Zeroing The Probe - Hach sension8 Manual

SECTION 3,
continued

3.3.3 Zeroing the Probe

ion
Zeroing the sens
when measuring dissolved oxygen levels less than 1 mg/L or 10%
saturation. When measuring in this range, zero the meter prior to
calibration.
1. Measure about 150 mL of sample or deionized water into a
250-mL beaker. Add a magnetic stir bar.
2. Add 0.25 g sodium sulfite or the contents of one Silica 3
Reagent Powder Pillow to the water. Stir to dissolve
the reagent.
3. Catalyze the reduction of dissolved oxygen by adding 0.1 mL
of a 1000 mg/L Cobalt Standard solution to the water.
4. Place the probe in the stirring sample for at least 10 minutes.
This solution is good for 30 minutes or more.
5. Press the key. The Cal icon will appear in the upper left
CAL
corner of the display, a flashing question mark will appear in
the upper right corner of the display, and the keypad icon will
appear in the lower left corner of the display.
6. Press the
ENTER
showing .
100%
7. Press the key on the keypad then press
0
8. The meter shows
the meter's zero DO criteria have been met it will return to
the Read Mode. The meter will not exit the zeroing routine
until the meter's zero criteria have been met.
33
8 Dissolved Oxygen meter is necessary only
key three times to skip to the display
while readings are taken. When
Stabilizing...
.
ENTER