YSI 3100 - Manual (Page 14)

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4. Advanced Setup
For highest accuracy, the 3100 and cell may be calibrated as a system using standard conductivity
calibration solutions. See the following section, 4.1 Cell Calibration, for details.
The default temperature compensation settings of the YSI Model 3100 are appropriate for the
vast majority of measurement applications. However, some measurement applications require
very specific measurement criteria. For that reason, we have made the YSI Model 3100 flexible
to accommodate these “advanced users.”
If, for example, you are using the YSI Model 3100 for a process control application which
requires that the conductivity readings be compensated to 20°C instead of 25°C -- see section,
4.3 Reference Temperature. Or, if your application involves the measurement of a very specific
saline solution, the default temperature coefficient may need to be changed to get the very best
measurement of that specific salt. See section 4.2 Temperature Coefficient.
4.1 Cell Calibration
Prior to calibration of the YSI Model 3100, it is important to remember the following:
•
The cell constant must be set correctly before calibrating. See section 3.3 Configure the 3100,
Cell Constant.
•
Always use clean, properly stored, NIST traceable calibration solutions (see section 9.2
Standard Calibrator Solutions). When filling a calibration container prior to performing the
calibration procedures, make certain that the level of calibrant buffers is high enough in the
container to cover the electrodes. Gently agitate the cell to remove any bubbles in the
conductivity cell.
•
Rinse the cell with distilled water (and wipe dry) between changes of calibration solutions.
•
During calibration, allow the cell time to stabilize with regard to temperature (approximately
60 seconds) before proceeding with the calibration process. The readings after calibration are
only as good as the calibration itself.
•
Perform calibration at a temperature as close to 25°C as possible. This will minimize any
temperature compensation error.
Follow these steps to perform an accurate calibration of the YSI Model 3100:
1. Select a calibration solution which is most similar to the sample you will be measuring.
•
For sea water choose a 50mS/cm conductivity standard (YSI 3165 or 3169)
•
For fresh water choose a 1mS/cm conductivity standard (YSI 3161 or 3167)
•
For brackish water choose a 10mS/cm conductivity standard (YSI 3163 or 3168)
2. Place at least 3 inches of solution in a clean glass beaker.
3. Insert the cell into the beaker deep enough to completely cover the electrodes. Do not rest the
cell on the bottom of the container -- suspend it above the bottom at least 1/4 inch.