Abstract
The results of analysis are given for the experimental studies of the metrological characteristics of the reference conductivity cells carried out during the calibration of the conductivity sensors of CTD probes from 2008 to 2017 using “Installation for measuring conductivity sea water VNIRO” The factors determining the uncertainty of calibration of the conductivity reference cell are considered. The calculations were carried out for the combined standard uncertainty (CSU) of the cell calibration and standard uncertainties of its components. The expanded CSU of their calibration at any point in the range (53÷27) mS/cm was concluded not to exceed (2.2÷1.0)·10 –3 mS/cm, which corresponds to the relative expanded CSU calibration equal to 4·10 –5 . The analysis of the contribution of individual components to the total uncertainty is given. It was shown that CSU of the cell calibration is mainly estimated by the CSU of determining the reference value of the CSU SSW, due to the uncertainty in determining of the sample temperature inside the cell because of instability and inhomogeneity of the temperature field around it u ΣС(Т) . The value of u ΣС(Т) varies from 9.7·10 –4 mS/cm to 3.6·10–4 mS/cm at the level of instability of sea water in the thermal tank ranging from (1.1 ± 0.17)·10 –3 °C at a temperature of 25 °C to (0.53±0.19)·10 –3 °C at a temperature of 1 °C. The drift of the static cell conversion function for 413 days did not exceed ±0.003 mS/cm.
Published Version
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