Yokogawa SPS24 - Manual (Page 21)

<3. Sensor Management>
3-4
IM 12A01S02-01E 1st Edition : May 10, 2013-00
l Zero/slope1,2(3point)
This calibration type is the line-segment type three-point calibration.
If the relation between electromotive force and pH is not in proportion for a wide range, divide the
relevant range into two sections and obtain the zero (asymmetry) and slope (sensitivity) in each
section to perform calibration.
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.
n pH Calibration (Auto)
Calibration can easily be performed by following the calibration menus.
Pre-select the buffer solution to be used from among NIST/DIN 19266, DIN 19267, US, and
Programmable in [Setup] – [pH/ORP] – [pH/ORP common settings] – [pH calibration settings] –
“Select buffer set”.
If you select Programmable, calibration is performed based on the conditions registered in buffer
tables 1 to 3. Use of the proper buffer table allows the system to perform reliable calibration.
In the same way as manual pH calibration, select the calibration type from among [Zero/slope],
[Zero/slope/ITP(3point)], and [Zero/slope1,2(3point)].
Calibration is performed stepwise; follow the prompts displayed on the screen.
A stability check is conducted at each measurement point. Proceed to the next step only after the
reading has stabilized.
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 (3 points)
Calibration is performed in the sequence of the sequence selection menu (Table 3.4) 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 user defined buffer tables should be pH 7 ± 2 (at 25ºC).
• The temperature difference between the 1st and 3rd buffer solutions should be 20ºC or
more.
• The temperature difference between the 2nd and 3rd buffer solutions should be 20ºC or
more.
l Zero/Slope 1, 2 (3 points)
Calibration is performed in the sequence of the sequence selection menu (Table 3.4) of the
solution that works with the “buffer solution” selected in calibration settings. Perform calibration
by following the prompts on the screen.