I explain thermal mass flow meter theory and working principle in a new video that was just released.
Thermal Mass Flow Working Principle
The thermal flow mass meter measures gas flow based upon the idea of convective heat transfer.
Either in-line flow bodies or insertion-style probes of the meter support two sensors that interface with the gas. The sensors are resistance temperature detectors (RTDs) in the Sage thermal mass meter case, consisting of highly durable reference-grade platinum windings clad in a protective 316 SS or Hastelloy C cover.
One sensor is heated by an integrated circuit and functions as the flow sensor, while a second sensor acts as the reference sensor and determines the gas temperature. The Sage proprietary circuitry maintains an ongoing overheat between the flow and reference sensor. As gas flows by the heated sensor, gas molecules transport heat away from the sensor, and as a result, the sensor cools, and energy is lost. The circuit balance disrupts, and the temperature difference (ΔT) between the heated RTD and the reference sensor has changed. Within a second, the circuit restores the lost energy by heating the flow sensor to adjust the overheat temperature. Learn more.
New Video on Thermal Flow Meter Theory
Watch and listen as I explain how the electrical power required to maintain this overheat denotes the mass flow signal.