Gravity Table - Contd...

There is a series of fans blow air which create pressure under a porous cover. This upward force gradually lifts the lighter material and produces a reduced amount of friction force between the material and gravity table surface. With the action of vibration, heavier materials which touching the surface of gravity table slowly move up, while the lighter materials which are not touching the table surface slowly move down.

Factors effect the separation: airflow, material quality (e.g. poor quality kernels that have low test weight)

Applications:

Seed separation (corn, grain, etc)

References:

Gaul , Alan D., Manjit K. Misra, C. J. Bern, R. Hurburgh, Jr. 1986. Variation of physical properties on gravity separated soybeans. Transactions of the ASAE . 29(4): 1146-1149.

Risse, J. H., M. K. Misra, A. D. Knapp, C. J. Bern. 1991b. Conditioning shriveled

soybean seed Part II Correlation of physiological characteristics with physical properties.

Transactions of the ASAE. 31(2): 487-491.

Aspirator Schematic

• Separates materials by density and resistance to air flow

• Less dense or resistant material is blown out the top

• More dense material falls through the bottom