YSI Pro20 - Manual (Page 24)

If the calibration is unsuccessful, an error message will display on the screen. Press
the Cal key to exit the calibration error message and return to the run screen. See
the Troubleshooting guide for possible solutions.
CALIBRATING IN PERCENT (DO LOCAL% ENABLED)
Perform this calibration procedure when DO Local% is enabled in the System
Setup menu.
Prepare a 100% humid environment for the sensor as described in the One Touch
Calibration section.
Power the instrument on and wait approximately 5 to 15 minutes for the storage
chamber to become completely saturated and to allow the sensor to stabilize if
using a Polarographic sensor. If using a Galvanic sensor, wait approximately 5 to
10 minutes for the chamber to become completely saturated. Auto Shutoff time
should be disabled or set to at least 20 minutes, see System Setup menu for more
information on adjusting the Auto Shutoff.
Ensure the barometer reading is accurate. If necessary, perform a barometer
calibration.
Press and hold the Calibrate key for 3 seconds. %Local will be automatically
highlight, press enter. The Pro20 will display the current DO% and temperature
readings along with the % calibration value. The % calibration value will always
be 100% for DO Local%.
Wait at least 3 seconds, then, once the DO% and temperature readings are stable,
press enter to complete the calibration. Or, press the Cal key to cancel the
calibration.
Calibration Successful will display for a few seconds to indicate a successful
calibration and then the instrument will return to the run screen.
If the calibration is unsuccessful, an error message will display on the screen. Press
the Cal key to exit the calibration error message and return to the run screen. See
the Troubleshooting guide for possible solutions.
CALIBRATING IN MG/L
Power the instrument on and place the sensor into a sample that has been titrated
to determine the dissolved oxygen concentration. Continuously stir or move the
probe through the sample at a rate of at least ½ foot per second (16 cm per
second) during the entire calibration process. A stir plate may be helpful in this
calibration.
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