Multi-path single-point leak detection system

Abstract

The invention relates to a multi-path single-point leak detection system, and belongs to the technical field of leak detection. The gas circuit protection leak detection cover box 1 is connected to the detection valve 1 through the hose 1 to form a detection branch 1; the gas circuit protection leak detection cover box 2 is connected to the detection valve 2 through the hose 2 to form a detection branch 2; the gas circuit protection leak detection cover box 3 is connected to a calibration valve through a hose 3 to form a calibration branch; the detection branch 1, the detection branch 2 and the calibration branch are connected in parallel and then connected to the helium mass spectrometer leak detector; the gas circuit protection leak detection cover box 1 and the gas circuit protection leak detection cover box 2 are internally connected with a detected part 1 and a detected part 2 of a detected part respectively. The gas circuit protection leak detection cover box 3 is connected with a test port of the positive pressure standard leak hole; the protective gas source is sequentially connected with the protective gas pressure reducer, the mass flow controller and the protective gas path; a pressure sensor is arranged between the mass flow controller and the protective gas circuit; the method is not affected by environmental helium background fluctuation and sampling gas flow, and the leak detection efficiency and the accuracy and consistency of leak detection results are improved.

Description

Technical Field

[0001] This invention belongs to the field of leak detection technology and relates to a multi-channel single-point leak detection system. Background Technology

[0002] When using the helium mass spectrometer (HMS) leak detection method for single-point leak testing of a product, the HMS leak detector's suction gun is first used to measure the background helium reaction value of the ambient atmosphere. Then, the product is filled with helium, and the suction gun is used to carefully sample each area being tested. The HMS leak detector measures the reaction value at the leaking area. To determine the actual leak rate at the tested area, calibration using a positive pressure standard leak is required. This involves first measuring the background helium reaction value of the ambient atmosphere with the leak detector's suction gun, then carefully sampling the positive pressure standard leak with the suction gun, and finally measuring the reaction value at the positive pressure standard leak. The difference between the reaction value at the tested area and the ambient helium background reaction value (value 1) is calculated, as is the difference between the reaction value at the positive pressure standard leak and the ambient helium background reaction value (value 2). These two differences are compared; the ratio of these two differences is equal to the ratio of the leak rates of the tested area and the positive pressure standard leak. Since the leak rate of the positive pressure standard leak is known, the actual leak rate of the tested area can be calculated based on this principle. When performing single-point leak detection using a helium mass spectrometer (HMS) suction gun, the ambient atmospheric helium background concentration needs to remain stable. This is because, firstly, multiple measurements of the ambient helium background are required; secondly, the gas drawn into the leak detector's suction gun during testing is a mixture of ambient atmospheric helium and helium leaking from the tested area. If the ambient helium concentration fluctuates, the detector's response value will also fluctuate after being superimposed with the leaked helium from the tested area, thus making it impossible to accurately measure the helium leak rate at the tested area. Generally, helium background fluctuations are required to be within an acceptable range during leak detection. When there is a large helium leak in the testing environment, the helium background is difficult to stabilize, making leak detection impossible. When extending this detection method to a multi-channel single-point leak detection system, to improve detection efficiency, multiple suction guns or flow-limiting devices with similar flow-limiting functions are typically connected in parallel to the leak detector. Valves control the on / off state of each branch to achieve sequential detection of each branch. During measurement, the corresponding ambient atmospheric helium background response value, the response value of the tested area, and the positive pressure standard leak response value need to be measured separately. Patent ZL201620608772.8 discloses a multi-channel automated leak rate measurement device for a helium mass spectrometer leak detector. It uses multiple two-position three-way valves for gas path control, enabling helium mass spectrometry leak detection on multiple workpieces. However, the detection fixture of this multi-channel leak detection device is a sealed leak detection box, and the internal state during leak detection is a vacuum rather than atmospheric pressure, making it unsuitable for measurements in atmospheric environments. Using multiple suction guns or flow limiting devices in parallel not only suffers from the shortcomings of conventional helium mass spectrometry suction guns for single-point leak detection, but also requires maintaining consistent sampling flow rates for each detection channel to ensure consistency across all branches. This results in extremely high requirements for the consistency of sampling flow rates of the suction guns or flow limiting devices, leading to significant difficulties in selection and manufacturing. If different sampling flow rates are used for each branch, each branch needs to be calibrated separately using a positive pressure standard leak orifice before measurement of the inspected area, making the operation complex and resulting in low leak detection efficiency. Summary of the Invention

[0003] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a multi-channel single-point leak detection system and method that is not affected by the fluctuation of the ambient helium background and the sampling gas flow rate, thereby improving the leak detection efficiency and the accuracy and consistency of the leak detection results.

[0004] The solution of the present invention is:

[0005] A multi-channel single-point leak detection system includes a multi-channel leak detection device and a protective gas supply device; wherein, the multi-channel leak detection device includes a helium mass spectrometer leak detector, detection valve 1, detection valve 2, calibration valve, gas protective leak detection enclosure 1, gas protective leak detection enclosure 2, gas protective leak detection enclosure 3, positive pressure standard leak hole, hose 1, hose 2, and hose 3; the protective gas supply device includes a protective gas source, a protective gas pressure reducer, a mass flow controller, a pressure sensor, and a protective gas path;

[0006] Among them, the gas path protection leak detection box 1 is connected to the detection valve 1 through the hose 1, forming the detection branch 1; the gas path protection leak detection box 2 is connected to the detection valve 2 through the hose 2, forming the detection branch 2; the gas path protection leak detection box 3 is connected to the calibration valve through the hose 3, forming the calibration branch; the detection branch 1, the detection branch 2, and the calibration branch are connected in parallel and then connected to the helium mass spectrometer leak detector; the inside of the gas path protection leak detection box 1 and the gas path protection leak detection box 2 are respectively connected to the tested part 1 and the tested part 2 of the tested part; the gas path protection leak detection box 3 is connected to the test port of the positive pressure standard leak hole; the protective gas source is connected in sequence to the protective gas pressure reducer, the mass flow controller, and the protective gas path; a pressure sensor is installed between the mass flow controller and the protective gas path; the protective gas path is connected to the multi-channel leak detection device.

[0007] In the aforementioned multi-channel single-point leak detection system, the protective gas path includes protective gas branch 1, protective gas branch 2, and protective gas branch 3; protective gas branch 1, protective gas branch 2, and protective gas branch 3 are arranged in parallel; wherein, protective gas branch 1 is connected to gas protection leak detection enclosure 1; protective gas branch 2 is connected to gas protection leak detection enclosure 2; and protective gas branch 3 is connected to gas protection leak detection enclosure 3.

[0008] In the aforementioned multi-channel single-point leak detection system, the gas protection leak detection enclosure 1, gas protection leak detection enclosure 2, and gas protection leak detection enclosure 3 have the same composition; each includes an outer enclosure, an inner enclosure, a protective gas flow limiter, and a sampling flow limiter.

[0009] Both the inner and outer covers are cubic shell structures. The inner cover is located inside the cavity of the outer cover. The outer cover has a protective gas interface on its side wall. A protective gas flow limiter is installed in the protective gas interface. The protective gas interface is connected to the corresponding protective gas branch. The inner cover has a detection interface on its side wall. A sampling flow limiter is installed in the detection interface. The detection interface passes through the side wall of the outer cover and is connected to the corresponding hose.

[0010] In the aforementioned multi-channel single-point leak detection system, an air pressure balance port is provided on the side wall of the outer casing. The size of the air pressure balance port is adapted to the flow rate of the protective air inside the outer casing, so that the protective air pressure inside the outer casing is 90-110 Pa higher than the ambient atmospheric pressure, preventing backflow and contamination from the outside atmosphere.

[0011] In the aforementioned multi-channel single-point leak detection system, a protective gas inlet is provided on the side wall of the inner enclosure; the size of the protective gas inlet should be adapted to the flow rate of the sampling flow limiter; the diameter of the protective gas inlet is 0.5 mm, so that the air pressure inside the inner enclosure is 8-12 Pa lower than the air pressure inside the outer enclosure, preventing the gas to be measured from escaping to the outside of the inner enclosure.

[0012] In the aforementioned multi-channel single-point leak detection system, each gas protection leak detection box is designed according to the shape of the part being tested. When the part being tested is small enough to fit inside the gas protection leak detection box, it is placed inside the gas protection leak detection box. When the part being tested is too large to fit inside the gas protection leak detection box, only the leak test port portion of the positive pressure standard leak hole is inserted into the gas protection leak detection box.

[0013] In the aforementioned multi-channel single-point leak detection system, the detection branches can be increased or decreased according to actual needs.

[0014] In the aforementioned multi-channel single-point leak detection system, a protective gas source outputs protective gas to the protective gas circuit, and the protective gas is then input into gas protective leak detection enclosure 1, gas protective leak detection enclosure 2, and gas protective leak detection enclosure 3 respectively through protective gas branch 1, protective gas branch 2, and protective gas branch 3. High-purity nitrogen is used as the protective gas.

[0015] In the aforementioned multi-channel single-point leak detection system, the output flow rate of the protective gas is adjusted using a mass flow controller.

[0016] In the aforementioned multi-channel single-point leak detection system, the pressure of the protective gas in the pipeline is measured using a pressure sensor.

[0017] The advantages of this invention compared to the prior art are:

[0018] (1) The present invention uses a gas without helium as a protective gas. The helium content in the sampling gas is 0, so the helium background value is 0. Therefore, it is no longer necessary to measure the helium background value, making the leak detection process simpler and improving the leak detection efficiency.

[0019] (2) This invention uses a gas without helium components as the protective gas. The helium leak rate response value obtained at different sampling flow rates is always the same for the tested product. In principle, this avoids the influence of sampling flow rate on helium background measurement, ensuring the consistency of leak detection results, while also reducing the requirements for consistency in the selection and manufacturing of the flow limiter. This characteristic, in principle, guarantees the detection efficiency of the multi-channel single-point leak detection system.

[0020] (3) This invention establishes a stable local helium-free environment, isolates the external atmosphere, and makes the measurement unaffected by the fluctuation of the helium background in the external environment. It can be used for leak detection in any environment and has strong environmental adaptability.

[0021] (4) The gas protection box of the present invention is composed of inner and outer double-layer boxes, which establish two relatively independent environments. The structure of the outer box can prevent the backflow of external atmosphere and the structure of the inner box can prevent the gas being tested from escaping, ensuring the accuracy of the leak detection results. Both boxes have micropores to maintain a stable state.

[0022] (5) In this invention, the effective volume of the gas protection box and the sampling flow rate have no effect on the leak detection results. These two advantages make it unnecessary to calibrate each branch separately during the leak detection process. Instead, the leak rate of each tested part can be calculated using the calibration data of any one branch, which improves the leak detection efficiency.

[0023] (6) The present invention has a dedicated calibration path, which can avoid frequent replacement of the gas protection box for calibration and improve the leak detection efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the multi-channel leak detection device of the present invention;

[0025] Figure 2 This is a schematic diagram of the protective gas supply device of the present invention;

[0026] Figure 3 This is a schematic diagram of the gas protection leak detection cover box of the present invention;

[0027] Figure 4 This is a schematic diagram showing the connection between the gas protection leak detection cover and the part being inspected according to the present invention;

[0028] Figure 5 This is a schematic diagram showing the connection between the gas protection leak detection cover and the positive pressure standard leak hole of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments.

[0030] This invention provides a multi-channel single-point leak detection system. By adopting a scheme that combines a gas-protected leak detection enclosure with a protective gas, and by establishing a local helium-free environment, the leak detection process is not affected by fluctuations in the ambient helium background and differences in sampling flow rate. This improves the adaptability of the multi-channel single-point leak detection system, simplifies the leak detection measurement process, and ensures the accuracy and consistency of the leak detection results.

[0031] A multi-channel single-point leak detection system, characterized in that it includes a multi-channel leak detection device and a protective gas supply device; wherein, as shown in the figure... Figure 1As shown, the multi-channel leak detection device includes a helium mass spectrometer leak detector, detection valve 1, detection valve 2, calibration valve, gas protection leak detection enclosure 1, gas protection leak detection enclosure 2, gas protection leak detection enclosure 3, positive pressure standard leak hole, hose 1, hose 2, and hose 3; Figure 2 As shown, the protective gas supply device includes a protective gas source, a protective gas pressure reducer, a mass flow controller, a pressure sensor, and a protective gas path. Specifically, the protective leak detection enclosure 1 is connected to the detection valve 1 via a hose 1, forming detection branch 1; the protective leak detection enclosure 2 is connected to the detection valve 2 via a hose 2, forming detection branch 2; the protective leak detection enclosure 3 is connected to the calibration valve via a hose 3, forming a calibration branch; detection branch 1, detection branch 2, and calibration branch are connected in parallel to the helium mass spectrometer leak detector; the interiors of the protective leak detection enclosures 1 and 2 are respectively connected to the inspected part 1 and inspected part 2 of the tested component; the protective leak detection enclosure 3 is connected to the test port of the positive pressure standard leak hole; the protective gas source is sequentially connected to the protective gas pressure reducer, the mass flow controller, and the protective gas path; a pressure sensor is installed between the mass flow controller and the protective gas path; the protective gas path is connected to a multi-channel leak detection device. The number of detection branches in this invention can be increased or decreased according to actual needs.

[0032] The protective gas circuit includes protective gas branch 1, protective gas branch 2, and protective gas branch 3; protective gas branch 1, protective gas branch 2, and protective gas branch 3 are arranged in parallel; wherein, protective gas branch 1 is connected to gas protection leak detection cover 1; protective gas branch 2 is connected to gas protection leak detection cover 2; and protective gas branch 3 is connected to gas protection leak detection cover 3.

[0033] Protective gas is supplied from a protective gas source to the protective gas circuit, and then fed into gas protection leak detection enclosures 1, 2, and 3 respectively via protective gas branch lines 1, 2, and 3. The output flow rate of the protective gas is regulated by a mass flow controller. The pressure of the protective gas in the pipeline is measured by a pressure sensor; high-purity nitrogen is used as the protective gas.

[0034] like Figure 3 As shown, gas protection leak detection enclosures 1, 2, and 3 have the same composition; each includes an outer enclosure, an inner enclosure, a protective gas flow limiter, and a sampling flow limiter. Both the inner and outer enclosures are cubic shell structures; the inner enclosure is located within the cavity of the outer enclosure; the outer enclosure has a protective gas inlet on its side wall; the protective gas flow limiter is located within the protective gas inlet and is connected to the corresponding protective gas branch via the protective gas inlet; the inner enclosure has a detection interface on its side wall, within which the sampling flow limiter is installed; the detection interface passes through the side wall of the outer enclosure and is connected to the corresponding flexible hose.

[0035] A pressure balancing port is provided on the side wall of the outer casing; the size of the pressure balancing port is adapted to the flow rate of the protective gas inside the outer casing, so that the pressure of the protective gas inside the outer casing is 90-110 Pa higher than the ambient atmospheric pressure, preventing backflow and contamination from the outside atmosphere. A protective gas inlet is provided on the side wall of the inner casing; the size of the protective gas inlet should be adapted to the flow rate of the sampling flow limiter; the diameter of the protective gas inlet is 0.5 mm, so that the air pressure inside the inner casing is 8-12 Pa lower than the air pressure inside the outer casing, preventing the measured gas from escaping outside the inner casing.

[0036] Each gas protection leak detection enclosure is designed according to the shape of the part being inspected; when the part being inspected is small enough to fit inside the gas protection leak detection enclosure, it is placed inside the enclosure. Figure 4 As shown, when the volume of the part to be inspected is too large to fit inside the gas protection leak detection box, only the leak test port portion of the positive pressure standard leak hole is inserted into the gas protection leak detection box, such as... Figure 5 As shown.

[0037] The usage method is as follows:

[0038] (1) Select and install a gas protection leak detection box and a protective gas flow limiter.

[0039] The effective volume of the inner cavity between the outer and inner covers of the gas protection leak detection enclosure 1 is 10 cm³. 3 The effective volume of the inner cavity between the outer and inner covers of the gas protection leak detection cover 2 is 12 cm³. 3 The effective volume of the inner cavity between the outer and inner covers of the gas protection leak detection enclosure 3 is 15 cm³. 3 During the pre-blowing time range of 1s to 10s, the local atmospheric pressure is 1×10⁻⁶. 5 Pa, calculate the theoretical flow rate Q of the protective gas flow limiter according to the following formula. p Scope:

[0040] Q p =V o ×P0 / t

[0041] The effective volume V of the cavity between the outer and inner enclosures of each branch is... o t is the pre-blowing time, and P0 is the local atmospheric pressure.

[0042] The calculated flow range of the protective gas flow limiter is as follows:

[0043] Gas protection leak detection cover box 1: 1.0×10 5 Pa·cm 3 / s~1.0×10 6 Pa·cm 3 / s

[0044] Gas protection leak detection cover box 2: 1.2×105 Pa·cm 3 / s~1.2×10 6 Pa·cm 3 / s

[0045] Gas protection leak detection cover box 3: 1.5×10 5 Pa·cm 3 / s~1.5×10 6 Pa·cm 3 / s

[0046] Within the above range, the flow rate of the protective gas flow limiter is selected as 4.0 × 10⁻⁶. 5 Pa·cm 3 / s, 5.0×10 5 Pa·cm 3 / s, 6.0×10 5 Pa·cm 3 / s, corresponding to pre-blowing times of 2.5s, 2.4s, and 2.5s. Install the protective gas flow limiter to the corresponding gas protection leak detection box protective gas interface.

[0047] (2) Select and install a gas protection leak detection box sampling current limiter

[0048] The upper limit of the working pressure P at the inlet of the leak detector in suction gun mode l1 10 Pa and lower limit P l2 The pressure is 5 Pa, and the pumping speed S at the inlet is... l Given a flow rate of 10 L / s, calculate the theoretical upper limit Q of the sampling current limiter. s1 and the lower limit of traffic Q s2 .

[0049] Q s1 =S l ×P l1 =100Pa·L / s

[0050] Q s2 =S l ×P l2 =50Pa·L / s

[0051] Randomly select sampling flow limiters with flow rates of 55 Pa·l / s, 58 Pa·l / s, and 60 Pa·l / s within the above range, and arbitrarily install the sampling flow limiters at the corresponding gas protection leak detection box detection interface.

[0052] (3) Connect the inspected part

[0053] like Figure 4 and Figure 1As shown, the part to be tested 1 is connected to the gas path protection leak detection cover 1, and the part to be tested 2 is connected to the gas path protection leak detection cover 2. Figure 5 and Figure 1 The positive pressure standard leak test port is connected to the corresponding gas path protection leak detection cover box 3, as shown.

[0054] like Figure 2 , Figure 4 , Figure 5 As shown, the protective gas interfaces of the gas circuit protection leak detection cover boxes 1 to 3 are connected to the corresponding protective gas branches 1 to 3 respectively.

[0055] like Figure 1 , Figure 4 , Figure 5 As shown, the detection interfaces of the gas circuit protection leak detection cover boxes 1 to 3 are connected to the corresponding hoses 1 to 3 respectively.

[0056] (4) Propagate with protective gas

[0057] Open and adjust the pressure output of the protective gas pressure reducer, and set the mass flow controller flow rate to the sum of the protective gas flow restrictor flow rates of all branches, i.e., 1.5 × 10⁻⁶. 6 Pa·cm 3 / s. The pressure of the protective gas is monitored by a pressure sensor, typically ranging from 100Pa to 1000Pa. The protective gas must be supplied for at least three times the maximum pre-blowing time of each branch (2.5s), i.e., at least 7.5s, before subsequent leak detection can proceed. The protective gas supply must be maintained throughout the leak detection process.

[0058] (5) Single-point leak detection

[0059] Record the calibration value Q0 of the positive pressure standard leak hole as 1.5 × 10⁻⁶. -6 Pa·m 3 / s.

[0060] Open the calibration valve to connect the gas protection leak detection enclosure corresponding to the positive pressure standard leak hole to the helium mass spectrometer leak detector. Use the helium mass spectrometer leak detector to measure the helium reaction value of the sampling gas. After the helium reaction value stabilizes, record the corresponding helium reaction value I. s =3.0×10 -6 Pa·m 3 / s. Close the calibration valve.

[0061] Open detection valve 1 to connect the gas protection leak detection enclosure 1 corresponding to the inspected part 1 to the helium mass spectrometer leak detector. Use the helium mass spectrometer leak detector to measure the helium reaction value of the sampling gas. After the helium reaction value stabilizes, record the corresponding helium reaction value I1 = 2.0 × 10⁻⁶. -6 Pa·m 3 / s. Close detection valve 1.

[0062] Open detection valve 2 to connect the gas protection leak detection enclosure 2 corresponding to the inspected part 2 to the helium mass spectrometer leak detector. Use the helium mass spectrometer leak detector to measure the helium reaction value of the sampling gas. After the helium reaction value stabilizes, record the corresponding helium reaction value I1 = 4.0 × 10⁻⁶. -6 Pa·m 3 / s. Close detection valve 2.

[0063] Calculate the leak rate of the tested site

[0064] Examined area 1:

[0065] Examined area 2:

[0066] Conventional leak detection systems and methods typically require measuring the helium background reaction value of the ambient atmosphere and the reaction value of the product under test, calculating the leak rate of the product by the difference between the two. This invention uses a helium-free gas as a protective gas, with a helium content of 0 in the sampling gas, resulting in a helium background value of 0. Therefore, it eliminates the need to measure the helium background value, simplifying the leak detection process and improving leak detection efficiency.

[0067] In environments containing helium, inconsistent sampling flow rates when using the same leak detector for multi-channel single-point leak detection will result in unequal helium background values ​​in the helium measurements of each branch. Therefore, it is necessary to control the consistency of the sampling flow rate. This invention uses a helium-free gas as a protective gas, ensuring that the helium leak rate response value obtained at different sampling flow rates is the same for the tested product. In principle, this avoids the influence of sampling flow rate on helium background measurement, ensuring the consistency of leak detection results, and reducing the requirements for consistency in the selection and manufacturing of the flow limiter. This characteristic, in principle, guarantees the detection efficiency of the multi-channel single-point leak detection system.

[0068] When the helium concentration fluctuates in a normal environment, the helium background measurement will also fluctuate, making leak detection of the tested product impossible. This invention establishes a stable, localized helium-free environment, isolating it from the external atmosphere, so that the measurement is not affected by fluctuations in the helium background of the external environment. Leak detection can be performed in any environment, demonstrating strong environmental adaptability.

[0069] The gas protection enclosure consists of inner and outer double-layer enclosures, creating two relatively independent environments. The structure of the outer enclosure can prevent the backflow of external atmosphere and contamination, while the structure of the inner enclosure can prevent the gas being tested from escaping, ensuring the accuracy of leak detection results. Both enclosures have micropores to maintain a stable state.

[0070] In this invention, the effective volume of the gas protection cover box and the sampling flow rate have no impact on the leak detection results. These two advantages mean that there is no need to calibrate each branch separately during the leak detection process. Instead, the leak rate of each tested part can be calculated using the calibration data of any one branch, thus improving the leak detection efficiency.

[0071] This invention features a dedicated calibration path, which avoids frequent replacement of the calibration gas protection box and improves leak detection efficiency.

[0072] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A multi-channel single-point leak detection system, characterized in that: It includes a multi-channel leak detection device and a protective gas supply device; wherein, the multi-channel leak detection device includes a helium mass spectrometer leak detector, detection valve 1, detection valve 2, calibration valve, gas protective leak detection enclosure 1, gas protective leak detection enclosure 2, gas protective leak detection enclosure 3, positive pressure standard leak hole, hose 1, hose 2, and hose 3; the protective gas supply device includes a protective gas source, a protective gas pressure reducer, a mass flow controller, a pressure sensor, and a protective gas circuit; Among them, the gas path protection leak detection box 1 is connected to the detection valve 1 through the hose 1, forming the detection branch 1; the gas path protection leak detection box 2 is connected to the detection valve 2 through the hose 2, forming the detection branch 2; the gas path protection leak detection box 3 is connected to the calibration valve through the hose 3, forming the calibration branch; the detection branch 1, the detection branch 2, and the calibration branch are connected in parallel and then connected to the helium mass spectrometer leak detector; the inside of the gas path protection leak detection box 1 and the gas path protection leak detection box 2 are respectively connected to the tested part 1 and the tested part 2 of the tested part; the gas path protection leak detection box 3 is connected to the test port of the positive pressure standard leak hole; the protective gas source is connected in sequence to the protective gas pressure reducer, the mass flow controller, and the protective gas path; a pressure sensor is installed between the mass flow controller and the protective gas path; the protective gas path is connected to the multi-channel leak detection device.

2. The multi-channel single-point leak detection system according to claim 1, characterized in that: The protective gas circuit includes protective gas branch 1, protective gas branch 2, and protective gas branch 3; protective gas branch 1, protective gas branch 2, and protective gas branch 3 are arranged in parallel; wherein, protective gas branch 1 is connected to gas protection leak detection cover 1; protective gas branch 2 is connected to gas protection leak detection cover 2; and protective gas branch 3 is connected to gas protection leak detection cover 3.

3. The multi-channel single-point leak detection system according to claim 2, characterized in that: Gas protection leak detection enclosure 1, gas protection leak detection enclosure 2, and gas protection leak detection enclosure 3 have the same composition; each includes an outer enclosure, an inner enclosure, a protective gas flow limiter, and a sampling flow limiter. Both the inner and outer covers are cubic shell structures. The inner cover is located inside the cavity of the outer cover. The outer cover has a protective gas interface on its side wall. A protective gas flow limiter is installed in the protective gas interface. The protective gas interface is connected to the corresponding protective gas branch. The inner cover has a detection interface on its side wall. A sampling flow limiter is installed in the detection interface. The detection interface passes through the side wall of the outer cover and is connected to the corresponding hose.

4. A multi-channel single-point leak detection system according to claim 3, characterized in that: An air pressure balancing port is provided on the side wall of the outer cover; the size of the air pressure balancing port is adapted to the flow rate of the protective air inside the outer cover, so that the protective air pressure inside the outer cover is 90-110 Pa higher than the ambient atmospheric pressure, preventing the backflow of external air and pollution.

5. A multi-channel single-point leak detection system according to claim 3, characterized in that: The inner enclosure has a protective gas inlet on its side wall; the size of the protective gas inlet should be adapted to the flow rate of the sampling flow limiter; the diameter of the protective gas inlet is 0.5 mm, so that the air pressure inside the inner enclosure is 8-12 Pa lower than the air pressure inside the outer enclosure, to prevent the gas to be measured from escaping to the outside of the inner enclosure.

6. A multi-channel single-point leak detection system according to claim 5, characterized in that: Each gas protection leak detection box is designed according to the shape of the part being tested. When the part being tested is small enough to fit inside the gas protection leak detection box, it is placed inside the gas protection leak detection box. When the part being tested is too large to fit inside the gas protection leak detection box, only the leak test port of the positive pressure standard leak hole is inserted into the gas protection leak detection box.

7. A multi-channel single-point leak detection system according to claim 1, characterized in that: The number of detection branches can be increased or decreased according to actual needs.

8. A multi-channel single-point leak detection system according to claim 2, characterized in that: Protective gas is output from the protective gas source to the protective gas circuit, and is input into the gas protection leak detection box 1, gas protection leak detection box 2, and gas protection leak detection box 3 respectively through protective gas branch 1, protective gas branch 2, and protective gas branch 3; the protective gas is high-purity nitrogen.

9. A multi-channel single-point leak detection system according to claim 1, characterized in that: The output flow rate of the protective gas is adjusted by a mass flow controller.

10. A multi-channel single-point leak detection system according to claim 1, characterized in that: The pressure of the protective gas in the pipeline is measured using a pressure sensor.

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