What is The Best Way to Calibrate a Thermal Mass Flow Meter?

Saeed Lanjekar

01 Jul, 2025

5 Mins

What is The Best Way to Calibrate a Thermal Mass Flow Meter?

Factory calibration is an essential component of any thermal mass flow meter. Thermal flow meters measure inferred flow rates. The instrument measures the amount of power required to maintain the overheating temperature of the heated sensor above the reference temperature. During calibration, this relationship between power and mass flow rate is established. Although considerable effort is put into designing and building the sensors, each has slightly different heat transfer characteristics, requiring that each instrument be calibrated separately.

It is the first step to calibrate the two platinum RTDs, after which the performance of the two RTDs will be assessed at various temperatures over the specified operating range, according to their calibration results. Because the flowmeter operates according to the temperature and heat theory, it is necessary to perform this temperature compensation step to ensure its performance is independent of the gas temperature.

Burak strives to provide calibration capabilities that are as close as possible to replicating the actual operating conditions of our customers to improve our calibration capabilities. A mixture of gases or the actual gas is used during calibration, according to the circumstances. If the actual gas cannot be flown due to safety or hazardous conditions, the calibration is conducted using a surrogate gas; in these situations, the calibration is performed using a model based on the thermal properties of the surrogate gas.

How to Calibrate a Flow Meter

As part of the calibration process, the sensor is placed in one of several test sections, a known amount of gas is pumped through the pipe, and then the signal is measured to determine the desired overheat level. During the operating range, this must be done a minimum of 12 times—high-precision turbine flow meters with pressure and temperature correction measure actual flow rates. There is a 0.5% uncertainty in the readings of the turbine meters. In the case of lower flow rates, a Bell Prover is used with an uncertainty of 0.5% of reading.