Measurement
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10.3. PRESSURE COMPENSATION
Both concentration (mg/L and ppm) and % saturation values vary with pressure.
Automatic Pressure Source
• Select
Automatic
under Pressure Source to use meter’s integrated barometer.
Manual Pressure Source
1. Use a reference barometer to obtain the true local barometric pressure reading source.
Note:
Do not use the weather‑reported barometric pressure readings as local references as readings are
corrected for altitude and only show sea‑level values.
2. From Measurement screen, tap (Measurement Menu icon).
3. Tap
Reading
tab.
4. Configure Pressure Source to
Manual
and configure preferred pressure unit.
5. Tap
Pressure
and
input value.
6. Tap
Save
.
10.4. SALINITY COMPENSATION
Concentration measurements (ppm and mg/L) in sea water samples require the salinity value input to account
for the lower solubility of oxygen in salt water.
Procedure
1. From Measurement screen, tap (Measurement Menu icon).
2. Tap
Reading
tab.
3. Tap to configure preferred Salinity unit.
4. Tap
Salinity,
input value.
5. Tap
Save
.
11. MEASUREMENT
Options: Direct, Direct/Autohold
•
Direct
: sample measurements are displayed continuously.
•
Direct/Autohold:
reading is displayed until measurement stability is reached. A measurement that has
not reached equilibrium will not be used. After stability criteria is reached, the meter holds the value until
the user changes to direct measurement again.
11.1. GUIDELINES
• Verify the temperature sensor is submerged in sample during measurement.
• Allow the probe to reach thermal equilibrium with the sample.
• Verify if pressure and temperature measurements are reading correctly, and the probe is calibrated in
accordance with sampling protocols.
• The probe should be measuring the partial pressure of the dissolved oxygen in water. Gas bubbles have a
greater partial pressure due to the surface tension of the bubble. Noisy or erratic measurement, or higher
measurements are possible.