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6. pH Mode
6.1 Selecting the pH Buffer Set
The
90-FL
can be programmed to automatically recognise any of the following buffer sets during
pH calibration. All pH values listed below are at 25
O
C.
1.
pH4.00, pH6.88, pH9.22
2.
pH4.00, pH6.88, pH10.06
3.
pH4.00, pH7.00, pH9.22
4.
pH4.00, pH7.00, pH10.06.
To select the pH buffer set for automatic recognition…
1.
Select the pH Buffer set-up menu.
(
→
→
F4:Setup
→
→
F1:Standards
→
→
F3:pH Buffers
).
2.
The primary buffer selection menu is now displayed…
Select Primary Buffer
>F1:6.88pH F2:7.00pH
The arrow indicates the current selection.
Press
to select pH6.88 as the Primary Buffer.
Press
to select pH7.00 as the Primary Buffer.
Press
to quit without changing the current setting.
3.
The secondary buffers selection menu is now displayed…
Select Secondary Buffers
>F1:4.00/9.22pH F2:4.00/10.06pH
The arrow indicates the current selection.
Press
to select pH4.00 and pH9.22 as the Secondary Buffers.
Press
to select pH4.00 and pH10.06 as the Secondary Buffers.
Press
to quit without changing the current setting.
Notes
1.
The selected buffer set is kept in memory when the meter is switched off.
2.
The buffers are re-set to pH4.00, pH6.88 and pH9.23 during initialisation.
3.
pH6.88 buffer is a DIN 19266 and NBS Primary-standard pH solution. Its use as the primary
buffer is highly recommended for the most accurate possible results. If pH7.00 buffer is used,
ensure that it is manufactured to at least 0.01pH accuracy. pH7.00 buffer has a buffer capacity
less than half that of pH6.88 buffer and is therefore much less stable.
4.
pH9.23 and pH10.06 buffers are highly unstable. Avoid using these buffers if possible. Discard
immediately after use.
5.
If you wish to use a pH buffer other than one of those listed above, its value can be keyed in
during calibration. Make sure that you have pH versus Temperature data for the buffer.