LaMotte Tracer Dissolved Oxygen Meter - Manual (Page 12)

5. When the reading is stable. Press and hold the CAL/RECALL button
for 2 seconds until CAL appears on the display. Release the button.
6. The display will blink until it is stable. 101.7% and “SA” will appear on
the display. When the calibration is complete, “END” will appear on
the display and the meter will return to the measurement mode.
Note: “SA” will not appear if the calibration fails.
7. The % saturation value that is displayed should be 101.7%. If not, allow
electrode to fully polarize, repeat step 5 until the display reads 101.7%.
Zero Oxygen Calibration
The optional zero oxygen calibration will improve the accuracy of
measuring samples with very low or very high dissolved oxygen levels.
1. Place the electrode in a zero oxygen calibration standard, such as 5%
sodium sulfite. Slowly stir the standard with the meter or use a stirring
plate.
2. Wait for the reading to stabilize. This may take a while, depending on
the electrode history.
3. Press the CAL/RECALL button for 2 seconds until CAL is displayed.
4. 0.00 and “SA” will appear on the display. When the calibration is
complete, “END” will appear on the display and the meter will return to
the measurement mode.
Note: “SA” will not appear if the calibration fails.
Note: Sodium sulfite can become deposited on the electrode and on the
coined surface of the electrode-retaining collar. If the sodium sulfite
deposits are not completely removed, it will cause negative error in
future DO measurements.
The meter can also be calibrated with the probe removed. (Zero
current).
5. The % saturation value that is displayed should be 0.00%. If not, allow
the electrode to fully polarize, repeat step 3 until the display reads
0.00%.
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