Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 136)

<11. CALIBRATION OF ISC (Inductive Conductivity)>
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IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
11. CALIBRATION OF ISC (Inductive
Conductivity)
Inductive conductivity meters must be calibrated after being installed in a measurement location
or moved to a different location.
Inductive conductivity meters do not generally need to be calibrated repetitively if they have been
calibrated once before the start of use. If the cell is severely contaminated or has been subject to
abrasion (possibly during cleaning), calibration may be necessary.
Execute air calibration first, if needed.
When using solutions, manual, automatic, and sample calibrations are available.
Execute:
Calibration
HOLD
Setup:
Commissioning
Change language
Start Quick Setup
Execute & Setup Calibration
Cell constant(manual)
Cell constant(automatic)
Air calibration
Sample
Temperature coefficient
Temperature calibration
Figure 11.1 Calibration
NOTE
A default is “10 min” for “Auto Return”. When maintenance like a calibration that may take much
time is performed, “60 min” or “Disable” is recommended to be selected. (Refer to the section
10.6.3.)
Calibration is carried out by measuring a solution which has a known conductivity and adjusting
the instrument to show the correct conductivity value.
● “Cell constant (manual)”, “Cell constant (automatic)
A calibration solution can be prepared in the laboratory. A salt solution is prepared with a
known precise concentration. The temperature is stabilized to the reference temperature of the
instrument (usually 25°C). The actual conductivity of the solution is taken from literature data. The
typical calibration solutions include NaCl and KCl; see Appendix 3. To calibrate the instrument,
the sensor is removed from a process and suspended in the solution, the conductivity value from
the literature data is then entered and the calibration routine completed.
Make sure the sensor does not touch the sides of the container (see Figure 11.2).
● “Sample calibration”
This calibration uses a process solution. In this method, the conductivity of the process solution
under measurement is measured with a standard instrument. In this case, care must be taken to
make the measurement at the reference temperature since differences in the type of temperature
compensation of the instruments may cause an error. With this method, it is not necessary to
remove the sensor from the process. Because the sensor is immersed in the process, errors
caused by the installation characteristics are compensated for.
ISC
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