Method for calibrating volume of gas measurement system

Abstract

The invention relates to the field of gas measurement, and discloses a method for calibrating the volume of a gas measurement system, which comprises the following steps: vacuumizing the system, removing residual gas and setting the initial state of a valve; high-purity He gas is injected into the target area, and the target pipe section is filled with the gas through diffusion; measuring the He gas signal intensity of the pipe section closest to the mass spectrometer by using the mass spectrometer, and calculating the volume of the pipe section by combining the known volume of the mass spectrometer; valves are opened section by section according to the sequence from the nearest to the farthest of the mass spectrometer, and the volume of each section is calculated through difference recursion of signal intensity; and finally recording and outputting the volume of each section of pipeline and the total volume data of the system. According to the method, recursive calculation is adopted, the calibration precision is remarkably improved, the method is suitable for volume calibration requirements of various complex pipeline systems, and reliable volume distribution data support is provided for subsequent gas measurement and analysis.

Description

Technical Field

[0001] The invention relates to the technical field of gas measurement, and in particular to a method for calibrating the volume of a gas measurement system. Background Art

[0002] Gas measurement systems are widely used in scientific research and industrial applications, and accurate calibration of their volume distribution is the key to ensuring the accuracy of system measurement results. However, existing volume calibration methods are usually difficult to adapt to gas measurement systems with complex pipeline structures, such as multi-segment pipelines, irregular fillers, and cold trap structures. In such systems, direct measurement of the volume of each pipe segment is often limited by the shape, position, and complex internal environment of the pipeline, making it difficult to accurately obtain the actual volume of each pipe segment.

[0003] In traditional methods, the system volume is usually calibrated once or by the system geometry, but these methods have significant limitations. The overall calibration cannot distinguish the specific distribution of each volume segment and can only obtain the total volume of the system, while the geometric structure estimation is prone to large deviations due to ignoring the internal complexity of the pipeline or actual installation errors. In addition, since the measurement process is easily affected by gas mixing, signal interference and equipment errors, the existing methods also have obvious deficiencies in accuracy and applicability.

[0004] Especially in scenarios with high requirements for volume parameters, such as rare gas measurement and high-precision gas flow control, existing technologies often cannot meet actual needs. Therefore, a technical method is needed that can adapt to complex pipeline systems, calibrate volumes section by section, and ensure that the calibration results are accurate, reliable, and traceable, so as to overcome the defects of existing technologies and provide support for further optimization of gas measurement systems. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for calibrating the volume of a gas measurement system, which solves the problems of insufficient accuracy, poor adaptability and inability to obtain complete volume distribution data in the existing gas measurement system volume calibration method in complex pipeline structures.

[0006] To achieve the above object, the present invention is implemented by the following technical solution: A method for calibrating the volume of a gas measurement system, comprising the following steps: S1. Preparation: Vacuum the gas measurement system, remove the residual gas in the system, and set each valve of the system to the initial state; S2. Calibrate the volume of the tube section closest to the mass spectrometer (V1): S2.1. High-purity gas injection: high-purity He gas is injected into the mass spectrometer by diffusion; the He gas signal intensity is measured by the mass spectrometer; during the measurement, except for the mass spectrometer, the remaining pipelines are evacuated to remove residual gas; S2.2, diffuse the gas in the mass spectrometer back to the target section, measure the He gas signal intensity again through the mass spectrometer, and calculate the volume of the tube section in combination with the inner cavity volume of the mass spectrometer; S2.3, repeat the above S2.1 and S2.2 processes several times, and calculate the average value to obtain the volume of the tube section closest to the mass spectrometer; S3. Calibrate the volume of other pipe sections: S3.1. High-purity gas injection: Inject high-purity He gas into the entire pipeline; S3.2. Open the corresponding valves one by one in the order from the closest to the mass spectrometer to the farthest, measure the signal intensity difference through the mass spectrometer, and recursively calculate the volume of each section; S3.3, record and output: record the volume of each section of the pipeline to obtain the complete volume distribution data of the system; S3.4. Repeat S3.1-3.3 several times and calculate the average value.

[0007] Preferably, the step of calibrating the volume of the tube section closest to the mass spectrometer specifically includes: The step of calibrating the volume of the tube section closest to the mass spectrometer specifically includes: By opening and closing the corresponding valve, high-purity He gas is diffused into the mass spectrometer; Measure the He signal intensity by mass spectrometer and record the initial signal value; Close all other valves connected to this pipe section; Back-diffusion of the gas in the mass spectrometer to the tube section, and measurement of the back-diffusion signal value; Calculate the pipe segment volume using the following formula: in, is the volume of the tube section closest to the mass spectrometer to be calibrated, To measure the He signal intensity for the mass spectrometer, is the He signal intensity after the He gas in the mass spectrometer diffuses back to the tube section closest to the mass spectrometer (V1), is the volume of the mass spectrometer cavity.

[0008] 4. Preferably, when calibrating the volumes of other pipe sections, the calibration is performed section by section in the order from near to far from the mass spectrometer; when calibrating a certain pipe section, the gas in the pipe section is first diffused into the pipe section (V1) closest to the mass spectrometer, and the gas in the pipe section (V1) closest to the mass spectrometer is taken into the mass spectrometer for measurement; and the calculation is performed according to the following recursive formula: in, To be calibrated Pipeline volume, For mass spectrometer measurement The He gas signal strength of the pipeline section, The signal intensity of He gas in the initial calibration tube section is measured for the mass spectrometer. For the front The sum of the volumes of the pipe segments.

[0009] Preferably, during the calibration process, the injection amount of high-purity He gas is controlled at 1×10 -3 ccSTP~5×10 - 3 ccSTP.

[0010] Preferably, the volume of each pipe section is calibrated by repeating the measurement for at least 3 times, and the average value is taken as the final volume value of the section.

[0011] Preferably, the gas measurement system comprises a plurality of valves, pipelines and a mass spectrometer, wherein: Valves GVTP and GVIP1 are connected to the vacuum pump; valves GV2-GV8 are connected to the various sections of the pipeline of the gas measurement system in sequence to achieve isolation or connection of the various pipe sections; valve GVMS is connected to the inlet of the mass spectrometer. The initial state of the system is: GVTP, GVIP1, GV2, GV3, GV4, GV5, GV6, and GV7 are in the open state, and the remaining valves are in the closed state.

[0012] The present invention provides a method for calibrating the volume of a gas measurement system. The method has the following beneficial effects: 1. The present invention adopts a recursive calibration method step by step, combines the signal intensity measurement of the mass spectrometer and the known reference volume parameters, avoids the result deviation problem caused by system complexity or measurement error accumulation in the traditional overall calibration method, and thus greatly improves the accuracy of volume calibration.

[0013] 2. The present invention can flexibly cope with gas measurement systems with complex pipeline structures, including special structures such as multi-section pipelines, irregular fillers, cold traps, etc., through the technical solution of segment-by-segment isolation calibration, and can ensure the adaptability and accuracy of the calibration process, and has a wide range of applications.

[0014] 3. The present invention realizes the traceability of volume distribution data by recording, organizing and outputting the volume of each section of the pipeline and the total volume of the system, providing reliable basic data support for subsequent experimental design, equipment calibration and improvement of measurement accuracy.

[0015] 4. The present invention ensures the independent connection between the target pipe section and the mass spectrometer by precisely controlling the gas diffusion path and the valve state, thereby reducing the possibility of gas mixing or interference in the uncalibrated area, thereby ensuring the reliability of signal measurement and the accuracy of volume calculation.

[0016] 5. The present invention provides a scientific basis for the calibration and optimization of the gas measurement system by generating complete system volume distribution data. It is particularly suitable for application scenarios such as gas flow measurement and rare gas analysis that require high-precision volume parameter support, further enhancing the practicality and functionality of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the method flow of the present invention; Figure 2 Schematic diagram of the gas measurement system of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Please see attached Figure 1 -Attached Figure 2 The present invention provides a method for calibrating the volume of a gas measurement system. By calibrating the internal volume of each section of the gas measurement system, the method is applicable to a complex gas measurement system with multiple pipe sections, valves, mass spectrometers and other related components. The method can effectively solve the problem of large errors in traditional volume calibration methods caused by complex and irregular internal volumes of the system.

[0020] like Figure 1 As shown, the method for calibrating the volume of a gas measurement system may include the following steps: S1. Preparation: Vacuum the gas measurement system, remove the residual gas in the system, and set each valve of the system to the initial state; S2. Calibrate the volume of the tube section closest to the mass spectrometer: S2.1. High-purity gas injection: high-purity He gas is injected into the mass spectrometer by diffusion; the He gas signal intensity is measured by the mass spectrometer; during the measurement, except for the mass spectrometer, the remaining pipelines are evacuated to remove residual gas; S2.2, diffuse the gas in the mass spectrometer back to the target section, measure the He gas signal intensity again through the mass spectrometer, and calculate the volume of the tube section in combination with the inner cavity volume of the mass spectrometer; S2.3. Repeat the above steps S2.1 and S2.2 several times and calculate the average value to obtain the volume of the tube section closest to the mass spectrometer.

[0021] S3. Calibrate the volume of other pipe sections: S3.1. High-purity gas injection: Inject high-purity He gas into the entire pipeline; S3.2. Open the corresponding valves one by one in the order from the closest to the mass spectrometer to the farthest, measure the signal intensity difference through the mass spectrometer, and recursively calculate the volume of each section; S3.3. Record and output: record the volume of each section of the pipeline to obtain the complete volume distribution data of the system.

[0022] S3.4. Repeat S3.1-3.3 several times and calculate the average value.

[0023] Each step of the method of the present invention is described in detail below.

[0024] Regarding step S1, in this embodiment, step S1 is mainly the preparation work of the gas measurement system to ensure the accuracy and stability of the subsequent calibration process.

[0025] Specifically, in this embodiment, the gas measurement system needs to be evacuated first to remove the gas and impurities that may remain in the system and ensure the cleanliness of the measurement environment. The evacuation operation can be achieved by connecting a vacuum pump, which should have sufficient pumping speed and final vacuum degree to meet the experimental requirements.

[0026] As an option, in specific implementation, a combination of a mechanical pump and a molecular pump can be used to evacuate the pipeline, wherein the mechanical pump is used to initially evacuate the gas under atmospheric pressure, and the molecular pump is used to further reduce the air pressure in the system to achieve a high vacuum state. It should be noted that the vacuum operation should continue until the system reaches the preset vacuum condition, for example, the system vacuum degree can reach <10 -3 Pa to ensure that the influence of residual gas on the subsequent high-purity He gas calibration process is minimized.

[0027] In one possible implementation, the connection between the vacuum pump and the system is controlled by a main valve (such as GVTP). After the main valve is opened, the vacuum pump starts to evacuate the system. After the vacuum degree reaches the required level, the main valve is closed to isolate the vacuum pump from the system. This operation method can reduce the interference of external gas leakage on the system vacuum degree.

[0028] It should be noted that during the vacuuming process, in order to avoid gas residue caused by irregular fillings in the system (such as adsorbents in the cold trap) or complex pipeline structures, vacuuming can be assisted by heating operations. For example, by applying appropriate heating to the pipeline surface and raising the system temperature to 100℃-200℃, the presence of residual gas or adsorbed gas can be further reduced.

[0029] In this embodiment, each valve in the system needs to be set to a specific initial state according to the requirements of the experimental design. The state setting of these valves is crucial for the diffusion path of He gas and the signal acquisition of the mass spectrometer. Specifically, in the initial state, all valves directly related to the target pipe section (such as GVTP, GVIP1) should be in the open state, and valves related to non-target areas or non-working modules (such as GVMS or valves connected to other pipe sections) should be in the closed state. It should be understood that this valve state setting ensures that the flow path of the gas in subsequent operations is controllable and avoids interference from non-calibrated areas.

[0030] In an exemplary operation, the system can be divided into several independent sub-areas, each of which is isolated or connected by a valve to ensure that vacuuming only acts on the target area. Other areas can open valves to perform independent vacuuming operations when needed. This segmented vacuuming method is particularly suitable for systems with complex pipeline structures.

[0031] It is understandable that the initial state setting of the above-mentioned valve is adjustable. According to the actual structure and experimental requirements of different systems, the opening or closing state of the specific valve can be appropriately adjusted, but it should be ensured that the target area is in a working state and the non-target area is in an isolated state.

[0032] As an optimization measure, after setting the valve state, the vacuum degree of the system can be monitored in real time through a pressure sensor. For example, the pressure sensor can be arranged at the connection between the target area and the vacuum pump, or at the entrance of the mass spectrometer, to ensure that the vacuum conditions of each target area meet the experimental requirements. If the pressure sensor detects that the pressure value does not meet the preset requirements, it can be corrected by extending the vacuum pumping time or checking possible leaks.

[0033] It should be noted that the above-mentioned preparatory work plays a role in laying the foundation for the technical solution of the present invention, and its core purpose is to ensure that the internal environment of the system is in a pure state, providing reliable guarantee for the subsequent He gas injection and calibration process.

[0034] Regarding step S2, in this embodiment, step S2 mainly involves the injection operation of high-purity He gas, which is used to ensure that the target pipe section of the gas measurement system is filled with high-purity calibration gas, laying the foundation for subsequent volume calibration.

[0035] Specifically, in this embodiment, the injection of high-purity He gas is completed through a preset gas injection path, and the gas source can be a high-purity He gas cylinder or a gas generator. As an option, the high-purity He gas used should meet the purity requirements, and the purity is usually required to reach ≥99.999% to avoid interference of other impurity gases on the mass spectrometry results.

[0036] In one possible implementation, high-purity He gas is introduced into the system through a connected injection pipe (e.g., the area between SV1 and SV2). It should be noted that the injection path of He gas should be as short as possible to reduce gas diffusion delay and gas loss caused by a long path. In specific operations, the SV1 valve is opened to allow high-purity He gas to be injected into the predetermined injection volume at a stable flow rate, and SV1 is closed after a certain period of time (e.g., 2 minutes). It can be understood that this gas injection method ensures that the He gas in the injection volume can be fully filled by controlling the time and flow rate.

[0037] It should be noted that after He gas is injected, it gradually fills the target pipe section through diffusion. In this embodiment, the diffusion operation is achieved by opening the valve related to the target pipe section. For example, by opening the SV2 valve and other control valves (such as GV2) connected to the target pipe section, the injected He gas is diffused from the area between SV1 and SV2 to the target pipe section. The time of the diffusion operation is generally controlled at 1-2 minutes to ensure that the He gas can fully enter the target area. As an option, the air pressure change in the target pipe section can be monitored by a pressure sensor. When the air pressure reaches equilibrium, it means that the diffusion process has been completed.

[0038] In a possible implementation, in order to further improve the diffusion efficiency, the target pipe section can be heated. For example, by setting a heating belt or heating jacket outside the pipe section, the temperature of the pipe section is raised to 30°C-50°C to improve the diffusion speed and uniformity of He gas. It should be noted that this heating operation is particularly suitable for pipe sections containing complex fillings, such as irregular structures such as cold traps.

[0039] The control of the diffusion path is a key technical point in this embodiment. Specifically, in order to ensure the accuracy of the He gas diffusion range, other valves not related to the target pipe section (such as GV3 and subsequent valves) should be closed during the diffusion process. This operation method can effectively isolate the non-target pipe section and ensure that the diffusion only occurs in the target pipe section, thereby avoiding interference from gases in other areas.

[0040] It is understandable that during the diffusion process, if the diffusion range of He gas cannot be fully controlled, it may cause gas leakage to non-target areas or uncalibrated areas, thereby affecting the subsequent measurement accuracy. Therefore, in order to further reduce the complexity of the diffusion path, in some embodiments, the gas can be gradually guided to diffuse to the target pipe section by dividing the system into multiple independent modules. Exemplarily, the pressure in the target pipe section can be used to determine whether the diffusion is completed by the pressure difference with the adjacent pipe section. For example, if the pressure in the target pipe section reaches a stable value close to the pressure in the injection area, the diffusion process can be considered to be completed.

[0041] It should be noted that the completion of the diffusion process is marked by the He gas in the target pipe section reaching a stable state, and the gas state at this time is crucial to the subsequent mass spectrometry measurement. In this case, in order to avoid the fluctuation of He gas concentration affecting the measurement, you can wait for a period of time (e.g., 1-2 minutes) after the diffusion is completed to ensure that the gas distribution in the target pipe section is completely uniform.

[0042] As a possible improvement, after the diffusion is completed, the He gas concentration in the target pipe section can be preliminarily measured by a mass spectrometer to ensure that the gas purity and concentration meet the expected requirements. If the measurement result deviates from the set value, high-purity He gas can be re-injected and the above diffusion steps can be repeated until the gas in the target pipe section reaches a stable state.

[0043] In step S2 of this embodiment, the purity and uniformity of the gas in the target pipe section can be ensured by accurately controlling the injection and diffusion of He gas, thereby providing reliable experimental conditions for subsequent volume calibration.

[0044] For step S2, in this embodiment, step S2 involves a calibration operation of the volume of the pipe section closest to the mass spectrometer. By measuring the He gas signal intensity and combining it with the known volume parameters of the mass spectrometer, the actual volume of the target pipe section is calculated, providing a basis for the subsequent calibration of other pipe sections.

[0045] Specifically, when calibrating the volume of the target pipe section closest to the mass spectrometer, the gas path of the system needs to be adjusted first to ensure that only the target pipe section is connected to the mass spectrometer and the valves of the other pipe sections are closed. It should be noted that at this time, the target pipe section is filled with evenly diffused high-purity He gas, and the rest of the system has been evacuated to a vacuum state to avoid interference of gases in other areas on the measurement signal.

[0046] In a possible implementation, the He gas is allowed to enter the mass spectrometer from the target pipe section by opening the control valve (e.g., GVMS) between the target pipe section (e.g., V1) and the mass spectrometer and closing the valves of other pipe sections (e.g., GV2, GVIP2, etc.). In the exemplary operation, the mass spectrometer detects the He gas signal intensity through its internal sensor and records the signal value as the first measured signal value. .

[0047] As an option, the running time of the mass spectrometer can be set according to the specific situation of the system structure, and is generally controlled to measure 10 cycles to ensure the stability of signal detection. After the first signal measurement is completed, the He gas in the mass spectrometer is diffused back to the target pipe section. The reverse diffusion operation is implemented by closing the valve corresponding to the target pipe section (such as GV2), opening the connecting valve between the mass spectrometer and the target pipe section (such as GVMS), and allowing the He gas in the mass spectrometer to flow back into the target pipe section. It can be understood that the reverse diffusion operation can effectively eliminate the influence of gas residue in the mass spectrometer on subsequent measurements.

[0048] In a possible implementation, after the above-mentioned reverse diffusion operation, the signal measurement of the mass spectrometer is performed again, and the signal value after reverse diffusion is recorded as the second measurement signal value. It should be noted that the stability of the second signal measurement is critical to the accuracy of the volume calculation, so it is usually necessary to wait for 30 seconds to 1 minute after the back diffusion is completed to ensure uniform gas distribution.

[0049] In this embodiment, the volume of the target pipe section is calculated by the following formula: in: is the volume of the tube section closest to the mass spectrometer; is the He signal intensity measured for the first time; is the He signal intensity measured for the second time after anti-diffusion; is the inner cavity volume of the mass spectrometer, a known parameter provided by the mass spectrometer manufacturer.

[0050] As an optimization method, when calculating the volume, the values ​​of the first and second signal measurements can be measured repeatedly (for example, 3 times or more), and then the average value can be taken to reduce the impact of experimental errors on the calculation results. It can be understood that repeated measurements help eliminate deviations caused by fluctuations in the equipment itself or changes in gas flow, thereby improving the accuracy of volume calibration.

[0051] In the exemplary operation, the inner cavity volume of the mass spectrometer is usually a fixed value, such as 1000 cc, but the actual volume may vary depending on the model. It should be noted that the inner cavity volume of the mass spectrometer is a known reference value, and its accuracy is crucial for the calculation of the target tube volume. Therefore, the mass spectrometer should be calibrated before use to ensure that the reference value it provides is accurate.

[0052] As a possible extension method, in order to verify the reliability of the volume calculation results, the calculated target pipe volume can be Compare with the theoretical estimate. The theoretical estimate can be calculated based on the geometric dimensions of the target pipe section, such as length and inner diameter. If the two are significantly different, recheck whether there is an abnormality in the mass spectrometer signal measurement process, such as gas leaks or signal detection errors.

[0053] It should be noted that the volume calibration of the target pipe section closest to the mass spectrometer is the basis for the subsequent volume calibration of other pipe sections, and its result directly affects the accuracy of the subsequent recursive calculation. Therefore, the rigor of the calibration process and the reliability of the data should be ensured during the operation. This step achieves the accurate calibration of the target pipe section volume by measuring the signal intensity of high-purity He gas and combining it with the known reference volume, providing a reliable basis for the volume calibration of the entire gas measurement system.

[0054] As for step S3, in this embodiment, step S3 mainly involves the operation of calibrating the volume of other pipe sections far from the mass spectrometer, and calculating the volume of each pipe section in turn by recursive section by section. This step is based on the known volume of the pipe section closest to the mass spectrometer, and combines the change relationship of the mass spectrometry signal intensity to complete the calibration of the volume of the remaining pipe sections.

[0055] Specifically, in this embodiment, when calibrating the volume of the pipe section far from the mass spectrometer (such as V2, V3, etc.), it is necessary to measure the target pipe section section by section in the order from the closest to the mass spectrometer to the farthest. It can be understood that this recursive operation mode of section by section can avoid the interference of system complexity on the calibration process and gradually improve the calibration accuracy.

[0056] In a possible implementation, the valve status of the system needs to be adjusted first to ensure that the current target pipe section is connected to the mass spectrometer and the calibrated pipe section, while other pipe sections that have not been calibrated remain isolated. For example, when calibrating the second pipe section V2, it is necessary to open the valve connected to V2 (such as GV2), and at the same time close the valves related to other pipe sections (such as V3 and further pipe sections) (such as GV3, GV4, etc.). Through this valve operation, it is ensured that He gas diffuses only from the current target pipe section to the calibrated part and finally enters the mass spectrometer.

[0057] For example, when the target pipe section (such as V3) is to be calibrated, the gas in the target pipe section needs to be diffused to the calibrated area (V1, V2) by opening valve GV3, and then valve GV2 is closed to allow only the gas in the pipe section closest to the mass spectrometer to enter the mass spectrometer for measurement. The signal value obtained is recorded as the signal value of the current section. As an option, the deviation caused by environmental fluctuations or equipment errors can be reduced by repeatedly measuring the signal value (for example, repeating the measurement three times) and taking the average value. When calibrating the volume of each target pipe section, the gas in it needs to be diffused to the pipe section closest to the mass spectrometer, and only the gas in the pipe section closest to the mass spectrometer is measured, which can reduce error transmission during data calculation and improve the accuracy of volume calibration.

[0058] It should be noted that during the calibration of each pipe section, the calibrated part of the diffusion path should always be kept in a vacuum state. This can be achieved by opening the vacuum pump control valve (such as GVTP) to evacuate the calibrated part. For example, when calibrating V2, the calibrated pipe section of V1 needs to be evacuated to ensure that there is no residual gas in it, so as to avoid gas mixing interfering with the current section measurement.

[0059] In this embodiment, the volume of the target pipe section is calculated by the following formula: in: To be calibrated The volume of the pipeline segment; For mass spectrometer measurement He gas signal strength in the pipeline section; Measure the He gas signal intensity of the initial calibration tube section (such as V1) for the mass spectrometer; For the front The sum of the volumes of the pipe segments.

[0060] Specifically, when calibrating V2, use the above formula: in, is the calibrated volume of the first pipe section, is the signal strength of the current segment.

[0061] In a possible optimization implementation, the calibration accuracy can be improved by adjusting the diffusion time. For example, during the diffusion process, GV2 is opened and kept for 2 minutes to allow the He gas to fully diffuse to the connecting area between V2 and V1. After the diffusion is completed, GV2 is closed to allow the gas in V1 to enter the mass spectrometer and be measured, ensuring that the diffusion range is consistent with the measurement path.

[0062] It should be noted that when calibrating the third section (such as V3) and further pipe sections, recursive calculations should be performed based on the volumes of the calibrated sections (such as V1 and V2).

[0063] It can be understood that this recursive calculation method can ensure that the calibration result of each volume segment is based on the measurement data of the previous segment, avoiding the cumulative error that may be caused by independent calibration.

[0064] As an improvement measure, the accuracy of the calculation results can be further improved by measuring the target pipe section multiple times and fitting the measurement results. For example, by linearly fitting the measurement results of different diffusion times, the error caused by signal fluctuations or changes in experimental conditions can be reduced.

[0065] In an exemplary operation, for a pipe section containing multiple complex structures (such as cold traps or fillers), the diffusion efficiency can also be improved by heating operation to ensure the stability of signal strength. The heating temperature can be controlled at 30°C-50°C, and the specific temperature can be adjusted according to the system material and structural characteristics.

[0066] It should be noted that the process of calibrating the volume of other pipe sections should be carried out section by section, and the calibration of each section is based on the calibrated volume, and is completed in strict order from near to far. This sequential calibration method can not only improve the overall measurement accuracy, but also verify the calibration result of the current section through the gradually accumulated volume value.

[0067] This embodiment achieves accurate calibration of the volumes of other pipe sections far from the mass spectrometer through recursive calculation of the mass spectrometry signal intensity, providing reliable data support for the complete volume distribution of the entire gas measurement system.

[0068] Regarding step S3.3, in this embodiment, step S3.3 mainly involves recording and outputting the calibration results of the gas measurement system volume. By sorting and summarizing the calibration data of each section of the pipeline volume, a complete system volume distribution is obtained, thereby providing an accurate reference basis for subsequent gas measurement, analysis and equipment calibration.

[0069] Specifically, in this embodiment, after the volume of all pipe sections is calibrated, the volume value of each pipe section is Record them in the order of connection relative to the mass spectrometer and calculate the total volume of the system by accumulation. The calculation formula is as follows: in: For the The volume of the pipeline segment; is the total number of pipe segments in the system.

[0070] As an option, when recording volume data, a tabular format can be used to record the number, connection location, volume value, and relevant conditions during measurement (such as ambient temperature, gas type, diffusion time, etc.) of each pipe section. This information can provide a traceability basis for subsequent analysis.

[0071] It should be noted that the system volume distribution record can be output in different forms according to specific needs. For example, in a laboratory environment, the volume data is usually saved in the form of a spreadsheet or database for subsequent reference and use; in an industrial environment, the volume data can also be directly output to a display screen or printing device through the control system integrated with the equipment.

[0072] In a possible implementation, the recorded data can be automatically sorted and processed by a software program. Exemplarily, the measurement data can be transmitted to the data processing software through the communication interface between the sensor and the computer (such as RS232, USB, etc.), and the volume calculation, data storage and output operations are completed in the software. For example, the software can automatically calculate the volume of each segment based on the input signal strength value and the calibration formula, and generate a system volume distribution map. This automated processing method can improve the efficiency of data recording and output and avoid errors that may be caused by manual recording.

[0073] It is understood that the uncertainty factors in the calibration process should be clearly marked when the data is output. For example, calibration accuracy information can be added to the output results, such as the measurement error range of signal strength or the uncertainty of different segment volume calculations. Specifically, the error range can be calculated based on the signal strength measurement value in the calibration formula and the sensitivity of the measuring device. For example, for the measurement value The error range , the error range of volume calculation is It can be estimated using the error propagation formula.

[0074] It should be noted that for complex pipeline systems, the calibration results can also include distribution information of spatial positions. For example, the volume values ​​of each section of the pipeline can be combined with its spatial position through a 3D modeling tool to generate a visual volume distribution model. This visualization result can help technicians understand the volume distribution characteristics of the system more intuitively and provide a basis for the subsequent gas measurement experiment design.

[0075] In some embodiments, the output of the calibration results can also be combined with the control system of the mass spectrometer itself to achieve linkage with subsequent measurement processes. For example, the calibration results are directly stored in the built-in memory of the mass spectrometer, making it a reference data for subsequent gas measurements. When the mass spectrometer is running, it can automatically perform signal calibration based on the stored volume distribution data, thereby improving the accuracy of the measurement results.

[0076] This embodiment uses the recording, sorting and output of the volume values ​​of each section of the pipeline as the final step of the calibration method, which not only achieves the acquisition of the complete volume distribution data of the system, but also provides a reliable basic support for subsequent applications.

[0077] In general, the present invention evacuates the gas measurement system, injects high-purity gas, and uses a mass spectrometer to measure the gas signal strength section by section, and calibrates the volume of each pipe section in turn in combination with the system structure and calculation formula, and finally obtains the complete volume distribution data of the system. The method adopts a recursive calculation method, calibrating from the pipe section closest to the mass spectrometer to the far end, avoiding the error accumulation problem of direct volume measurement of complex systems, and has the characteristics of high precision and high reliability. It provides technical support for the calibration and optimization of gas measurement systems and is suitable for the calibration needs of complex pipeline volumes in laboratories and industrial fields.

[0078] In order to better understand the present invention, the above method is described in detail below in conjunction with specific embodiments.

[0079] Example: This embodiment uses Figure 2 The calibration method of the present invention is described in detail with the system in FIG. Before calibration, the status of each valve in the system is: GVTP, GVIP1, GV2, GV3, GV4, GV5, GV6, GV7 are open, and the remaining valves are closed.

[0080] 1. Calibrate the volume of system V1 between GV2 and GVMS by reverse diffusion .

[0081] a) Take high-purity He gas into the volume between SV1 and SV2. The specific operation is: open SV1 and close SV1 after 2 minutes.

[0082] b) He standard gas diffuses into the whole system, the specific operation is: close GVTP, GVIP1, open GV8, SV2, and close SV2 after 2 minutes. At this time, the gas has diffused from SV1 and SV2 to the whole pipeline.

[0083] c) Mass spectrometry. Turn off GVIP2, turn on GVMS, turn off GVMS after 1 minute, and then perform mass spectrometry. 4 He, the test result is recorded as S1. At the same time, open the GVTP to remove the residual gas in the system pipeline to keep it in a vacuum state.

[0084] d) After the mass spectrometer measurement is completed, the gas in the mass spectrometer is diffused back to the tube section closest to the mass spectrometer (V1), that is, the section from GV2 to GVMS. The specific operation is to close GV2 and open GVMS. After 1 minute, the mass spectrometer measurement 4He, the test result is recorded as S2. After the measurement, close GVMS and open GV2 and GVIP2. Provided by the mass spectrometer manufacturer, then .

[0085] e) Repeat the above steps three times or more, and take multiple The average value of V1 between GV2 and GVMS is taken as The fixed value.

[0086] 2. Determine the volume of each part of V2-V8 .

[0087] a) Pour high purity He gas into the volume between SV1 and SV2: open SV1, and close SV1 after 2 minutes.

[0088] b) He standard gas diffuses into the whole system. The specific operation is: close GVTP, GVIP1, open GV8, SV2, and close SV2 after 2 minutes. At this time, the gas has diffused from SV1 and SV2 to the whole pipeline. Then close all valves (GV1, GV2, GV3, GV4, GV5, GV6, GV7). In this way, the gas is isolated and stored in V1-V8 respectively.

[0089] c) Close GVIP2, open GVMS, and let the gas in V1, i.e. the gas between GV2 and GVMS, enter the mass spectrometer. After 1 minute, close GVMS and perform mass spectrometry. 4 He, the test result is recorded as Sig1. After the measurement, open GVIP2, GVMS, pump out the residual gas, and close GVMS after 5 minutes.

[0090] d) Calibration volume The specific operation is: open GV2, close GV2 after 2 minutes. Close GVIP2, open GVMS, close GVMS after 1 minute, and mass spectrometry measurement 4 He, the test result is recorded as Sig2. After the measurement, turn on GVIP2, GVMS, GV2, and turn off GVMS after 5 minutes. The formula is .

[0091] e) Calibration volume The specific operation is: open GV3, close GV2 after 2 minutes. Close GVIP2, open GVMS, close GVMS after 1 minute, and mass spectrometry measurement 4 He, the test result is recorded as Sig3. After the measurement, turn on GVIP2, GVMS, GV2, and turn off GVMS after 5 minutes. The formula is .

[0092] f) Calibration volume The specific operation is: open GV4, close GV2 after 2 minutes, open GVIP1. Close GVIP2, open GVMS, close GVMS after 1 minute, open GV2, and perform mass spectrometry measurement. 4 He, the test result is recorded as Sig4. After the measurement, turn on GVIP2. The formula is .

[0093] g) Calibration volume The specific operation is: close GVIP1, open GV5, close GV2 after 2 minutes, open GVIP1. Close GVIP2, open GVMS, close GVMS after 1 minute, open GV2, and mass spectrometry measurement 4 He, the test result is recorded as Sig5. After the measurement, turn on GVIP2. The formula is .

[0094] h) Calibration volume The specific operation is: close GVIP1, open GV6, close GV2 after 2 minutes, open GVIP1. Close GVIP2, open GVMS, close GVMS after 1 minute, open GV2, and perform mass spectrometry measurement. 4 He, the test result is recorded as Sig6. After the measurement, turn on GVIP2. The formula is .

[0095] i) Calibration volume The specific operation is: close GVIP1, open GV7, close GV2 after 2 minutes, open GVIP1. Close GVIP2, open GVMS, close GVMS after 1 minute, open GV2, and perform mass spectrometry measurement. 4 He, the test result is recorded as Sig7. After the measurement, turn on GVIP2. The formula is .

[0096] j) Calibration volume The specific operation is: close GVIP1, open GV8, close GV2 after 2 minutes, open GVIP1. Close GVIP2, open GVMS, close GVMS after 1 minute, open GV2, and perform mass spectrometry measurement. 4 He, the measured signal is recorded as Sig8. After the measurement, turn on GVIP2. Turn off GV8 and turn on GVIP1. The formula is .

[0097] k) Repeat the above steps three or more times and take the average value as the fixed value of each part volume.

[0098] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calibrating the volume of a gas measurement system, characterized in that: The following steps are involved: S1. Preparation: Vacuum the gas measurement system, remove the residual gas in the system, and set each valve of the system to the initial state; S2. Calibrate the volume of the tube section closest to the mass spectrometer: S2.

1. High-purity gas injection: high-purity He gas is injected into the mass spectrometer by diffusion; the He gas signal intensity is measured by the mass spectrometer; during the measurement, except for the mass spectrometer, the remaining pipelines are evacuated to remove residual gas; S2.2, diffuse the gas in the mass spectrometer back to the target section, measure the He gas signal intensity again through the mass spectrometer, and calculate the volume of the tube section in combination with the inner cavity volume of the mass spectrometer; S2.3, repeat the above S2.1 and S2.2 processes several times, and calculate the average value to obtain the volume of the tube section closest to the mass spectrometer; S3. Calibrate the volume of other pipe sections: S3.

1. High-purity gas injection: Inject high-purity He gas into the entire pipeline; S3.

2. Open the corresponding valves one by one in the order from the closest to the mass spectrometer to the farthest, measure the signal intensity difference through the mass spectrometer, and recursively calculate the volume of each section; S3.3, record and output: record the volume of each section of the pipeline to obtain the complete volume distribution data of the system; S3.

4. Repeat S3.1 to S3.3 several times and calculate the average value.

2. A method for calibrating the volume of a gas measurement system according to claim 1, characterized in that: The step of calibrating the volume of the tube section closest to the mass spectrometer specifically includes: By opening and closing the corresponding valve, high-purity He gas is diffused into the mass spectrometer; Measure the He signal intensity by mass spectrometer and record the initial signal value; Close all other valves connected to this pipe section; Back-diffusion of the gas in the mass spectrometer to the tube section, and measurement of the back-diffusion signal value; Calculate the pipe segment volume using the following formula: in, is the volume of the tube section closest to the mass spectrometer to be calibrated, To measure the He signal intensity for the mass spectrometer, is the He signal intensity after the He gas in the mass spectrometer diffuses back to the tube section closest to the mass spectrometer, is the volume of the mass spectrometer cavity.

3. A method for calibrating the volume of a gas measurement system according to claim 2, characterized in that: When calibrating the volumes of other pipe sections, the calibration is performed section by section in the order from near to far from the mass spectrometer; when calibrating a certain pipe section, the gas in the pipe section is first diffused into the pipe section closest to the mass spectrometer, and the gas in the pipe section closest to the mass spectrometer is taken into the mass spectrometer for measurement; Calculate according to the following recursive formula: in, To be calibrated Pipeline volume, For mass spectrometer measurement The He gas signal strength of the pipeline section, The signal intensity of He gas in the initial calibration tube section is measured for the mass spectrometer. For the front The sum of the volumes of the pipe segments.

4. A method for calibrating the volume of a gas measurement system according to claim 1, characterized in that: During the calibration process, the injection amount of high-purity He gas was controlled at 1×10 -3 ccSTP~5×10 -3 ccSTP.

5. A method for calibrating the volume of a gas measurement system according to claim 1, characterized in that: The volume calibration of each pipe section was repeated at least 3 times, and the average value was taken as the final volume value of the section.

6. A method for calibrating the volume of a gas measurement system according to claim 1, characterized in that: The gas measurement system comprises a plurality of valves, pipes and a mass spectrometer, wherein: Valves GVTP and GVIP1 are connected to the vacuum pump; valves GV2-GV8 are connected to the various sections of the pipeline of the gas measurement system in sequence to achieve isolation or connection of the various pipe sections; valve GVMS is connected to the inlet of the mass spectrometer. The initial state of the system is: GVTP, GVIP1, GV2, GV3, GV4, GV5, GV6, and GV7 are in the open state, and the remaining valves are in the closed state.

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