10
CALIBRATING THE SALINITY FUNCTION (Salinity Multimeter)
Caution: This should only be done as a last resort after you have tried everything else and
you are certain that it is required.
We have provided two methods of calibrating the salinity function. The first method is more
convenient for laboratory or controlled conditions; the second is more convenient in the field.
The calibration knob “CAL” is located on the upper left hand side of the meter’s panel. Make
sure that the knob to the right of the meter’s panel “W” is turned the furthest clockwise
position for liquids and set to 100 for soils.
First Method:
Using a Bench Top Meter
– If you have a calibrated bench-top or laboratory EC meter:
1. Prepare a water sample at or near the field EC using table salt and your bench top
meter.
2. Follow instructions for measuring liquid salinity. Remember to give the meter two to
three minutes to reach temperature equilibrium.
3. Compare the Multimeter meter reading to the bench top reading.
4. Adjust the Multimeter calibration knob “CAL” (left of the meter) until the meters
agree.
Second Method:
Air
– This will set your meter to a repeatable value, but not to the accuracy which can be
obtained by calibration with a bench top meter.
1. Place the Multimeter in the sample and wait two or three minutes to reach
temperature equilibrium (the longer the better).
2. Quickly take the meter out of the sample, wipe off the tip and press EC button.
3. When the EC-ON light comes on adjust the calibration knob “CAL” (left of the
meter) until the Multimeter reads 0.1 in the air. This is the best starting point for
field use.
If neither of these methods work, remove the battery cover (four small Phillips head screws),
and carefully disconnect the battery cable from the battery. Then locate the coarse zero set
(see diagram), and using a small screwdriver, rotate the small screw counterclockwise to
increase, clockwise to decrease, and follow the above directions.
