Liquid nitrogen tank airtightness weight loss rate detection system based on weighing device and application method

Abstract

A liquid nitrogen tank airtight weight loss rate detection system based on a weighing device comprises a body and a temperature sensor, and is further provided with a selection unit, a weight acquisition unit, a temperature acquisition unit, a data analysis and calculation unit, a timing unit, a display unit and a setting unit. The signal output end of the temperature sensor is electrically connected with the signal input end of a main control module in the weighing device; the selection unit, the weight acquisition unit, the temperature acquisition unit, the data analysis and calculation unit, the timing unit, the display unit and the setting unit are application software installed in the main control module; the application method of the liquid nitrogen tank airtightness weight loss rate detection system based on the weighing device comprises five steps. The liquid nitrogen weighing device is relatively low in cost and convenient to use, weight data of liquid nitrogen in the liquid nitrogen container and the liquid nitrogen in the liquid nitrogen container can be given at the corresponding environment temperature and the corresponding time period under the action of related software and corresponding processes in the weighing device, whether current leakage data exceed normal values or not can be judged, and powerful technical support is provided for effective use of the liquid nitrogen container.

Description

Technical Field

[0001] The present invention belongs to the technical field of detection systems and application methods, and in particular to a liquid nitrogen tank airtightness weight loss rate detection system based on a weighing device and an application method. Background Art

[0002] Liquid nitrogen tanks, as containers for storing and transporting liquid nitrogen, dry ice, etc., play an irreplaceable role in the transportation and preservation of vaccines, bacterial and viral strains, cells, and organs of humans and animals in the biomedical field. After liquid nitrogen and dry ice are placed in liquid nitrogen tanks, they will evaporate and decrease over time. If the samples or drugs in the liquid nitrogen tanks lose the adapted environment, they are likely to fail and cause economic losses. Therefore, the airtightness of liquid nitrogen tanks is a very important indicator. Furthermore, due to structural limitations, existing liquid nitrogen tanks cannot be 100% completely sealed when storing liquid nitrogen and dry ice. Liquid nitrogen and dry ice will leak more or less, but the degree of leakage is different. If the sealing is relatively poor and the leakage is large, it is possible that the internal medium will evaporate too much before the tank is transported to the destination (or the storage time is too short). Therefore, how to detect the airtightness of the tank in real time and give a qualified standard value has become a problem that must be solved.

[0003] In the prior art, the helium leakage method, water immersion method and weighing method are generally used to measure the air tightness of the tank. The helium leakage method is as follows: During the test, the tank is filled with helium and tested using a helium mass spectrometer. The leakage rate allowed by the standard is usually no more than 1x10^-9mbar·L / s (exceeding the benchmark value means that the leakage rate is too large); specifically, in the helium leakage test method, helium and helium mass spectrometer equipment are required. The use of helium requires environmental ventilation. To detect a liquid nitrogen tank, the tank needs to be filled with helium. If multiple liquid nitrogen tanks need to be tested, a large amount of helium is required. In actual situations, there will be many transportation stations in various places, and the tanks will circulate between the stations. If the number of tests is to be guaranteed, corresponding devices (special test rooms and helium gas supply mechanisms, helium mass spectrometer equipment, etc.) need to be arranged at multiple stations. The requirements for the environment and funds are very high, and there are limitations in practical applications. The water immersion method is as follows: immerse the liquid nitrogen tank in water and observe whether bubbles are generated (bubbles represent poor air tightness). Although this method is simple and easy, it requires the construction of a water storage tank for air tightness testing. After the test is completed, the water on the surface of the liquid nitrogen tank needs to be wiped dry and left to stand until it is completely dry before it can be used. Due to the large volume of the liquid nitrogen tank itself, if batch testing is performed, the construction cost of the water storage tank (and because the water storage tank is fixed, it is not flexible to use) is high, and the subsequent drying steps will also cost a certain amount of time and money, so it is not convenient to use. In the weighing method measurement, the liquid nitrogen tank is directly placed on the scale, and then the inspector obtains the air tightness data of the liquid nitrogen tank by observing the weight change (observing the weight data change within a certain period of time, when the weight is lower than the normal value, it means that the air tightness is not good).

[0004] Among the above three detection methods, the weighing method has low cost and is widely used. However, like the helium leakage method and the water immersion method, it requires the inspectors to observe the leakage data in real time, which will bring inconvenience to the inspectors. In addition, the leakage of the liquid nitrogen tank is also related to the temperature environment and the time after the liquid nitrogen is added (usually, in the initial time period, the weight loss rate of the liquid nitrogen tank gradually changes from fast to slow, and there is an unstable transition period). Therefore, the air tightness results of the liquid nitrogen tank obtained by the existing detection method are not reliable (it is impossible to combine the dynamically changing temperature data and time for analysis). Specifically, for example, the inspectors conclude that the air tightness of the liquid nitrogen tank is not good when the detection environment temperature is relatively high and in the initial period after filling with liquid nitrogen. In other words, if the weight loss rate of the liquid nitrogen tank is not actually mastered to judge the air tightness of the liquid nitrogen tank, the data obtained is not true (the leakage volume is relatively large in the initial period, which is actually normal), which will more or less have an adverse effect on the normal use of the liquid nitrogen tank. Summary of the invention

[0005] In order to overcome the drawbacks as described in the background technology in the existing liquid nitrogen tank air tightness detection due to technical limitations, the present invention provides a liquid nitrogen tank air tightness weight loss rate detection system and application method based on a weighing device, which is relatively low in cost and easy to use, and adopts a weighing device as a basis. Under the action of relevant software and corresponding processes in the weighing device, the liquid nitrogen tank and the liquid nitrogen weight data inside it can be given at the corresponding ambient temperature and the corresponding time period, as well as whether the current leakage data exceeds the normal value (whether the liquid nitrogen tank is airtight). It provides strong technical support for the effective use of the liquid nitrogen tank.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] The liquid nitrogen tank air tightness weight loss rate detection system based on a weighing device comprises a desktop weighing device body with a liquid crystal display screen, a temperature sensor, and also comprises a selection unit, a weight acquisition unit, a temperature acquisition unit, a data analysis and calculation unit, a timing unit, a display unit, and a setting unit; the signal output end of the temperature sensor is electrically connected to the signal input end of the main control module in the weighing device; the selection unit, the weight acquisition unit, the temperature acquisition unit, the data analysis and calculation unit, the timing unit, the display unit, and the setting unit are application software installed in the main control module; the selection unit can select different gases to be filled into the liquid nitrogen tank and then perform air tightness test of the corresponding gas. Detection; the weight acquisition unit and the temperature acquisition unit can respectively collect the weight data of the liquid nitrogen tank located at the weighing position of the weighing device and the ambient temperature data output by the temperature sensor in real time, and the weight acquisition unit and the temperature acquisition unit output the weight and temperature data to the data analysis unit after preliminary processing; the timing unit can set the time interval for the weight acquisition unit to collect the weight of the liquid nitrogen bottle, and the total detection time; the data analysis and calculation unit can derive the weight loss rate of the liquid nitrogen bottle based on the changes in the ambient temperature data and the weight data of the liquid nitrogen bottle, and output the signal to the display unit, and the display unit can display the weight data of the liquid nitrogen bottle and the weight loss rate curve in real time.

[0008] Furthermore, the timing unit sets the time interval for the weight collection unit to collect the weight of the liquid nitrogen bottle and the total detection time, which is selected through the buttons of the main control module, and the selected time is a plurality of gears.

[0009] Furthermore, the setting unit can set normal data values ​​of gas leakage at different temperatures and at different times when different types of liquid nitrogen tanks are filled with different types of detection gases.

[0010] The application method of the liquid nitrogen tank air tightness weight loss rate detection system based on the weighing device comprises the following steps: S1: different types of liquid nitrogen tanks are filled with different types of detection gases through the setting unit interface, and the normal values ​​of the gas leakage rates at different temperatures and different times are set. When the actual detected leakage rate of the liquid nitrogen tank is greater than the normal value, the quality of the liquid nitrogen tank is unqualified; when the actual detected leakage rate of the liquid nitrogen tank is less than the normal value, the quality of the liquid nitrogen tank is qualified. After all the steps are completed, the data are displayed in two ways: digitally and in a curve chart; S2: the inflated liquid nitrogen bottle is placed on the desktop weighing device body, the desktop weighing device body weighs the liquid nitrogen tank, the temperature sensor collects the temperature data of the on-site environment in real time, the weight acquisition unit and the temperature acquisition unit can respectively collect the weight data of the liquid nitrogen tank located at the weighing position of the weighing device in real time, The temperature sensor outputs the ambient temperature data, and the weight acquisition unit and the temperature acquisition unit perform preliminary processing on the weight and temperature data and output them to the data analysis unit. The inspector observes the weight data of the liquid nitrogen bottle and the surrounding environment data in real time through the LCD screen of the desktop weighing device body; S3: After selecting different gases to be filled into the liquid nitrogen tank through the selection unit interface, the corresponding gas tightness test is performed, and the time interval for the weight acquisition unit to collect the weight of the liquid nitrogen bottle and the total time of the test can be set through the timing unit. The time interval is divided into three levels: <1 hour, 1 to 3 hours and >3 hours: S4: The data analysis calculation unit records the weight data of the liquid nitrogen bottle based on the weight data input by the weight acquisition unit every 20 minutes. Specifically, the weight M of the current tank is recorded once at the beginning of the measurement. 1 (kg), after 20 minutes, measure the data M again 2 , will (M 1 -M 2 )*3000, combined with the ambient temperature data input by the temperature acquisition unit, the current weight loss rate dM (g / h) can be calculated, that is, the current weight loss rate dM n =(M n-1 -M n )*3000, in order to ensure the accuracy of the measurement, the average value of the current weight loss rate for three consecutive times is calculated, that is, the average weight loss rate

[0011] S5: The data analysis and calculation unit performs fitting verification on the average weight loss rate data to verify the reliability of the data again. The verification formula is as follows

[0012]

[0013] Furthermore, in step S3, if the time interval is greater than 3 hours, the data can only be used after measuring for 1 hour. Adding the weight recorded for the first time, there are at least 4 current weight data and 3 current weight loss rate data. The average weight loss rate is calculated from the 4th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

[0014] Furthermore, in step S3, if the time interval is less than 1 hour, the data can only be used after 4 hours of measurement. Adding the weight recorded for the first time, there are at least 12 current weight data and 11 current weight loss rate data. The average weight loss rate is calculated from the 12th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

[0015] Furthermore, in step S3, if the filling time is 1 to 3 hours, the data can only be used after 9 measurements. The average weight loss rate is calculated from the 9th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

[0016] Furthermore, in step S5, the smaller the slope m value is, the more stable the average weight loss rate is. When the m value is negative and the value is stable and close to zero, it means that the slope of the straight line is negative, and the weight loss rate is slowly decreasing and eventually tends to be stable. The fitting check can assist in cross-verifying the reliability of the former average weight loss rate. If the m value in the check is close to zero, the test result is reliable.

[0017] The beneficial effects of the present invention are as follows: the present invention adopts a weighing device as a basis, has relatively low cost and is easy to use, and only needs to fill the liquid nitrogen tank with a medium (liquid nitrogen or dry ice, etc.) and place it on the weighing device for a certain period of time (up to 4 hours), and then the data on whether the air tightness of the liquid nitrogen tank is qualified can be intuitively obtained through the numbers and curves displayed on the display screen of the instrument; in specific use, it can be dynamically adjusted at any time according to actual conditions to meet the air tightness test requirements of various media and different models of liquid nitrogen tanks; since the weighing device is small in size, multiple weighing devices can be placed in different areas, and can also be conveniently carried, without the need for professional personnel and fixed environmental testing, ordinary operators (users) can perform large-scale testing at any time in their daily work, which greatly improves the efficiency of the test and ensures the safe use of the liquid nitrogen bottle; and since the air tightness of the liquid nitrogen tank can be judged based on the actual weight loss rate of the liquid nitrogen tank at the corresponding ambient temperature and the corresponding time period, the obtained data is more real, which provides strong technical support for the effective and safe use of the liquid nitrogen tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an actual product photo of the liquid nitrogen tank air tightness weight loss rate detection system based on a weighing device.

[0019] Figure 2 It is a schematic diagram of the weight loss curve of the present invention.

[0020] Figure 3 , 4 , 5, and 6 are schematic diagrams of the display screen interface of the present invention.

[0021] Figure 7 It is a software architecture block diagram of the liquid nitrogen tank air tightness weight loss rate detection system based on a weighing device of the present invention. DETAILED DESCRIPTION

[0022] Figure 7 As shown, the liquid nitrogen tank airtightness weight loss rate detection system based on the weighing device includes a desktop weighing device body with a liquid crystal display screen, a temperature sensor, and also has a selection unit, a weight acquisition unit, a temperature acquisition unit, a data analysis and calculation unit, a timing unit, a display unit, and a setting unit; the signal output end of the temperature sensor and the signal input end of the main control module in the weighing device are connected via a data line; the selection unit, the weight acquisition unit, the temperature acquisition unit, the data analysis and calculation unit, the timing unit, the display unit, and the setting unit are application software installed in the main control module; the selection unit can select different gases to be filled into the liquid nitrogen tank and then perform the corresponding gas Airtightness detection; the weight acquisition unit and the temperature acquisition unit can respectively collect the weight data of the liquid nitrogen tank located at the weighing position of the weighing device and the ambient temperature data output by the temperature sensor in real time. The weight acquisition unit and the temperature acquisition unit will output the weight and temperature data to the data analysis unit after preliminary processing; the timing unit can set the time interval for the weight acquisition unit to collect the weight of the liquid nitrogen bottle and the total time of the detection; the data analysis and calculation unit can derive the weight loss rate of the liquid nitrogen bottle based on the changes in the ambient temperature data and the weight data of the liquid nitrogen bottle, and output the signal to the display unit, and the display unit can display the weight data of the liquid nitrogen bottle and the weight loss rate curve in real time. The timing unit sets the time interval for the weight acquisition unit to collect the weight of the liquid nitrogen bottle and the total time of the detection, which is selected through the buttons of the main control module, and the selected time is multiple gears. The setting unit can set the normal data values ​​of gas leakage at different temperatures and different times when different types of liquid nitrogen tanks are filled with different types of detection gases.

[0023] Figure 7As shown, the application method of the liquid nitrogen tank air tightness weight loss rate detection system based on the weighing device includes the following steps. The first step is to set different types of liquid nitrogen tanks to be filled with different types of detection gases through the setting unit interface, and the normal value of the gas leakage rate at different temperatures and different times. When the actual detected liquid nitrogen tank leakage rate is greater than the normal value, the quality of the liquid nitrogen tank is unqualified. When the actual detected liquid nitrogen tank leakage rate is less than the normal value, the quality of the liquid nitrogen tank is qualified, and the weight loss curve Figure 2 As shown in the figure, the data after all the steps are completed are displayed in two ways: digital and curve graphs; the core algorithm of the present invention is mainly based on Figure 2 The weight loss curve is as follows: specifically, when the liquid nitrogen tank is in a stable weight loss range, the corresponding ambient temperature of the liquid nitrogen tank is based on the corresponding value. Therefore, as long as the weight loss rate of the tank is known, the airtightness of the tank can be judged (when the liquid nitrogen bottle is filled with liquid nitrogen, a weight loss of less than 20g in one hour is normal; when the liquid nitrogen bottle is filled with dry ice, a weight loss of less than 18g in one hour is normal).

[0024] Figure 7 As shown, the second step: put the inflated liquid nitrogen bottle on the desktop weighing machine body, the desktop weighing machine body weighs the liquid nitrogen tank, the temperature sensor collects the temperature data of the on-site environment in real time, the weight collection unit and the temperature collection unit respectively collect the weight data of the liquid nitrogen tank located at the weighing position of the weighing machine and the ambient temperature data output by the temperature sensor in real time, the weight collection unit and the temperature collection unit preliminarily process the weight and temperature data and output them to the data analysis unit, and the inspection personnel observe the weight data of the liquid nitrogen bottle and the surrounding environment data in real time through the LCD screen of the desktop weighing machine body;

[0025] Figure 7 As shown, the third step: display operation interface Figure 3As shown, after different gases are filled into the liquid nitrogen tank through the selection unit interface, the corresponding gas tightness test is performed, and the time interval for the weight collection unit to collect the weight of the liquid nitrogen bottle and the total time of the test are set through the timing unit. The time interval is divided into three levels: <1 hour, 1-3 hours and >3 hours: Specifically, the reason for selecting the time interval is that in the actual detection process, it is often encountered that the test is not performed immediately after the dry ice or liquid nitrogen is filled. After many experiments, it is found that within the first 4 hours after the liquid nitrogen tank is filled with dry ice or liquid nitrogen, the weight loss rate of the liquid nitrogen tank gradually changes from fast to slow, and there is an unstable transition period. The data within this time range is unreliable, and only the data after this can be taken for judgment. The longer the time, the more reliable it is. Therefore, the present invention has three options for the time after adding dry ice or liquid nitrogen: <1 hour, 1-3 hours and >3 hours. When the detection personnel selects <1 hour, the data analysis and calculation unit will continuously measure for 4 hours to make a judgment result. When the detection personnel selects >3 hours, the data analysis and calculation unit can make a judgment result after continuous measurement for 1 hour. This option is intended to reduce the measurement time.

[0026] Figure 7 As shown, the fourth step: the data analysis and calculation unit records the weight data of the liquid nitrogen bottle based on the weight data input by the weight acquisition unit every 20 minutes. Specifically, the weight M of the current tank is recorded once at the beginning of the measurement. 1 (kg), after 20 minutes, measure the data M again 2 , will (M 1 -M 2 )*3000, combined with the ambient temperature data input by the temperature acquisition unit, the current nitrogen bottle weight loss rate dM (g / h) can be calculated, that is, the current weight loss rate dM n =(M n-1 -M n )*3000, in order to ensure the accuracy of the measurement, the average value of the current weight loss rate for three consecutive times is calculated, that is, the average weight loss rate

[0027]

[0028] Specifically, if the time interval is >3 hours, the data can only be used after measuring for 1 hour, plus the weight recorded for the first time, there are at least 4 current weight data and 3 current weight loss rate data. The average weight loss rate is calculated from the 4th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified" (every 20 minutes thereafter, the three latest current weight loss rates are taken as the average weight loss rate and compared with the qualified standard value until the tester stops measuring. Each average weight loss rate will be recorded in the historical data for the convenience of the tester to review); if the time interval is <1 hour, the data can only be used after measuring for 4 hours. Plus the weight recorded for the first time, there are at least 12 current weight data and 11 current weight loss rate data. The average weight loss rate is calculated from the 12th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified". In step S3, if the filling time is 1 to 3 hours, the data can only be used after 9 measurements. The average weight loss rate is calculated from the 9th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

[0029] Figure 7 As shown, the fifth step: the data analysis and calculation unit performs fitting verification on the average weight loss rate data to verify the reliability of the data again; specifically, the user (tester) can intuitively obtain whether the test result of the liquid nitrogen tank (including the current nitrogen tank weight and the weight loss rate data of the liquid nitrogen tank at the corresponding ambient temperature and the corresponding time period) is qualified through the display screen. In order to make the data more accurate, the present invention performs fitting verification on the average weight loss rate data to verify the reliability of the data again (the display screen operation interface is as shown in FIG. Figure 4 The fitting verification guidance formula is as follows:

[0030]

[0031] Σy i =m*Σx i +b*n (2),

[0032] In the formula, n means that a total of n measurements were made, that is, n 20-minute data, which are known data; x i is the time value, which is measured every 20 minutes and is known data; i is the average weight loss rate value to be calculated after measurement, which is unknown data; ∑(x i *y i ) represents the sum of (average weight loss rate value each time * elapsed time) n times; ∑xi is the sum of n different times that have passed; ∑x i 2 is the sum of the squares of the different times that have passed n times; ∑y i is the sum of the average weight loss data values ​​for each time. The present invention needs to find the two values ​​of m and b, where m represents the slope value. The solution is as follows:

[0033]

[0034] Thus the following formula is derived:

[0035]

[0036] In the formula, the smaller the slope m value is, the more stable the average weight loss rate is. Generally, the m value is negative, and the value is stable and close to zero, which means that the slope of the straight line is negative, and the weight loss rate is slowly decreasing and eventually tends to be stable. The fitting check can assist the previous step in cross-verifying the reliability of the average weight loss rate of the former. If the m value in the check is close to zero, the test result is reliable.

[0037] Figure 7 As shown, the display operation interface Figure 5 As shown, the detector of the present invention can also display historical data in the form of curves on the display screen, so that the tester can see the changes in the weight loss rate very intuitively. Display screen operation interface Figure 6 As shown, the present invention uses a USB interface to export into a table when needed, and the application is more convenient. The present invention uses a weighing device as a basis, which is relatively low in cost and easy to use. It only needs to fill the liquid nitrogen tank with medium (liquid nitrogen or dry ice, etc.) and place it on the weighing device for a certain period of time (the fastest 4 hours). The numbers and curves displayed on the display screen of the instrument can be intuitively obtained. Whether the air tightness of the liquid nitrogen tank is qualified data; in specific use, it can be dynamically adjusted at any time according to actual conditions to meet the air tightness test requirements of various different media and different models of liquid nitrogen tanks; due to the small size of the weighing device, multiple can be placed in different areas, and it can also be convenient to carry, without the need for professional personnel and fixed environmental detection, ordinary operators (users) can perform large-scale detection at any time in their usual work, greatly improving the efficiency of detection and ensuring the safe use of liquid nitrogen bottles; and because the air tightness of the liquid nitrogen tank can be judged on the basis of the actual weight loss rate of the liquid nitrogen tank at the corresponding ambient temperature and the corresponding time period, the obtained data is more real, which plays a strong technical support for the effective and safe use of the liquid nitrogen tank.

[0038] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0039] In addition, it should be understood that although the present specification is described according to the implementation mode, the implementation mode does not only include an independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A liquid nitrogen tank air tightness weight loss rate detection system based on a weighing device, comprising a desktop weighing device body with a liquid crystal display screen and a temperature sensor, characterized in that: The invention also comprises a selection unit, a weight collection unit, a temperature collection unit, a data analysis and calculation unit, a timing unit, a display unit and a setting unit; the signal output end of the temperature sensor is electrically connected to the signal input end of the main control module in the weighing device; the selection unit, the weight collection unit, the temperature collection unit, the data analysis and calculation unit, the timing unit, the display unit and the setting unit are application software installed in the main control module; the selection unit can select different gases to be filled into the liquid nitrogen tank and then perform air tightness detection of the corresponding gas; the weight collection unit and the temperature collection unit can respectively collect the weight data of the liquid nitrogen tank located at the weighing position of the weighing device and the ambient temperature data output by the temperature sensor in real time, and the weight collection unit and the temperature collection unit output the weight and temperature data to the data analysis unit after preliminary processing; the timing unit can set the time interval for the weight collection unit to collect the weight of the liquid nitrogen bottle and the total detection time; the data analysis and calculation unit can obtain the weight loss rate of the liquid nitrogen bottle based on the changes of the ambient temperature data and the weight data of the liquid nitrogen bottle, and output the signal to the display unit, and the display unit can display the weight data of the liquid nitrogen bottle and the weight loss rate curve in real time.

2. The liquid nitrogen tank air tightness weight loss rate detection system based on a weighing device according to claim 1 is characterized in that: The timing unit sets the time interval and the total detection time for the weight collection unit to collect the weight of the liquid nitrogen bottle. The selection is made through the buttons of the main control module, and the selected time is a plurality of gears.

3. The liquid nitrogen tank air tightness weight loss rate detection system based on a weighing device according to claim 1 is characterized in that: The setting unit can set normal data values ​​of gas leakage at different temperatures and at different times when different types of liquid nitrogen tanks are filled with different types of detection gases.

4. The application method of the liquid nitrogen tank airtightness weight loss rate detection system based on a weighing device according to any one of claims 1 to 3 is characterized in that: The method comprises the following steps: S1: setting different types of liquid nitrogen tanks to be filled with different types of detection gases through a setting unit interface, and determining normal values ​​of gas leakage rates at different temperatures and at different times; when the actual detected leakage rate of the liquid nitrogen tank is greater than the normal value, the quality of the liquid nitrogen tank is unqualified; when the actual detected leakage rate of the liquid nitrogen tank is less than the normal value, the quality of the liquid nitrogen tank is qualified; and the data after all steps are completed and detected are displayed in two ways: digital and curve graphs; S2: placing the inflated liquid nitrogen bottle on a desktop weighing machine body, and the desktop weighing machine body weighs the liquid nitrogen tank, and the temperature sensor collects the temperature data of the on-site environment in real time; the weight collection unit and the temperature collection unit can respectively collect the weight data of the liquid nitrogen tank located at the weighing position of the weighing machine and the ambient temperature data output by the temperature sensor in real time; the weight collection unit and the temperature collection unit preliminarily process the weight and temperature data and output them to the data analysis unit, and the inspector communicates with the inspector through the computer; The weight data of the liquid nitrogen bottle and the surrounding environment data detected are observed in real time through the LCD display screen of the desktop weighing device body; S3: After filling different gases into the liquid nitrogen tank through the selection unit interface, the corresponding gas tightness test is performed, and the time interval for the weight collection unit to collect the weight of the liquid nitrogen bottle and the total detection time can be set through the timing unit. The time interval is divided into three levels: <1 hour, 1 to 3 hours and >3 hours: S4: The data analysis and calculation unit is based on the weight data of the liquid nitrogen bottle input by the weight collection unit, and the weight data is recorded every 20 minutes. Specifically, at the beginning of the measurement, the weight M1 (kg) of the current tank is recorded first, and after 20 minutes, the data M2 is measured again. (M1-M2)*3000 is combined with the ambient temperature data input by the temperature collection unit to calculate the current weight loss rate dM (g / h), that is, the current weight loss rate dM n =(M n-1 -M n )*3000, in order to ensure the accuracy of the measurement, the average value of the current weight loss rate for three consecutive times is calculated, that is, the average weight loss rate S5: The data analysis and calculation unit performs fitting verification on the average weight loss rate data to verify the reliability of the data again. The verification formula is as follows 5. The application method of the liquid nitrogen tank airtightness weight loss rate detection system based on a weighing device according to any one of claim 4, characterized in that: In step S3, if the time interval is greater than 3 hours, the data can only be used after measuring for 1 hour. Adding the weight recorded for the first time, there are at least 4 current weight data and 3 current weight loss rate data. The average weight loss rate is calculated from the 4th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

6. The application method of the liquid nitrogen tank airtightness weight loss rate detection system based on a weighing device according to any one of claim 4, characterized in that: In step S3, if the time interval is less than 1 hour, the data can only be used after 4 hours of measurement. Adding the weight recorded for the first time, there are at least 12 current weight data and 11 current weight loss rate data. The average weight loss rate is calculated from the 12th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

7. The application method of the liquid nitrogen tank airtightness weight loss rate detection system based on a weighing device according to any one of claim 4, characterized in that: In step S3, if the filling time is 1 to 3 hours, the data can be used after 9 measurements. The average weight loss rate is calculated from the 9th record, and then the calculated result is compared with the qualified standard value. If the average weight loss rate is ≤ the qualified standard value, the display screen displays "qualified", otherwise it is "unqualified".

8. The application method of the liquid nitrogen tank airtightness weight loss rate detection system based on a weighing device according to any one of claim 4, characterized in that: In step S5, the smaller the slope m value is, the more stable the average weight loss rate is. When the m value is negative and the value is stable and close to zero, it means that the slope of the straight line is negative, and the weight loss rate is slowly decreasing and eventually tends to be stable. The fitting check can assist in cross-verifying the reliability of the former average weight loss rate. If the m value in the check is close to zero, the test result is reliable.

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