K-Patents PR-33-S - Manual (Page 29)

5 Configuration and calibration 25
© Copyright K-Patents 2015. All rights reserved.
LAB%
Sample concentration determined by the user
CALC
Calculated concentration value
T
Process temperature measurement in Centigrade
nD
Actual refractive index n
D
CONC
Measurement in concentration units, the large size number
In addition to the calibration data, write down the sensor serial number.
Accurate calibration is only achieved if the sample is taken correctly. Pay special atten-
tion to following details:
−
The sampling valve and the refractometer should be installed close to each other
in the process.
!
Warning! Wear protective clothing appropriate to your process when operating the
sampling valve and handling the sample.
−
Run the sample before starting to collect data points to avoid sampling old process
liquid that has remained in the sampling valve.
−
Read the values
CALC
,
T
(emp),
nD
and
CONC
at exactly the same time with sam-
pling.
−
Use a tight container for the sample to avoid evaporation.
Important: Offline calibration using process liquid very seldom gives reliable results,
as problems are caused by
−
low flow which makes sample to form an unrepresentative film on the prism
−
sample evaporation at high temperature or undissolved solids at low temperature
giving deviations from laboratory determinations
−
an ageing sample which is not representative
−
outside light reaching the prism
Thus calibration using the process liquid should always be made inline.
5.2.2 Direct BIAS adjustment
The concentration measurement value can also be directly adjusted by changing the
field adjustment parameter f00.
The value of the bias parameter f00 will be added to the concentration value:
NEW CONC
=
OLD CONC
+
f00
.