Campbell Scientific DMM600 Duff Moisture Meter - Manual (Page 22)

DMM600 Duff Moisture Meter
7.7 Drying Samples and Calculating Volumetric Water
Content
7.7.1 Conventional Oven Method
For this method a thermostatically controlled oven is required and sample
containers suitable for oven temperature of 105°C.
Procedure
1. Weigh and record the weight of sample container
2. Place the sample in the container and record the weight of the container
and sample.
3. Place the container with sample in the drying oven and dry at 105°C for 12
to 16 hours or until the sample weight does not decrease with drying time.
4. Remove sample from oven, and allow the material and container to cool to
room temperature. Determine and record the weight of the dried sample
and the container using the same balance.
Calculation of gravimetric water content of the sample using spreadsheet or as
follows:
water content
massof container and wet sample massof container and dry sample
mass of container and dry sample massof container
=
−
−
⎛
⎝
⎜
⎞
⎠
⎟ *100
Multiply gravimetric water content by bulk density to obtain volumetric water
content.
7.7.2 Microwave Oven Method
For this method a microwave oven is required and sample containers suitable
for use in microwave oven.
Procedure
1. Weigh and record the weight of sample container.
2. Place the sample in the container and record the weight of the container
and sample.
3. Place the container with sample in the microwave oven with the heat sink
and turn the oven on for 3 min. The heat sink can be a cup of water
covered with a paper towel. The heat sink absorbs microwave energy once
the sample is dry.
4. After the set time has elapsed, remove the container from the oven. Allow
to cool so that it can be handled and then weight the sample and record the
weight.
5. Carefully stir the sample, taking special precautions not to lose any.
16