The mass flowmeter applies the thermal measurement, measuring the flow through measuring the mass of the taken molecules. Because of the thermal measurement, the result will not be affected by the temperature and pressure changes of the gas. As a accurate, fast, reliable, efficient, stable and flexible flow measuring instrument, mass flowmeter will be widely used in the fields of petroleum processing and chemical industry. It has great potential in promoting flow measurement. The mass flow meter is not able to control the flow, but detect the mass flow of liquid or gas, with the flow value output through analog voltage, current or serial communication.
However, the mass flow controller is an instrument that can detect, at the same time control the flow. The mass flow controller itself has an electromagnetic regulating valve or a piezoelectric valve in addition to the measurement part, so a closed loop system is formed which enables it to control the mass flow. The set value of a mass flow controller can be provided by analog voltage, analog current, or computer and PLC.