A BROAD-BAND AND HIGH-SENSITIVITY DIELECTRIC-SPECTROSCOPY MEASUREMENTSYSTEM FOR QUALITY DETERMINATION OF LOW-PERMITTIVITY FLUIDS

Traditional quality measurement systems in the petroleum-related indus try are complex in structure and difficult to maintain. A measurement system for high-sensitivity and accurate permittivity measurements has been built in order to investigate dielectric spectroscopy as a basis for an easier-to-maintain system, which can replace some of the tradi tional instrumentation systems. The permittivity measurement system ha s been designed and tested for]ow-permittivity and low-loss fluids in the frequency range from 1 kHz to 5 GHz. In the lower part of the freq uency range impedance measurements are used, and in the higher range r eflection coefficient measurements are employed. The characteristics o f the measurement cells are optimized to give high sensitivity. High-a ccuracy permittivity measurements are obtained by calibration with sev eral known fluids. Temperature control and careful experimental routin es ensure good repeatability. Estimated overall uncertainty and presen ted measurement results on low-permittivity and low-loss oils and refe rence fluids confirm the performance of the system.