6
MI605 Dissolved Oxygen Meter
5. PROBE POLARIZATION
The probe is under polarization with a fixed voltage of
approximately 800 mV.
Probe polarization is essential for stable measurements with the
same recurring degree of accuracy.
With the probe properly polarized, oxygen is continually "consumed"
by passing through the sensitive diaphragm and dissolving in the
electrolyte solution inside the probe.
If this operation is interrupted, the electrolyte solution continues
to be enriched with oxygen until it reaches an equilibrium with the
surrounding solution.
Whenever measurements are taken with a non-polarized probe,
the oxygen level indicated is both that of the test solution as well
as that present in the electrolyte solution.
This reading is obviously incorrect.