Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 78)

<5. CALIBRATION OF pH/ORP>
5-4
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
l zero/slope
Select the solution that works with the “buffer solution” selected in calibration settings and
perform calibration by following the prompts on the screen.
l zero/slope/ITP(3point)
Calibration is performed in the sequence of the sequence selection menu (Table 5.1) of the
solution that works with the “buffer solution” selected in calibration settings. Perform calibration
by following the prompts on the screen.
Limitations
• Three different buffer solutions whose difference in pH value between buffer solutions is 1
pH or more should be used.
(1st buffer < 2nd buffer < 3rd buffer or 1st buffer > 2nd buffer > 3rd buffer)
• The 2nd buffer solution in the buffer table in the Free programmable screen should be pH 7
± 2 (at 25ºC).
• Either of the following conditions should be met.
- The temperature difference between the 1st and 2nd buffer solutions should be 5ºC or less.
The temperature of the 1st and 2nd buffer solutions is at least 20ºC higher or lower than the
temperature of the 3rd buffer solution.
- The temperature difference between the 2nd and 3rd buffer solutions should be 5ºC or less.
The temperature of the 2nd and 3rd buffer solutions is at least 20ºC higher or lower than the
temperature of the 1st buffer solution.
l zero/slope1,2(3point)
Calibration is performed in the sequence of the sequence selection menu (Table 5.1) of the
solution that works with the “buffer solution” selected in calibration settings. Perform calibration
by following the prompts on the screen.
Limitations
• Three different buffer solutions whose difference in pH value between buffer solutions is 1
pH or more should be used.
(1st buffer < 2nd buffer < 3rd buffer or 1st buffer > 2nd buffer > 3rd buffer)
• The temperature difference between the 1st and 2nd buffer solutions should be 20ºC or
less.
• The temperature difference between the 2nd and 3rd buffer solutions should be 20ºC or
less.
Table 5.1 Selection of Buffer Solutions in Three-point Calibration
Buffer settings Buffer sequence selection menus
NIST/DIN 19266 PH1.7→PH6.9→PH9.2
PH4.0→PH6.9→PH9.2
PH9.2→PH6.9→PH1.7
PH9.2→PH6.9→PH4.0
DIN 19267 PH4.7→PH6.8→PH9.2
PH9.2→PH6.8→PH4.7
US PH4.0→PH7.0→PH10.0
PH10.0→PH7.0→PH4.0
User defined buffer table1→table2→table3
able3→table2→table1