22
CALIBRA
TION
8.2. DO PROBE CALIBRATION (HI764103)
It is recommended to calibrate the instrument frequently, especially if high accuracy is required.
More frequent calibrations may be required depending on the type of sample being tested, i.e. turbid
biologically active water samples will require more frequent cleanings and calibrations than cleaner
waters.
The probe should be recalibrated:
• Whenever the probe or membrane is replaced.
• At least once a week.
• After testing aggressive samples.
• After cleaning the sensor.
• If “Outside Cal Range” message blinks during measurement (the measurement is outside the
current calibration range).
• If enabled, when the “CAL DUE” calibration time out message is displayed.
It is recommended to calibrate dissolved oxygen at the measurement site to prevent changes in
altitude and barometric pressure.
Note:
If %DO saturation is calibrated, the DO concentration range will also be calibrated and
vice versa.
% DO SATURATION
From the
Calibration
menu, use the
/
keys to highlight
Dissolved oxygen
and then press
Select
.
• To change the calibration point, press the
Cal. point
, use the
/
keys to select the new value,
press
Select
to use the highlighted value.
• To calibrate at 100 %, fill the calibration beaker with approximately 4 mm (5/32”) of water and
screw it onto the probe. The membrane should not be wet.
• Once the reading has stabilized, the countdown timer will count down until the display shows the
“Ready” message.
• Press
Accept
to accept the calibration point.
• To save a one-point calibration press
ESC
after the calibration point has been confirmed.