
3. Comparative calibration method (series comparison verification) installs the flow meter to be calibrated in series with a certified standard flow meter, synchronously measures the flow data of the same pipeline, and compares the differences. This method is suitable for online calibration or environments with mature flow systems, but standard flow meters must be regularly calibrated, and the installation positions of the two meters must meet the requirements of flow stability. After understanding the logic of selecting calibration methods, it is necessary to confirm whether the fluid properties parameters (such as gas composition, viscosity), temperature and pressure range are consistent with the calibration conditions before operation, in order to avoid calibration failure due to differences in operating conditions.
The core of a mass flowmeter is to directly or indirectly calculate the mass flow rate of a fluid by measuring the changes in physical parameters when the fluid flows through it, without the need for additional compensation for fluid density, temperature, and pressure parameters.
. ### 1. The principle of a thermal mass flowmeter relies on the difference in heat carried away by the fluid to calculate the mass flow rate. 1. Two temperature measuring elements are installed inside the sensor, one for active heating and the other as a reference for temperature measurement When the fluid is stationary, the temperature at two temperature measurement points is the same; When fluid flows through, the heat of the heating element is carried away by the fluid. The larger the fluid flow rate, the more heat is carried away, and the greater the temperature difference between the heating element and the reference element By calibrating the temperature difference and power parameters, the mass flow rate can be directly converted without being affected by fluid density or pressure. ### 2. The principle of Coriolis mass flowmeter is currently the most accurate type of mass flowmeter, which works by utilizing the Coriol