YSI Pro20 - Manual (Page 22)

DISSOLVED OXYGEN
The Pro20 can be easily calibrated with the press of one key by enabling One
Touch Cal in the System Setup menu and following the One Touch Calibration
procedure.
Ensure the barometer is reading accurately before performing a One Touch
Calibration, DO %, or DO Local% calibration. These calibration procedures use
the barometer reading during calibration. If the barometer reading is erroneous
during a calibration, your dissolved oxygen values will be inaccurate.
It is not necessary to calibrate in both % and mg/L or ppm.
Calibrating in % will simultaneously calibrate mg/L and ppm and
vice versa. YSI recommends calibrating dissolved oxygen in % for
both ease and accuracy.
L
ONE TOUCH CALIBRATION
Perform this calibration procedure when One Touch Cal is enabled in the System
Setup menu.
If using a field cable, install the sensor guard onto the probe. Moisten the sponge
in the grey calibration/storage sleeve with a small amount of water and install it
over the sensor guard. The sleeve should be moist, but should not have excess
water that could cause water droplets to get on the membrane. The storage sleeve
ensures venting to the atmosphere.
If using the ProBOD sensor/cable assembly, place the probe in 300 ml BOD bottle
with a small amount of water (1/8 inch or 0.3 cm). The dissolved oxygen and
temperature sensors should not be immersed in water.
If the calibration/storage sleeve is not available, substitute with a chamber of 100%
relative humidity, vented to the atmosphere (not completely sealed).
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.
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