User's Manual

ments are in the 1.2 to 2.5 EC range. Similarly, utilize

HI 7039L with a value of 5.00 mS/cm at 25 °C if controlling your

process with HI 9923 and HI 70442L with a value of 1500 ppm

(mg/L) value if working with HI 9935.

• Immerse the probe in the beaker ensuring that the holes on the

sleeve of the probe are completely covered.

• Stir the probe and tap it gently on the

bottom of the beaker to ensure that any

air bubbles trapped inside the sleeve

escape. Best results are obtained when

the probe is not too close to the walls of

the beaker nor lying on the bottom.

• Wait for the reading to stabilize. Adjust the "CAL SLOPE" trimmer

to display the same value as the

calibrations solution at 25 °C. For

example, with HI 7031L, you

should adjust the display to 1.41

mS/cm and with HI 70442 to

1500 ppm.

• Once the controller is calibrated to a solution by referring to its

value at 25 °C, all subsequent measurements are temperature

compensated to 25 °C. You can also obtain temperature compen-

sation to a different temperature reference point by calibrating

the meter to that value. For example, the conductivity and TDS

values of HI 7031L and HI 70442L at 20 C are 1.28 mS/cm and

1358 ppm, respectively. By adjusting the display to these values,

all subsequent measurements are compensated to a base tem-

perature of 20 °C.

Conductivity/TDS calibration is now complete.

SLOPE CAL

ALARM

ZERO CAL

1.41

Min7cm

(2.8“)