The principle of Mass Flow Controller/gas mass flow meter/thermal mass gas flow meter for gas like nitrogen, natural gas, argon,CO2 etc. is that a fluid flowing past a heated temperature sensor removes a known quantity of heat as it passes.In a thermal flowmeter, the fluid has to pass two temperature sensors.One sensor obtains a reference value by measuring the actual process temperature. The second sensor is a heating element and it receives precisely as much energy as is needed to compensate for dispersed heat and maintain a precisely defined temperature difference.The higher the mass flow past the heated temperature sensor, the more heat is dissipated and the more power has to be input to the element to maintain the temperature difference.
Oxygen, nitrogen, hydrogen, chlorine and mixed gas blast furnace gas, flue gas, biogas, compressed air, natural gas, liquefied gas, primary and secondary air and etc.