| 摘要 |
PROBLEM TO BE SOLVED: To reduce an error cause due to a change in a delay time and to realize accurately measuring by measuring a delay time generated by a delay time generating means by a delay time measuring means. SOLUTION: An ultrasonic signal oscillated from a first vibrator 2 according to a burst signal from a transmitter 4 is propagated through a flow of a channel 1, sensed by a second vibrator 3, a delay time generated from a delay time generating means 9 is placed, and then the burst signal is again transmitted from the transmitting circuit 4. The signal from the transmitting circuit 4 is repeated predetermined number of times, and a time required for the repetition is measured by an accumulation time measuring means 12, and the delay time is measured by a delay time measuring means 10. The delay time obtained by the means 10 is subtracted from a value obtained by the means 12 in a flow rate operating means 8 to obtain a predetermined time T only for the transmission of the ultrasonic wave. To actually measure the delay time, even if a change cause occurs, the time T can be accurately obtained.
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