| 摘要 |
PROBLEM TO BE SOLVED: To provide a vortex flowmeter minimizing the impact imposed on a vortex signal by noise of a pressure pulsation, etc., due to less phase modulation in lower flow rate area. SOLUTION: In the vortex flowmeter 35, a control circuit 62 monitors whether the frequency-amplitude value of the vortex signal is in a proportionality relation or not, and then detects any flow abnormality from such a monitoring result of the frequency-amplitude value for the vortex signal to change an amplifier for vortex signal amplification into a first amp circuit 54 or a second amp circuit 56. Thus the above frequency-amplitude value can be changed into a vortex amplitude value suitable for measurement of higher flow area or the one suitable for measurement of lower flow area to determine if it deviates from the rated value in a vortex frequency-vortex amplitude values table.
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