Hach-Lange POLYMETRON 9240 Operator Manual - Manual (Page 98)

96
Calibration
If the volume of solution is OK, the background point
measurement (P0) to be used as the base measurement
value is taken. This is the measurement against the sample
before any additions of the calibration solution have been
made.
A progress bar is displayed showing the progress to date and
approximate time remaining.
The instrument waits for a stable measurement (a variation of
less than 1 mV per minute).
The measurement must be stable and less than 1 per
thousand of the calibration solution concentration, otherwise
the instrument returns to normal measurement with the
original parameters. Provided the measurement is OK, the P0
measurement details are displayed on screen.
If the reactivation frequency parameter is not zero (as is
highly recommended), the electrode will be reactivated.
When the reactivation process is complete, the overflow
vessel is rinsed to remove all traces of sample.
After rinsing, the overflow vessel is re-filled with sample plus
2mL of the calibration solution.
The sample is then measured and the details displayed
against P1.