Hach-Lange POLYMETRON 9240 Operator Manual - Manual (Page 100)

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Calibration
8.4.3 Two point calibration
When prompted, fill the overflow vessel with the calibration
solution and select OK to start the measurement.
The calibration solution is measured and the results
displayed.
Once the final measurement is stable, the offset for the
calibration is calculated.
The success or failure screen is then displayed (see
examples in
Calibration results on page 100 ).
Select the MAN.OFFSET+SLOPE CAL option to start the two
point calibration process.
This process requires that two calibration solutions of known
sodium concentrations are available.
Refer to Calibration solution concentrations on page 93 for
information regarding the concentrations of the calibration
solution.
If necessary, enter the concentrations of the calibration
solution, and select START to initiate the calibration process.
Then, provided the reactivation frequency parameter is not
zero (as is highly recommended), the electrode is reactivated.
On completion this is followed by a rinsing of the overflow
vessel.
The process is then very similar to the one-point calibration
above, except after the instrument measures the low value
calibration solution, the overflow vessel will be rinsed and you
will be asked to fill it with the high value calibration solution.
The success or failure screen is then displayed (see
examples in
Calibration results on page 100 ).