Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 111)

<8. CALIBRATION OF SC (Conductivity)>
8-3
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
8.4 Sample
With the sensor in situ, a sample can be taken for laboratory analysis. Sample calibration records
the time and reading, and holds these in memory until the analysis has been completed. The
laboratory data can then be entered regardless of the current process value, without the need for
calculations.
When sample calibration is made with temperature compensation activated, the types of
temperature compensation for laboratory analysis equipment should be matched. Use of a
different type of temperature compensation between equipment causes an error. The standard
conductivity meter to be used should always be based on the accurate and same temperature
compensation calculation method. Yokogawa recommends that the Model SC82 pocket
conductivity meter be used for this purpose.
Press [Take Sample] to record a collected sample value in memory. Re-enter the Sample Cal.
screen and press [Start calibration] to perform a sample calibration. This updates the recorded
data.
8.5 Temperature coefficient
Simply input the solution conductivity at the reference temperature (TR) after allowing the sensor
to stabilize at elevated temperatures. The FLXA21 will calculate the temperature coefficient for
you. The ideal temperature for this calibration is the normal process value (TP).
This calibration is enabled if the Temperature Compensation is set to “TC.” (Section 7.1.4)
8.6 Temperature calibration
In order to make the most accurate measurements, it is important to have a precise temperature
measurement. This affects the display of temperature, and the output signal (when used). More
important, however, is the temperature compensation, and calibration accuracy.
The temperature of the sensor system should be measured independently with a high precision
thermometer. The value of “Measured temperature” should then be adjusted to agree with the
reading (zero offset calibration only).
For best accuracy, this should be done as near to the normal operating temperature as possible.
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