Hydronix Hydro-Probe XT, User Manual

Page: 49 / 67

Sensor Integration and Calibration Chapter 5
Hydro-Probe XT User Guide HD0538 Rev: 1.6.0 49
2.4.4 Calculating the moisture content
Moisture content may be referred to as a percentage of the wet weight or as a percentage of
dry weight of the material. Industries that generally operate at higher moisture percentages
will often use the wet method. For those operating at lower moisture values and where the
calculations are often made to ascertain the true dry weight of material excluding moisture the
dry method commonly used.
The calculation either divides by the wet weight (B) or the dry weight (C) to ascertain the
percentage value.
Using the dry weight method, a 100% moisture value would indicate a 50% mass of dry
material and a 50% mass of water. Using this method it is therefore possible to have a
moisture value of more than 100%.
All Hydronix calculations are based on a dry weight method unless otherwise specified.
2.5
Good / bad calibration
A good calibration is made by measuring samples and taking readings over the full working
moisture range of the material. As many points as practical should be made as more points
provide higher accuracy. The graph below shows a good calibration with high linearity.
Good Moisture Calibration Data
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Sensor Unscaled Output
B
ake
-O
ut
Mo
is
tu
re
%
Figure 37: Example of good material calibration
Moisture content = (B - C) x 100%
(C - A)
Example
Moisture content =
1288g – 1236g
x 100% = 5.7%
1236g – 320g