부산대학교 도서관

This paper reports a closed-flow-loop electrolytic conductivity measurement system enabling calibration of conductivity sensors from the conductivity level of ultrapure water (UPW) at $5.5~\mu \text{S}$ /m up till the range of 10 to 140 mS/m, where stable certified reference materials (CRMs) for conductivity are available. The system is traceable to the SI unit system. A comparison made with another electrolytic conductivity measurement system, which is based on Jones-type conductivity cells designed to be used primarily for conductivities larger than ~10 mS/m, shows an agreement better than 0.1%. The most commonly used calibration method of conductivity sensors is based on CRMs and the extrapolation of the data to low conductivity values ( $< 1000~\mu \text{S}$ /m). In contrast, the present closed-flow-loop electrolytic conductivity measurement system is based on the measurements made at conductivity levels where the sensor is used; it is, therefore, a better alternative.