Development of a Gas Flow Sensor Based on FS5 Hot-Film Probe

On the basis of thermal measuring method, a hot-film gas flow sensor is proposed. Its sensitive element is a FS5 probe, which is integrated with measuring resistance and temperature compensating resistance inside. In order to achieve temperature compensation, the main measuring circuit is designed. Considering minimizing errors in this circuit, the temperature correcting circuit is added to further modify output voltage. By fitting measurement data of gas flow and the final output voltage with least square method, an operating characteristic curve is obtained as well as its 4th order polynomial. Under equivalent conditions, the proposed sensor, a high-precision standard sensor and an industrial sensor are experimented upon and the contrast analysis of their measurement results is given. The experimental results prove that the proposed sensor has high precision with measurement error less than 3%. Therefore the proposed sensor is feasible for industrial applications.