Thermal mass flow measurement working principle

Working principle of thermal Mass Flow Meters & Controllers

The thermal Mass Flow Meter or Controller is capable of providing direct measurement of mass flow, as opposed to most other methods that measure volumetric flow and require separate measurements for temperature and pressure in order to calculate density and, ultimately, the mass flow.
These thermal flow instruments actually measure and control the flow on a molecular level and so are able to provide an extremely accurate, repeatable, and reliable delivery of gas into the process.

Thermal Mass Flow Meters and Controllers can be divided into 3 different sensor principles:

1. Thermal Mass Flow Sensor for gases, using the bypass principle
2. Thermal Mass Flow Sensor for gases, using the inline/CTA  principle
3. Thermal Mass Flow Sensor for liquids, using the inline/CTA/CPA principle