Hanna Instruments HI 99121 - Manual (Page 7)

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T o connect the probe
With the meter turned off, connect the HI 1292D probe to the DIN
socket on the top of the meter by aligning the pins and pushing in
the plug. Tighten the nut to ensure a good connection. Remove
the protective cap from the probe before taking any measure-
ments.
To turn the meter ON and check the battery status
Press the ON/OFF/MODE button until the display lights up. At
start-up, all the LCD segments are displayed for 1 second, then
the percent indication of the remaining battery life is shown for
another second (E.g. % 100 BATT). The meter then enters the
normal measuring mode.
Note: If the display needs to be checked, keep the ON button
pressed while turning the meter on. The meter will display all
segments as long as the button is pressed.
To freeze the display
While in measurement mode, press the SET/HOLD button,
HOLD appears on the secondary display and the reading will
be frozen on the LCD (E.g. pH 5.73 HOLD). Press any button
to return to normal mode.
To turn the meter OFF
While in normal measurement mode, press the ON/OFF/MODE
button. OFF will appear on the secondary display. Release the
button.
Note: The meter is provided with an acoustic signal feature, which
can be disabled using the switch located in the battery com-
partment.
Note: When the meter detects the absence of a temperature probe
at its input, the Automatic Temperature Compensation is turned
off, and the meter uses a default value of 25°C (77°F) for the
temperature measurement and compensation. In this condi-
tion, the secondary LCD shows 25.0°C (77.0°F) blinking.
When a probe is connected, the meter automatically returns
to the ATC mode, the ATC tag is turned on, and the tempera-
ture is shown on the secondary display.
• 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 stability symbol on the LCD is turned off.
• The LCD shows the pH value (automatically compensated 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 avoid contaminations. After cleaning,
rinse the probe tip with some of the sample to be measured.
pH calibration
For better accuracy, a frequent electrode cleaning (see
also pag. 15) and meter calibration 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 & hold ON/OFF/MODE 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 fea-
ture. 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, indicat-
ing 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 de-
sired, then after the calibration point has been accepted press
the ON/OFF/MODE button in order to return to the normal
measuring mode. After the button is pressed, the meter shows
OPERATING THE pH METER pH MEASUREMENT & CALIBRATION