The ST98 thermal mass flow meter in our factory always gives inaccurate readings; how can it be calibrated?

For such a professional question, ask the manufacturer; it should be FCI

It is not possible to conduct verification within the company; it is necessary to take the instrument to a **certified testing facility for verification. Inaccurate measurements by instruments can be simply assessed based on the principles of those instruments and their installation. 1. First, check whether the insertion depth of the instrument meets the required standards; if not, it can be adjusted accordingly, as this has a significant impact on the instrument’s measurement values. 2. Check whether the platinum resistor of PT100 is functioning properly. 3. If everything is normal, remove the sensors and clean them. 4. If that doesn’t work, check the resistance and voltage values of each circuit according to the instructions. 5. If everything is fine, then modify the instrument coefficients or installation parameters. 6. If the problem persists, use another type of instrument for measurement; it’s likely there’s an issue with the selection of the instrument!

Insertion-type thermal testing is also ineffective; differences in the installation location and changes in the installation angle can all cause deviations. One can only find ways to apply coefficient corrections; as long as the repeatability is good and stable, it does not affect measurement.