Buffer temperature dependencies
Buffer temperature
At temperatures that differ by 25 °C in
the process, adjust the pH of the
buffer solution by entering the refer‐
ence values printed on the buffer sol‐
ution bottle into the controller prior to
calibration.
Buffer temperature dependen‐
cies
An incorrectly entered buffer tempera‐
ture can lead to incorrect calibration.
Each buffer has different temperature
dependencies. You have various
choices in terms of compensating for
these temperature dependencies, so
that the controller can correctly
process the buffer temperature.
–
Buffer temperature [Manual]:
Ensure that the buffer tempera‐
ture is identical for both buffers.
Enter the buffer temperature in
the [CAL Setup] menu item in the
controller.
–
Buffer temperature [Automatic]:
Then immerse the temperature
sensor connected to the con‐
troller together with the pH sensor
into the buffer. Wait for a suffi‐
ciently long period of time until
the pH and temperature sensor
have recorded the buffer tem‐
perature.
–
Buffer temperature [Off]: this set‐
ting is not recommended. Please
use another setting.
The sensor stability information displayed
during calibration,
[acceptable]
,
[good]
and
[very good]
, indicates to what extent
the sensor signal fluctuates during calibra‐
tion. At the start of calibration, the waiting
time for stabilising of the measured value
is 30 seconds; during this waiting time,
[Please wait!]
flashes in the display. You
cannot continue with calibration during
this waiting time.
If the pH sensor is cold, e.g. < 10 °C, then
the pH sensor responds slowly and you
have to wait a few minutes until the
sensor signal has stabilised.
The controller has no waiting time limit.
You will see the actual [sensor voltage] in
mV and can identify high fluctuations and
assign influences to them, such as the
movement of the sensor cable.
Calibration is impossible if the sensor
signal is very unsteady and the sensor
signal is disrupted by external influences,
or if the sensor cable has a cable break or
the coaxial cable is damp. Rectify any
fault or cable break.
You can only continue with calibration
once the signal bar has reached the
[acceptable]
range and remains there or
moves towards
[good]
or
[very good]
.
Changes to the signal within the ranges
[acceptable]
,
[good]
and
[very good]
are
permitted.
The signal fluctuation width within the
ranges is specified as follows:
n first 30 seconds wait time, then evalu‐
ation of the sensor signal
– Acceptable: 0.5 mV/30s
– Good: 0.3 mV/30s
– Very good: 0.1mV/30s
Calibration
64
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