Yokogawa EXA ISC202 2-wire Conductivity Transmitter/Analyzer - Manual (Page 80)

IM 12D06A03-01E
2-8 Appendix
3. Examples
While washing a reactor, HOLD is turned ON to prevent interference with control. When washing finish-
es, and a new batch starts, HOLD is turned OFF again and the sensor reverts to conductivity measure-
ment.
4. Auto Return
If AutoReturn functions are enabled, the instrument reverts to measurement mode after a preset time (10
min. by default) Refer to Sec. 5-3-5 User Interface.
12-4-2-3 Temperature Compensation
Refer to Sec. 5-2-3 for details.
1. Why is temperature compensation necessary?
Solution conductivity varies greatly with temperature ― in general it varies by about 2%/°C. (Conductivity
depends on ion mobility, i.e. on solution composition, concentration as well as temperature).
For details, refer to 5-2-3 Temperature Compensation, 5-2-4 First temperature compensation for conduc-
tivity , 5-2-5 Second temperature compensation for conductivity .
12-4-2-4 Correcting Zero Offset Error by Calibration in Air (Air Set)
Refer to Sec. 5-3 for details.
1. Why does Calibration in Air correct Zero Offset error?
It compensates for leakage resistance of sensor cable and the like.
2. When is such Calibration required?
You should correct zero offset error by calibration in air at startup time, and when the sensor is replaced.
3. What is the procedure for Correcting Zero Offset Error by Calibration in Air
Dry the sensor (conductivity of air should be effectively zero).
Ensure that the sensor is not in an electromagnetic (e.g. radio) field.
Enter Service Code 04.
When AIR is displayed, touch the YES key, and ― after START is displayed ― touch the YES key
again. After END is displayed, touch the YES key again.
*NOTE: The temperature compensation of NaCl should be selected to confirm zero offset after Air Set.