Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 109)

<8. CALIBRATION OF SC (Conductivity)>
8-1
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
8. CALIBRATION OF SC (Conductivity)
The cell constant of a conductivity meter does not change during operation, as long as it remains
undamaged, and clean. Therefore, it is vital that in any calibration check, the first step should be
to clean the sensor, or at least to check its cleanliness. After cleaning, ensure that the sensor is
carefully rinsed in distilled water to remove all traces of the cleaning medium.
The nominal cell constant of a conductivity meter is determined by the size of the electrodes and
their distance apart. In Yokogawa, the cell constant is calculated based on the results obtained
by calibrating the conductivity meter with JIS (NIST) standard solution and is indicated on the
nameplate or cable marker.
For input of the cell constant, see section 7.1.2.
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
8.6.3.)
Execute:
Calibration
HOLD
Temporary output
Setup:
Commissioning
Change language
Start Quick Setup
Execute & Setup Calibration
Cell constant(manual)
Cell constant(automatic)
Air calibration
Sample
Temperature coefficient
Temperature calibration
Figure 8.1 Calibration
Calibration for conductivity can be selected from Cell constant (manual), Cell constant
(automatic), Air calibration, and Sample. In most cases, Air calibration is not required.
NOTE
The standard instrument to be used in calibration with a process solution should always be
accurate. Yokogawa recommends that the Model SC72 pocket conductivity meter be used for
this purpose.
Where temperature compensation 1 (SC1) and temperature compensation 2 (SC2) have been
configured, the configured temperature compensation is effective even during calibration.
Therefore, the reading is the value converted to a conductivity value at the reference temperature
set in Temperature settings.
There are temperature compensation 1 (SC1) and temperature compensation 2 (SC2), but this
does not mean that calibration is required twice. It means that either SC1 or SC2 temperature
compensation should be selected and calibration should be made once to obtain the cell
constant. The cell constant after calibration can be checked on the Detail screen.
SC
8