ULTRASONIC FLOWMETER

摘要

PROBLEM TO BE SOLVED: To improve the flow rate measurement precision and to increase the stability of instrumental error characteristics of the flowmeter by eliminating the temperature gradient of fluid and improving the detection precision of a received wave. SOLUTION: A plastic-made internal cylinder 6 is arranged inside the cylindrical part of a metallic external cylinder 5 across an air layer 9. The fluid (gas) flows through the flow passage between the external-diameter surface B1 of a bossed member 10 and the inner peripheral wall surface A1 of the internal cylinder 6. An ultrasonic wave is propagated from one ultrasonic transducer 1 which is arranged at a distance to the other ultrasonic transducer 2 and the flow velocity and flow rate are found from its propagation time. Bases 7 and 8 are made of plastic materials and the conduction of heat through the bases is small. The fluid flowing in the flow passage 40 is less affected by the temperature of the external cylinder 5.