Method and system for measuring gas density through cooperation of quantitative tank and flowmeter

Abstract

The invention discloses a method and system for measuring gas density through cooperation of a quantitative tank and a flow meter, relates to the technical field of gas density measurement, and remarkably improves the accuracy and repeatability of gas density measurement by adopting a high-precision sensor and automatic data processing. High-quality input of data is ensured through accurate measurement of the mass flow meter, the precise pressure meter and the precise thermometer, and accurate calculation of the data is ensured through the powerful data processing capacity of the PLC or the ARM architecture single-chip microcomputer. In addition, the volume of the quantitative tank is accurately calibrated through standard gas, so that the accuracy of density calculation is further improved. The high-precision measurement not only ensures the reliability of the result, but also is crucial to the quality control link in scientific research and industrial production, and is beneficial to improving the product quality and the production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of gas density measurement, and in particular relates to a method and a system for measuring gas density by using a quantitative tank and a flow meter in combination. Background Art

[0002] At present, there is a wide demand for accurate density measurement of gases, mixed gases and other gases in various scientific research and industrial production processes. In particular, the precise measurement of the density of mixed gases is a key production step in the gas distribution production process. Whether the gas distribution ratio is accurate seriously affects the stability and safety of the production process. Currently, the density meters on the market are rarely used for gas measurement, or can only measure the gas density under working density, which is difficult for use in situations where standard density needs to be measured. Traditional gas density measurement methods mostly use the volume-weight method or are calculated based on the gas state equation at a specific temperature and pressure. Although these methods meet the needs to a certain extent, they have problems such as complex operation, low accuracy, long sampling cycle, and high cost. With the advancement of science and technology, people have begun to explore simpler and more efficient new methods to improve measurement accuracy while reducing costs.

[0003] In order to overcome the shortcomings of traditional methods, the industry usually adopts two main approaches: one is to increase the sensitivity and stability of the instrument by improving its design, such as optimizing the sensor structure and improving the integration of electronic circuits; the other is to introduce new physical and chemical principles as the basis for measurement, such as using non-contact measurement technologies such as laser interferometry and acoustic wave propagation time difference method. However, no matter which method is used, it is inevitable to face certain limitations. For example, the former may be difficult to popularize because it is too dependent on hardware performance, and the latter may be limited to a narrow scope of application under specific conditions.

[0004] Although the above-mentioned improvement measures can improve measurement efficiency and accuracy to a certain extent, the following problems still exist in practical applications: high-end equipment is often expensive, which is not conducive to large-scale promotion and application; secondly, it is difficult to operate and requires professionals to ensure the reliability of the data; at the same time, although some new measurement principles are feasible in theory, they are greatly affected by external interference factors in the actual environment, and their stability and repeatability are poor. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for measuring gas density by using a quantitative tank and a flow meter in combination in order to solve the above-mentioned problems.

[0006] The technical solution adopted by the present invention is as follows: a system for measuring gas density by using a quantitative tank and a flow meter, the system is composed of a gas source, a filter, a mass flow meter, a gas pipeline, a valve control system, a quantitative tank, a precision pressure gauge, a precision thermometer, a control system and an external power supply interface; The valve control system includes a three-way valve and an exhaust valve; The control system is provided with a microprocessor control unit and a touch screen inside; The gas source is connected to the filter through a gas pipeline, the exhaust port of the filter is connected to a mass flow meter, the mass flow meter measures the gas mass flow, and then the gas enters the quantitative tank through the gas pipeline.

[0007] The quantitative tank is internally connected with a precision pressure gauge and a precision thermometer for real-time monitoring of the pressure and temperature changes in the tank.

[0008] The control system is connected to a precision pressure gauge and a precision thermometer via a signal line, receives sensor data, and calculates the density of the gas to be measured via a built-in equation.

[0009] The control system is connected to an external power supply interface.

[0010] In a preferred embodiment, the gas source is the source of the gas to be tested and is connected to other parts of the system through a gas pipeline. The gas inlet and outlet pipelines are respectively connected to the gas source to be tested and the exhaust gas outlet to ensure that the gas can smoothly enter and discharge the system. For dangerous gases, the gas outlet can be guided to a safe area for discharge to ensure operational safety. The gas source part can be provided with a pressure regulating device to adjust the gas pressure as needed.

[0011] In a preferred embodiment, the filter is installed between the gas source and the gas pipeline to filter impurities and particulate matter in the gas, ensuring that the gas entering the mass flow meter is pure and avoiding interference with the measurement results. The filter element can be replaced regularly to ensure the filtering effect.

[0012] In a preferred embodiment, the mass flow meter is connected to the gas pipeline to measure the mass flow of the gas entering the quantitative tank. Its accuracy is 0.2%, and it can accurately measure the mass flow of the gas to provide data support for subsequent density calculation. The mass flow meter can be provided with a flow regulating device to adjust the flow rate of the gas as needed.

[0013] In a preferred embodiment, the gas pipeline is connected to various modules such as the gas source, filter, mass flow meter, quantitative tank, etc. to ensure that the gas can flow smoothly. At the same time, the gas pipeline is also connected to a three-way valve and an exhaust valve to control the flow direction and discharge of the gas. The gas pipeline should be made of corrosion-resistant and pressure-resistant materials and should be inspected and maintained regularly.

[0014] In a preferred embodiment, the valve control system includes a three-way valve and an exhaust valve, and adopts an electromagnetically driven fast switching valve with fast response speed and good sealing. The three-way valve is used to control the flow direction of the gas and can flexibly adjust the flow rate; the exhaust valve is used to discharge waste gas or perform safe exhaust to ensure safe operation. The valve control system can be provided with a control panel for users to remotely control.

[0015] In a preferred embodiment, the quantitative tank is made of stainless steel, which has good corrosion resistance and long service life. Its internal volume is determined by standard gas. When the density of the standard gas is known, the volume of the quantitative tank can be calculated by the gas mass measured by the mass flow meter. A thermometer and a precision pressure gauge are provided outside the quantitative tank to monitor the pressure and temperature changes in the tank in real time. The quantitative tank can be provided with a safety valve to prevent safety accidents caused by excessive pressure.

[0016] In a preferred embodiment, the precision pressure gauge is installed on the quantitative tank to monitor the pressure change in the tank in real time. Its range is set to 0-1MPa, and the resolution can reach 0.001MPa. It can accurately measure the pressure in the tank and provide data support for subsequent density calculation. The precision pressure gauge can be provided with a calibration device to ensure the accuracy of the measurement results; The precision thermometer is installed on the quantitative tank and is used to monitor the gas temperature in the tank in real time. Its working range is -20℃~+200℃±0.1℃, which can accurately measure the gas temperature in the tank and provide data support for subsequent density calculation. The precision thermometer can be provided with a calibration device to ensure the accuracy of the measurement results.

[0017] In a preferred embodiment, the control system includes a PLC or ARM architecture microcontroller, which has powerful data processing capabilities and low power consumption. The control system receives sensor data from a precision pressure gauge and a precision thermometer, and calculates the density of the gas to be measured according to a built-in equation. The calculation results are displayed on a touch screen for the user to view. At the same time, the control system can also set system parameters, such as a cyclic sampling period, etc. The control system can be provided with a remote monitoring function so that the user can remotely view the measurement results and system status; The touch screen is used as a user interface to display measurement results and set system parameters. The touch screen supports Chinese character display, and the interface is friendly and easy to understand, which is convenient for users to operate and use. The touch screen can be set with a password protection function to ensure data security.

[0018] The external power interface supplies power to the entire system to ensure normal operation of the system. The external power interface can be provided with an overload protection device to ensure power safety.

[0019] In a preferred embodiment, a method for measuring gas density using a quantitative tank and a flow meter comprises the following steps: 1) First, make sure all connections are tight and leak-free, and then connect to a stable power supply. Once everything is ready, make corrections and start the cycle mode; 2) Start the valve and run it once to ensure that the medium is full in the pipe; 3) Close the front and rear valves to perform zero point calibration; 4) Calibration method: Password 020 - Modify settings - Zero calibration - "Yes" - Confirm - Wait... 40 seconds for calibration; 5) The completion of zero point calibration can be checked from the touch screen parameter interface; 6) After running the device normally for a few times and the density value becomes stable, it can be corrected to obtain the correction factor.

[0020] After correction, conduct formal measurement, the steps are as follows: 1) Connect the gas to be tested to the gas inlet and observe whether the pressure indication on the display panel is normal; 2) Follow the prompts and open and close the corresponding valves in sequence to inflate and deflate; 3) Record the gas density value shown on the display screen; 4) After the measurement, cut off the power supply and discharge the remaining gas.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In the present invention, the accuracy and repeatability of gas density measurement are significantly improved by adopting high-precision sensors and automated data processing. The precise measurement of mass flow meters, precision pressure gauges and precision thermometers ensures high-quality data input, while the powerful data processing capabilities of PLC or ARM architecture microcontrollers ensure accurate data calculation. In addition, the volume of the quantitative tank is accurately calibrated by standard gas, which further improves the accuracy of density calculation. This high-precision measurement not only ensures the reliability of the results, but is also crucial for quality control in scientific research and industrial production, and helps to improve product quality and production efficiency.

[0022] 2. In the present invention, the automated measurement process greatly simplifies the operation steps and reduces the intensity and complexity of manual operation. The user only needs to start the measurement program through the touch screen to obtain accurate measurement results in a short time. This simple operation method reduces the user's learning cost and makes the device more suitable for non-professional users. At the same time, the device's fast measurement capability (a cycle sampling cycle is completed within 10 to 60 seconds) improves work efficiency and reduces the time and labor cost required for measurement, which is particularly beneficial for occasions where frequent gas density measurements are required.

[0023] 3. In the present invention, relatively low-cost sensors and control systems are used while maintaining high precision and reliability. The low-power design further reduces the operating cost, making the device more economical and practical. In addition, the compact and reasonable design of the device makes maintenance easier, reduces maintenance costs, and improves the durability of the device. These characteristics make the device economical while meeting the needs of high-precision measurement, and suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the overall system block diagram of the present invention; Figure 2 A flowchart of the modification process in the present invention; Figure 3 This is a flow chart of the formal measurement steps in the present invention.

[0025] Markings in the figure: 1. Control system; 2. Gas source; 3. Filter; 4. Mass flow meter; 5. Three-way valve; 6. Quantitative tank; 7. Exhaust valve; 8. Valve control system; 9. Gas pipeline; 10. Precision thermometer; 11. Precision pressure gauge. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Example: Reference Figure 1-3 , a system for measuring gas density by using a quantitative tank and a flow meter, the system consists of a gas source 2, a filter 3, a mass flow meter 4, a gas pipeline 9, a valve control system 8, a quantitative tank 6, a precision pressure gauge 11, a precision thermometer 10, a control system 1 and an external power supply interface; The valve control system 8 includes a three-way valve 5 and an exhaust valve 7 .

[0028] The control system 1 is internally provided with a microprocessor control unit and a touch screen; The gas source 2 is connected to the filter 3 through a gas pipeline 9 , the exhaust port of the filter 3 is connected to a mass flow meter 4 , the mass flow meter 4 measures the gas mass flow rate, and then the gas enters the quantitative tank 6 through the gas pipeline 9 .

[0029] The quantitative tank 6 is internally connected with a precision pressure gauge 11 and a precision thermometer 10 for real-time monitoring of the pressure and temperature changes in the tank.

[0030] The control system 1 is connected to the precision pressure gauge 11 and the precision thermometer 10 via a signal line, receives sensor data, and calculates the density of the gas to be measured through a built-in equation.

[0031] The control system 1 is connected to an external power supply interface.

[0032] As the source of the gas to be tested, it is connected to other parts of the system through the gas pipeline 9. The gas inlet and outlet pipelines are respectively connected to the gas source 2 to be tested and the exhaust gas outlet to ensure that the gas can smoothly enter and discharge the system. For dangerous gases, the gas outlet can be guided to a safe area for discharge to ensure operational safety. The gas source 2 can be provided with a pressure regulating device to adjust the gas pressure as needed.

[0033] The filter 3 is installed between the gas source 2 and the gas pipeline 9 to filter impurities and particulate matter in the gas, ensuring that the gas entering the mass flow meter 4 is pure and avoiding interference with the measurement result. The filter element of the filter 3 can be replaced regularly to ensure the filtering effect.

[0034] The mass flow meter 4 is connected to the gas pipeline 9 and is used to measure the mass flow of the gas entering the quantitative tank 6. Its accuracy is 0.2%, which can accurately measure the mass flow of the gas and provide data support for subsequent density calculation. The mass flow meter 4 can be provided with a flow regulating device to adjust the flow rate of the gas as needed.

[0035] The gas pipeline 9 connects the gas source 2, the filter 3, the mass flow meter 4, the quantitative tank 6 and other modules to ensure that the gas can flow smoothly. At the same time, the gas pipeline 9 is also connected to the three-way valve 5 and the exhaust valve 7 to control the flow direction and discharge of the gas. The gas pipeline 9 should be made of corrosion-resistant and pressure-resistant materials and should be inspected and maintained regularly.

[0036] The valve control system 8 includes a three-way valve 5 and an exhaust valve 7, which adopts an electromagnetically driven fast switching valve with fast response speed and good sealing. The three-way valve 5 is used to control the flow direction of the gas and can flexibly adjust the flow rate; the exhaust valve 7 is used to discharge waste gas or perform safe exhaust to ensure safe operation. The valve control system 8 can be provided with a control panel for users to remotely control.

[0037] The quantitative tank 6 is made of stainless steel, which has good corrosion resistance and long service life. You can choose a suitable internal volume. The volume of the tank can be determined by the standard gas. When the density of the standard gas is known, the gas mass measured by the mass flow meter 4 is assumed to be m, then, v quantitative tank = m / ρ 标准 .

[0038] The dosing tank 6 is provided with a thermometer and a precision pressure gauge 11 outside to monitor the pressure and temperature changes in the tank in real time. The dosing tank 6 can be provided with a safety valve to prevent safety accidents caused by excessive pressure.

[0039] The precision pressure gauge 11 is installed on the quantitative tank 6 to monitor the pressure change in the tank in real time. Its range is set to 0-1MPa, and the resolution can reach 0.001MPa. It can accurately measure the pressure in the tank and provide data support for subsequent density calculation. The precision pressure gauge 11 can be provided with a calibration device to ensure the accuracy of the measurement results.

[0040] Use pressure gauges with different ranges to adapt to a wider range of pressure measurements; you can also replace higher-precision temperature sensors to further improve measurement accuracy.

[0041] The precision thermometer 10 is installed on the quantitative tank 6 to monitor the temperature of the gas in the tank in real time. Its working range is -20℃~+200℃±0.1℃, which can accurately measure the temperature of the gas in the tank and provide data support for the subsequent density calculation. The precision thermometer 10 can be provided with a calibration device to ensure the accuracy of the measurement result.

[0042] The three-way valve 5 is integrated with an air inlet valve. By following the above steps, the mass flow entering the tank can be obtained, the pressure difference before and after the air inlet valve is opened, the measured temperature of the thermometer, and the volume of the tank can be reversed. The measurement accuracy of the device after calibration can reach 0.01kg / m 3 .

[0043] The control system 1 includes a PLC or ARM architecture microcontroller, which has powerful data processing capabilities and low power consumption. The control system 1 receives sensor data from the precision pressure gauge 11 and the precision thermometer 10, and calculates the density of the gas to be measured according to the built-in equation. The calculation results are displayed on the touch screen for the user to view. At the same time, the control system 1 can also set system parameters, such as the cycle sampling period, etc. The control system 1 can be provided with a remote monitoring function so that the user can remotely view the measurement results and system status; When the measurement program is started, the air inlet valve is opened to fill the quantitative tank 6 with the gas to be measured until the preset pressure value is reached, and the air intake is stopped. The mass of the gas entering the tank is measured using a Coriolis mass flowmeter (flowmeter accuracy 0.2%), and the pressure difference is recorded by the pressure transmitter (accuracy 0.075%) before and after the start, as well as the gas temperature after the air intake is completed, through the following equation: ρwork = ρstandard / (P / 101.325)*(293.15 / (273.15+t))*K Example: ρ standard = 1kg / m³; P = 60Kpa; t = 15℃; correction factor K = 1.0 Then: ρwork = 1 / (60 / 101.325)*(293.15 / (273.15+15))*1=1.718kg / m³ The touch screen is used as a user interface to display measurement results and set system parameters. The touch screen supports Chinese character display, and the interface is friendly and easy to understand, which is convenient for users to operate and use. The touch screen can be set with a password protection function to ensure data security. The system is activated by simple button operation to enable it to achieve automatic measurement. During the entire measurement cycle, the microprocessor continuously collects feedback information from each sensor element, calculates the density of the target gas using the built-in equation, and displays it on the screen in a timely manner for reference.

[0044] The external power interface supplies power to the entire system to ensure normal operation of the system. The external power interface can be provided with an overload protection device to ensure power safety.

[0045] A method for measuring gas density by using a quantitative tank and a flow meter, comprising the following steps: 1. Preparation: a. Check the connection: Carefully check all gas pipelines 9, valves, quantitative tanks 6, sensors and other connection parts to ensure that there is no leakage or looseness. Use special sealants or sealing gaskets to strengthen the sealing of the connection.

[0046] b. Fixed placement: Ensure that all equipment is securely fixed to avoid errors caused by vibration or movement during measurement. Check whether the equipment installation location meets the design requirements and is convenient for operation and observation.

[0047] c. Power supply: Connect to a stable external power supply and ensure that the power voltage and frequency meet the system requirements. Check whether the power cord is firmly connected to avoid poor contact or short circuit.

[0048] d. System correction and circulation: Turn on the system and make initial corrections to ensure that all components are operating normally. Start the circulation mode to allow the gas to circulate in the system and check for abnormal sounds or leaks.

[0049] 2. Pre-operation and calibration: a. Valve start-up and medium full pipe: Start the valve control system 8 and run it once to ensure that the gas fills the pipeline and the quantitative tank 6. Observe the readings of the flow meter and pressure gauge to confirm that the gas flows normally.

[0050] b. Zero calibration: Close the front and rear valves, cut off the gas flow, and perform zero calibration. Enter the password (020) as prompted on the touch screen, enter the modification settings menu, and select the zero calibration option. After confirmation, start the calibration and wait for about 40 seconds to complete. Check the "Phase Difference" value on the touch screen to ensure that it is as small as possible, indicating that the calibration is accurate.

[0051] c. Normal operation and correction: Run the machine normally for several times and observe whether the density value is stable. If the density value is stable, perform correction operations and obtain the correction coefficient. The correction coefficient is used to correct the data in the subsequent formal measurement to improve the measurement accuracy.

[0052] 3. Formal measurement: a. Connect the gas to be tested: Connect the gas to be tested to the gas inlet end, and ensure that the connection is firm and leak-free. Observe the pressure indication on the display panel to confirm that the pressure is within the normal range.

[0053] b. Inflation and deflation operation: follow the prompts on the touch screen and open and close the corresponding valves in turn to inflate and deflate. Observe the flow meter reading during inflation to ensure that the gas flow is stable. Pay attention to safety during deflation to avoid danger caused by rapid release of gas.

[0054] c. Record density value: After the density value stabilizes, record the gas density value displayed on the display. You can measure multiple times to get the average value to improve data reliability.

[0055] d. End of measurement and cleaning: After the measurement, cut off the power supply to ensure the safety of the system. Open the exhaust valve 7 to exhaust the remaining gas to avoid gas residue. Clean up the measurement site to ensure that the equipment is clean and tidy and ready for the next measurement.

[0056] During the entire measurement process, keep the operating environment stable to avoid environmental factors such as temperature and humidity from affecting the measurement results. Regularly check and maintain the system to ensure the normal operation of each component and extend the service life of the equipment. Operators should undergo professional training and be familiar with the system operation process and safety precautions. When performing zero point calibration and correction, strictly follow the operating procedures to avoid data errors caused by misoperation. Through the steps described in detail above, it can be ensured that the method of measuring gas density with a quantitative tank and a flow meter is more detailed, accurate and reliable, meeting the high-quality measurement needs in scientific research and industrial production.

[0057] It can be known from the above that in the present invention, the accuracy and repeatability of gas density measurement are significantly improved by adopting high-precision sensors and automated data processing. The accurate measurement of mass flow meter 4, precision pressure gauge 11 and precision thermometer 10 ensures high-quality data input, while the powerful data processing capability of PLC or ARM architecture single-chip microcomputer ensures accurate calculation of data. In addition, the volume of quantitative tank 6 is accurately calibrated by standard gas, which further improves the accuracy of density calculation. This high-precision measurement not only ensures the reliability of the result, but also is crucial for the quality control link in scientific research and industrial production, and helps to improve product quality and production efficiency.

[0058] In the present invention, the automated measurement process greatly simplifies the operation steps and reduces the intensity and complexity of manual operation. The user only needs to start the measurement program through the touch screen to obtain accurate measurement results in a short time. This simple operation method reduces the user's learning cost and makes the device more suitable for non-professional users. At the same time, the device's rapid measurement capability completes a cycle sampling cycle within 10-60 seconds, improves work efficiency, reduces the time and labor cost required for measurement, which is particularly beneficial for occasions where frequent gas density measurements are required.

[0059] In the present invention, relatively low-cost sensors and control systems are used while maintaining high precision and reliability. The low-power design further reduces the operating cost, making the device more economical and practical. In addition, the compact and reasonable design of the device makes maintenance easier, reduces maintenance costs, and improves the durability of the device. These characteristics make the device economical while meeting the needs of high-precision measurement, and suitable for large-scale promotion and application.

[0060] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for measuring gas density by using a quantitative tank and a flow meter, characterized in that: The system is composed of a gas source (2), a filter (3), a mass flow meter (4), a gas pipeline (9), a valve control system (8), a quantitative tank (6), a precision pressure gauge (11), a precision thermometer (10), and a control system (1); The valve control system (8) comprises a three-way valve (5) and an exhaust valve (7); The control system (1) is provided with a microprocessor control unit and a touch screen inside; The gas source (2) is connected to the filter (3) via a gas pipeline (9); the exhaust port of the filter (3) is connected to a mass flow meter (4); the mass flow meter (4) measures the gas mass flow rate; and then the gas enters the quantitative tank (6) via the gas pipeline (9); The quantitative tank (6) is internally connected with a precision pressure gauge (11) and a precision thermometer (10) for real-time monitoring of changes in pressure and temperature in the tank; The control system (1) is connected to a precision pressure gauge (11) and a precision thermometer (10) via a signal line, receives sensor data, and calculates the density of the gas to be measured using a built-in equation; The control system (1) is connected to an external power supply interface.

2. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The gas source (2) is the source of the gas to be tested and is connected to other parts of the system through a gas pipeline (9); the gas inlet and outlet pipelines are respectively connected to the gas source to be tested (2) and the exhaust gas outlet, ensuring that the gas enters and exits the system gas outlet to guide the dangerous gas to a safe area for discharge.

3. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The filter (3) is installed between the gas source (2) and the gas pipeline (9) and is used to filter impurities and particulate matter in the gas to ensure that the gas entering the mass flow meter (4) is pure and avoid interference with the measurement result.

4. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The mass flow meter (4) is connected to the gas pipeline (9) and is used to measure the mass flow of gas entering the quantitative tank (6); the accuracy of the mass flow meter (4) is 0.2%.

5. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The gas pipeline (9) is connected to the gas source (2), the filter (3), the mass flow meter (4), and the quantitative tank (6) modules to ensure smooth flow of gas. The gas pipeline (9) is also connected to the three-way valve (5) and the exhaust valve (7) to control the flow direction and discharge of gas. The gas pipeline (9) should be made of corrosion-resistant and pressure-resistant materials and should be inspected and maintained regularly.

6. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The valve control system (8) comprises a three-way valve (5) and an exhaust valve (7), and adopts an electromagnetically driven fast switching valve. The three-way valve (5) is used to control the flow direction of the gas and flexibly adjust the flow rate; the exhaust valve (7) is used to discharge waste gas or perform safe exhaust to ensure safe operation; the valve control system (8) is provided with a control panel to facilitate remote control by a user.

7. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The quantitative tank (6) is made of stainless steel and has good corrosion resistance and long service life. Its internal volume is determined by standard gas. When the density of the standard gas is known, the volume of the quantitative tank (6) is calculated by the gas mass measured by the mass flow meter (4). A thermometer and a precision pressure gauge (11) are arranged outside the quantitative tank (6) to monitor the pressure and temperature changes in the tank in real time. The quantitative tank (6) is provided with a safety valve to prevent safety accidents caused by excessive pressure.

8. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The precision pressure gauge (11) is installed on the quantitative tank (6) and is used to monitor the pressure change in the tank in real time; its range is set to 0-1MPa, and the resolution can reach 0.001MPa, accurately measuring the pressure in the tank and providing data support for subsequent density calculation; the precision pressure gauge (11) is provided with a calibration device to ensure the accuracy of the measurement result; The precision thermometer (10) is installed on the quantitative tank (6) and is used to monitor the temperature of the gas in the tank in real time; its working range is -20°C to +200°C ± 0.1°C, and it accurately measures the temperature of the gas in the tank to provide data support for subsequent density calculation; the precision thermometer (10) is provided with a calibration device.

9. A system for measuring gas density by using a quantitative tank and a flow meter as claimed in claim 1, characterized in that: The control system (1) is internally provided with a PLC; the control system (1) receives sensor data from a precision pressure gauge (11) and a precision thermometer (10), and calculates the density of the gas to be measured according to a built-in equation; the calculation result is displayed on a touch screen for a user to view; the control system (1) is also provided with system parameters, including a cyclic sampling period; the control system (1) is provided with a remote monitoring function, so that a user can remotely view the measurement results and system status; The touch screen is used as a user interface to display measurement results and set system parameters; The external power interface supplies power to the entire system to ensure normal operation of the system; the external power interface is provided with an overload protection device.

10. A method for measuring gas density by using a quantitative tank and a flow meter, characterized in that: The method operates the system for measuring gas density by using a quantitative tank and a flow meter as described in any one of claims 1 to 9, comprising the following steps: 1) First, make sure all connections are tight and leak-free, and then connect to a stable power supply. Once everything is ready, make corrections and start the circulation mode. 2) Start the valve and run it once to ensure that the medium is full in the pipe; 3) Close the front and rear valves to perform zero point calibration; 4) Calibration method: Password 020 - Modify settings - Zero calibration - "Yes" - Confirm - Wait... 40 seconds for calibration; 5) The completion of zero point calibration can be checked from the touch screen parameter interface; 6) After running the device normally for several times and the density value is stable, it can be corrected to obtain the correction factor; After correction, conduct formal measurement, the steps are as follows: 1) Connect the gas to be tested to the gas inlet and observe whether the pressure indication on the display panel is normal; 2) Follow the prompts and open and close the corresponding valves in sequence to inflate and deflate; 3) Record the gas density value shown on the display; 4) After the measurement, cut off the power supply and discharge the remaining gas.

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