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Page 18
8. Select pH Calibration (
→
F1:Cal.
→
F3:pH
).
9. When the reading has stabilised, press the
key to calibrate. If a 1
point calibration has been performed, the “
∗∗
“ will not be removed
until a full 2 point calibration has been performed.
10. Rinse the sensors in distilled water and blot them dry.
11. Place both sensors into a small sample of pH4.00, pH9.23 or
pH10.00 Buffer, so that the bulb and reference junction are both
covered as per the diagram in step 8, above.
DO NOT
place the
sensors directly into the buffer bottle.
NOTE: pH9.23 and pH10.00 buffers are highly unstable. Avoid
using these buffers if possible. Discard immediately after use
.
12. Select pH Calibration (
→
F1:Cal.
→
F3:pH
).
13. When the reading has stabilised, press the
key to calibrate. The
∗
will now be replaced by a decimal point, if calibration was successful.
14. The
WP-91
is now calibrated for pH and is ready for use. Discard the
used samples of buffer.