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Note
: It is always recommended to carry out a
two-point calibration for better accuracy.
• For a two-point calibration, place the probe in
pH 7.01 (or pH 6.86) buffer. After the calibration
point has been accepted, the “pH 4.01 USE”
message appears. The message is held for
12 seconds, unless a valid buffer is recognized.
If no valid buffer is recognized, then the WRNG
message is shown. If a valid buffer (pH 4.01,
pH 10.01 or pH 9.18) is detected, then the meter
completes the calibration procedure. When the
buffer is accepted, the LCD shows the accepted
value with the “OK 2” message on the secondary
display. The meter then returns to the normal
measuring mode.
Note
: When the calibration procedure is completed,
the CAL tag is turned on.
To quit calibration and to reset to the default
values
• After entering the calibration mode and before
the first point is accepted, it is possible to quit
the procedure and return to the last calibration
data by pressing the ON/OFF/MODE button. The
secondary LCD displays ESC for 1 second and
the meter returns to normal mode.
• To reset to the default values and clear a previous
calibration, press the SET/HOLD button
after entering the calibration mode and before
the first point is accepted.
The secondary LCD displays CLR for 1 second,
the meter resets to the default calibration
and the “CAL” tag on the LCD disappears.
METER SETUP
Setup mode allows the selection of the temperature
unit and of the pH buffer set.
To enter the Setup mode, press and hold the ON/
OFF/MODE button until CAL on the secondary dis-
play is replaced by TEMP and the current tempera-
ture unit (E.g. TEMP °C). Then:
•
for °C/°F selection, use the SET/HOLD button.
After the temperature unit has been selected,
press ON/OFF/MODE to enter the buffer set
selection mode; press ON/OFF/MODE twice to
return to the normal measuring mode.
•
to change the calibration buffer set, after setting
the temperature unit, the meter will show the cur-
rent buffer set: “pH 7.01 BUFF” (for 4.01/7.01/
10.01) or “pH 6.86 BUFF” (for 4.01/6.86/9.18).
Change the set with the SET/HOLD button, then
press ON/OFF/MODE to return to normal mode.
PH MEASUREMENT & CALIBRATION
• Make sure the meter has been calibrated before
use.
• If the probe is dry, soak it in
HI 70300
storage
solution for one hour to reactivate it.
• Place the tip of the probe into the sample to be
tested.
• Stir briefly and wait until the ¹ symbol on the top
left of the LCD is turned off.
• The LCD shows the pH value (automatically com-
pensated for temperature) on the primary LCD,
while the secondary LCD shows the temperature
of the solution.
• If measurements are taken in different samples
successively, rinse the probe tip thoroughly to eli-
minate cross-contamination. After cleaning, rinse
the probe tip with some of the sample to be
measured.
pH calibration
For better accuracy, frequent calibration of the
instrument is recommended. In addition, the
instrument must be recalibrated whenever:
a) The pH electrode is replaced.
b) After testing aggressive chemicals.
c) Where high accuracy is required.
d) At least once a month.
• From normal mode, press and hold the ON/
OFF/MODE button until OFF on the secondary
display is replaced by CAL. Release the button.
• The LCD enters the calibration mode, displaying
“pH 7.01 USE” (or “pH 6.86 USE” if the NIST
buffer set was selected). After 1 second the meter
activates the automatic buffer recognition feature.
If a valid buffer is detected, then its value is
shown on the primary display, and REC appears
on the secondary LCD. If no valid buffer is
detected, the meter keeps the USE indication
active for 12 seconds, and then replaces it with
WRNG, indicating that the sample being measured
is not a valid buffer.
• For a single-point calibration with buffers pH
4.01, 9.18 or 10.01, the meter automatically
accepts
the calibration when the reading is stable;
the meter will show on the primary display the
accepted buffer, with the message “OK 1” on
the secondary display, and an audible signal is
produced. After 1 second the meter automatically
returns to the normal measuring mode.
If a single-point calibration with buffers pH 7.01
or 6.86 is desired, then after the calibration point
has been accepted the ON/OFF/MODE button
must be pressed in order to return to the normal
measuring mode. After the button is
pressed, the meter shows "7.01" (or "6.86") -
"OK 1", and an audible signal is produced. After
1 second, the meter automatically returns to
the normal measuring mode.
