Campbell DMM600 Manuel d'instructions télécharger pdf (Page 5)

DMM600 Duff Moisture Meter

1. Introduction

The DMM600 Duff Moisture Meter is the product of collaboration between

Campbell Scientific, Inc. and USDA-Forest Service, Rocky Mountain

Research Station and Missoula Technology and Development Center. 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 kinks 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

sample is placed in the sample chamber, the lid is attached, and the sample is

compressed to a density determined by precision springs. When proper density

is reached, an audible indicator sounds and the result is displayed on the

readout. Readings are displayed in real time. There is no memory for

measurement storage.

A standard calibration converts the output of the measurement circuit to

volumetric water content. Alternatively, a user-defined calibration can be

downloaded using PC software PCDMM which is supplied with the DMM600.

When user-defined calibrations are used, measurements derived from the

standard calibration and the user-defined calibration are alternately displayed

on the LCD.

PCDMM is software supplied with the DMM600 and provides an interface

using serial communications. PCDMM allows downloading and uploading of

calibration coefficients, checking battery voltage and resetting the DMM600.

DMM600 comes with a 3 inch (7.5 cm) diameter sieve, and a case for easy

carrying and storage for small items including a spare battery, screwdriver and

pencil.

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Campbell DMM600 Manuel d'instructions Page 5