kajaaniMCA
i
– Installation, Operating & Service - 9.2 - W4610201 V2.5 EN
9.B.3. Performing chemical compensation
Go from MAIN MENU => SELFDIAGNOSTICS => SPECIAL
FUNCTIONS
=> CHEMICAL COMPENSATION (Fig. 9.4).
The graph shows the total error (MCA – Lab.) of
calibration points 1 & 2 as a function of signal level
Mlev. Calibration point 1 has been temperature-com-
pensated to make it correspond to the temperature of
calibration point 2, and the result is the point 1'. The
temperature and conductivity of each sample is also
shown below the graph.
NOTE: Before the first calibration the graph is blank!
9.B.2. Setting chemicals compensation
In the example shown in Fig. 9.2, the calibration points
are selected from the laboratory follow-up data as
follows:
1. Choose a calibration point with a high signal level.
At this point the chemicals content has been low and
the MCAi has not shown a too high reading (Sample
1, Fig. 9.3).
2. Choose a calibration point with a low signal level.
At this point the chemicals content has increased
and the MCAi has shown a high reading (Sample 2,
Fig. 9.3).
3. Enter the Lab. and MCAi values of the calibration
points to the sensor: laboratory consistency and
conductivity, and consistency, temperature and sig-
nal level measured by the MCAi sensor. Make sure
to give the consistencies measured by the MCAi and
laboratory so that the error (MCAi – Lab.) is of the
right magnitude; the absolute Cs levels have no
significance. In other words, it does not matter
whether the Cs values for sample 2 are MCAi = 3.2
and Lab = 3.0 or MCAi = 5.2, Lab = 5.0. Before
determining the compensation graph through sam-
ples 1 & 2, the MCAi will perform temperature
compensation based on the temperature and con-
ductivity.
When the chemicals compensation is in use, the
MCAi will place the measured signal level result
(Mlev) on the compensation line, determine the error
(MCAi – Lab.) and correct the measured consistency by
the calculated amount.
Fig. 9.3. Choosing the calibration points.
-0.05
0
0.05
0.1
0.15
0.2
0.25
35 40 45 50 55 60 65 70
Mlev (u)
MCAi - Lab (%)
Sample 2
Sample 1
F7
F6
F5
F4
F8
F3
F1
F2
F9
F10
F11
F12
F13
F14
F15 F16
i
Fig. 9.4. “Chemical compensation” display.
CHEMICAL COMPENSATION
Compensation: 0.13%
Coefficient: -0.02 %/u
Tot.error [%]
2
0.32
1’ 1 Mlev
[u]
0.04
1’:60.2 u
1 :63.2 u 2 :36.4 u
65.3 °C 60.2 °C
1.2 mS/cm 5.00 mS/cm
Take Enter History Turn off
sample lab
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