Hanna Instruments HI 23 - Manual (Page 18)

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CELL CONSTANT DIRECT SELECTION
Whenever the EC/TDS probe cell constant is known, it is
possible to directly calibrate the meter using that value.
• Press CAL to enter calibration mode. The LCD will show 0.
• Press LCD to display the current cell constant on the pri-
mary LCD (factory default value is 2.000 cm -1 ).
• Press SETUP key.
• Using , and , enter the probe cell constant (the
value must be between 1.333 and 4.000 cm -1 ) and con-
firm by pressing CFM.
Note If the entered cell constant value is invalid, the “ERROR” indi-
cator appear on the LCD.
Note Press SETUP before CFM to exit without changing the cell
constant.
CALIBRATION BUFFER DIRECT SELECTION
This feature allows to set a user-defined calibration point,
in order to perform calibration at a point different from the
memorized standards.
• Press CAL to enter calibration mode. The LCD will show 0.
• Press SETUP key.
• Using , and , enter the desired buffer value and
confirm by pressing CFM.
• When the reading is stable, "CAL" will stop
flashing (after about 30 seconds) and
"CFM" indicator will blink.
• Press CFM to confirm the calibration
point; if the reading is close to the selected
solution, the meter stores the reading.
If the reading is not close to the selected
solution, "ERROR" will blink.
A 2-point calibration is always suggested. However the EC/
TDS calibration can also be performed at 1 point. To cali-
brate offset only, just press CAL after confirmation (with CFM)
of the zero reading; the meter will return to normal opera-
tional mode. To have the cell constant calibrated first, press
the up or down arrow keys after entering the calibration pro-
cedure to skip to the next possible calibration buffer. In this
case, after confirmation of the cell constant, the meter will
ask for the offset calibration displaying zero on the LCD; press
CAL to exit or calibrate the offset, if desired.
Note The EC or TDS calibration value shown is referenced at 25°C
even if the reference temperature of 20°C has been selected.
Note During calibration, press LCD to display the cell constant
value on the primary display. Press LCD again to return to
calibration buffer visualization.
Note To interrupt the calibration procedure press CAL to exit to
normal operational mode.
Note If the process meter has never been calibrated or an EE-
PROM reset has occurred, the meter continues to perform
measurements. However, the user is informed of an EC or
TDS calibration requirement by a blinking “CAL” indication
(see “Startup” section).
Note The device must be calibrated within the temperature range
specified for the EC or TDS calibration solution.