Yokogawa SC25F - Manual (Page 17)

5. WIRING
The SC25F is provided with a multipole M9 male connector for connection to the
Yokogawa FLXA analyzer using the WU11 interconnection cable for SENCOM™ sensors.
The connections of this M9 male connector (see Section 2.7 for details), the WU11
interconnection cable and the FLXA terminal strip are given in Table 3.
Table 3: Definition M9 sensor connector pin to WU11 cable and FLXA analyzer
M9 Pin # WU11 wire # WU11 wire color FLXA terminal # Signal description
1 83 Yellow 83 Data -
2 84 Green 84 Data +
3 87 Brown 87 Supply +
4 82 Black 82 Shield
5 86 White 86 Supply Gnd
6. GENERAL CALIBRATION & MAINTENANCE PROCEDURE
Calibration of the SC25F pH SENCOM™ sensor can be done on site with the FLXA
analyzer connected, or in the laboratory with another FLXA analyzer or with the dedicated
Yokogawa SENCOM™ PC software, model SPS24. When using another FLXA analyzer, it
has to be set correctly for each calibration. Refer to the FLXA analyzer Instruction Manual
for details. After calibration all data will be stored in the sensor itself.
If the sensor is reconnected to the FLXA analyzer in the field, the calibration data of the
sensor is automatically read by the analyzer.
6.1 Calibration for pH measurement
To calibrate the SC25F pH SENCOM™ sensor, two buffer solutions with known pH values
are required. It is recommended that one buffer solution has a value near to pH 7.00.
Depending on the process value to be measured, the second buffer solution should be
either acidic (below pH 7.00) or alkaline (above pH 7.00). Normally the IEC buffers (pH 4.01,
6.87 and 9.18) are used.
The following is a very general 2-point calibration procedure:
1. Clean the sensor using a 5% solution of HCl;
2. Rinse sensor thoroughly with demineralized water;
3. Immerse the sensor in the first buffer (pH 6.87 is recommended) and execute calibration
as described in the instruction manual of the analyzer or SPS24 PC software;
4. Rinse sensor thoroughly with demineralized water;
5. Immerse the sensor in the second buffer (pH 4.01 or 9.18 is recommended) and execute
calibration as described in the instruction manual of the analyzer or SPS24 PC software;
6. Rinse sensor thoroughly with demineralized water.
During calibration, the temperature compensation should be active. The FLXA analyzer
automatically compensates for the sensitivity change of the pH sensor at different
temperatures.
After calibration, replace or re-install the sensor into the process.
IM 12B6J1-41E-E
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