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7.4.1 Preparation
Appendix D – ACCESSORIES lists Hanna solutions used for ORP calibrations.
The calibration should be conducted at temperatures between 20-26°C. The
sensor should be clean and oil free.
7.4.2 Procedure
• From the "Calibration" menu select "Single
param. calibration" and then "ORP calibration".
The display shows two options: "Custom ORP"
and "Restore factory calib.".
• For a user calibration select "Custom ORP".
• Fill a beaker with an ORP test solution (see
APPENDIX D "Accessories").
• Using the keypad, insert the numerical ORP
value and then press <Accept> to confirm.
• The stability counter will count down and the
message "Ready" and <Confirm> will be
displayed.
• Press <Confirm> to accept the calibration
point.
• After confirmation, the following messages are displayed: "Storing" and
"Calibration completed".
• Press OK to return to the Calibration menu.
• Press <Measure> to return to the measurement screen.
• To restore the factory calibration data, select the corresponding option in the
"ORP calibration" menu and then press <Select>.
7.5 DISSOLVED OXYGEN CALIBRATION
The accuracy of dissolved oxygen measurements is directly related to membrane
cleanliness and calibration technique. Oily coating and biological contaminants
are the primary cause of calibration drift in dissolved oxygen sensors. Unfortu-
nately, brushes or other cleaning objects may damage the membrane. Replac-
ing the membrane cap and electrolyte is the best way to perform periodic main-
tenance.
Although it may be easier to calibrate the D.O. sensor prior to deployment, it is
advised to calibrate at the site of deployment. Errors in measurement may result
if altitude and barometric pressure differ between the calibration and measure-
ment site. This is very important for autonomously logging probes.
Note Perform either the % D.O. Saturation or D.O. Concentration calibration.
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