YSI 5000 - Manual (Page 28)

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A standard method for creating such an environment is to dissolve excess sodium sulfite
(Na
2
SO
3
) and a trace of cobalt chloride (CoCl
2
) in water. Preferably, the water should come from
the sample to be measured. These chemicals will remove all oxygen from the sample (See
Standard Methods for the Examination of Water & Wastewater, method 4500-O G, 19th edition).
Alternatively, you may place the probe in 100% nitrogen gas.
1. Place the probe in the zero oxygen sample and allow at least 20 minutes for the probe to
come to equilibrium.
2. Press the [CALIBRATE] soft-key to change to Calibration mode. The following screen will
be displayed.
98.0 * % 8.15 mg/L
Calibration
0.0 ppt 740 mmHg
24.38°C 11:33 AM
AUTO CAL DO CAL SETUP DIAGNOSTICS
3. Press the [DO CAL] soft-key to enter the manual DO calibration menu.
000.0 * % 0.00 mg/L
Cal %
0.0
ppt
740
mmHg
24.38°C 11:33
AM
UP DOWN DIGIT NEXT
4. Make sure that the display readings are stable, then use the [UP], [DOWN] and [DIGIT] soft-
keys to enter the calibration value of 0.0% (or 0.00 mg/L).
NOTE: The instrument will not except any value other than zero for the first point of a two-point
calibration.
5. Press [ENTER] to confirm your calibration. The screen will momentarily display “ D.O.
CALIBRATION SAVED ”.
The Model 5000/5100 is calibrated at two points: the calibration value you select, and its default
zero.
NOTE: When you change the zero calibration point, you offset the other value, so that after
zeroing the probe for zero oxygen, you must recalibrate in an oxygen environment.
6. You must now recalibrate in an oxygen environment (see 6.1 Dissolved Oxygen Calibration,
Auto Cal or DO Cal).