Thermal flow meter is an instrument which measures fluid flow by means of heat conduction The working principle is be adopted constant temperature differential method is adopted to measure gas mass flow accurately, featured by small volume, high degree of digitization, convenient installation and accurate measurement. The flow sensor is made up of two platinum resistance temperature sensors. One sensor is measuring the fluid temperature, the other sensor is to maintain the constant temperature differential. The primary reason Thermal flow meter are popular in industrial applications is the way they are designed and built. No moving parts, nearly straight through flow path, temperature or pressure don’t need to do corrections and retain accuracy over a wide range of flow rate.