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Avalanche Portable Refrigerated Sampler
Section 7 SDI-12 Sondes
7.7 Sonde Calibration and
Validation
You should calibrate your sonde in the lab, according to
manufacturer’s recommendations.
Note
The AQ700 sonde’s PC software program provides calibration
for its sensors. Refer to the AQ700 user manual for complete
instructions for calibration of each parameter.
The Avalanche allows for field calibration of level, pH, Dissolved
Oxygen (DO), and Oxidation Reduction Potential (ORP);
however, field calibrations are stored in the sampler, not in the
sonde. They are used to modify readings from the sonde until a
new sonde is connected. When a sonde is moved to another
sampler, it will retain internal calibration constants set in the
lab, but will not retain any that were set in the field.
Although field calibration is limited to four parameters, you can
validate any of the available parameters. Validation allows you
to immerse the sonde in a known solution and verify the sonde’s
readings. The validation process does not modify any readings
like calibration does; it merely alerts you to inaccurate ones.
No data will be stored, nor will enable conditions be updated,
while calibration or validation is being performed.
7.7.1 Calibration Screens
To access the calibration screens from the main menu, select
Other Functions > Hardware. Advance to SDI-12 DATA:
NO SDI-12 SONDE
SETUP KNOWN SONDES
SCAN SDI-12 SONDES
Select SETUP KNOWN SONDES and DONE. The screen will
list the parameters you can calibrate, similar to the example
below. The sonde’s address will appear after the parameter (such
as pH0 and pH5).
SELECT PARAMETER
TO CALIBRATE:
pH5 DO5 ORP5 DONE
The parameter selected will determine the content of the calibration screens:
• Level - Enter the current measured level. The sampler
will use this value to offset the level reading of the
sonde.
• pH - You will be given the choice of three different pH
solutions: 4.00, 7.00, and 10.00. After making your
selection, rinse the probe and place in the pH buffer. If
the reading is off by more than 0.5 pH units, you will be
asked to verify if the reading is correct.
• DO - For dissolved oxygen, you can choose between two
methods: DO Standard and Saturation. The saturation
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