Hach LBOD101, User Manual

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5.3 Zero-point calibration procedure
A zero-point calibration can increase the measurement accuracy of samples that have less than
1 mg/L O
2
. A zero point calibration is not recommended for samples that have more than 1 mg/L O
2
.
Set the calibration mode to "100% with 0". The meter starts the calibration with the 100%
measurement, then continues to the zero-point measurement.
1. Fill a BOD bottle
with deionized water.
2. Add 300 mg of
sodium sulfite to the
bottle.
3. Add 2 mL of
cobalt chloride
solution to the bottle.
4. Put a stopper on
the bottle and fully
mix for 30 seconds.
5. Remove the
stopper. Put the
probe in the bottle.
6. Tap the probe to
remove air bubbles.
7. Wait
approximately
10 minutes for the
contents to adjust to
ambient
temperature.
8. Start the stirrer.
9. Read the
dissolved oxygen
value. Wait for the
measurement to
become stable.
10. Save the
calibration.
11. Rinse the probe
with deionized water.
Dry the probe with a
lint-free cloth.
12. Fill a BOD bottle
with deionized water.
Put the probe in the
bottle and stir for
10 minutes to fully
remove the sulfite
from the probe.
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