Pr
o
Minent
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Page 61
8.4.2.4
DULCOTEST
®
CDP Chlorine Dioxide Sensor, Calibration
Calibration
The sensor can be calibrated after the run-in period.
IMPORTANT
• A slope test must be carried out after replacing the diaphragm cap or electrolyte!
• Slope tests must be carried out at regular intervals to ensure correct functioning of the
sensor! For testing drinking water, calibration of the sensor every 3 - 4 weeks is suf fi -
cient.
• Avoid incorrect dosing due to air bubbles in the water. Air bubbles clinging to the sensor
diaphragm can reduce the measured variable and thereby lead to overdosing.
• Observe applicable national directives for calibration intervals!
Preconditions
• The sensor is run-in
•
Constant
fl ow to the in-line probe housing
• Constant sample water temperature
• Same sample water and sensor temperatures (wait approx. 15 min.)
Zero Point Calibration
If a ProMinent controller is being used to operate the sensor there is no need for zero point
calibration. Zero point calibration should be carried out, however, if operating the sensor in the
lower measurement range.
Preconditions
Insert the sensor into a container of clean, ozone-, chlorine and ClO
2
-free water.
Stir with the sensor until the measured variable displayed at the controller has remained stable
for 5 min.
Calibrate the controller to zero in accordance with the operating instructions.
Replace sensor into the in-line probe housing (DGM; DLG).
Slope
Test
Determine the chlorine dioxide content in the sample water using an appropriate measurement
device (e.g. DPD-1).
Set the resulting value at the controller in accordance with the operating instructions.
Repeat calibration after 1 day!
NOTE
Calibration at high temperatures
As chlorine dioxide, in contrast to chlorine, is only physically dissolved in water, it evap o-
rates out of the liquid very quickly at high temperatures (> 30 °C). We therefore rec om-
mend that you act quickly when carrying out the DPD measurement. There should be no
more than 1 min. between the sample extraction and the addition of reagents. Therefore
the reagent should be added directly at the sample extraction point and measurement
should follow as soon as possible afterwards in the laboratory.
Chlorine Dioxide Sensor CDP
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