• Read the values CALC, T, nD and CONC in the DTR’s display at exactly the same time
with sampling.
T
he easiest way of doing this is to use the FIELD SAMPLE soft key available through the
Sensor status display (DTR program version 2.0 or newer). The value of each sample is
the average of 10 consequent measurements to increase accuracy and reduce possible
process noise.
Press the FIELD SAMPLE
soft key
Wait while DTR measures
(take sample for lab)
Press REPEAT for next
data point or BACK to get to
the Sensor status display.
1
2 3
Figure 40 Using FIELD SAMPLE soft key
•
Use a tight container for the sample to avoid evaporation.
Oine calibr
ation using process liquid very seldom gives reliable results, as problems are
caused by:
• Low flow which makes sample to form an unrepresentative film on the prism
• Sample evaporation at high temperature or undissolved solids at low temperature
giving deviations from laboratory determinations
• An ageing sample which is not representative
• Outside light reaching the prism
Calibration using the process liquid must always be made in‑line
.
7.4.4 Entering field calibr
ation parameters
Enter the field calibr
ation parameters supplied by Vaisala by selecting 5 CALIBRATION from
the Main menu, followed by 1 CHEMICAL & FIELD PARAMETERS and then 2 FIELD
CALIBRATION PARAMETERS.
If there is already a previous field calibr
ation, it should be cleared (by setting
all values to 0) before entering a new field calibration.
CAUTION!
7.4.5 Direct BIAS adjustment
The concentration measurement value can also be directly adjusted by changing the field
adjustment parameter f00.
PR-23 Series User Guide
IM-EN-PR23-E
76
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