The sensor unit of a thermal mass flowmeter consists of two sheath
pipe-shaped sensors acting as flow speed sensor and temperature
sensor, respectively. The flow speed sensor is controlled (heated)
to a specified temperature difference from ambient temperature. The
heat taken away from the flowrate sensor due to the fluid flow is
correlated to the mass flow. Therefore, the mass flowrate can be
obtained from the amount of power applied to the flowrate sensor to
compensate for the removed heat. A thermal mass flowmeter features
wide flow range and enables direct measurement of mass flowrate
without compensating temperature and pressure.
