user manual

Input Calibration
January 2009 UDA2182 Universal Dual Analyzer Product Manual 159
8.7.5 Performing Calibration Trim
Introduction
For most applications entering the cal factor for each cell will achieve satisfactory system
performance. However, it is possible to perform a calibration trim procedure in which the
Analyzer and cell combination are used to measure a reference solution of known
conductivity; the reading of the Analyzer is adjusted to match.
The same procedure can be used to adjust the Analyzer’s reading while the cell is in the
process, if a reference instrument is used to determine the process conductivity. In this
case, the process fluid becomes the “reference solution”.
Calibration trim is recommended for acid concentration measurements above 5%.
Materials
To perform calibration trim using a standard reference solution, follow the instructions in
Table 8-9.
Materials required are:
• A reference solution of known conductivity near the point of interest, with the
temperature controlled (or measured and compensated) to within
± 1 °C.
Conductivities of potassium chloride solutions are provided in Table 8-8. Solutions
must be prepared with high-purity de-ionized, CO
2
-free water, and dried potassium
chloride.
• For acid concentration applications, a certified reagent grade solution with the
temperature controlled.
• A container for the reference solution, large enough to immerse the cell to measuring
depth.
• De-ionized water to rinse the cell.