5.10
Calibration
This function group is used to calibrate the
transmitter.
Calibration options
• Three-point calibration
• Correction of an existing calibration with
the laboratory value
• Modification of individual values of the
three-point calibration
• Installation adjustment
• One-point calibration
Note:
•
If the calibration procedure is
aborted by pressing the PLUS and
MINUS keys at the same time
(return to C115, C123, C135, C143
or C153) or if the calibration is
faulty, then the previous
calibration data are reinstated. A
calibration error is indicated by the
“ERR” message and flashing of
the electrode symbol on the
display. Repeat calibration!
•
After calibration, the system
returns to Measuring mode.
During the hold delay time (Field
S4), the Hold symbol appears in
the display.
Overview of calibration
The calibration of the meeasuring chain is
three-point calibration, i.e., a turbidity
ascertained from three samples or from a
known solids content of the medium is used
to calculate the complete calibration
characteristic of the measuring chain for the
medium of the transmitter CUM 223 / 253.
It is wise to undertake calibration in the
turbidity or solids concentration range in
which you want to make measurements.
To simplify the three-point calibration, we
suggest to produce three samples required
for calibration by thinning a medium sample.
Usually, very good calibration results are
achieved with the concentration graduations
10 %, 33 % and 100 % of the original
concentration. The transmitter suggests this
concentration graduation for the three-point
calibration. This method also has the
advantage the only the turbidity or solids
concentration value of the original laboratory
sample need be defined exactly.
Note:
In particular, the concentration
graduation must changed for
samples with a very high
concentration or a very dark colour.
Very good results are achieved with
a graduation of 3%, 10% and 100%.
The original sample must also be
measured in the laboratory for
results correction after the laboratory
measurement.
9 parts zero
solution
+
1 part original
sample
Sample 1
original sample ×
1
/
10
2 parts zero
solution
+
1 part original
sample
Sample 2
original sample ×
1
/
3
Original sample
Calibration value 3
Sample 3
original sample
UM_3PROB.CDR
Fig. 5.13
Creation of samples for a
three-point calibration
Instrument configuration
Liquisys M CUM 223 / 253
46
Hauser
