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Bulk density

Bulk density, also known as bulk density, is a measure of the weight of a given volume of a bulk material under specific conditions. It takes into account both the density of the solid itself and the space between the particles, including the air and other possible cavities. Bulk density is crucial when sampling bulk materials, as it affects the handling, transport and storage of the material.


The bulk density is defined as the weight of the bulk material per unit volume. It can be influenced by various factors, such as:

  • Particle size and shape: Different particle sizes and shapes can cause the material to behave differently and differ in bulk density.
  • Moisture content: Moisture content can increase bulk density because water is heavier than air.
  • Compaction and settling: Depending on how the bulk material is stored and handled, it can settle or compact, which changes the bulk density.


The measurement of bulk density can be carried out using different methods, depending on the type of bulk material and the requirements for accuracy and representativeness:

  • Standard method: The bulk material is poured into a container of known size and weighed. The bulk density is then the weight divided by the volume of the container.
  • Tapping method: This method uses a special apparatus that taps or vibrates the bulk material to achieve constant compaction. This can lead to a more accurate measurement of bulk density.
  • Flowability tester: There are also specialized instruments that can measure bulk density in conjunction with other properties such as fluidity. These can be useful in industrial environments where these properties are critical for processing.

Accurate measurement of bulk density is important for various aspects of bulk material handling, including storage, transportation, and mixing. It can also affect the quality and representativeness of samples taken from the bulk material. The selection of the appropriate measurement method depends on the type of bulk material and the specific requirements of the respective application.