Device and method for measuring leakage rate of sealing body based on oxygen-containing method

Abstract

The invention discloses a sealing body leakage rate measuring device and method based on an oxygen method. According to the sealing body leakage rate measuring device based on the oxygen-containing method, the boosting suppression module is introduced, so that the boosting overrun of the relative pressure of the internal pressure of the measured sealing body and the atmospheric pressure is effectively suppressed in one direction within the detection time, the relative pressure change is maintained within a safe change range, and a measurement result meeting effective detection conditions is given. According to the sealing body leakage rate measurement method based on airtight pressure tank calibration, loop background leakage and an additional volume effect in an oxygen-containing method measurement process can be removed; the more real unit volume hourly leakage rate of the measured object is used for replacing the unit volume hourly leakage rate of the negative pressure internal circulation gas path system directly measured by the oxygen-containing method to serve as a basis for evaluating the sealing performance of the measured object, so that the measurement precision of the leakage rate measured by the oxygen-containing method is improved; and the application lower limit of a standard oxygen-containing method can be extended to a small-volume high-airtightness assembly.

Description

Technical Field

[0001] This article relates to the field of sealing performance testing technology for sealed equipment, and in particular to a device and method for measuring the leakage rate of a sealed body based on the oxygen-containing method. It is suitable for accurate and quantitative leakage detection of various sealed bodies with high airtightness requirements. It also relates to a method for measuring the leakage rate of a sealed body based on the calibration of an airtight pressure tank. This measurement method is based on the strategy of removing loop background leakage and volume effect, and is particularly suitable for small-volume sealed bodies under test. Background Technology

[0002] Sealed chambers, sealed containers, and similar sealed bodies are critical infrastructure in many high-tech industries and research fields. Their core function is to provide a controlled internal atmosphere space isolated from the external environment to enable the safe handling, processing, or storage of internal materials (such as radioactive, toxic, highly reactive, moisture- or oxygen-sensitive, or high-purity substances) and to prevent leakage or the intrusion of external contaminants. To ensure safety and process integrity, the sealing performance of such equipment must be accurately quantified and rigorously monitored.

[0003] Currently, mainstream leak detection methods include the bubble method, constant pressure method, pressure change method, helium mass spectrometry leak detection method, and oxygen-containing method. Among these, the oxygen-containing method measures the increase in oxygen content over time within a sealed body that has been pre-cleaned with inert gas and maintained at a certain negative pressure to calculate the leak. Essentially, it characterizes the infiltration of atmospheric oxygen into the negative pressure system. The purpose of pre-cleaning the sealed body with inert gas is to reduce the oxygen content inside the sealed body to a level compatible with the leak rate to be measured. By measuring the change in oxygen content inside the sealed body from the start to the end of the measurement, the hourly leak rate per unit volume can be calculated using equation (I): (I) In the formula, O 2f It is the oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement, in ppm; O 2i It is the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement, in ppm; t It measures the duration, in minutes. T f This represents the leakage rate per unit volume per hour of the entire negative pressure internal circulation air circuit system of the measuring device, in h. -1 . T fThis refers to the physical quantity used in the Chinese nuclear industry standard EJ / T 1096—1999, "Classification of Sealing Performance of Sealed Containers and Test Methods," for classifying sealing levels. EJ / T 1096—1999 clearly specifies the leakage rate per unit volume per hour. T f The system of sealing ratings, with the highest level, Class 1, requiring... T f No more than 5×10 -4 h -1 It is suitable for handling extremely hazardous substances or sensitive applications requiring extremely stringent controlled inert atmospheres.

[0004] After the oxygen-containing method measurement is completed, the following three valid inspection conditions must be met for the test results to be accepted: 1. The internal temperature change of the sealed body is less than 3℃; 2. The atmospheric pressure change is less than 1000 Pa; 3. The absolute value of the relative pressure change between the internal pressure of the sealed body and the atmospheric pressure is less than 50 Pa (to ensure the relative stability of the leakage driving pressure difference). If all three conditions are not met during the measurement process, the results will not be accepted and must be re-inspected. If they are within the limits, it is not necessary to correct the measurement results due to these changes. Summary of the Invention

[0005] While existing oxygen-based leak detection technologies are theoretically mature, in practical engineering applications, they suffer from significant "detection blind spots" due to stringent validity criteria and the diversity of the objects being tested. (1) Hard constraints on validity criteria According to EJ / T 1096—1999 "Classification and Test Methods for Sealing Performance of Sealed Chambers", a crucial prerequisite for the validity of the oxygen-containing method test is that the absolute value of the relative pressure change between the internal pressure of the tested seal and atmospheric pressure is less than 50 Pa (i.e., the third valid test condition). However, this condition is difficult to maintain in the following two common scenarios. First, for gas circuit systems containing the tested seal with relatively poor sealing performance, continuous leakage leads to gas accumulation inside, causing the relative pressure to easily rise towards atmospheric pressure and exceed the 50 Pa limit, directly resulting in test interruption or invalid results. Second, when the external atmospheric pressure continuously decreases, even if the gas circuit system has good sealing performance and the internal pressure remains relatively stable, the relative pressure difference between the inside and outside of the tested seal will passively increase, potentially exceeding the 50 Pa limit within the test time range, causing a previously qualified test to be deemed invalid due to environmental interference; or, if the external atmospheric pressure rises abnormally and the magnitude exceeds the system leakage accumulation rate, the relative pressure may also continuously decrease and exceed the limit.

[0006] (2) Measurement distortion of small-volume objects The measurement principle of the oxygen-containing method determines the leakage rate per unit volume per hour that it measures. T f The measurement method considers not only the hourly leakage rate of the tested seal, but also the entire negative pressure internal circulation gas path system constructed during the measurement phase. Oxygen permeates and neutralizes within the entire effective volume of the gas path system. Standard oxygen-based methods typically ignore the influence of additional loop volume and background leakage on the tested object, because the volume of the tested object is usually much larger than the additional volume, which includes connected pipes, filters, valves, sensors, oxygen analyzers, etc. However, when the volume of the tested object is small, this influence can cause the hourly leakage rate of the system measured by the oxygen-based method to deviate significantly from the true hourly leakage rate per unit volume of the tested object, resulting in substantial measurement errors and even misjudgments of seal classification.

[0007] From a formulaic perspective, the relationship between the total hourly leakage of the entire negative pressure internal circulation air circuit system of the measuring device and the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device is as follows: (1) In equation (1), Q total The leakage rate measurement indicates the total hourly leakage of the entire negative pressure internal circulation air circuit system (including the measured seal) of the measuring device during leakage rate measurement, in L / h. T f This represents the hourly leakage rate per unit volume of the entire negative pressure internal circulation gas path system, calculated using equation (I) after the oxygen content method measurement is completed. The unit is h. -1 ; V total The total effective volume of the negative pressure internal circulation air circuit system of the measuring device represents the entire internal space involved in flow mixing during the internal circulation process. The unit is L (liters). It can be further broken down into the volume of the sealed body being measured. V test With additional volume V add .

[0008] also, Q total It can also be expressed as follows: (2) Right now Q total This can be considered as the hourly leakage of the tested seal. Q test Hourly leakage rate with additional volume Q add The sum of T test and T addThese correspond to the leakage rate per unit volume per hour of the tested seal and the leakage rate per unit volume per hour of the additional volume, respectively. Combining equations (1) and (2), we get: (3) It can be seen from equation (3) that when the volume of the sealed body being measured... V test Much larger than the additional volume V add Furthermore, the additional volume corresponding to the part should be properly sealed to control the leakage rate to a low level. At this time, we can obtain equation (3) T test ≈ T f Therefore, it can be directly used T f To evaluate the sealing performance of the tested seal. However, when V test V add No longer sufficient, especially when measuring small-volume boxes, the results obtained directly from the oxygen content method are no longer satisfactory. T f It will deviate significantly T test It is no longer possible to directly rate the sealing performance. Figure 4 This demonstrates the leakage rate per unit volume of the tested seal in the embodiments of this application, assuming the actual volume of the tested seal is small. T test Under different conditions, the volume of the tested sealed body V test The leakage rate per unit volume per hour of the negative pressure internal circulation air circuit system directly measured by the oxygen-containing method T f The relationship between them.

[0009] Based on this, in a first aspect, embodiments of this application provide a sealing body leakage rate measuring device based on an oxygen-containing method, comprising: The test sealing body 26, the cleaning gas source 11, the vacuum pump 34, the oxygen analyzer 36, the sampling pump 35, the pressure rise suppression module 27, the inlet pipeline 371, the oxygen analyzer inlet and outlet pipelines 374, the circulation pipeline 376, the first exhaust pipeline 372, the second exhaust pipeline 373, the third exhaust pipeline 375, and the valve groups installed on each pipeline. The outlet of the cleaning air source 11 is connected to the inlet of the tested sealing body 26 through the inlet pipe 371. The outlet of the tested sealing body 26 is connected to one end of the oxygen analyzer inlet / outlet pipeline 374, and the other end of the oxygen analyzer inlet / outlet pipeline 374 is connected to one end of the circulation pipeline 376, and the other end of the circulation pipeline 376 is connected to the inlet of the tested sealing body 26; a sampling pump 35 and an oxygen analyzer 36 are provided on the oxygen analyzer inlet / outlet pipeline 374; wherein, the sampling pump 35 is used to pump gas at a specific sample gas flow rate required by the oxygen analyzer 36. One end of the first exhaust pipe 372 is connected to the outlet of the test sealing body 26, and the other end is connected to the atmosphere. It can be used to divert and discharge the gas inside the test sealing body 26 and the inlet pipe 371 when cleaning with cleaning gas, and to depressurize the device after cleaning. One end of the second exhaust pipe 373 is connected to the outlet of the tested sealing body 26, and the other end is connected to the inlet of the vacuum pump 34. The outlet of the vacuum pump 34 is connected to the atmosphere and can be used to draw negative pressure on the sealing body leakage rate measuring device so that the interior of the tested sealing body 26 reaches the relative pressure required for measurement. One end of the third exhaust pipe 375 is connected to the connection between the oxygen analyzer inlet / outlet pipe 374 and the circulation pipe 376, and the other end is connected to the atmosphere. It is used to discharge the sampling gas flow through the oxygen analyzer inlet / outlet pipe 374 or the gas discharged from the circulation pipe 376 when cleaning with cleaning gas. The boost suppression module 27 is connected to the tested sealing body 26, and the boost suppression module 27 includes: A pressure-boosting and suppression exhaust pipe 377 is provided, with one end connected to the tested sealing body 26 and the other end connected to the atmosphere; the pressure-boosting and suppression exhaust pipe 377 is provided with an eighth ball valve 271, a normally closed pressure-holding solenoid valve 272, a third one-way valve 273, and a vacuum pump 275 in sequence from the tested sealing body 26 to the atmosphere; The pressure transmitter 274 is connected to the pressure-boosting and pressure-suppressing exhaust pipe 377 between the eighth ball valve 271 and the normally closed pressure-holding solenoid valve 272, and is electrically connected to the measuring and control instrument 276. It is used to detect the relative pressure between the internal pressure of the measured sealing body 26 and the atmospheric pressure and transmit it to the measuring and control instrument 276 as an analog signal. The measuring and control instrument 276 is electrically connected to the normally closed pressure-holding solenoid valve 272, the pressure transmitter 274 and the air pump 275. It is used to receive and process the signal transmitted by the pressure transmitter 274 and control the on / off state of the normally closed pressure-holding solenoid valve 272 and the air pump 275. Using the relative pressure between the internal pressure of the tested seal 26 and atmospheric pressure, which is required for the seal leakage rate measurement, as the reference value, the measuring and control instrument 276 is set with a first upper limit value, a second upper limit value, a first hysteresis value, and a second hysteresis value, wherein the first upper limit value - the first hysteresis value = the second upper limit value - the second hysteresis value, and the second upper limit value, the first upper limit value, the reference value, and the second hysteresis value satisfy one of the following conditions: (a) the second upper limit value > the first upper limit value > the reference value ≥ the second upper limit value - the second hysteresis value, wherein the value of the second hysteresis value is taken from the relative pressure change between the internal pressure of the tested seal 26 and atmospheric pressure that meets the requirements of the oxygen-containing method for measuring the seal leakage rate. (a) Within the range of absolute values; (b) Second upper limit value > First upper limit value > Second upper limit value - Second hysteresis value ≥ Reference value, wherein the value of the second upper limit value - Reference value is within the range of the absolute value of the relative pressure change between the internal pressure of the tested sealing body 26 and the atmospheric pressure, which meets the requirements of the oxygen-containing method for measuring the leakage rate of the sealing body; the measuring and control instrument is set to control the air pump to start when the relative pressure between the internal pressure of the tested sealing body and the atmospheric pressure rises to the first upper limit value; control the normally closed pressure-holding solenoid valve to start when the relative pressure rises to the second upper limit value; control the normally closed pressure-holding solenoid valve and the air pump to stop when the relative pressure drops from the second upper limit value to the second hysteresis value.

[0010] Secondly, embodiments of this application provide a leakage rate measurement method for a sealing body leakage rate measurement device based on an oxygen-containing method. The measurement method employs the sealing body leakage rate measurement device of the first aspect, and includes: S101. Turn on the oxygen analyzer 36, the cleaning gas source 11, the valve group installed in the inlet pipe 371, and the valve group installed in the first exhaust pipe 372. Open the eighth ball valve 271 to control the cleaning gas flow rate, so that the sealed body 26 under test is kept under positive pressure relative to atmospheric pressure. Control the pipeline valve group to complete the following cleaning steps: (i) Open the valve group installed in the circulation pipeline 376 and the valve group installed in the third exhaust pipeline 375 to clean the tested sealing body 26 and the circulation pipeline 376; after cleaning, close the valve group installed in the third exhaust pipeline 375 and the valve group installed in the circulation pipeline 376. (ii) Turn on the sampling pump 35, open the valve group set in the oxygen analyzer inlet and outlet gas line 374, open the valve group set in the third exhaust gas line 375, control the cleaning gas flow rate pumped by the sampling pump 35 to meet the requirements of the oxygen analyzer 36, and clean the tested sealing body 26 and the oxygen analyzer inlet and outlet gas line 374; until the oxygen concentration measured by the oxygen analyzer 36 (usually about 100 ppm or lower) and the oxygen concentration decrease rate (this requirement can be determined according to the actual situation, for example, the decrease does not exceed 1 ppm every 2 minutes) reach the measurement requirements, close the valve group set in the third exhaust gas line 375 and the sampling pump 35, open the valve group set in the circulation line 376, and stop cleaning; Adjust the cleaning air flow rate to 0, and close the valve group installed in the first exhaust pipe 372 and the valve group installed in the intake pipe 371 when the internal pressure of the tested sealing body 26 remains positive relative to atmospheric pressure. S102. Turn on the vacuum pump 34, open the valve group set in the second exhaust pipe 373, draw negative pressure to the measuring device, and when the relative pressure between the internal pressure of the measured sealing body 26 and the atmospheric pressure reaches the relative pressure required for measurement, close the valve group set in the second exhaust pipe 373 and turn off the vacuum pump 34. S103. Turn on the sampling pump 35, turn on the measuring and control instrument 276 and pressure transmitter 274 to activate the function of the pressure rise suppression module 27. When the oxygen concentration reading of the oxygen analyzer 36 is relatively stable and shows a near-linear increase, the measurement stage begins. S104. Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement. O 2i Unit: ppm, after a measurement period of time t Unit: min (corresponding to the measured hourly leakage rate, typically 30 min). After the measurement, record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the end of the measurement. O 2f (Unit: ppm), and during the measurement process, the internal temperature, atmospheric pressure and relative pressure changes of the internal pressure of the tested seal 26 to the atmospheric pressure are monitored; S105. Based on the changes in internal temperature, atmospheric pressure, and relative pressure between the internal pressure and atmospheric pressure of the tested seal 26 during the measurement process, determine whether all the effective conditions for the oxygen-containing method test are met. If not all conditions are met, the test fails and must be repeated. If all conditions are met, use formula (I) to calculate the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device. T f Unit: h -1 ; (I).

[0011] Thirdly, embodiments of this application provide a method for measuring the leakage rate of a sealed body based on an oxygen-containing method. This method employs a loop background leakage and volume effect removal strategy based on an airtight pressure tank calibration, including: S100. The leakage rate measurement device for the sealed body based on the oxygen-containing method is used to measure the leakage rate of the sealed body under test, and the oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device is recorded at the beginning of the measurement. O 2i (Unit: ppm) Oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement.O 2f (Unit: ppm) and measurement duration t (Unit: min), calculate the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device when the tested sealing body is the test object using formula (I). T f Unit: h -1 ; (I) S200. Define the additional volume as the total effective volume of the negative pressure internal circulation air circuit system of the measuring device, excluding the volume of the object being measured, during leakage rate measurement. V add (Unit: L); Following the same measurement method as in step S100 when the tested sealing body is used as the test object, the tested sealing body is replaced with two or more different volumes. V tank Leakage rate measurements were performed on an airtight pressure vessel (unit: L) to account for additional volume in measurements using the tested seal as the test object and in measurements using the airtight pressure vessel as the test object. V add and hourly leakage of additional volume Q add (Unit: L / h) is considered a constant; wherein, the hourly leakage rate of the airtight pressure tank is... Q tank Hourly leakage of additional volume Q add That is, satisfying equation (II), so that when the airtight pressure tank is the object being measured, the total hourly leakage of the entire negative pressure internal circulation air circuit system of the measuring device is... Q total_tank Hourly leakage rate approximately equal to the additional volume Q add ; Q total_tank = Q tank + Q add ≈ Q add (II) Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement when each of the aforementioned airtight pressure tanks is used as the test object. O 2i (Unit: ppm) Oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f(Unit: ppm) and measurement duration t (Unit: min), the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device is calculated using formula (I) when the airtight pressure tank is the object of measurement, and is denoted as T f_tank ; S300. The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device when the airtight pressure tanks of different volumes are used as the test objects. T f_tank Value and rated volume of airtight pressure vessel V tank Substitute the values ​​into equation (III) respectively; when measuring two airtight pressure tanks of different volumes, the values ​​can be substituted into each group simultaneously. T f_tank Value and V tank Solving the system of equations for the additional volume V add and hourly leakage of additional volume Q add When measuring three or more airtight pressure vessels of different volumes, the values ​​can be substituted into each group simultaneously. T f_tank Value and V tank The system of overdetermined equations composed of values ​​is obtained using the least squares method. V add and Q add ; Q add = T f_tank ×( V tank + V add (III) S400. The solution obtained V add and Q add The unit volume per hour leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device, calculated when the sealed body under test is taken as the test object. T f and the volume of the sealed body being tested. V test Substituting into equation (IV), the leakage rate per unit volume per hour of the tested seal is obtained after removing background leakage from the loop and the additional volume effect. T test ; Ttest = ( T f × ( V test + V add ) – Q add ) / V test (IV).

[0012] Compared with the prior art, the embodiments of this application have the following beneficial effects: 1. The oxygen-containing method-based sealing leakage rate measurement device provided in this application utilizes a pressure rise suppression module to effectively unidirectionally clamp the increase of relative pressure inside the tested sealing body beyond the limit during the detection time, maintaining the relative pressure change within a safe range (e.g., 50 Pa). This allows for successful testing of internal gas path leakage conditions that would otherwise be impossible to detect due to excessive pressure rise, as well as unstable conditions with decreasing atmospheric pressure, providing measurement results that meet the valid testing conditions.

[0013] 2. The leakage rate measurement method for sealed bodies based on the calibration of an airtight pressure tank provided in this application can eliminate the background leakage and additional volume effect in the oxygen-containing method measurement process, and use a more realistic leakage rate per unit volume per hour of the measured object. T test The hourly leakage rate per unit volume of the negative pressure internal circulation air circuit system, which can be directly measured using the oxygen-containing method instead of the oxygen-containing method. T f As a basis for evaluating sealing performance, it improves the measurement accuracy of leakage rate by oxygen-containing method, solves the problem of accurate measurement of sealing performance of the tested object, especially small-volume tested object, and can extend the lower limit of application of standard oxygen-containing method to high airtight components with small volume (such as 1 L level).

[0014] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0015] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0016] Figure 1 This is a schematic diagram of a sealing leakage rate measuring device based on the oxygen-containing method according to an embodiment of this application.

[0017] Figure 2 yes Figure 1 The diagram shows the internal structure of the boost suppression module.

[0018] Figure 3 This is a simplified diagram of the gas path markings for a sealing body leakage rate measuring device based on the oxygen-containing method, according to an embodiment of this application.

[0019] Figure 4 This is a sealing leakage rate measuring device based on the oxygen-containing method, according to an embodiment of this application, which obtains an additional volume after calibration. V add and hourly leakage of additional volume Q add Based on this, assume the actual leakage rate per unit volume per hour of the tested seal. T test At different critical lines of sealing performance, the volumes of the tested sealing bodies are different. V test The leakage rate per unit volume per hour of the negative pressure internal circulation gas circuit system of the measuring device directly measured by the oxygen-containing method. T f A diagram showing the relationships between them.

[0020] Figure 5 This is a schematic diagram of the structure of a small-volume test sealing chamber for an O-ring flange end face seal used in an embodiment of this application.

[0021] Figure 6 This application presents a sealing leakage rate measuring device based on the oxygen-containing method. The results compare the hourly leakage rate per unit volume of the negative pressure internal circulation gas circuit system of the measuring device directly measured by the oxygen-containing method under different operating conditions with the hourly leakage rate per unit volume calculated by removing the background leakage of the loop and the volume effect.

[0022] Figure label: 11-Cleaning air source, 12-Pressure reducing valve, 13-First ball valve, 14-Second ball valve, 15-Third ball valve, 16-Fourth ball valve, 17-Fifth ball valve, 18-Sixth ball valve, 19-Seventh ball valve, 20-Mass flow controller, 21-First check valve, 22-Second check valve, 23-First high-efficiency particulate filter, 24-Second high-efficiency particulate filter, 25-Third high-efficiency particulate filter, 26-Tested sealing body, 27-Pressure rise suppression module, 28-First thermometer, 29-Second thermometer, 30-First differential pressure gauge, 31-Barometer, 32-Second differential pressure gauge, 33-Needle valve, 34-Vacuum pump, 35-Sampling device Pump, 36-Oxygen analyzer, 271-Eighth ball valve, 272-Normally closed pressure-holding solenoid valve, 273-Third check valve, 274-Pressure transmitter, 275-Air pump, 276-Control instrument, 371-Inlet pipe, 372-First exhaust pipe, 373-Second exhaust pipe, 374-Oxygen analyzer inlet and outlet pipes, 375-Third exhaust pipe, 376-Circulation pipe, 377-Pressure boosting and suppressing exhaust pipe, 261-Groove cover plate, 262-Rectangular annular O-ring seal, 263-Flanged sealing housing, 264-Fastening bolts, 2631-Inlet, 2632-Outlet, 2633-External module interface. Detailed Implementation

[0023] This application describes several embodiments, but these descriptions are exemplary and not limiting, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0024] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0025] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of that feature.

[0026] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0027] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0030] Firstly, embodiments of this application provide a sealing body leakage rate measurement device based on an oxygen-containing method, such as... Figures 1 to 3 As shown, the measuring device includes: The test sealing body 26, the cleaning gas source 11, the vacuum pump 34, the oxygen analyzer 36, the sampling pump 35, the pressure rise suppression module 27, the inlet pipeline 371, the oxygen analyzer inlet and outlet pipelines 374, the circulation pipeline 376, the first exhaust pipeline 372, the second exhaust pipeline 373, the third exhaust pipeline 375, and the valve groups installed on each pipeline. The outlet of the cleaning air source 11 is connected to the inlet of the tested sealing body 26 through the inlet pipe 371. The outlet of the tested sealing body 26 is connected to one end of the oxygen analyzer inlet / outlet pipeline 374, and the other end of the oxygen analyzer inlet / outlet pipeline 374 is connected to one end of the circulation pipeline 376, and the other end of the circulation pipeline 376 is connected to the inlet of the tested sealing body 26; a sampling pump 35 and an oxygen analyzer 36 are provided on the oxygen analyzer inlet / outlet pipeline 374; wherein, the sampling pump 35 is used to pump gas at a specific sample gas flow rate required by the oxygen analyzer 36. One end of the first exhaust pipe 372 is connected to the air outlet of the tested sealing body 26, and the other end is connected to the atmosphere. It can be used to divert and discharge the gas inside the tested sealing body 26 and the air inlet pipe 371 when cleaning with cleaning gas, and to depressurize the sealing body leakage rate measuring device after cleaning. One end of the second exhaust pipe 373 is connected to the outlet of the tested sealing body 26, and the other end is connected to the inlet of the vacuum pump 34. The outlet of the vacuum pump 34 is connected to the atmosphere and can be used to draw negative pressure on the sealing body leakage rate measuring device so that the interior of the tested sealing body 26 reaches the relative pressure required for measurement. One end of the third exhaust pipe 375 is connected to the connection between the oxygen analyzer inlet / outlet pipe 374 and the circulation pipe 376, and the other end is connected to the atmosphere. It is used to discharge the sampling gas flow through the oxygen analyzer inlet / outlet pipe 374 or the gas discharged from the circulation pipe 376 when cleaning with cleaning gas. The boost suppression module 27 is connected to the tested sealing body 26, and the boost suppression module 27 includes: A pressure-boosting and suppression exhaust pipe 377 is provided, with one end connected to the tested sealing body 26 and the other end connected to the atmosphere; the pressure-boosting and suppression exhaust pipe 377 is provided with an eighth ball valve 271, a normally closed pressure-holding solenoid valve 272, a third one-way valve 273, and a vacuum pump 275 in sequence from the tested sealing body 26 to the atmosphere; The pressure transmitter 274 is connected to the pressure-boosting and pressure-suppressing exhaust pipe 377 between the eighth ball valve 271 and the normally closed pressure-holding solenoid valve 272, and is electrically connected to the measuring and control instrument 276. It is used to detect the relative pressure between the internal pressure of the measured sealing body 26 and the atmospheric pressure and transmit it to the measuring and control instrument 276 as an analog signal. The measuring and control instrument 276 is electrically connected to the normally closed pressure-holding solenoid valve 272, the pressure transmitter 274 and the air pump 275. It is used to receive and process the signals transmitted by the pressure transmitter 274 and control the on / off state of the normally closed pressure-holding solenoid valve 272 and the air pump 275.

[0031] The pressure rise suppression module 27 is used to suppress excessive relative pressure rise caused by leakage in the internal gas path system or a decrease in external atmospheric pressure during the measurement of the seal leakage rate. The pressure rise suppression module 27 can effectively unidirectionally clamp the excessive relative pressure rise between the internal pressure of the tested seal and atmospheric pressure during the detection time, maintaining the relative pressure change within a safe range (e.g., 50 Pa). This allows for successful testing under conditions of high internal gas path leakage that would otherwise be impossible to measure due to excessive pressure rise, as well as unstable conditions of atmospheric pressure drop, providing measurement results that meet the valid testing conditions.

[0032] In this article, the term "sealed body" refers to a device that has a controlled internal atmosphere space isolated from the external environment to enable the safe operation, handling, or storage of internal substances (such as radioactive, toxic, highly active, moisture- or oxygen-sensitive, or high-purity substances) and to prevent their leakage or the intrusion of external contaminants. This includes, but is not limited to, sealed chambers, glove boxes, vacuum tube furnaces, double-lid transfer sealed barrels, and gas storage tanks.

[0033] In one exemplary embodiment, the relative pressure between the internal pressure of the tested seal 26 and atmospheric pressure, which is required for the seal leakage rate measurement, is used as the reference value. The measuring and control instrument 276 is set with a first upper limit value, a second upper limit value, a first hysteresis value, and a second hysteresis value, wherein the first upper limit value - the first hysteresis value = the second upper limit value - the second hysteresis value, and the second upper limit value, the first upper limit value, the reference value, and the second hysteresis value satisfy one of the following conditions: (a) the second upper limit value > the first upper limit value > the reference value ≥ the second upper limit value - the second hysteresis value, wherein the value of the second hysteresis value is within the range of the absolute value of the relative pressure change between the internal pressure of the tested seal 26 and atmospheric pressure that meets the requirements of the oxygen-containing method for measuring the seal leakage rate; (b) the second upper limit value > the first upper limit value > the second upper limit value - the second hysteresis value ≥ the reference value, wherein the value of the second upper limit value - the reference value is within the range of the absolute value of the relative pressure change between the internal pressure of the tested seal 26 and atmospheric pressure that meets the requirements of the oxygen-containing method for measuring the seal leakage rate. The measuring and control instrument 276 is configured to control the air pump 275 to open when the relative pressure between the internal pressure of the tested sealing body 26 and atmospheric pressure rises to a first upper limit value; control the normally closed pressure-holding solenoid valve 272 to open when the relative pressure rises to a second upper limit value; and control the normally closed pressure-holding solenoid valve 272 and the air pump 275 to close when the relative pressure drops from the second upper limit value to a second hysteresis value. This ensures that the air pump 275 opens slightly before the normally closed pressure-holding solenoid valve 272 opens and closes as the normally closed solenoid valve 272 closes, preventing the backflow of gas inside the pressure rise suppression module 27 from contaminating the internal atmosphere of the tested sealing body 26. Wherein, relative pressure = internal pressure of the tested sealing body 26 - atmospheric pressure.

[0034] In one exemplary embodiment, the value of the second backlash in scenario (a) or the value of the second upper limit value-reference value in scenario (b) is within 60% to 80% of the maximum absolute value of the relative pressure change between the internal pressure of the tested sealing body 26 and atmospheric pressure, which meets the requirements for measuring the leakage rate of the sealing body using the oxygen-containing method, to ensure the validity of the test results. In another exemplary embodiment, the leakage rate of the sealing body is measured according to EJ / T 1096—1999 "Classification of Sealing Performance of Sealing Chambers and Its Test Methods", which requires that the maximum absolute value of the relative pressure change between the internal pressure of the tested sealing body and atmospheric pressure be 50 Pa. Therefore, the value of the second backlash in scenario (a) or the value of the second upper limit value-reference value in scenario (b) can be within 60% to 80% of 50 Pa, i.e., 30 Pa to 40 Pa.

[0035] In one exemplary embodiment, the air pump 275 has an adjustable flow rate and can be used in conjunction with the measuring and control instrument 276 to perform quantitative pulse pumping of the gas inside the sealed body 26 under test, ensuring that the relative pressure between the internal pressure of the sealed body 26 under test and atmospheric pressure is within a relatively stable range.

[0036] In one exemplary embodiment, the sealing body leakage rate measuring device may further include at least one filter device for filtering impurities such as solid and liquid particles in the pipeline to prevent contamination of the measuring system. The filter device may be a high-efficiency particulate filter. In one exemplary embodiment, the sealing body leakage rate measuring device further includes a first high-efficiency particulate filter 23; the first high-efficiency particulate filter 23 is disposed between the air inlet pipeline 371 and the circulation pipeline 376 and the sealing body 26 under test, the air inlet of the first high-efficiency particulate filter 23 is connected to the air inlet pipeline 371 and the circulation pipeline 376, and the air outlet of the first high-efficiency particulate filter 23 is connected to the air inlet of the sealing body 26 under test. In one exemplary embodiment, the sealing body leakage rate measuring device further includes a second high-efficiency particulate filter 24. The second high-efficiency particulate filter 24 can be disposed between the tested sealing body 26 and the oxygen analyzer inlet / outlet pipeline 374, the first exhaust pipeline 372, and the second exhaust pipeline 373. The inlet of the second high-efficiency particulate filter 24 is connected to the outlet of the tested sealing body 26, and the outlet of the second high-efficiency particulate filter 24 is connected to the oxygen analyzer inlet / outlet pipeline 374, the first exhaust pipeline 372, and the second exhaust pipeline 373. In another exemplary embodiment, the sealing body leakage rate measuring device further includes a third high-efficiency particulate filter 25. The third high-efficiency particulate filter 25 is disposed between the oxygen analyzer inlet / outlet pipeline 374 and the oxygen analyzer 36. The inlet of the third high-efficiency particulate filter 25 is connected to the oxygen analyzer inlet / outlet pipeline 374, and the outlet of the third high-efficiency particulate filter 25 is connected to the oxygen analyzer 36.

[0037] In one exemplary embodiment, the seal leakage rate measuring device may further include at least one mass flow controller. In one exemplary embodiment, the mass flow controller 20 is disposed on the air inlet pipe 371 and is used to control the cleaning air flow rate to achieve a stable cleaning and purification process.

[0038] In one exemplary embodiment, the sealing body leakage rate measuring device may further include at least one monitoring instrument for monitoring temperature or pressure affecting the leakage rate measurement. In another exemplary embodiment, the sealing body leakage rate measuring device may further include one or more of the following monitoring instruments: a first thermometer 28 disposed inside the sealed body 26 under test for monitoring its temperature; a second thermometer 29 for monitoring the ambient temperature; a first differential pressure gauge 30 for monitoring the relative pressure between the internal pressure of the sealed body 26 and atmospheric pressure; a barometer 31 for monitoring atmospheric pressure; and a second differential pressure gauge 32 for monitoring the relative pressure at the inlet of the oxygen analyzer 36, to determine the validity of the oxygen-containing method testing conditions and ensure the safety of the operation process. In one exemplary embodiment, the first thermometer 28 may have wireless Bluetooth transmission functionality, so that the internal temperature of the sealed body 26 under test can be obtained without the need for transparency or an observation window. In one exemplary embodiment, the first differential pressure gauge 30 and the second differential pressure gauge 32 can be connected to the tested sealing body 26 and the oxygen analyzer inlet pipe 374 respectively by threaded connection, and sealant can be used at the threaded connection to ensure sealing.

[0039] In one exemplary embodiment, the vacuum pump 34 has pressure-adjustable or speed-adjustable functions, which can relatively accurately control the relative pressure required for measurement by drawing gas from the measuring device.

[0040] In one exemplary embodiment, the cleaning gas source 11 can be selected from high-purity nitrogen or high-purity argon, used to efficiently clean and purify the gas inside the sealing body leakage rate measuring device, and quickly reduce the oxygen concentration inside the measuring device.

[0041] In one exemplary embodiment, the oxygen analyzer 36 measures the volume concentration of oxygen (O2) from 0.1 ppm to 25%, with a resolution of 0.1 ppm in the range of 0.1 ppm to 100 ppm and 1 ppm in the range of 100 ppm to 1000 ppm. The oxygen analyzer 36 has an automatic switching function between different ranges. The oxygen analyzer 36 may also contain a flow valve and a float flow meter. The opening of the flow valve can be adjusted by a knob, and the float flow meter displays the flow rate passing through the oxygen analyzer 36 in real time.

[0042] In one exemplary embodiment, the sampling pump 35 has an adjustable flow rate. The sampling pump 35 can be an airtight micro-pump with a flow rate 1.5 times that required by the maximum flow rate oxygen analyzer 36. In another exemplary embodiment, the inlet and outlet of the sampling pump 35 have tapered or pagoda-shaped connectors for connecting high-airtightness hoses. During installation, sealant can be evenly applied to the connector before installing the high-airtightness hose of the appropriate diameter, and clamps can be used to tighten the connector end to ensure a tight seal at the connector.

[0043] In one exemplary embodiment, the valves or valve groups installed on each pipeline in the sealing body leakage rate measuring device include any one or more of the following: pressure reducing valve (for reducing and stabilizing the gas delivery pressure), check valve (for preventing gas backflow), ball valve (for opening or closing the gas path), and needle valve (for regulating gas flow rate), used to guide the airflow to switch between different gas paths and ensure the safety of the operation process. In one exemplary embodiment, a pressure reducing valve 12, a first ball valve 13, and a first check valve 21 are sequentially installed on the inlet pipeline 371 from the cleaning gas source 11 to the tested sealing body 26. In one exemplary embodiment, a fourth ball valve 16 and a fifth ball valve 17 are installed on the oxygen analyzer inlet and outlet pipelines 374. In one exemplary embodiment, a sixth ball valve 18 is installed on the circulation pipeline 376. In one exemplary embodiment, a second ball valve 14 and a needle valve 33 are sequentially installed on the first exhaust pipeline 372 from the outlet of the tested sealing body 26 to the atmosphere. In one exemplary embodiment, a third ball valve 15 and a second check valve 22 are sequentially arranged in the direction from the outlet of the tested sealing body 26 to the vacuum pump 34 in the second exhaust pipe 373. In another exemplary embodiment, a seventh ball valve 19 is provided on the third exhaust pipe 375.

[0044] In one exemplary embodiment, the gas lines (371-377) are connected to other components via quick-connect fittings or compression fittings to ensure a tight seal at the connection.

[0045] Secondly, embodiments of this application provide a leakage rate measurement method for a sealing body leakage rate measurement device based on an oxygen-containing method. The measurement method employs the sealing body leakage rate measurement device of the first aspect, and includes: S101. Turn on the oxygen analyzer 36, the cleaning gas source 11, the valve group installed in the inlet pipe 371, and the valve group installed in the first exhaust pipe 372. Open the eighth ball valve 271 to control the cleaning gas flow rate, so that the sealed body 26 under test is kept under positive pressure relative to atmospheric pressure. Control the pipeline valve group to complete the following cleaning steps: (i) Open the valve group installed in the circulation pipeline 376 and the valve group installed in the third exhaust pipeline 375 to clean the tested sealing body 26 and the circulation pipeline 376; after cleaning, close the valve group installed in the third exhaust pipeline 375 and the valve group installed in the circulation pipeline 376. (ii) Turn on the sampling pump 35, open the valve group set in the oxygen analyzer inlet and outlet gas line 374, open the valve group set in the third exhaust gas line 375, control the cleaning gas flow rate pumped by the sampling pump 35 to meet the requirements of the oxygen analyzer 36, and clean the tested sealing body 26 and the oxygen analyzer inlet and outlet gas line 374; until the oxygen concentration measured by the oxygen analyzer 36 (usually about 100 ppm or lower) and the oxygen concentration decrease rate (this requirement can be determined according to the actual situation, for example, the decrease does not exceed 1 ppm every 2 minutes) reach the measurement requirements, close the valve group set in the third exhaust gas line 375 and the sampling pump 35, open the valve group set in the circulation line 376, and stop cleaning; Adjust the cleaning air flow rate to 0, and close the valve group installed in the first exhaust pipe 372 and the valve group installed in the intake pipe 371 when the internal pressure of the tested sealing body 26 remains positive relative to atmospheric pressure. S102. Turn on the vacuum pump 34, open the valve group set in the second exhaust pipe 373, draw negative pressure to the measuring device, and when the relative pressure between the internal pressure of the measured sealing body 26 and the atmospheric pressure reaches the relative pressure required for measurement, close the valve group set in the second exhaust pipe 373 and turn off the vacuum pump 34. S103. Turn on the sampling pump 35, turn on the measuring and control instrument 276 and pressure transmitter 274 to activate the function of the pressure rise suppression module 27. When the oxygen concentration reading of the oxygen analyzer 36 is relatively stable and shows a near-linear increase, the measurement stage begins. S104. Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement. O 2i Unit: ppm, after a measurement period of time t Unit: min (corresponding to the measured hourly leakage rate, typically 30 min). After the measurement, record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the end of the measurement. O 2f (Unit: ppm), and during the measurement process, the internal temperature, atmospheric pressure and relative pressure changes of the internal pressure of the tested seal 26 to the atmospheric pressure are monitored; S105. Based on the changes in internal temperature, atmospheric pressure, and relative pressure between the internal pressure and atmospheric pressure of the tested seal 26 during the measurement process, determine whether all the effective conditions for the oxygen-containing method test are met. If not all conditions are met, the test fails and must be repeated. If all conditions are met, use formula (I) to calculate the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device. T f Unit: h -1 ; (I).

[0046] According to EJ / T 1096—1999 "Classification and Test Methods for Sealing Performance of Sealed Chambers", the valid conditions for the oxygen-containing method test include: (1) The internal temperature change of the sealed body being measured during the measurement process is less than 3℃; (2) The atmospheric pressure change during the measurement process is less than 1000 Pa; (3) The absolute value of the relative pressure change between the internal pressure of the sealed body and the atmospheric pressure during the measurement process is less than 50 Pa.

[0047] Thirdly, embodiments of this application provide a method for measuring the leakage rate of a sealed body based on an oxygen-containing method. This method employs a loop background leakage and volume effect removal strategy based on an airtight pressure tank calibration, including: S100. The leakage rate measurement device for the sealed body based on the oxygen-containing method is used to measure the leakage rate of the sealed body under test, and the oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device is recorded at the beginning of the measurement. O 2i (Unit: ppm) Oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f (Unit: ppm) and measurement duration t (Unit: min), calculate the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device when the tested sealing body is the test object using formula (I). T f Unit: h -1 ; (I) S200. Define the additional volume as the total effective volume of the negative pressure internal circulation air circuit system of the measuring device, excluding the volume of the object being measured, during leakage rate measurement. V add (Unit: L); Following the same measurement method as in step S100 when the tested sealing body is used as the test object, the tested sealing body is replaced with two or more different volumes. Vtank Leakage rate measurements were performed on an airtight pressure vessel (unit: L) to account for additional volume in measurements using the tested seal as the test object and in measurements using the airtight pressure vessel as the test object. V add and hourly leakage of additional volume Q add (Unit: L / h) is considered a constant; wherein, the hourly leakage rate of the airtight pressure tank is... Q tank Hourly leakage of additional volume Q add That is, satisfying equation (II), so that when the airtight pressure tank is the object being measured, the total hourly leakage of the entire negative pressure internal circulation air circuit system of the measuring device is... Q total_tank Hourly leakage rate approximately equal to the additional volume Q add ; Q total_tank = Q tank + Q add ≈ Q add (II) Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement when each of the aforementioned airtight pressure tanks is used as the test object. O 2i (Unit: ppm) Oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f (Unit: ppm) and measurement duration t (Unit: min), the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device is calculated using formula (I) when the airtight pressure tank is the object of measurement, and is denoted as T f_tank (Unit: h) -1 ); S300. The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device when the airtight pressure tanks of different volumes are used as the test objects. T f_tank Value and the rated volume of the airtight pressure vessel V tank Substitute the values ​​into equation (III) respectively; when measuring two airtight pressure tanks of different volumes, the values ​​can be substituted into each group simultaneously. T f_tank Value and Vtank Solving the system of equations for the additional volume V add and hourly leakage of additional volume Q add When measuring three or more airtight pressure vessels of different volumes, the values ​​of T in each group can be substituted together. f_tank Value and V tank The system of overdetermined equations composed of values ​​is obtained using the least squares method. V add and Q add ; Q add = T f_tank ×( V tank + V add (III) S400. The solution obtained V add and Q add The unit volume hourly leakage rate T of the entire negative pressure internal circulation air circuit system of the measuring device is calculated when the sealed body under test is taken as the test object. f and the volume of the sealed body being tested. V test Substituting into equation (IV), the leakage rate per unit volume per hour of the tested seal is obtained after removing background leakage from the loop and the additional volume effect. T test ; T test = ( T f × ( V test + V add ) – Q add ) / V test (IV).

[0048] The third aspect of this application describes a method for measuring the leakage rate of a sealed body based on an oxygen-containing method, in which the sealed body under test is sequentially replaced with different volumes. V tank And its hourly leakage volume Q tank Hourly leakage of additional volume Q addThe oxygen content method was used to measure the oxygen content of the airtight pressure tank, and the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device was calculated by formula (I) when the airtight pressure tank was the test object. T f_tank The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device when using tanks with different airtight pressures as the test objects. T f_tank Value and the corresponding rated volume of the airtight pressure vessel V tank Substituting the values ​​into equation (III) and solving the simultaneous equations, the additional volume is calculated. V add and its hourly leakage volume Q add Then, according to equation (IV), the leakage rate per unit volume per hour of the tested seal body after removing background leakage from the circuit and the additional volume effect is obtained. T test This method uses a more realistic leakage rate per unit volume of the tested object per hour. T test The hourly leakage rate per unit volume of the negative pressure internal circulation air circuit system, which can be directly measured using the oxygen-containing method instead of the oxygen-containing method. T f As a basis for evaluating sealing performance, it improves the measurement accuracy of leakage rate by oxygen-containing method, solves the problem of accurate measurement of sealing performance of the tested object, especially small-volume tested object, and can extend the lower limit of application of standard oxygen-containing method to high airtight components with small volume (such as 1 L level).

[0049] In one exemplary embodiment, step S100 of the third aspect of the method for measuring the leakage rate of a seal based on an oxygen-containing method can be performed according to steps S101 to S105 of the second aspect of the method for measuring the leakage rate of a seal based on an oxygen-containing method.

[0050] In one exemplary embodiment, in step S200, the hourly leakage rate of the tested airtight pressure tank is... Q tank hourly leakage rate for additional volume Q add Less than 1 / 100.

[0051] In one exemplary embodiment, in steps S100 and S200, each object under test is measured at least three times to ensure repeatability.

[0052] In one exemplary embodiment, all airtight pressure tanks of different volumes are manufactured in the same production process, using continuous argon arc welding and passing non-destructive testing to ensure that their hourly leakage is within the same range. Q tank Consistent and significantly lower than the hourly leakage rate of the additional volume Qadd This is to improve the calibration accuracy of background leakage.

[0053] In one exemplary embodiment, all airtight pressure tanks of different volumes are calibrated by filling them with water. For example, their actual volume is obtained using a graduated cylinder. V tank This is to improve the calibration accuracy of background leakage.

[0054] In one exemplary embodiment, the volumes of the airtight pressure vessels of different capacities can be distributed across the estimated additional volume. V add The range is from 20% to 200%. The different volumes of the airtight pressure tanks used also have a certain range between them (for example, the difference between adjacent volumes is not less than the additional volume). V add 20% of the calculated additional volume V add and its hourly leakage volume Q add The computational robustness.

[0055] Example 1 This embodiment combines Figures 1 to 3 This application describes the specific structure of the oxygen-based seal leakage rate measuring device and the leakage rate measuring method based on the device.

[0056] like Figures 1 to 3 As shown, the sealing body leakage rate measuring device includes: a cleaning air source 11, a sealing body under test 26, a vacuum pump 34, a sampling pump 35, an oxygen analyzer 36, a pressure boost suppression module 27, a mass flow controller 20, a first high-efficiency particulate filter 23, a second high-efficiency particulate filter 24, a third high-efficiency particulate filter 25, monitoring instruments (28-32), an inlet pipe 371, an oxygen analyzer inlet and outlet pipes 374, a circulation pipe 376, a first exhaust pipe 372, a second exhaust pipe 373, and a third exhaust pipe 375, and valve groups (12-19, 21-22, 33) installed on each pipe. The outlet of the cleaning air source 11 is connected to the inlet of the tested sealing body 26 via the inlet pipe 371; the first high-efficiency particle filter 23 is disposed between the inlet pipe 371 and the inlet of the tested sealing body 26, the inlet of the first high-efficiency particle filter 23 is connected to the inlet pipe 371, and the outlet of the first high-efficiency particle filter 23 is connected to the inlet of the tested sealing body 26; the inlet pipe 371 is sequentially provided with a pressure reducing valve 12, a first ball valve 13, a mass flow controller 20, and a first check valve 21 in the direction from the cleaning air source 11 to the tested sealing body 26; The outlet of the tested sealing body 26 is connected to one end of the oxygen analyzer inlet / outlet pipeline 374, and the other end of the oxygen analyzer inlet / outlet pipeline 374 is connected to one end of the circulation pipeline 376. The other end of the circulation pipeline 376 is connected to the inlet of the first high-efficiency particulate filter 23. A second high-efficiency particulate filter 24 is disposed between the tested sealing body 26 and the oxygen analyzer inlet / outlet pipeline 374. The inlet of the second high-efficiency particulate filter 24 is connected to the outlet of the tested sealing body 26, and the outlet of the second high-efficiency particulate filter 24 is connected to the oxygen analyzer inlet / outlet pipeline 374. A fourth ball valve 16, a sampling pump 35, a second differential pressure gauge 32 (used to monitor the relative pressure at the inlet of the oxygen analyzer 36), an oxygen analyzer 36, and a fifth ball valve 17 are installed in the gas pipeline 374 from the tested sealing body 26 to the circulation pipeline 376. A third high-efficiency particulate filter 25 is installed between the oxygen analyzer inlet / outlet pipeline 374 and the oxygen analyzer 36. The inlet of the third high-efficiency particulate filter 25 is connected to the oxygen analyzer inlet / outlet pipeline 374, and the outlet of the third high-efficiency particulate filter 25 is connected to the oxygen analyzer 36. A sixth ball valve 18 is installed on the circulation pipeline 376. One end of the first exhaust pipe 372 is connected to the outlet of the second high-efficiency particle filter 24, and the other end is connected to the atmosphere; the first exhaust pipe 372 is provided with a second ball valve 14 and a needle valve 33 in sequence from the outlet of the tested sealing body 26 to the atmosphere. One end of the second exhaust pipe 373 is connected to the outlet of the second high-efficiency particle filter 24, and the other end is connected to the inlet of the vacuum pump 34. The outlet of the vacuum pump 34 is connected to the atmosphere and can be used to draw negative pressure to the sealing body leakage rate measuring device so that the inside of the sealed body under test reaches the relative pressure required for measurement. The second exhaust pipe 373 is provided with a third ball valve 15 and a second one-way valve 22 in sequence from the outlet of the sealed body under test 26 to the vacuum pump 34. One end of the third exhaust pipe 375 is connected to the connection between the oxygen analyzer inlet / outlet pipe 374 and the circulation pipe 376, and the other end is connected to the atmosphere. A seventh ball valve 19 is installed on the third exhaust pipe 375. The pressure suppression module 27 is connected to the tested sealing body 26. The pressure suppression module 27 includes: a pressure suppression exhaust pipe 377, a pressure transmitter 274, and a measuring and controlling instrument 276. One end of the pressure suppression exhaust pipe 377 is connected to the tested sealing body 26, and the other end is connected to the atmosphere. The pressure suppression exhaust pipe 377 is sequentially arranged with an eighth ball valve 271, a normally closed pressure-holding solenoid valve 272, a third check valve 273, and a vacuum pump 275 in the direction from the tested sealing body 26 to the atmosphere. The pressure transmitter 274 is connected to the pressure suppression unit between the eighth ball valve 271 and the normally closed pressure-holding solenoid valve 272. The exhaust pipe 377 is electrically connected to the measuring and control instrument 276, used to detect the relative pressure between the internal pressure of the tested sealing body 26 and atmospheric pressure and transmit it to the measuring and control instrument 276 as an analog signal; the measuring and control instrument 276 is electrically connected to the normally closed pressure-holding solenoid valve 272, the pressure transmitter 274 and the air pump 275, used to receive and process the signal transmitted by the pressure transmitter 274 and control the on / off state of the normally closed pressure-holding solenoid valve 272 and the air pump 275; the relative pressure between the internal pressure of the tested sealing body 26 and atmospheric pressure required by the sealing body leakage rate measurement is used as the reference value (in this embodiment, it is -1000). The controller 276 is set with a first upper limit value (-970 Pa), a first hysteresis value (20 Pa), a second upper limit value (-960 Pa), and a second hysteresis value (30 Pa). The controller 276 is configured to control the air pump 275 to open when the relative pressure between the internal pressure of the tested sealing body 26 and atmospheric pressure rises to the first upper limit value; control the normally closed pressure-holding solenoid valve 272 to open when the relative pressure rises to the second upper limit value; and control the normally closed pressure-holding solenoid valve 272 and the air pump 275 to close when the relative pressure drops from the second upper limit value to the second hysteresis value. This ensures that the air pump 275 opens slightly before the normally closed pressure-holding solenoid valve 272 and closes when the normally closed solenoid valve 272 closes, thus preventing the backflow of gas inside the pressure rise suppression module 27 from contaminating the internal atmosphere of the tested sealing body 26. A first thermometer 28 is installed inside the sealed body 26 under test, and the sealed body 26 under test is connected to a first differential pressure gauge 30. The second thermometer 29 is used to monitor the ambient temperature; the barometer 31 is used to monitor the atmospheric pressure.

[0057] according to Figures 1 to 3 A leak rate measurement device for a sealed body is constructed, with all components kept in the closed state. The leak rate measurement method based on the aforementioned leak rate measurement device includes the following steps: S1010. Turn on the oxygen analyzer 36, turn on the cleaning gas source 11, adjust the pressure reducing valve 12 to generate a suitable output pressure, open the first ball valve 13 and the second ball valve 14, open the eighth ball valve 271, appropriately open the needle valve 33, turn on the mass flow controller 20 and set the flow rate to a suitable parameter (adapt the cleaning flow rate according to the volume of the sealed body 26 being measured), fine-tune the opening of the needle valve 33 to maintain the reading of the first differential pressure gauge 30 in a suitable positive pressure state, and complete the following cleaning steps by controlling the pipeline valve group: (i) Open the sixth ball valve 18 and the seventh ball valve 19 in sequence to clean the tested sealing body 26 and the circulation pipeline 376. The circulation pipeline 376 has low resistance and forms the main cleaning. After cleaning, close the seventh ball valve 19 and the sixth ball valve 18 in sequence. (ii) Open the fifth ball valve 17, start the sampling pump 35, and then open the fourth ball valve 16 and the seventh ball valve 19 in sequence. Gradually open the flow valve built into the oxygen analyzer 36, and simultaneously adjust the pumping flow of the sampling pump 35. Observe the reading of the second differential pressure gauge 32, so that the air float flow meter built into the oxygen analyzer 36 can stably indicate the required specific sample gas flow (250 mL / min in this embodiment). Clean the tested sealing body 26 and the oxygen analyzer inlet and outlet gas pipeline 374. Until the oxygen concentration measured by the oxygen analyzer 36 (approximately 100 ppm or lower) and the oxygen concentration decrease rate (no more than 1 ppm decrease every 2 min) meet the measurement requirements, close the seventh ball valve 19, then close the sampling pump 35, open the sixth ball valve 18, and stop cleaning. Turn off the mass flow controller 20, observe the reading of the first differential pressure gauge 30, and when the reading leaves a slight positive pressure, quickly close the second ball valve 14 to release the pressure of the measurement system, and close the first ball valve 13. S1020. Turn on the vacuum pump 34 (preset pressure), open the third ball valve 15, draw negative pressure into the measurement system, and when the relative pressure between the internal pressure of the measured sealing body 26 and the atmospheric pressure (the reading of the first differential pressure gauge 30) reaches the relative pressure required for measurement (the acceptance pressure used in this embodiment is -1000 Pa), close the third ball valve 15 and turn off the vacuum pump 34. S1030. Turn on the sampling pump 35, turn on the measuring and control instrument 276 and pressure transmitter 274 to activate the function of the pressure rise suppression module 27. At this time, the gas inside the entire measuring device is in a negative pressure internal circulation state. When the oxygen concentration reading of the oxygen analyzer 36 is relatively stable and shows a near-linear increase, the measurement stage begins. S1040. Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement. O 2i (Unit: ppm), after a measurement duration t(Unit: min; corresponding to the measured hourly leakage rate, typically 30 min) After the measurement, record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the end of the measurement. O 2f (Unit: ppm), and during the measurement process, the changes in the internal temperature of the tested sealing body 26 (reading of the first thermometer 28), the ambient temperature (reading of the second thermometer 29), the atmospheric pressure (reading of the barometer 31), and the relative pressure between the internal pressure of the tested sealing body and the atmospheric pressure (reading of the first differential pressure gauge 30) are monitored. S1050. According to EJ / T 1096—1999 "Classification and Inspection Method of Sealing Performance of Sealed Chambers", the effective conditions for oxygen-containing method inspection include: (1) the internal temperature change of the tested sealing body during the measurement process is less than 3℃; (2) the atmospheric pressure change during the measurement process is less than 1000 Pa; (3) the absolute value of the relative pressure change between the internal pressure of the tested sealing body and the atmospheric pressure during the measurement process is less than 50 Pa; based on the changes in atmospheric pressure, the relative pressure between the internal pressure of the tested sealing body 26 and the atmospheric pressure, and the internal temperature change of the tested sealing body 26 during the measurement process, it is determined whether all the effective conditions for oxygen-containing method inspection are met. If not all are met, the test fails and must be re-measured; if all are met, the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device is calculated using formula (I). T f Unit: h -1 ; (I).

[0058] After the experiment is completed, shut down all gas path components and restore the measuring device to its initial state.

[0059] Example 2 This embodiment provides a method for measuring the leakage rate of a sealed body based on an oxygen-containing method. This method uses a strategy for removing background leakage and volumetric effects from a calibrated airtight pressure tank. This is illustrated in Example 1. Figures 1 to 3 The described sealing leakage rate measuring device is implemented, and the measurement method includes: S1000. Adopted by Figures 1 to 3 The described sealing leakage rate measuring device measures the leakage rate of the sealed body 26 (volume 1.8 L) according to steps S1010 to S1050 of the sealing leakage rate measuring method in Example 1 at a reference value of -1000 Pa for the relative pressure between the internal pressure of the sealed body 26 and atmospheric pressure. The oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device is recorded at the start of the measurement. O 2i (Unit: ppm) Oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f(Unit: ppm) and measurement duration t (Unit: min), the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device is calculated using formula (I) when the tested sealing body 26 is the tested object. T f Unit: h -1 ; (I) S2000. The additional volume is defined as the total effective volume of the negative pressure internal circulation air circuit system of the measuring device, excluding the volume of the object being measured, during leakage rate measurement. V add (V in this embodiment) add The estimated value is approximately 4.2 L); following the same measurement method as in step S1000 when the tested seal 26 is the test object, the tested seal 26 is replaced with 1L, 2L, and 3L airtight pressure vessels for leakage rate measurement, respectively, to add volume in the measurements when the tested seal 26 is the test object and when the airtight pressure vessel is the test object. V add and hourly leakage of additional volume Q add Considered a constant; in this embodiment, the hourly leakage rate of the airtight pressure tank is... Q tank Hourly leakage of additional volume Q add That is, satisfying equation (II), so that when the airtight pressure tank is the object being measured, the total hourly leakage of the entire negative pressure internal circulation air circuit system of the measuring device is... Q total_tank Hourly leakage rate approximately equal to the additional volume Q add ; Q total_tank = Q tank + Q add ≈ Q add (II) When each airtight pressure vessel is used as the test object, record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement. O 2i (Unit: ppm) Oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f (Unit: ppm) and measurement duration t(Unit: min), the hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device is calculated using formula (I) when the airtight pressure tank is the object being measured, and is denoted as T f_tank ; S3000. The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device when using airtight pressure tanks of different volumes as the test object. T f_tank Value and rated volume of airtight pressure vessel V tank Substitute the values ​​into equation (III) respectively, and then combine them into the equation. T f_tank Value and V tank The system of overdetermined equations composed of values ​​is obtained using the least squares method. V add = 4.24 L, Q add = 12.18×10 -4 L / h; Q add = T f_tank ×( V tank + V add (III) S4000. The solution obtained V add and Q add The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device, calculated when the tested sealing body 26 is taken as the tested object. T f and the volume of the tested sealed body 26 V test Substituting into equation (IV), the leakage rate per unit volume per hour of the tested seal 26 after removing background leakage from the loop and the additional volume effect is obtained. T test ; T test = ( T f × ( V test + V add ) – Q add ) / Vtest (IV).

[0060] This embodiment also provides a leakage rate measuring device for the sealed body, within the aforementioned calibrated additional volume. V add =4.24 L, hourly leakage rate of additional volume Q add = 12.18×10 -4 Based on L / h, assuming the actual unit volume hourly leakage rate of the tested seal body 26. T test For seals at levels one through four, using formula (IV), the volumes of the tested seals can be plotted. V test The unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device, directly measured by the oxygen-containing method when the tested sealing body 26 is used as the test object. T f Theoretical relationship diagram between them (see) Figure 4 ), showing the change in the volume of the measured sealed body. V test The increase, T f The closer T test This indicates that for large-volume sealed bodies, the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device, which can be directly measured by the oxygen-containing method, can be obtained. T f The leakage rate per unit volume per hour of the measured object is approximately considered as T test It is directly used to classify and determine the sealing performance of a sealing body; however, for small-volume sealing bodies, such as... V test With additional volume V add When the levels are within the same order of magnitude or differ by only one order of magnitude, for the calibration results of this embodiment, the measured hourly leakage rate per unit volume of the entire negative pressure internal circulation air circuit system of the measuring device at the critical line of sealing performance for levels one to four is... T f This will be significantly lower than the hourly leakage rate per unit volume of the corresponding tested object. T test If we do not deduct the background leakage and volume effect of the loop, but instead use T f Directly judging sealing performance can underestimate the actual leakage of the tested seal and may even lead to incorrect classification of the sealing level. In short, the hourly leakage rate obtained directly from the oxygen-based method... T f There is an inherent systematic bias, especially when the volume of the sealed body being tested is...V test At very low speeds, the hourly leakage rate per unit volume of the entire negative pressure internal circulation gas path system of the measuring device, directly measured using the oxygen-containing method, is... T f Leakage rate per unit volume per hour of the tested object T test The error is significant.

[0061] Example 3 This embodiment provides a small-volume box (1.8 L) sealed at a certain end face as the sealed body 26, using a material... Figures 1 to 3 The described sealing leakage rate measuring device, according to Example 2, uses a loop background leakage and volume effect removal strategy based on the oxygen-containing method for measuring the sealing leakage rate, and performs oxygen-containing method leakage rate measurement under different operating conditions.

[0062] The structure of the end-face sealed small-volume box is as follows: Figure 5 As shown, the sealed chamber includes a grooved cover plate 261, a rectangular annular O-ring seal 262, a flanged sealed chamber 263, and fastening bolts 264. The grooved cover plate 261 has several circumferentially evenly arranged threaded holes. The rectangular annular O-ring seal 262 is installed in the groove of the grooved cover plate 261. The flanged sealed chamber 263 has through holes corresponding to the threaded holes of the grooved cover plate 261, and also has an air inlet 2631 for air intake, an air outlet 2632 for air exhaust, and an external module interface 2633 for connecting the pressure boost suppression module 27 and the first differential pressure gauge 30. The fastening bolts 264 are used to tighten the flange surface of the flanged sealed chamber 263 to the surface of the grooved cover plate 261, while simultaneously compressing the rectangular annular O-ring seal 262 within the groove of the grooved cover plate 261, filling the gap between the mating surfaces to form a seal. The fastening bolt 264 can achieve different degrees of fit between the mating surfaces by adjusting the tightness, that is, control different compression rates of the rectangular annular O-ring seal 262, thereby changing the sealing performance of the tested sealing chamber.

[0063] In this embodiment, the leakage rate was measured by the oxygen method under three different working conditions, with only the tightness of several fastening bolts 264 being changed. Working condition 1: Fastening bolts 264 were tightened; Working condition 2: Fastening bolts 264 were slightly loosened; Working condition 3: Fastening bolts 264 were further loosened.

[0064] Figure 6 The results of the leakage rate measurement of the small-volume test sealing chamber of the O-ring flange end face seal are shown, and compared with the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device directly measured by the oxygen method. T fThe actual hourly leakage rate per unit volume of the tested object, calculated by removing background leakage and volumetric effect. T test This indicates that for small-volume sealed chambers under test, the leakage is significantly affected by background leakage in the circuit and volume effect. The unit volume per hour leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device, directly measured by the oxygen-containing method, is... T f At this point, compared to the actual leakage rate per unit volume of the tested sealed chamber, the leakage rate is... T test It is clearly underestimated, with a correction margin exceeding 150%, if it is still used T f Using this as a criterion for sealing performance can easily lead to misjudgment of the risk of sealing failure, highlighting the necessity of background leakage and volume effect removal strategies for this circuit, especially for small-volume test objects.

[0065] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A device for measuring the leakage rate of a sealed body based on an oxygen-containing method, characterized in that, The measuring device includes: The test sealing body, cleaning gas source, vacuum pump, oxygen analyzer, sampling pump, pressure boost suppression module, inlet pipeline, oxygen analyzer inlet and outlet pipelines, circulation pipeline, first exhaust pipeline, second exhaust pipeline, third exhaust pipeline, and valve groups installed on each pipeline. The outlet of the cleaning air source is connected to the inlet of the sealed body under test through the inlet pipe; The outlet of the tested sealing body is connected to one end of the oxygen analyzer's inlet and outlet pipeline, the other end of the oxygen analyzer's inlet and outlet pipeline is connected to one end of the circulation pipeline, and the other end of the circulation pipeline is connected to the inlet of the tested sealing body; a sampling pump and an oxygen analyzer are installed on the oxygen analyzer's inlet and outlet pipeline; wherein, the sampling pump is used to pump gas at a specific sample gas flow rate required by the oxygen analyzer. One end of the first exhaust pipe is connected to the air outlet of the tested sealing body, and the other end is connected to the atmosphere; One end of the second exhaust pipe is connected to the outlet of the tested sealing body, and the other end is connected to the inlet of the vacuum pump. The outlet of the vacuum pump is connected to the atmosphere. One end of the third exhaust pipe is connected to the connection between the oxygen analyzer's inlet / outlet pipe and the circulation pipe, and the other end is connected to the atmosphere. The voltage boost suppression module is connected to the tested sealing body, and the voltage boost suppression module includes: A pressure-boosting and suppression exhaust pipe is provided, with one end connected to the tested sealing body and the other end connected to the atmosphere; the pressure-boosting and suppression exhaust pipe is provided with an eighth ball valve, a normally closed pressure-holding solenoid valve, a third check valve, and a vacuum pump in sequence from the tested sealing body to the atmosphere. The pressure transmitter is connected to the pressure boosting and suppression exhaust pipeline between the eighth ball valve and the normally closed pressure-holding solenoid valve, and is electrically connected to the measuring and control instrument. It is used to detect the relative pressure between the internal pressure of the measured sealing body and the atmospheric pressure and transmit it to the measuring and control instrument as an analog signal. The measuring and control instrument is electrically connected to the normally closed pressure-holding solenoid valve, pressure transmitter and air pump. It is used to receive and process the signals transmitted by the pressure transmitter and control the on / off state of the normally closed pressure-holding solenoid valve and air pump. Using the relative pressure between the internal pressure of the tested seal and atmospheric pressure required for measuring the seal leakage rate as the reference value, the measuring and control instrument is set with a first upper limit value, a second upper limit value, a first hysteresis value, and a second hysteresis value, wherein the first upper limit value - the first hysteresis value = the second upper limit value - the second hysteresis value, and the second upper limit value, the first upper limit value, the reference value, and the second hysteresis value satisfy one of the following conditions: (a) the second upper limit value > the first upper limit value > the reference value ≥ the second upper limit value - the second hysteresis value, wherein the value of the second hysteresis value is within the absolute range of the relative pressure change between the internal pressure of the tested seal and atmospheric pressure required for measuring the seal leakage rate using the oxygen-containing method. (a) The range of values; (b) the second upper limit value > the first upper limit value > the second upper limit value - the second hysteresis value ≥ the reference value, wherein the value of the second upper limit value - the reference value is within the range of the absolute value of the relative pressure change between the internal pressure of the tested sealing body and the atmospheric pressure that meets the requirements of the oxygen-containing method for measuring the leakage rate of the sealing body; the measuring and control instrument is set to control the air pump to start when the relative pressure between the internal pressure of the tested sealing body and the atmospheric pressure rises to the first upper limit value; control the normally closed pressure-holding solenoid valve to start when the relative pressure rises to the second upper limit value; control the normally closed pressure-holding solenoid valve and the air pump to stop when the relative pressure drops from the second upper limit value to the second hysteresis value.

2. The sealing body leakage rate measuring device according to claim 1, characterized in that, In scenario (a), the value of the second backlash or in scenario (b), the value of the second upper limit value minus the benchmark value, is within 60% to 80% of the maximum absolute value of the relative pressure change between the internal pressure of the tested seal and atmospheric pressure, which meets the requirements for measuring the leakage rate of the seal using the oxygen-containing method.

3. The sealing body leakage rate measuring device according to claim 1 or 2, characterized in that, The sealing body leakage rate measuring device also includes at least one filter device; Optionally, the sealing body leakage rate measuring device further includes a first high-efficiency particle filter, a second high-efficiency particle filter, and a third high-efficiency particle filter; The first high-efficiency particle filter is disposed between the air inlet pipe and the circulation pipe and the sealed body under test. The air inlet of the first high-efficiency particle filter is connected to the air inlet pipe and the circulation pipe, and the air outlet of the first high-efficiency particle filter is connected to the air inlet of the sealed body under test. The second high-efficiency particle filter is disposed between the tested sealing body and the oxygen analyzer's inlet and outlet pipes, first exhaust pipe, and second exhaust pipe. The inlet of the second high-efficiency particle filter is connected to the outlet of the tested sealing body, and the outlet of the second high-efficiency particle filter is connected to the oxygen analyzer's inlet and outlet pipes, first exhaust pipe, and second exhaust pipe. The third high-efficiency particulate filter is disposed between the oxygen analyzer inlet / outlet pipeline and the oxygen analyzer. The inlet of the third high-efficiency particulate filter is connected to the oxygen analyzer inlet / outlet pipeline, and the outlet of the third high-efficiency particulate filter is connected to the oxygen analyzer.

4. The sealing body leakage rate measuring device according to claim 1 or 2, characterized in that, The sealing body leakage rate measuring device further includes at least one mass flow controller; optionally, the mass flow controller is disposed on the air inlet pipe; or The sealing body leakage rate measuring device further includes at least one monitoring instrument for monitoring temperature or pressure that affects the leakage rate measurement; optionally, the sealing body leakage rate measuring device includes: a first thermometer disposed inside the sealing body under test, a first differential pressure gauge for monitoring the relative pressure between the internal pressure of the sealing body under test and atmospheric pressure, a barometer for monitoring atmospheric pressure, and a second differential pressure gauge for monitoring the relative pressure at the inlet of the oxygen analyzer.

5. The sealing body leakage rate measuring device according to claim 1, characterized in that, The valve assemblies installed on each pipeline include: The pressure reducing valve, the first ball valve, and the first check valve are sequentially arranged on the air intake pipe from the cleaning air source to the tested sealing body. The fourth and fifth ball valves are installed on the inlet and outlet gas pipelines of the oxygen analyzer; The sixth ball valve is installed on the circulation pipeline; The first exhaust pipe route includes a second ball valve and a needle valve arranged sequentially in the direction from the outlet of the tested sealing body to the atmosphere; The second exhaust pipe route includes a third ball valve and a second check valve arranged sequentially in the direction from the outlet of the tested sealing body to the vacuum pump; The seventh ball valve is installed on the third exhaust pipe.

6. A leakage rate measurement method for a sealing body leakage rate measurement device based on an oxygen-containing method, characterized in that, The measurement method employs the sealing body leakage rate measuring device as described in any one of claims 1-5, and the measurement method includes: S101. Turn on the oxygen analyzer, the cleaning gas source, the valve group installed in the inlet pipeline, and the valve group installed in the first exhaust pipeline. Open the eighth ball valve to control the cleaning gas flow rate, so that the sealed body under test is kept under positive pressure relative to atmospheric pressure. Control the pipeline valve group to complete the following cleaning steps: (i) Open the valve group installed in the circulation pipeline and the valve group installed in the third exhaust pipeline to clean the tested seal and the circulation pipeline; after cleaning, close the valve group installed in the third exhaust pipeline and the valve group installed in the circulation pipeline. (ii) Turn on the sampling pump, open the valve group installed in the inlet and outlet gas lines of the oxygen analyzer, open the valve group installed in the third exhaust gas line, control the cleaning gas flow rate pumped by the sampling pump to meet the requirements of the oxygen analyzer, and clean the sealed body under test and the inlet and outlet gas lines of the oxygen analyzer; until the oxygen concentration and oxygen concentration decrease rate measured by the oxygen analyzer reach the measurement requirements, close the valve group installed in the third exhaust gas line and the sampling pump, open the valve group installed in the circulation line, and stop cleaning; Adjust the cleaning air flow rate to 0, and close the valve group installed in the first exhaust pipe and the valve group installed in the intake pipe when the internal pressure of the tested sealing body remains positive relative to atmospheric pressure. S102. Turn on the vacuum pump, open the valve group installed in the second exhaust pipe, draw negative pressure into the measuring device, and when the relative pressure between the internal pressure of the measured sealing body and the atmospheric pressure reaches the relative pressure required for measurement, close the valve group installed in the second exhaust pipe and turn off the vacuum pump. S103. Turn on the sampling pump, the measuring and control instrument and the pressure transmitter to activate the function of the pressure rise suppression module. When the oxygen concentration reading of the oxygen analyzer is relatively stable and shows a near-linear increase, enter the measurement stage. S104. Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement. O 2i Unit: ppm, after a measurement period of time t Unit: min. After the measurement ends, record the oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device. O 2f The unit is ppm, and the internal temperature, atmospheric pressure, and relative pressure changes of the internal pressure of the sealed body and the atmospheric pressure are monitored during the measurement process. S105. Based on the changes in internal temperature, atmospheric pressure, and relative pressure between the internal pressure and atmospheric pressure of the tested seal during the measurement process, determine whether all the effective conditions for the oxygen-containing method test are met. If not all conditions are met, the test fails and must be repeated. If all conditions are met, use formula (I) to calculate the unit volume hourly leakage rate of the entire negative pressure internal circulation gas circuit system of the measuring device. T f Unit: h -1 ; (I)。 7. The leakage rate measurement method of the sealing body leakage rate measuring device according to claim 6, characterized in that, According to EJ / T 1096—1999 "Classification and Test Methods for Sealing Performance of Sealed Chambers", the valid conditions for the oxygen-containing method test include: (1) The internal temperature change of the sealed body being measured during the measurement process is less than 3℃; (2) The atmospheric pressure change during the measurement process is less than 1000 Pa; (3) The absolute value of the relative pressure change between the internal pressure of the sealed body and the atmospheric pressure during the measurement process is less than 50 Pa.

8. A method for measuring the leakage rate of a sealed body based on an oxygen-containing method, characterized in that, The measurement method employs a loop background leakage and volume effect removal strategy based on an airtight pressure tank calibration, including: S100. The leakage rate measurement device for the sealed body based on the oxygen-containing method is used to measure the leakage rate of the sealed body under test, and the oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device is recorded at the beginning of the measurement. O 2i Unit: ppm, oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f Unit: ppm, and measurement duration t Unit: min; The unit volume per hour leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device is calculated using formula (I) when the tested sealing body is used as the test object. T f Unit: h -1 ; (I) S200. Define the additional volume as the total effective volume of the negative pressure internal circulation air circuit system of the measuring device, excluding the volume of the object being measured, during leakage rate measurement. V add Unit: L; Following the same measurement method as in step S100 when the tested sealing body is used as the test object, the tested sealing body is replaced with two or more different volumes. V tank Leakage rate measurements were performed on the airtight pressure vessel to account for the additional volume in measurements using the tested seal as the test object and in measurements using the airtight pressure vessel as the test object. V add and hourly leakage of additional volume Q add Considered a constant; wherein, the hourly leakage of the airtight pressure tank. Q tank Hourly leakage of additional volume Q add That is, satisfying equation (II), so that when the airtight pressure tank is the object being measured, the total hourly leakage of the entire negative pressure internal circulation air circuit system of the measuring device is... Q total_tank Hourly leakage rate approximately equal to the additional volume Q add Unit: L / h; Q total_tank = Q tank + Q add ≈ Q add (II) Record the oxygen volume concentration of the entire negative pressure internal circulation gas path system of the measuring device at the start of the measurement when each of the aforementioned airtight pressure tanks is used as the test object. O 2i Unit: ppm, oxygen volume concentration of the entire negative pressure internal circulation gas circuit system of the measuring device at the end of the measurement. O 2f Unit: ppm, and measurement duration t Unit: min. The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device, when the airtight pressure tank is the object of measurement, is calculated using formula (I) and denoted as: T f_tank Unit: h -1 ; S300. The unit volume hourly leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device when the airtight pressure tanks of different volumes are used as the test objects. T f_tank Value and the rated volume of the airtight pressure vessel V tank Values, unit: L, are substituted into equation (III); when measuring two airtight pressure vessels of different volumes, the values ​​can be substituted into each group simultaneously. T f_tank Value and V tank Solving the system of equations for the additional volume V add and hourly leakage of additional volume Q add When measuring three or more airtight pressure vessels of different volumes, the values ​​can be substituted into each group simultaneously. T f_tank Value and V tank The system of overdetermined equations composed of values ​​is obtained using the least squares method. V add and Q add ; Q add = T f_tank ×( V tank + V add ) (III) S400. The solution obtained V add and Q add The unit volume per hour leakage rate of the entire negative pressure internal circulation air circuit system of the measuring device, calculated when the sealed body under test is taken as the test object. T f and the volume of the sealed body being tested. V test Substituting the unit (L) into equation (IV), we obtain the leakage rate per unit volume per hour of the tested seal after removing background leakage from the loop and the additional volume effect. T test Unit: h -1 ; T test = ( T f × ( V test + V add ) – Q add ) / V test (IV)。 9. The method for measuring the leakage rate of a sealed body according to claim 8, characterized in that, The sealing body leakage rate measuring device according to any one of claims 1-6 is used to measure the sealing body in step S100 according to the measurement method of claim 7.

10. The method for measuring the leakage rate of a sealed body according to claim 8, characterized in that, In step S200, the hourly leakage rate of the tested airtight pressure tank is... Q tank hourly leakage rate for additional volume Q add Less than 1 / 100; the volume distribution of the airtight pressure vessels of different volumes used is within the estimated additional volume. V add The range is between 20% and 200%; or In steps S100 and S200, each object being tested is measured at least three times.

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