DMM600 Duff Moisture Meter
6.
View the volumetric water content from the display at the bottom of the
DMM600 (see FIGURE 4-5). If user calibrations are loaded, the display
will toggle between factory and user values. Water content is only
displayed while the sample is compressed.
FIGURE 4-5. Bottom of DMM600
Toggle
Switch
9-Pin Serial
Port
7.
Turn the knob counter-clockwise to stop. A single beep indicates the
sample is no longer compressed and the measured water content value is
no longer displayed. Loosen the thumbscrew, and remove the sample
chamber cap. Remove the sample from the sample chamber. If residual
water is apparent on the sample chamber surfaces, wipe dry.
5. Overview
The DMM600 measures volumetric water content of organic forest floor
material. It is a portable, battery-powered device that uses measurement
methods that are sensitive to the dielectric permittivity of the material being
measured. The dielectric permittivity is strongly dependent on the water
content of the forest floor material.
The forest floor can contain several kinds of organic material including a litter
layer, the recognizable plant debris that has not decomposed; the fermentation
layer, partially decomposed litter often bound with fungus; and the humus
layer, extensively decomposed unrecognizable organic material. Duff is an
inclusive term that refers to the fermentation and humus layers. Duff thickness
and duff water content strongly influence duff consumption and soil heating
during fires.
The parts of the DMM600 include a cylinder that houses the electronics, a
sample chamber, and an LCD readout. To measure duff water content, the
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