Abstract: This sensing element, which is to be installed in a pipeline conducting the fluid to be measured, consists of a straight section of pipe (1) with an unrestricted cross-sectional area and an uninterrupted wall to the external surface of which are positively fixed, successively in the downstream direction and in a spaced-apart relationship: a first resonance absorber (11) at the inlet end consisting of at least one absorber disk (111), a first transducer disk (21) having a first ultrasonic transducer (31) attached to one lateral surface thereof which excites the radial resonance frequency of said first transducer disk (21), a second transducer disk (22) having a second ultrasonic transducer (32) attached to one lateral surface thereof which excites the radial resonance frequency of said second transducer disk (22), and a second resonance absorber (12) at the outlet end consisting of at least one absorber disk (121), the absorber disks (111, 121) being dimensioned so that their respective radial resonance freque

Abstract: An ultrasonic flowmeter includes first and second ultrasonic transducers which are mounted along a fluid measuring section opposite each other and whose connecting line makes an angle different from 90.degree. with the axis of the fluid measuring section. The transducers can be switched to transmit mode or receive mode by a switching arrangement having first and second switching paths per transducer, one conducting and the other simultaneously nonconducting, or vice versa. One end of the first and second switching paths is coupled to the associated first or second transducer. The first switching paths associated with the first and second transducers having their other ends coupled to the input of a measuring circuit, and the second switching paths associated with said first and second transducers having their other ends coupled to an oscillator.

Abstract: For flow rate measurement by means of ultrasonic waves, on a measuring tube two ultrasonic transducers are arranged spaced apart from each other, one operating as transmitting transducer and the other as receiving transducer. For determining the flow rate the phase shift between the transmission signal and the reception signal is measured digitally in that the measuring time intervals corresponding to the phase shift the periods of a signal are counted with a counting frequency which is substantially greater than the frequency of the transmission signal. The start phase which the counting frequency signal has at the beginning of each counting operation with respect to the measuring time interval is varied from measuring time interval to measuring time interval in a measuring cycle including a plurality of successive measuring time intervals and the counts obtained in the course of the measuring cycle are evaluated to form a measured value with increased measurement resolution.