Introduction
Principle & Structure
The thermal gas mass flowmeter is designed based on the principle of thermal diffusion. The instrument uses the constant temperature difference method to accurately measure the gas. It has the advantages of small size, high degree of digitization, convenient installation and accurate measurement.
The sensor part is composed of two reference-grade platinum resistance temperature sensors. When the instrument is working, one sensor continuously measures the medium temperature T1; the other sensor is self-heating to be higher than the medium temperature T2, which is used to sense the fluid flow rate, which is called velocity sensor. The temperature ΔT=T2-T1, T2>T1, when there is fluid flowing, the temperature of T2 drops because the gas molecules collide with the sensor and take away the heat of T2. To keep ΔT unchanged, it is necessary to increase the temperature of T2. With the power supply current, the gas flows faster, and the more heat is taken away. There is a fixed function relationship between the gas flow rate and the added heat.