| 摘要 |
PURPOSE:To dispense with an orifice or a measuring pot, by allowing the air column pressure in a columnar body and a purge pipe to vary upon the reception of the effect of pressure variation due to a Karman vortex and detecting the variation of said pressure by a pressure transmitter. CONSTITUTION:A phenomenon such that the gas-liquid boundary surface generated at the part of the hole 9 bored in a vortex generator receives pressure variation due to a Karman vortex to vary is utilized. That is, the air column pressure in a columnar body 8 and a purge pipe 7c receives the effect of pressure variation of the Karman vortex to vary and this variation is detected by a pressure transmitter 10. After only the output signal of the pressure transmitter 10 is amplified by an AC amplifier 11, the frequency of an AC signal is calculated by a frequency operator 12 and it is utilized that the above mentioned frequency is proportional to a flow speed to measure a flow rate by a flow rate converter 13.
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