The quality laboratory of China's independent China Metrology Institute has successfully developed an air density measurement system and a weight measurement system with higher accuracy and range than similar devices abroad, which greatly improved the accuracy of mass value transmission.
The price scale of the supermarket, the balance of the gold and silver jewelry store, the truck scale of the toll station, the baggage scale, the baby scale, the postal scale... Our daily life almost coincides with the balance and the scale. Measuring the balance and scale is accurate and fair, can not be separated from the weight. Depending on the accuracy requirements of the different scales, the accuracy of the weights is also different. In the process of magnitude transmission, in addition to the accurate measurement of the weight itself, it is also affected by external factors such as air buoyancy. The quality laboratory of China Metrology Institute is working on the study of air buoyancy correction. Ensure that the value is transmitted accurately and reliably.
“In modern scientific research and precision measurement, the accuracy of quality measurement is very high, and some have reached the order of micrograms.†Wang Jian, director of the quality laboratory, used an image metaphor to show that there are multiple “microgramsâ€. The fine fluff floating in the air is about 15 micrograms. We measure the accuracy of a kilogram of object, which is equivalent to measuring the weight of an Airbus A320 to four mosquitoes."
Wang Jian said that when the weight is measured in the air and the mass value is transmitted, the measured value on the measuring instrument does not correctly reflect the true quality of the measured weight. “Because the standard weight and the weight of the measured weight are affected by the buoyancy of the airâ€, the air buoyancy of the measured weight needs to be corrected during the mass transfer. Air density and volume of objects are the main parameters of air buoyancy correction, which plays a crucial role in the accuracy of mass transfer. To this end, some advanced countries have established corresponding air density measurement systems and weight measurement systems.
In China's metrology technology institutions, when determining the mass value transfer, the air density is usually determined by the look-up table method. The air density meter used in the look-up table method was completed in the 1970s. At that time, national quality professional researchers carried instruments and equipment to many parts of the country for on-the-spot measurement. Through the accumulation and calculation of a large amount of data, they jointly compiled this The monthly average air density table for parts of the country that is widely used provides a favorable technical basis for measurements that require air buoyancy correction. However, over the past 40 years, the atmospheric environment has undergone tremendous changes, and the air density calculation formula has also changed due to the revision of technical regulations. In order to meet the requirements of the relevant measurement and scientific research on the accuracy of the experiment, it is urgent to measure the air density in all major regions of the country in real time.
In the measurement of the weight of the weight, the hydrostatic method is usually adopted by the metrology technology institutions in China. This method uses the density of the liquid as the reference, and the measured weight is placed in the liquid for measurement, and the volume is calculated. The operation procedure is cumbersome, and the liquid will pollute the measured code body itself, affecting the stability of the mass transfer. Sex and accuracy. In addition, due to the defects of the hydrostatic method itself, it is currently impossible to measure the volume of the weight with the adjustment chamber.
In order to ensure the accuracy of air buoyancy correction and improve the accuracy of mass quantity transfer in China, it is necessary to accurately measure air density, measured mass volume and standard mass volume. After four years of hard work, Wang Jian's research team has developed an air density measurement system and a weight measurement system with higher accuracy and range than similar devices abroad, and passed the expert appraisal organized by the General Administration of Quality Supervision, Inspection and Quarantine. The system can accurately measure the air density, the measured mass volume and the standard mass volume, ensure the accuracy and reliability of the air buoyancy correction, and greatly improve the accuracy of the mass value transfer.
The size is similar to that of a laptop, the thickness is equivalent to the height of three laptops, and then connected to a computer. If it is not Wang Jian, it is really difficult to connect this simple and unexpected device with the air density measurement system. . This system adopts integrated design and realizes real-time measurement and correction of air density in real time through simultaneous real-time measurement of ambient parameters such as temperature, humidity, atmospheric pressure and carbon dioxide content. Urel = 7.2 x 10-4 (k = 2). Compared with similar devices in China, the measurement accuracy of the measurement system is greatly improved; compared with similar equipments such as the International Bureau of Metrology, the volume is small, the detection and calibration is faster and more convenient, in addition to long-term data storage, graphical analysis, and sensors. Real-time calibration and other functions, technical functions have reached the international advanced level.
Four cylindrical acoustic coupling cavities of different sizes, plus signal generator, microphone, power amplifier and signal acquisition system are the acoustic volume measurement systems developed by the research group. This system no longer needs to immerse the weight in the liquid for volume measurement. The measurement process is fast and pollution-free. The time for measuring a weight volume is reduced from the original half hour to 6 minutes. The measurement result is accurate and can be measured with a adjustment chamber. The weight of the weight is applicable to a wide range of applications. It is worth mentioning that this system “fills the gap of the volume measurement of the international 20kg weight acoustic method, expands the means and range of weight measurement, and the measurement range and accuracy reach the international leading level.â€
At present, the air density measurement system and the acoustic volume measurement system have been widely used in many provincial metrology departments and leading enterprises in the scale industry. With the further promotion and application of this quality standard air buoyancy correction system, accurate air buoyancy correction parameters will be provided for high-accuracy quality measurement, which provides technical guarantee for the transmission of high accurate metric values ​​of quality and related quantities in China. Develop quality standard air buoyancy correction system
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