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3.3.3 Span Calibration in Solution (Salinity-corrected ppM Mode only)
This span calibration provides an alternative to calibrating the Dissolved Oxygen sensor in air. It is
only available when the
smart
CHEM
-D
is in Salinity-corrected ppM mode. Please note that the
normal AIR calibration (section 3.3.2) is still available for Salinity-corrected ppM mode.
1. Measure the Dissolved Oxygen content of the solution to be used for calibration. This is
generally done with a Winkler titration. The
smart
CHEM
-D
span calibration should be
performed immediately the Dissolved Oxygen content of the solution is known, as the value
may not be stable.
2. Place the Dissolved Oxygen and Conductivity/TDS sensors (and Temperature sensor, if
applicable) into the calibration solution. Ensure that the Conductivity/TDS sensor is immersed
at least to the top of the vent hole in the side of the sensor.
The solution must be stirred at a moderate rate.
Allow the reading to stabilise. After a zero calibration, this may take up to 5 minutes.
3. Select Oxygen Calibration. (
→
→
F1:Calibrate
→
→
F1:Oxygen
)
When the reading is above approximately 2 ppM, the
smart
CHEM
-D
will display the
AIR/SPAN calibration screen. Note the cursor underlining the “
A
” in “
AIR
”.
9*00ppMs
25.0
O
C
Oxygen AIR/SPAN Cal.
Press Enter
Use the numeric keypad to enter the Dissolved Oxygen value of the solution. The words
“AIR/SPAN” are deleted and the value being entered is displayed. The Conductivity or TDS
reading also appears as soon as the first numeric key is pressed.
Press the
to correct any errors.
4. Press
to calibrate. The Automatic Stability Function will now show a and highlight any
unstable readings…
6.70
ppMs
33.0
ppK
25.0
O
C
Oxygen Cal.
Waiting to Stabilise
When the Dissolved Oxygen and Temperature readings have both stabilised, the unit will
calibrate itself.
To calibrate immediately without waiting for complete stability, press
to disable the
Automatic Stability Function.
A “
∗
” in the display will be replaced by a decimal point after a successful air calibration.
5. The
smart
CHEM
-D
is now calibrated and is ready for Dissolved Oxygen measurement. Rinse
the Dissolved Oxygen sensor in distilled water and blot dry before placing into unknown
samples.
Содержание smartCHEM-D
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