GENERAL OPERATIONS
13
Regular Maintenance
y
Inspect the probe. If cracked, replace the probe.
y
Inspect the cable. Cable and insulation must be intact.
y
Connectors should be clean and dry.
y
Rinse off salt deposits with water.
y
Follow storage recommendations.
If electrodes are not maintained correctly, both accuracy and
precision are affected. This can be observed as a steady decrease
in the slope of the electrode.
The slope (%) indicates the sensitivity of the glass membrane,
the offset value (mV) indicates the age of electrode and provides
an estimation when the probe needs to be changed. The slope
percentage is referenced to the ideal slope value at 25 °C.
Milwaukee Instruments recommends that the offset does not
exceed ± 30 mV and that the slope percentage is between 85 ‑ 105 %.
When the slope value drops below 50 mV per decade (85 %
slope efficiency) or the offset at the zero point exceeds ± 30 mV,
reconditioning may improve performance, but a change of
electrode may be necessary to ensure accurate pH measurements.
Electrode Status
MW806
displays electrode status after calibration. See probe icon
on the LCD screen. The assessment remains active for 12 hours
and is based on the electrode offset and slope during calibration.
5 bars
Excellent condition
4 bars
Very good condition
3 bars
Good condition
2 bars
Fair condition
1 bar
Poor condition
1 bar blinking Very poor condition
no bar
Not calibrated
Recommendations:
y
1 bar:
Clean the electrode and recalibrate. If there is still only
1 bar or 1 bar blinking after recalibration, replace the probe.
y
No bar:
Instrument was not calibrated on current day or a
one‑point calibration was performed with previous calibration
not yet deleted.
