CALIBRATION
PROBE POLARIZATION
The probe is under polarization with a fixed
voltage of approximately 800 mV.
Probe polarization is essential for stable mea-
surements 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 contained inside the probe.
If this operation is interrupted, the electrolyte
solution continues to be enriched with oxygen
until it reaches an equilibrium with the sur-
rounding solution. Whenever measurements
are taken with a non-polarized probe, the
oxygen level indicated is that of the test solu-
tion as well as any oxygen present in the
electrolyte solution. This reading is obviously
incorrect. The Hanna oxygen meter shown
here automatically polarize the probe when
they are switched on.
Calibration is simple and is recommended
every time the meter is switched on.
• Make sure the probe is ready for measure-
ment (see page 5), i.e. the membrane is
filled with electrolyte and probe is con-
nected to the meter and
properly polarized.
• Switch the meter on.
• "COND" appears on the
display to inform you that
the probe is in auto-condi-
tioning (automatic polariza-
tion) mode.
• Once "COND" disappears
the probe is polarized and instrument can
be calibrated.
ON/OFF
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