29
28
• Remove the protective cap from the
pH electrode and immerse it into the
selected buffer solution (e.g. pH 7.01)
with the Potential Matching Pin and
temperature probe, then stir gently.
Note
The electrode should be submerged ap-
proximately 4 cm (1½") in the solution.
The temperature probe should be located
as close as possible to the pH electrode.
Note
When it is not possible to immerse the Potential Matching Pin
together with the pH electrode in the solution, disable the
differential input by connecting the Connection for Potential
Matching Pin (#9 at page 7) with the Connection for Elec-
trode Reference (#8 at page 7) with a jumper wire.
• Only when the reading is stable the
probe indicator " " will stop flashing
(after about 30 seconds) and the
"CFM" indicator will start blinking.
• Press CFM to confirm the calibration; if the reading is close to
the selected buffer (±1.5 pH), the meter stores the reading
and the secondary LCD will display the expected second buffer
value. Offset and slope calculation is made at the end by
pressing CAL to exit.
If the reading is not close to the selected
buffer, "WRONG
BUF
" will blink.
• If CAL is pressed, the calibration pro-
cess ends by memorizing a new offset
value. The new offset value is stored
and a default value of 57.5 mV per
pH unit at 25°C is assigned as the
new slope value.
For best accuracy however, it is recommended that a two-
point calibration is performed.
HI 7007
CALIBRATION
HI 7007
RINSE
For accurate calibration, use two beakers for each buffer
solution, the first one for rinsing the electrode, the second
one for calibration. By doing this, contamination between
the buffers is minimized.
To obtain accurate readings, use pH 7.01 and pH 4.01 if
you measure acidic samples, or pH 7.01 and pH 10.01 for
alkaline measurements or perform a 3-point calibration for
the entire range.
One Point Calibration (Offset)
• To perform the pH calibration enter
the calibration mode, by pressing
CAL and entering the password.
• After the correct password is entered,
the control actions stop and the pri-
mary LCD will display the pH value
using the current offset and slope,
with the "CAL" and "
BUF
1
" indicators lit
and the probe indicator " " blink-
ing. The value displayed on the
secondary LCD is the buffer value
at the actual temperature.
Note
The actual pH value varies with temperature, thus the cali-
bration value displayed on the secondary LCD will vary around
pH 4.01, 7.01 and 10.01 with temperature changes: for ex-
ample at 25
o
C the display shows 4.01 - 7.01 - 10.01, at 20
o
C it shows 4.00 - 7.03 - 10.06 (see page 47 for other val-
ues).
• pH 7.01 is the default value for
the 1
st
calibration buffer. If a dif-
ferent value is needed, select it
on the secondary display by
pressing or .
Note
If the wrong password is entered the system reverts back and
restarts displaying the pH value.
