ABSTRACT

The design of a new standard for the specific electrical conductivity of liquids is based on an instrument, called the Eindhoven conductivity cell, used to determine the tortuosity or mass-coupling factor of a porous structure. This paper describes the measurements that were performed during the design process and gives a schematic display of the designed standard. From the measurements the following results were found. The specific electrical conductivity can be measured with an uncertainty of approximately 1%. The dominant uncertainty source are the distance between the electrodes, the temperature stability, the resistance measurement and the uncertainty contribution from the least squares fit. No significant frequency dependence of the specific conductivity was demonstrated. However, the uncertainty of the fit and the frequency of the bridge are positively correlated, which implies that DC operation results in the most accurate standard.