The gas meter is an important instrument for measuring gas usage , and its accuracy directly affects the interests of gas users. In order to ensure the accuracy of the gas meter, it needs to be calibrated regularly. However, during the actual calibration process, errors will occur, which will affect the accuracy of the gas meter. Therefore, it is necessary to understand the causes of these errors and take corresponding countermeasures to ensure the accuracy of gas meters.
The calibration of gas meters involves many influencing factors. Temperature and humidity are important factors affecting the calibration of diaphragm gas meters. The environment in which the gas meter is located has a certain impact on the calibration work. Calibration of gas meters needs to be done in a calibration room. At this time, the environment in the calibration room will directly affect the final calibration result. The "Calibration Regulations for Diaphragm Gas Meters" clearly stipulates the calibration environment of gas meters. Gas meters with a maximum flow rate less than 10m3/h need to be calibrated in an environment of 18 ℃ ~ 22 ℃, and gas meters with a maximum flow rate greater than 10m3/h need to be calibrated in an environment of 15 ℃ ~ 25 ℃.
The temperature difference between the calibration standard used for gas meter calibration and the surface temperature of the gas meter cannot exceed 1 °C. The atmospheric pressure in the gas meter calibration environment should be controlled at 86kPa ~ 106kPa , and the relative humidity in the calibration room should be 45% ~ 75% . The medium in the gas meter calibration process is air, which requires the environmental factors in the calibration room to be in a relatively stable state.
It is difficult to maintain a stable environment in the calibration room where the actual gas meter is located. For example, it is difficult to control the temperature in a calibration room at 20 ° C throughout the day . The ambient temperature in the calibration room is greatly affected by the outside temperature, and the alternation of the outside environment throughout the year increases the control pressure of indoor temperature calibration, so errors may occur during gas meter calibration.Temperature changes in the external environment will have varying degrees of impact on various materials used in diaphragm gas meters, such as the thermal expansion and mechanical movement performance of the sensor , and will also affect the measurement. Typically, diaphragm gas meters use aluminum or iron valve body surfaces, which have strong heat transfer properties. Changes in external ambient temperature will have a greater impact on diaphragm gas meters. Environmental tests were conducted on diaphragm gas meters and corresponding measurement tests were carried out. It can be seen that compared with the normal temperature of about 20 ° C , the measurement speed of the diaphragm gas meter is slower under lower temperature conditions, and the resulting error value can reach the error value under normal temperature conditions. It is 2.2 times to 3.8 times. It can be seen that the ambient temperature will seriously affect the measurement of diaphragm gas meters.
Technical engineers from Gongcai.com recommend using temperature and humidity sensors to monitor the gas meter calibration environment to ensure the accuracy of gas meter calibration. The French Humirel digital output temperature and humidity sensor HTU21D : adopts a DFN package suitable for reflow soldering , with a size of only 3 x 3x 1mm. ; Provides calibrated , linear IPC digital output signal. The digital output humidity and temperature signals can be interfaced directly to the microcontroller. Each sensor is calibrated and tested , and the batch number is not only printed on the housing , but also stored on the sensor chip so it can be read by command. Used in engines and motor vehicles, medical , industrial control, consumer electronics and household appliances and other industries.