8. Selecting Buffers for Automatic Buffer Recognition
The 901-PH is factory set to automatically recognise pH4.00, pH6.88 and
pH9.23 buffers. There is also the options of using pH7.00 instead of pH6.88 and
pH10.01 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 and wait for 10 seconds.
2. Press and HOLD the key while switching the meter back on.
3. The display will now show the currently selected primary buffer. For
example…
Buffer 1 SelectBuffer 1 Select
then:
Buffer 1=6.88pHBuffer 1=6.88pH
Press the or keys to alternate between pH6.88 and pH7.00 buffers.
4. Press the key to go on when the desired primary buffer has been
selected. The display will now show the currently selected high buffer. For
example…
Buffer 2 SelectBuffer 2 Select
then:
Buffer 2=9.23pHBuffer 2=9.23pH
Press the or keys to alternate between pH9.23 and pH10.01 buffers.
The display shows 10.0 for the latter, but this buffer is stored in memory as
10.01.
4. Press the key to exit when the desired high buffer has been selected.
The setting is kept in memory when the meter is switched off, even when the
power supply 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.
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