Calibration - ProMinent DULCOTEST CDE 2-mA-2 ppm Montage- Und Betriebsanleitung

Commissioning
7.1

Calibration

Calibrating at a higher water tem‐
perature
In contrast to chlorine, chlorine dioxide
can only be physically dissolved in
water.
At high temperatures (> 30 °C),
chlorine dioxide gasses out of the water
very quickly. It is therefore essential
that DPD measurements are performed
quickly. There should on no account be
more than 1 minute between taking the
sample and mixing it with the reagents.
The red dye should be generated by
the addition of the reagent directly at
the sampling point and the measure‐
ment should then be conducted in the
laboratory as quickly as possible.
CAUTION!
– Perform slope calibration following
the replacement of a diaphragm
cap or electrolyte.
– Repeat slope calibration at regular
intervals to ensure correct opera‐
tion of the sensor. The calibration
intervals are 3 ... 4 weeks,
depending on the quality of the
water.
– Avoid air bubbles in the sample
water. These air bubbles can
result in incorrect metering. Air
bubbles that adhere to the sensor
diaphragm may result in too low a
measured value and thus lead to
over-metering.
– Please note the applicable
national guidelines for calibration
intervals.
60
Requirements:
Constant flow in the bypass fitting.
–
Constant temperature of the
–
sample water.
Identical temperature of sample
–
water and sensor (wait approx. 15
minutes).
The sensor has been run in.
–
Constant pH value.
–
Zero point calibration:
If the sensor is operated with a ProMinent
measuring/control unit, then zero point calibra‐
tion is not generally necessary. However, per‐
form zero point calibration if you are using the
sensor at the lower threshold of the measuring
range.
Immerse the sensor in a bucket of clean
1.
water without disinfectant or oxidant
(e.g. commercially available still mineral
water).
Use the sensor to stir until the measured
2.
value on the measuring/control unit is
stable for 5 minutes.
Calibrate the measuring /control unit to
3.
zero in accordance with its operating
instructions.
Re-install the sensor in the bypass fitting
4.
(e.g. the DGMA; DLG III).
Slope calibration:
Immediately determine the disinfectant
1.
content of the sample water using a suit‐
able measuring kit (e.g. DPD 1).
Set the determined value on the meas‐
2.
uring/control unit in accordance with its
operating instructions.
Repeat calibration after one day to
ð
ensure that the sensor has reached
its maximum sensitivity (slope).