FIELD: liquid resistivity measurement and empty tube detection. SUBSTANCE: flowmeter incorporates empty tube detection circuit which generates common-mode asynchronous signal applied to two electrodes installed inside tube. Liquid resistivity is found by measuring asynchronous signal between mentioned electrodes and ground. Value of liquid resistivity shows if tube is empty or not. Detector that monitors tube state is independent of winding field frequency, does not polarize electrodes, and can operate with high- capacitance cables. EFFECT: simplified circuit arrangement of flowmeter. 8 cl, 3 dwg
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