Hanna Instruments HI 2550 User Manual

Page 19

RELATIVE

RELATIVE m

mV CALIBRATION

V CALIBRATION

• Press CAL when the instrument is in RELATIVE mV measurement

mode. The “mV” and “ ” tags will be displayed. Absolute mV is
displayed on the primary LCD and “AbS” message is displayed on the
secondary LCD.

• When the absolute reading is stable and in measurement range, the

instrument asks for confirmation.

• If the reading is out of range, “WRONG” tag will be displayed.
• Press CFM to confirm the absolute value. The instrument will display

0.0 mV on the primary LCD and “rEL” message on the secondary
LCD. In this moment the relative mV offset is equal to absolute mV
reading.

• Use the ARROW keys if you want to change the displayed relative

mV value.

• Press CFM to confirm the relative mV value. The instrument returns

to measurement mode.

Note: The relative mV value can be changed only inside the relative mV

offset window (± 2000 mV).

EC/TDS CALIBRATION

Selectable calibration points for conductivity are 0.00 μS for offset and
84.0 μS, 1413 μS, 5.00 mS, 12.88 mS, 80.0 mS, 111.8 mS for slope.
Rinse the probe with calibration solution or deionized
water. Submerse the probe into the solution. The sleeve
holes must be completely submersed. Tap the probe
repeatedly to remove any air bubbles that may be trapped
inside the sleeve.
To enter EC calibration, select the EC range and press
CAL.
The “BUF” and “CAL” tags are displayed. The primary
LCD will display the EC reading. The secondary LCD will display the value.
The “ ” and “~” tags will blink.
Note: The TDS reading is automatically derived from the EC reading and

no specific calibration for TDS is needed. Pressing CAL when TDS
range is selected has no effect.

For zero calibration, just leave the dry probe in the air. This calibration
is performed in order to correct the reading at 0.00 μS. The slope is
evaluated when the calibration is performed at any other point.