| 摘要 |
A method and instrument for comparing the dielectric properties of a flowing stream of fluid with the dielectric properties of a reference fluid in which a uniquely configured multi-capacitor sensor, formed of a first pair of capacitors having like dielectric spaces within which the reference fluid is maintained under non-flow conditions as the dielectric material and a second pair of capacitors having like dielectric spaces within which a sample portion of the flowing stream of fluid is continuously passed as the dielectric material, comprises all of the capacitance elements of a Wheatstone bridge circuit in a single cellular unit in which the capacitive elements are all subjected to the same sample fluid, temperature and pressure environment and which is not sensitive to stray capacitances. Each pair of capacitors forms opposing sides of the Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across a first set of bridge terminals at opposite corners of the bridge and a current detection circuit is connected across a second set of bridge terminals independent of the first set of terminals and at opposite corners of the bridge. Detection and measurement of the current value of the bridge is translated into a value of dielectric constant for the fluid sample in direct linear relationship with the current value.
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