Further Studies of the Accuracy of Clamp-on Transit-Time Ultrasonic Flowmeters for Liquids

The higher value of uncertainty in the flow measurement signal from transit-time clamp-on ultrasonic flowmeters (USFMs) compared with transit-time spool-piece USFMs is due to several factors, some of which have been considered in this paper. However, the main focus of this paper has been on the effect of separation distance between the transducers on the flowmeter output signal. The sources of experimental error that might affect the validity of the data obtained for the transducer separation are examined, and then, use of ray-tracing and finite-difference models is made to examine this relationship theoretically.