Hanna Instruments HI9126 User Manual

Page 7

ONE-POINT CALIBRATION
For optimum accuracy it is always recommended to perform a two-
point calibration, but for a faster operation it is also possible to carry
out a single-point calibration.
pH 7.01 or pH 6.86 (NIST) are typically used, however the meter can
be calibrated with any of the memorized calibration values.
After calibrating the first point (see two-point calibration), press the
CAL

key to end the calibration procedure.

Note:

With one-point calibration electrode “condition” is not available
and only the frame is shown. Calibration time-out is active.

CUSTOM BUFFER SELECTION
• The meter allows the user to calibrate with custom buffers.
• To select a custom buffer press the CUST BUF key while in calibration

mode. Use the arrow keys to set the desired value for C1 (the default
value is 7.00).

Note:

During calibration, the secondary LCD shows the selected buffer
value; press RANGE to display the buffer temperature.

Note:

To clear a previous calibration and return to the default
values, press CLR at any time after entering the calibration
mode. The LCD will show “CLr CAL” for one second, and then
will return to normal measurement mode.
The LCD will show an empty bargraph to warn the user that
the meter is not calibrated.

Note:

To increase the speed, continuously press the ARROW keys.

• Once the desired value is reached,

press CFM to confirm the value. The
meter will continue calibration as
with memorized buffers.

• The meter will display “C2”. Use the

arrow keys to change the value of
the second custom buffer, or press
CUST BUF

to select a memorized

buffer.

EXPIRED CALIBRATION
The instrument has a real time clock (RTC), in order to monitor the
time elapsed since the last pH calibration.
The real time clock is reset every time the meter is calibrated and the
“expired calibration” status is triggered when the meter detects a
calibration time-out. The CAL tag will start blinking to warn the user
that the meter should be recalibrated.
The calibration time-out can be set (see “Setup menu” section on
page 14) from 0 (function disabled) to 14 days.
For example, if a 4 days time-out has been selected the meter will
issue the alarm exactly 4 days after the last calibration.
If the expiration value is changed (e.g. to 7 days), then the alarm
will be immediately recalculated and appear 7 days after the last
calibration.
Notes:
• When the meter is not calibrated or calibration is cleared (default

values loaded) there is no “expired calibration”, and the display
always shows a blinking CAL tag.

• When an abnormal condition in the RTC is detected the meter

forces the “expired calibration” status.