Hanna Instruments HI 9321 - Manual (Page 13)

1 3
PROCEDURE
Calibration has a choice of 5 memorized buffers: 4.01, 6.86, 7.01,
9.18 and 10.01 pH.
It is always recommended to perform a two-point calibration, first in
an offset buffer (pH 6.86 or pH 7.01) and then a slope value
(pH 4.01, pH 9.18 or pH 10.01). The pH meter however also
provides for one-point calibration, as described below.
One-point calibration
• Immerse the pH electrode approximately
4 cm (1½") into a buffer solution of your
choice (pH 4.01, 6.86, 7.01, 9.18 or 10.01)
and stir gently. Attach the HI 7669/2W
temperature probe and immerse it too in
the buffer solution close to the pH electrode.
• Press CAL. The "CAL" and "
BUF
1
" indicators and "7.01" will be
displayed.
• Press
↑↑↑↑↑
°C or
↓↓↓↓↓
°C until the secondary display shows the same
value as the buffer solution.
• If the pH electrode has not completely
adjusted to the buffer value the LCD will
blink "NOT READY".
Only when the reading is stable, "READY"
and "CON" ("CFM" on HI 931401) will
blink.
• Press CFM to confirm the calibration.
If the value measured by the meter is not
close to the selected buffer, "WRONG
BUF
1 "
and "WRONG " will blink alternately (check
the buffers to ensure the correct one has
been used. If necessary change the buffer
or even the electrode). If the reading is
4 cm (1½
")
CAL
1
BUF
pH
NOT READY
READY
CON
WRONG WRONG 1
BUF