close the first pneumatic valve 9, adjust the needle valve 8 to let a small amount of helium into the four-way, then close the needle valve 8, open the first pneumatic valve 9, and use the mechanical pump 12 to evacuate the gas inside the pipe again;

[0017] S5. Close the first pneumatic valve 9, adjust the needle valve 8 to make the pressure in the gas pipe the pressure marked on the leak hole label or the pressure required by the customer, and the pressure value is displayed by the digital pressure gauge 11;

[0018] S6. Open the second pneumatic valve 4, and record the leak rate value Q of the calibrated vacuum helium leak hole when the display value of the helium mass spectrometer leak detector is stable 被校漏孔示值 ;

[0019] S7. According to Q 被校漏孔示值 Select a second standard leak hole 6 with a leak rate value greater than Q 被校漏孔示值 and close to Q 被校漏孔示值 and a first standard leak hole 5 with a leak rate value less than Q 被校漏孔示值 and close to Q 被校漏孔示值 respectively connect them to the helium mass spectrometer leak detector;

[0020] S8. Close the third pneumatic valve 2 at the front end of the first standard vacuum helium leak hole 5. When the background measured by the helium mass spectrometer leak detector is less than 1×10 -12 Pa·m 3 / s, open the third pneumatic valve 2, and record the leak rate value Q of the first standard vacuum helium leak hole 5 when the display value of the helium mass spectrometer leak detector is stable 标准漏孔示值1 ;

[0021] S9. Close the fourth pneumatic valve 3 at the front end of the second standard vacuum helium leak hole 6. When the background measured by the helium mass spectrometer leak detector is less than 1×10 -12 Pa·m 3 / s, open the fourth pneumatic valve 3, and record the leak rate value Q of the second standard vacuum helium leak hole 6 when the display value of the helium mass spectrometer leak detector is stable 标准漏孔示值2 ;

[0022] S10. The actual value of the calibrated leak hole is

[0023]

[0024] The beneficial effects of the present invention are as follows:

[0025] 1) Aiming at the problem of large errors in leak rate calibration using a traditional single standard leak hole, two standard leak holes are selected for calibration in this paper, and the leak rate value Q of one of the leak holes 标准漏孔漏率值1Less than and close to the leak rate value of the leak hole to be calibrated, and the leak rate value Q of the other one 标准漏孔漏率值2 Greater than and close to the leak rate value of the leak hole to be calibrated, and they are respectively connected to the helium mass spectrometer leak detector. The display values of the helium mass spectrometer leak detector are Q 标准漏孔示值1 and Q 标准漏孔示值2 , then the leak rate value of the leak hole to be calibrated is the average value of the two measurements, that is: This method can effectively reduce the error caused by the non-linearity of the helium mass spectrometer leak detector and improve the accuracy of the calibration data.

[0026] 2) Solve the calibration problem of the vacuum helium leak hole without a helium gas source. Through the design of a mechanical pump, a digital pressure gauge and a helium gas source, high-purity helium gas for the leak hole can be externally provided, realizing the calibration of the vacuum helium leak hole within the leak rate range of (-100~800) kPa pressure and (10 -10 ~10 -4 ) Pa﹒m 3 / s. Description of the Drawings

[0027] Figure 1 is a schematic structural diagram of the vacuum helium leak hole detection device without a helium gas source of the present invention.

[0028] In the figure, 1. Helium mass spectrometer leak detector, 2. Third pneumatic valve, 3. Fourth pneumatic valve, 4. Second pneumatic valve, 5. First standard vacuum helium leak hole, 6. Second standard vacuum helium leak hole, 7. Leak hole to be calibrated, 8. Needle valve, 9. First pneumatic valve, 10. Helium gas cylinder, 11. Digital pressure gauge, 12. Mechanical pump. Detailed Embodiment

[0029] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0030] This embodiment proposes a new detection device and method to solve the calibration problem of the vacuum helium leak hole without a helium gas source and the problem of large errors when calibrating the leak rate using a traditional single standard leak hole.

[0031] First, the structure of the vacuum helium leak hole detection device without a helium gas source is described as follows:

[0032] Refer to Figure 1, the detection device includes a first standard vacuum helium leak hole 5, a second standard vacuum helium leak hole 6, a vacuum helium leak hole 7 to be calibrated, a pressure gauge, a mechanical pump 12, and a helium gas cylinder 10; among them, the leak rate value of the first standard vacuum helium leak hole 5 is less than that of the vacuum helium leak hole 7 to be calibrated, and the leak rate value of the second standard vacuum helium leak hole 6 is greater than that of the vacuum helium leak hole 7 to be calibrated; the first standard vacuum helium leak hole 5, the second standard vacuum helium leak hole 6, and the vacuum helium leak hole 7 to be calibrated are connected in parallel to the helium mass spectrometer detector 1, and valves are provided at their respective fronts; a digital pressure gauge 11 is provided at the rear end of the vacuum helium leak hole 7 to be calibrated, and it is divided into two paths and connected to the mechanical pump 12 and the helium gas cylinder 10 respectively; valves are provided at the fronts of the mechanical pump 12 and the helium gas cylinder 10 respectively.

[0033] In this embodiment, the valves are all pneumatic valves.

[0034] In this embodiment, the pressure gauge is a digital pressure gauge 11.

[0035] In this embodiment, the leak rate value of the first standard vacuum helium leak hole 5 is less than and close to that of the vacuum helium leak hole 7 to be calibrated, and the leak rate value of the second standard vacuum helium leak hole 6 is greater than and close to that of the vacuum helium leak hole 7 to be calibrated.

[0036] Regarding the problem that the leak hole does not have a helium gas source, in this embodiment, through the design of a mechanical pump, a digital pressure gauge, and a high-purity helium gas source, high-purity helium gas with a pressure of (-100 to 800) kPa can be provided outside the vacuum helium leak hole to be calibrated. Regarding the problem of large errors when calibrating the leak rate using a traditional single standard leak hole, in this embodiment, two standard leak holes are selected for calibration, where the leak rate value Q 标准漏孔漏率值1 of one leak hole is less than and close to the leak rate value of the leak hole to be calibrated, and the leak rate value Q 标准漏孔漏率值2 of the other leak hole is greater than and close to the leak rate value of the leak hole to be calibrated. They are respectively connected to the helium mass spectrometer leak detector, and the display values of the helium mass spectrometer leak detector are Q 标准漏孔示值1 and Q 标准漏孔示值2 respectively. Then, the leak rate value of the leak hole to be calibrated is the average value of the two measurements, that is: This method can effectively reduce the error caused by the non-linearity of the helium mass spectrometer leak detector.

[0037] Specific operation steps:

[0038] 1) Place the vacuum helium leak hole and the helium mass spectrometer leak detector in the same environment for no less than 24 hours. After the helium mass spectrometer leak detector is started, it generally needs to be preheated for half an hour according to the instructions.

[0039] 2) Connect the vacuum helium leak hole to be calibrated to the helium mass spectrometer leak detector. Prepare a four-way gas pipe, one end is connected to the vacuum helium leak hole to be calibrated, one end is connected to the digital pressure gauge, one end is connected to the mechanical pump through a pneumatic valve, and one end is connected to the helium gas source through a needle valve. The measuring range of the digital pressure gauge is (-100 to 800) kPa.

[0040] 3) Close the pneumatic valve 4, start the helium mass spectrometer leak detector to measure the background, and the background should be less than 1×10 -12 Pa·m 3 / s.

[0041] 4) Start the mechanical pump 12, open the pneumatic valve 9, and evacuate the gas inside the four-way gas pipe. Close the pneumatic valve 9, adjust the needle valve 8 to put a small amount of helium into the four-way, then close the needle valve 8, open the pneumatic valve 9, and use the mechanical pump to evacuate the gas inside the pipe again to ensure that the air inside the pipe is evacuated.

[0042] 5) Close the pneumatic valve 9, adjust the needle valve 8 so that the pressure inside the pipe is the pressure marked on the leak hole label or the pressure required by the customer, and the pressure value is displayed by the digital pressure gauge 11.

[0043] 6) Open the pneumatic valve 4. When the display value of the helium mass spectrometer leak detector is stable, record the leak rate value Q of the calibrated vacuum helium leak hole under a certain pressure 被校漏孔示值 .

[0044] 7) According to Q 被校漏孔示值 Select a standard leak hole with a leak rate value greater than Q 被校漏孔示值 and close to Q 被校漏孔示值 , and a standard leak hole with a leak rate value less than Q 被校漏孔示值 and close to Q 被校漏孔示值 . Connect them to the helium mass spectrometer leak detector respectively. The leak rate values of the standard leak holes are calibrated and obtained by the upper-level metrology and technology institution.

[0045] 8) Close the pneumatic valve 2. When the background measured by the helium mass spectrometer leak detector is less than 1×10 -12 Pa·m 3 / s, open the valve 2. When the display value of the helium mass spectrometer leak detector is stable, record the leak rate value Q of the standard leak hole 标准漏孔示值1 .

[0046] 9) Close the pneumatic valve 3. When the background measured by the helium mass spectrometer leak detector is less than 1×10 -12 Pa·m 3 / s, open the valve 3. When the display value of the helium mass spectrometer leak detector is stable, record the leak rate value Q of the standard leak hole 标准漏孔示值2 .

[0047] 10) The actual value of the calibrated leak hole is

[0048] The present invention solves the calibration problem of vacuum helium leak holes without a helium source. Through the design of a mechanical pump, a digital pressure gauge and a helium source, high-purity helium gas for the leak hole can be externally provided, realizing a pressure of (-100 to 800) kPa and a (10 -10 to 10 -4 ) Pa·m 3Calibration of a vacuum helium leak hole within the / s leak rate range. By using two standard leak holes, the error caused by the nonlinearity of the leak detector is effectively reduced, and the accuracy of the calibration data is improved.

[0049] The above are the preferred embodiments of the present invention. Those of ordinary skill in the art can also make various transformations or improvements based on this. Without departing from the general concept of the present invention, these transformations or improvements should fall within the scope of protection required by the present invention.

Claims

1. A vacuum helium leak detector without a helium gas source, characterized in that: it includes a first standard vacuum helium leak (5), a second standard vacuum helium leak (6), a calibrated vacuum helium leak (7), a pressure gauge, a mechanical pump (12), and a helium gas cylinder (10); wherein, the leak rate value of the first standard vacuum helium leak (5) is less than that of the calibrated vacuum helium leak (7), and the leak rate value of the second standard vacuum helium leak (6) is greater than that of the calibrated vacuum helium leak (7); The first standard vacuum helium leak (5), the second standard vacuum helium leak (6), and the calibrated vacuum helium leak (7) are connected in parallel to a helium mass spectrometer detector (1), and valves are provided at their respective front ends; A digital pressure gauge (11) is provided at the rear end of the calibrated vacuum helium leak (7), and it is divided into two paths and connected to the mechanical pump (12) and the helium gas cylinder (10) respectively; Valves are provided at the front ends of the mechanical pump (12) and the helium gas cylinder (10) respectively; The valves are all pneumatic valves; The pressure gauge is a digital pressure gauge (11).

2. The vacuum helium leak detector without a helium gas source according to claim 1, characterized in that: the leak rate value of the first standard vacuum helium leak (5) is less than and close to that of the calibrated vacuum helium leak (7), and the leak rate value of the second standard vacuum helium leak (6) is greater than and close to that of the calibrated vacuum helium leak (7).

3. The vacuum helium leak detector without a helium gas source according to claim 1, characterized in that: Leak rate value Q of the first standard vacuum helium leak hole (5) 标准漏孔漏率值1 Less than and close to the leak rate value of the leak hole to be calibrated, leak rate value Q of the second standard vacuum helium leak hole (6) 标准漏孔漏率值2 Greater than and close to the leak rate value of the leak hole to be calibrated, respectively connected to the helium mass spectrometer leak detector, and the display values of the helium mass spectrometer leak detector are Q 标准漏孔示值1 and Q 标准漏孔示值2 , then the leak rate value of the calibrated leak is the average value of two measurements, that is:

4. A detection method for the vacuum helium leak detector without a helium gas source according to claim 3, characterized in that: it includes the following steps: S1. Place the first standard vacuum helium leak (5), the second standard vacuum helium leak (6), and the calibrated vacuum helium leak (7) in the same environment as the helium mass spectrometer leak detector for no less than 24 hours. After the helium mass spectrometer leak detector is started, preheat it for a set time first; S2. Connect the calibrated vacuum helium leak (7) to the helium mass spectrometer leak detector. Prepare a four-way gas pipe, one end is connected to the calibrated vacuum helium leak (7), one end is connected to the digital pressure gauge (11), one end is connected to the mechanical pump (12) through a first pneumatic valve (9), and one end is connected to the helium gas source through a needle valve (8); S3. Close the second pneumatic valve (4) at the front end of the vacuum helium leak hole (7) to be calibrated, start the helium mass spectrometer leak detector to measure the background, and the background is less than 1×10 -12 Pa·m 3 / s; S4. Start the mechanical pump (12), open the first pneumatic valve (9), and evacuate the gas inside the four-way gas pipe; close the first pneumatic valve (9), adjust the needle valve (8) to let a small amount of helium gas into the four-way pipe, then close the needle valve (8), open the first pneumatic valve (9), and use the mechanical pump (12) to evacuate the gas inside the pipe again; S5. Close the first pneumatic valve (9), adjust the needle valve (8) to make the pressure in the gas pipe the pressure marked on the leak label or the set pressure, and the pressure value is displayed by the digital pressure gauge (11); S6. Open the second pneumatic valve (4), and record the leakage rate value Q of the vacuum helium leak hole to be calibrated when the display value of the helium mass spectrometer leak detector is stable. 被校漏孔示值 ; S7. According to Q 被校漏孔示值 Select a second standard vacuum helium leak hole (6) with a leak rate value greater than Q 被校漏孔示值 and close to Q 被校漏孔示值 and a first standard vacuum helium leak hole (5) with a leak rate value less than Q 被校漏孔示值 and close to Q 被校漏孔示值 and connect them to the helium mass spectrometer leak detector respectively; S8. Close the third pneumatic valve (2) at the front end of the first standard vacuum helium leak hole (5). Wait until the background measured by the helium mass spectrometer leak detector is less than 1×10 -12 Pa﹒m 3 / s, then open the third pneumatic valve (2). When the display value of the helium mass spectrometer leak detector is stable, record the leak rate value Q of the first standard vacuum helium leak hole (5) 标准漏孔示值1 ; S9. Close the fourth pneumatic valve (3) at the front end of the second standard vacuum helium leak hole (6). Wait until the background measured by the helium mass spectrometer leak detector is less than 1×10 -12 Pa﹒m 3 / s, then open the fourth pneumatic valve (3). Record the leak rate value Q of the second standard vacuum helium leak hole (6) when the display value of the helium mass spectrometer leak detector is stable 标准漏孔示值2 ; S10. The actual value of the calibrated leak is

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