iMassFlow 200 measures gas flow rate by calculating time difference of ultrasonic pulse - the bigger time difference the higher gas flow rate. Appropriate compensation is made on algorithm to counteract effection of ultrasonic speed from fluctation of temperature and pressure. iMassFlow 200 is patented in China with algorithm, design and mounting structure. It could be used for measuring flow rate of exhaust gas from pipeline, flue and chimney, applicable both in closed loop and open gas circuit. Features . Creative design, adaptive to flues with difference size . Improved ultrasonic technology, no need regular calibration . Accuracy is guaranteed with flow rate uner 0.5m/s . Accuracy is guaranteed under high temperature/pressure/humidity . Titanium sensor, resistant to contamination and corrosion . Sensor and measurement unit are design in one body, easy to install and disassemble . Customized flange to fit different flue diameters . Both digital and analog outputs are available