During the calibration, the control module delta
®
sets the actuating
outputs to
„0“
. The mA standard signal outputs are frozen. The
reading frozen at the start of calibration is suggested as a DPD
value. The DPD value can be set using the arrow keys.
7.1.2 Calibration of Zero Point and Gradient
NOTICE!
Prerequisites for correct calibration of the sensor
gradient
– The DPD method required by the metering medium
employed will be used
–
The run-in time for the sensor has been adhered to
– There is permitted and constant flow at the flow
gauge
– There is temperature equalisation between the
sensor and the sample water
– There is a constant pH value in the permitted
range
The sensor is fitted, flushed with sample water and connected
electrically to the control module delta
®
and run-in.
There has to be adequate metering medium in the sample water
for calibration (> 2% of the measuring range of the sensor).
Remove sample water directly at the measuring point and using an
appropriate reference method (e.g. DPD, titration etc.), determine
the content of metering medium in the sample water in
„ppm“
.
Enter this value in the control module delta
®
as follows:
1. Select the calibration menu
[Sensor Calibration]
. The press
the button
2. Take a sample of water and perform a reference measure‐
ment immediately.
3. Select the unit
„DPD adjust“
to be calibrated using the
buttons or
4.
The press the button
ð
The current reading will now be frozen.
5. When necessary, adapt the ppm value determined using
keys and
ð
The ppm value of the sensor shown in this display now
corresponds to the reading in
„ppm“
.
6.
The press the button
ð
The display now shows the value determined for the zero
point and gradient. Refer to the Error Message table
should an error be displayed
Necessity of calibrating the zero point
Calibration of the zero point is not generally necessary.
Calibration of the zero point is only necessary if the
sensor is operated at the lower limit of the measuring
range or if the 0.5 ppm sensor version is used.
Calibrating the chlorine sensor: slope
Measured variables for the control module delta®
38
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