Thermal Massflowmeters

Thermal flow meters / switches are based on the thermal dispersion principle, a principle that describes how a heated body cools when a medium passes.

If the principle is to be used for flow measurement, it is done by controlling the heating of a body in the medium, as the heating is controlled so that there is always a constant difference temperature with an identically designed reference outside the medium, then the power to be used for heating will be proportional to the mass flow of the medium.