The importance of ray rescue angle orientation of ultrasonic transducers for high-rangeability ultrasonic llowmetering is known from earlier publications. The adaptive signal processing based on pulse compression in conjunction with the ray rescue angle orientation of the transducers is another important feature for achieving high-rangeability ultrasonic gas flowmetering. The technique of achieving the necessary broad bandwidth of the ultrasonic transducer, which has to be excited within a low lrequency band due to the absorption of ultrasound in gas increasing with lrequency is described. A signal processing system, catering to both very low and high times-ol-flight and their differences, is also presented. The usage of a special filtering technique based on assessing the gradient of the time series, in ascending order, of times-of-flight to eliminate spurious times-offlight observed in actual internogations of the flow is also presented. After presenting this technique, the paper preserlts a summary of user experience of high-rangeability gas flowmeters in use for over two years on different platlorms and in refineries. Hereby, the sensor performance and the long term tests that looked into the accuracy of the high-rangeability flowmeter are described. Results lrom on-and offshore installations of the ultrasonic flowmeters monitoring flare gas are also presented. TIMES-OF-FLIGHT IN HIGH-RANGEABILITY GAS FLOWMETERINGThe acoustic paths in the gas and along the geodesic line in the wall of a flow pipe are shown in Fig. 1. Two ultrasonic transducers are shown communicating with each other. The normalised timesof-llight for acoustic paths in the gas and the normalised propagation time in the wall of the flow pipe are shown in Fig. 2, where t,, and t, , are downstream and upstream times-of-flight respectively, 1, is the propagation time along the geodesic line in the pipe wall between the transducers and t, is the time-of-flight