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16. Selecting Buffers for Auto Buffer Recognition
The
WP-90
is factory set to automatically recognise pH4.00, pH6.88 and pH9.23
buffers. However, some users may prefer to use pH7.00 instead of pH6.88 and
pH10.00 instead of pH9.23. The following procedure describes how to set which
of these buffers are automatically recognised at calibration.
1.
Switch the meter
OFF
.
2.
Press and HOLD the
key while switching the meter back on.
The buffer selection menu is now displayed.
Select
→
→
F1
:
6.88pH
Buffer F2
:
7.00pH
The arrow indicates the current selection.
3.
Press
to select pH6.88 as the primary buffer.
Press
to select pH7.00 as the primary buffer.
Press
to quit buffer selection and retain the current setting.
4.
The display will now show the currently selected high pH buffer.
Select
→
→
F1
:
9.23pH
Buffer F2
:
10.0pH
The arrow indicates the current selection.
5.
Press
to select pH9.23 as the high pH buffer.
Press
to select pH10.00 as the high pH buffer (the display shows 10.0
for the latter, but this buffer is stored as pH10.00).
6.
Press
to quit buffer selection and retain the current setting.
7.
The setting is kept in memory when the meter is switched off, even if the
battery is removed. The buffers are re-set to pH6.88 and pH9.23 during
initialisation.
Note:
pH6.88 buffer is a DIN 19266 and NBS Primary-standard pH solution. Its
use is highly recommended for the most accurate possible results. If pH7.00
buffer is used, ensure that it is manufactured to 0.01pH accuracy. pH7.00
buffer has a buffer capacity less than half that of pH6.88 buffer and is
therefore much less stable.