Page 31
15. Selecting pH6.88 or pH7.00 as the Primary Buffer
The
WP-81T
is factory set to automatically recognise pH6.88 as the primary
buffer. However, some users may prefer to use pH7.00. The following procedure
describes how to alternate between pH6.88 and pH7.00 as the primary buffer.
1.
Switch the meter
OFF
with the
key.
2.
Press and HOLD the
key while switching the meter back on.
3.
The buffer selection menu is now displayed.
eg
Select
→
→
F1:6.88pH
Buffer
F2:7.00pH
The arrow indicates the current selection.
4.
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.
5.
The setting is kept in memory when the meter is switched off, even if the
battery is removed. The primary buffer is re-set to pH6.88 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.