Thermoanemometric technology for measuring the flow of air and gas

Thermo-anemometric technology is based on area-speed flow measurement.

One of the rods of the sensor module has a gas temperature in the pipeline, on the other - an electronic unit with an electric current maintains the temperature on it several tens of degrees higher than the gas temperature in the pipeline. When gas flows through the pipeline, the more heated rod is cooled by the gas flow. The temperature difference between the two sensors is kept constant by a loop based on a resistance bridge (using Wheatstone bridge), in which the heated sensor is a controllable element. The cooling rate of the rod depends on the gas velocity in the gas pipeline and the properties of the gas. The current required to maintain the temperature difference between the terminals of the sensor module is proportional to the mass velocity (mass flow) of gas in the pipeline.

This design provides unsurpassed responsiveness and other advantages of thermal anemometry at constant temperature. The microprocessor-based electronic unit measures heat transfer and calculates the standard gas velocity and temperature.