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Calibration of the dissolved Oxygen probe
The probe must be calibrated periodically using the DO9709/20 (for polarographic probe) or
DO9709/21 (for galvanic probe) calibrator.
The instrument checks the dissolved Oxygen probe efficiency. The "OFS_ERROR" message
indicates that the probe is exhausted.
The same message is displayed during calibration, when calibration is not possible or the reading
is unstable. Clean the measurement cell with replacement of the electrolyte and/or the membrane
covering the measurement electrodes: If the error indication persists, replace the probe.
Proceed as follows:
1. Connect the dissolved Oxygen probe to the instrument.
2. Disconnect the temperature only probe, if connected to the instrument, so that the indicated
temperature is that measured by the dissolved Oxygen probe built-in temperature sensor.
3. Turn the instrument on with the ON/OFF key.
4. Wet the sponge contained in the calibrator using 2ml of distilled water.
5. Insert the probe into the calibrator.
6. Wait at least 15 minutes until the system stabilizes thermally, saturation is reached inside the
calibrator and the reading is stable. If the membrane and/or electrolyte solution have been
replaced, wait at least 30 minutes.
7. Press
CAL
, then “
F2 = oxy
” (when accessing the calibration, the slope is set automatically to
1.000 and the previous calibration information is transferred to the “Dissolved Oxygen Probe
Calibration History” contained in the SICRAM module). The saturation index value, temperature,
barometric pressure and slope of the probe are displayed from top to bottom.
8. To proceed with the calibration press
F3 = CAL
. The calibration value 101.7% and the new
slope value, corrected according to the new calibration, are displayed.
9. If the measurement did not stabilize, press F3 = CAL again to repeat the calibration.
10. To end the calibration and return to measurement, press
ESC
.
The instrument is calibrated and ready for use.
If an error is made during calibration, you can press F1 = RESET to reset the slope value to 1.000.
Y
ou must repeat the calibration.
On pressing F3 = CAL during calibration, the instrument checks that the correction to be made
does not exceed the expected limits for correct functioning. If the calibration is rejected, the display
shows “
OFS_ERROR”,
the calibration is ended and the slope value is set to 1.000.
In case of “
OFS_ERROR
”, replace the electrolyte and the membrane. If the error persists, you can
try to clean the electrodes using very fine abrasive cloth (better if
impregnated with ammonia)
before
replacing the probe.
