| 摘要 |
<P>PROBLEM TO BE SOLVED: To expand a measurement flow rate range in an ultrasonic flowmeter. <P>SOLUTION: This ultrasonic flowmeter is provided with: a first ultrasonic sensor pair 2; a second ultrasonic sensor pair 4; propagation time measurement means 8 for measuring the propagation time of an ultrasonic wave between the first ultrasonic sensor pair 2 or the second ultrasonic sensor pair 4 by switching the first ultrasonic sensor pair 2 or the second ultrasonic sensor pair 4 by a changeover switch 9; and flow rate arithmetic means 10 for calculating a flow rate from the propagation time measured by the propagation time measurement means 8. The ultrasonic flowmeter is configured to make the frequency of the ultrasonic wave of the second ultrasonic sensor pair 4 lower than that of the first ultrasonic sensor pair 2, and to measure the propagation time by the second ultrasonic sensor pair 4 at a prescribed flow rate or more. <P>COPYRIGHT: (C)2012,JPO&INPIT |
