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Flow rates
High flow rates erode the soil sample
and lead to wrong measuring results.
Air bubbles outgassing from the sample
reduce the conductivity.
Extremely high flow rates cause turbulent
flow and invalidate the methodology.
Temperature influences
A temperature raise reduces the viscosity
of the measuring fluid.
E. g. increasing temperature from 20 to
23° C (68 to 73.4 F) causes a 18% change
of the measuring result.
Ion specification
Different ion composition and concen-
tration of water and soil affect the
value of the measured conductivity.
Outgassing from water
Dissolved gases outgas and form a
bubble film between the porous plate
and the soil sample. They reduce the
value of the measured conductivity.
Outgassing from soil sample
Soil samples can pass air bubbles that
form a film between the porous plate
and the soil sample. They reduce the
value of the measured conductivity.
Water discharge
Eroded particles from instable materials
like sand may plug the discharge
channel of the device.
Keep the flow rates as low as possible.
The scientific literature recommends
an initial water column of 5 cm (2 in).
Measuring device, environment and
water should have the same temperature.
Keep the temperature of your lab constant.
Make sure the ion composition and con-
centration of water and soil are similar.
If necessary adjust by adding CaCl
Use degassed water
(Boiling before measuring is ok).
Use degassed water. Saturate the soil
sample in vacuum.
Clean the measuring dome, remove
particles and rinse thoroughly.
.
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How to avoid trouble | 9
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