YSI ADV6600 - Manual (Page 61)

Section 4. Calibration and Diagnostics
ADV6600
Y S I
Environmental
Page 51
4-6.3. Dissolved Oxygen for Unattended Monitoring Studies
NOTE CAREFULLY: Before beginning the calibration of dissolved oxygen for unattended
monitoring studies, first assure that the Autosleep RS232 selection in the Advanced|Setup menu is
ACTIVE.
The dissolved oxygen calibration may be carried out in either % Saturation, or mg/L. The %
saturation method is the simplest to perform and recommended by YSI. Calibrating either of the
choices will automatically calibrate the other.
If % Saturation is chosen, the calibration will be performed in a water-saturated air environment. If
a mg/L calibration is chosen, the user will be calibrating in a solution with a known DO
concentration, usually determined by a Winkler Titration.
NOTE: If you have resurfaced your DO sensor, we recommend running the probe continuously
with a one minute averaging interval and one minute sampling interval for 15-30 minutes or until
good stability is realized before attempting to calibrate. After only a membrane change, no
resurfacing, run the probe continuously for 3-4 minutes or until good stability is realized.
Air Calibration in % Saturation:
1. With the sonde/calibration cup in the upright position, place approximately 3 mm (1/8 inch) of
water in the bottom of the calibration cup.
2. Carefully insert the probe end of the sonde into the cup, making certain that the DO and
temperature probes are not immersed in water.
3. Engage only 1 or 2 threads of the calibration cup to ensure the DO probe is vented to the
atmosphere.
4. Wait approximately 10-15 minutes for the air in the calibration cup to become water saturated
and for the temperature to equilibrate.
5. Select Dissolved Oxy.
6. Select 1-DO %.
7. The screen will prompt you to enter the local barometric pressure in mmHg.
8. Press Enter, and the calibration will automatically occur after a preset warm-up period of 60
seconds, followed by a message indicating that the DO calibration is complete.
9. Press Enter again to return to the Calibrate menu.
Note: At calibration, the DOsat % (percent air saturation) value will reflect the barometer value
that was entered. For example, if a barometric pressure of 720 mm is entered, the DOsat % value
will change to 94.7 % (720/760 x 100). The parameter “DOsat %Local” is also available for users
who prefer to set their percent air saturation value to 100%, no matter what barometer value is
entered. The method of activating this parameter, its use, and its limitations are described in
Appendix F of this manual. The key factor to remember, however, is that no matter which
convention (DOsat % or DOsat %Local) is selected, the barometric pressure must still be entered
during calibration and the mg/L value will not be affected.