MOISTURE OFFSET
Some soils contain hydrogen sources other than water and/or
neutron absorbers. Since the 3430 gauge measures moisture by
determining the hydrogen content of the material and relating this to
the water content, both types of material could cause gauge readings
that differ from the true moisture. If measuring such materials, use a
moisture offset to adjust the readings.
The offset factor (k) is determined by comparing the moisture
content of a laboratory sample with the moisture content determined
by a gauge reading. To determine the offset factor, use the following
procedure:
✓
Take a gauge reading at the site. Record the reading (%M
GAUGE
).
✓
Remove a sample from the measurement site, then use
laboratory methods methods (for example, oven dry, and so on)
to determine the moisture content of the sample (%M
LAB
).
Multiple samples and measurements may be taken. Calculate
the average moisture of the samples. This average value should
be used for the offset factor calculation.
✓
Calculate the offset factor (k).
k =
%M
LAB
– %M
GAUGE
100 + %M
GAUGE
×
1000
NOTE
If the k value is negative, a minus sign (–) must be
entered by pressing the down arrow before entering the
first digit.
To access the Special functions, press 〈SPECIAL〉.
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