K-Patents PR-21-S User Manual
Page 62
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PR-21-S instruction manual
LAB%
Sample concentration determined by the user
From DTR display:
(see Figure 6.13)
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 Indicating transmitter serial
number, the sensor serial number and the sensor position, i.e. whether it is in-
stalled as Sensor A or as Sensor B.
Accurate calibration is only achieved if the sample is taken correctly. Pay special
attention 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
in the DTR’s display at exactly the same
time with sampling.
The easiest way of doing this is to use the
FIELD SAMPLE
soft key available through
the Sensor status display (DTR program version 2.0 or newer). The value of
each sample is the average of 10 consequent measurements to increase accu-
racy and reduce possible process noise.
Press the
FIELD
SAMPLE
soft key...
...wait while
DTR measures...
(take sample for lab)
...and press
REPEAT
for next
data point or BACK to get to
the Sensor status display.
Figure 6.13
Using
FIELD SAMPLE
soft key
− 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 temper-
ature 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.