PASCO PS-2108 Dissolved Oxygen Sensor - Manual (Page 20)

PASPort Dissolved Oxygen Sensor Model No. PS-2108
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6. Click the Start button on the DataStudio toolbar to begin recording data (Data Run #2).
7. Allow the probe to rest undisturbed in the test solution and
observe the sensor reading.
8. After the sensor reading stabilizes at the new level, gently move
the probe back and forth through the test solution and observe
the sensor reading.
9. After the sensor reading stabilizes at the new level, repeat steps
6 and 7 several times.
10. . Click the Stop button to end data recording. Save the recorded
data.
Note: The concentration of dissolved O
2
should be about the level of the high
value that you entered during calibration. If not, check to be sure that there are no large air bubbles on the bottom
of the probe. If the value is still significantly (more than 10%) different than the high value, re-calibrate the
sensor.
Data Analysis/Questions
1. Why does the measured dissolved O
2
concentration decline when you leave the probe
undisturbed?
2. Why does measured dissolved O
2
concentration stop declining while the probe is
undisturbed?
3. Why does the measured dissolved O
2
concentration rise when you move the probe
through the test solution?
4. Why does the measured dissolved O
2
concentration stop rising while the probe is moving
through the test solution?
5. Which measurement is the most accurate representation of the dissolved O
2
concentration
of the test solution?
6. Explain why it is important to move a steady flow of the test solution by the membrane of
the Dissolved Oxygen Sensor while taking dissolved O
2
concentration measurements.
Figure 2
Allow the probe to rest
undisturbed in the test solution