Hanna Instruments HI 700 Series - Manual (Page 19)

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Offset Calibration
• To perform the EC 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 first
calibration value, with the "CAL" in-
dicator blinking. The secondary LCD
displays the temperature.
Note If the wrong password is entered the system reverts back to
normal operation, displaying EC values.
• 0 is the default value for the 1 st calibration point. Dry the
conductivity probe and leave it in air.
• Only when the reading is stable the
"CAL" indicator will stop flashing (af-
ter about 30 seconds) and the
"READY" and "CFM" indicators will
start blinking.
• Press CFM to confirm the calibration
point; the primary LCD will display
the second expected buffer value.
If the zero calibration cannot be per-
formed, "ERROR" will blink.
Cell constant calibration
• Select the solution value on the
primary display by pressing
or if the selected range has
two possibilities (e.g. 5.000
and 12.880 mS).
• Immerse the EC/TDS probe with the temperature sensor in
the selected solution. The level of solution must be higher
than the holes of the probe sleeve. Tap the probe repeat-
edly on the bottom of the beaker and stir to ensure that no
air bubbles are trapped inside the sleeve.
• When the reading is stable, "CAL"
will stop flashing (after about 30 sec-
onds) and the "READY" and "CFM"
indicators will blink.
CALIBRATION
The controller is factory calibrated for temperature as well as
for the analog input and outputs.
The user should periodically calibrate the instrument for EC
or TDS. For greatest accuracy, it is recommended that the
instrument is calibrated frequently.
Before beginning normal operation,it is recommended to stan-
dardize the probe with the Hanna calibration solution close
to the expected sample value and inside the selected range.
EC CALIBRATION
The calibration points are as follows:
Range Calibration point(s)
0.0 to 199.9 μS 84.0 μS
0 to 1999 μS 1413 μS
0.00 to 19.99 mS 5.00 - 12.88 mS
0.0 to 199.9 mS 80.0 - 111.8 mS
The user should select the appropriate range to calibrate (setup
code 03). Calibration must be performed for each range used.
The temperature probe should also be connected to the pro-
cess meter. The meters are equipped with a stability indicator.
The user is also guided with indications on the display during
the calibration procedure.
Initial Preparation
Pour a small quantity of the calibration solution (e.g. 1413 μS)
into a beaker. If possible, use a plastic beaker to minimize
any EMC interference.
For accurate calibration use two beakers containing the same
solution, the first one for rinsing the probe, the second one
for calibration. By doing this, contamination between the so-
lutions is minimized.
To obtain accurate readings, use the calibration solution in
the selected range and closer to the values to be measured.