Yokogawa Hokushin Electric Corp.

Tetsuo Ando

Hisashi Tamura

Ichizo Ito

Masashi Hirayama

A vortex flow metering apparatus comprising a sensor unit having first and second piezoelectric sensors selectively arranged in the concavity or a vortex generator having a measured fluid produce a Karman's vortex according to its velocity, a first conversion amplifier to which a signal from the first piezoelectric sensor is applied, a second conversion amplifier to which a signal from the second piezoelectric sensor is applied, an operator circuit to which outputs from the first and second conversion amplifiers are applied and which through addition or subtraction and other operations, removes noise components due to disturbance vibrations. The first and second piezoelectric sensors are selectively arranged at two points whereat stress distribution of the noise component due to disturbance vibration and stress distribution of a signal component due to vortex dynamic lift are different from each other. The invention thus has an unexpectedly high signal to noise ratio, and extraneous noise due to a variety of disturbance vibrations, is substantially eliminated.

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Tokyo, Japan

Tetsuo Ando