Yokogawa FU24 All-in-One pH/ORP Sensor - Manual (Page 14)

IM 12B6J3-03E-E
14
6.1 Calibration for pH measurement
To calibrate the FU24 pH/ORP 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.
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.
6. Rinse sensor thoroughly with demineralized water.
During calibration, the temperature compensation should be active.
The EXA/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.
5.3 Settings for PH402G and PH202G(S)
Function pH
pH&ORP pH&rH ORP
pH compensated
Setting (default) ORP
code 01 0(pH) 0(pH) 0(pH) 1(ORP) 1(ORP)
code 02 0(off) 1(ORP) 2(rH) 0(off) 0(off)
code 03 1.1.1 1.1.1 1.1.1 0.0.1 0.0.1
code 04 0.0.1 0.0.1 0.0.1 0.0.1 1.1.1
code 31 0 2 2
jumper input 1 no no no yes yes
jumper input 2 yes yes yes yes no
5.4 Settings for PH150, PH450G and FLXA
Function pH
pH&ORP pH&rH ORP
pH compensated
Setting (default) ORP
sensor setup pH pH+ORP pH+ORP ORP ORP
measurement
setup
pH+ORP pH+rH
Impedance
setting
input1 High High High Low Low
input 2 Low Low Low Low High
jumper input 1 no no no yes yes
jumper input 2 yes yes yes yes no
6. GENERAL CALIBRATION & MAINTENANCE PROCEDURE