User Guide

11
EC/TDS CALIBRATION
Accessories needed:
• Use HI 70031 (1413 µS/cm = 1.413 mS/cm) EC calibration
solution or HI 70442 (1500 ppm) TDS calibration solution.
Note: The conversion between EC and TDS is made by a built-in
circuit, hence it is requested to calibrate the meter only in EC
or TDS range. The other range is thus automatically cali-
brated.
PROCEDURE
• Pour approximately 4 cm (1½") of a conductivity calibration
solution (e.g. HI 7031) into a beaker. If possible, use plastic
beaker to minimize any EMC interference.
• Immerse the probe in the solution.
• Wait for a couple of minutes for thermal equilibrium to be
reached.
• Tap the probe on the bottom, then shake it lightly while rotating
to make sure no air bubbles remain trapped inside the probe.
• Press the "mS/cm" (or "ppm") key.
• Turn the EC/TDS calibration knob until
the display shows the EC or TDS reading
at 25°C.