8
9
•
For an accurate calibration, it is recom-
mended to wait an additional 5-10 minutes to
ensure optimum conditioning of the probe.
•
Remove the protective cap.
•
Press CAL. The disply shows
"----" together with the "CAL"
symbol to indicate that the
instrument is in calibration
mode.
•
The instrument will automati-
cally standardize itself to the
actual saturation value. After
approx. 1 minute it will dis-
play "100%" with "SAMPLE"
to indicate that the calibra-
tion is complete.
•
HI 9143 only: press FACTOR and ensure
that F1 and F2 are set to the appropriate
altitude and salinity values.
Notes: • The instrument must be calibrated
whenever the probe, membrane or
electrolyte is changed.
• To exit the calibration
mode at any time,
press CAL.
• The display may be
switched from readings
in % saturation to ppm
(mg/L) by simply
pressing the RANGE
key. Recalibration is
not needed.
CALIBRATION
PROBE POLARIZATION
The probe is under polarization with a fixed
voltage of approximately 800 mV. Probe polar-
ization 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 elec-
trolyte 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 surround-
ing solution. Measurements taken with a non-
polarized probe give an oxygen level that indi-
cates that of the test solution as well as any
oxygen present in the electrolyte solution. This
reading is obviously incorrect.
The HANNA HI 9143 and HI 9145 oxygen meter
automatically polarize the probe each time 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 7), i.e. the membrane is
filled with electrolyte, probe is connected to
the meter and properly polarized.
•
Switch the meter on.
•
"COND" appears on the dis-
play to inform the user that
the probe is in auto-condi-
tioning (automatic polariza-
tion) mode.
•
Once "COND" disappears, the probe is po-
larized and the instrument can be calibrated.
ON/OFF
CAL
CAL
SAMPLE
%
°C
CAL
RANGE
