World Grain - December 2014 - 66

FEED OPERATIONS

years, but again they only measure the
depth distance from the top of the bin
to a single point.
A more recent type of level detector
has been marketed by BinMaster. The
BinMaster website says, "The BinMaster 3DLevelScanner provides continuous, non-contact level measurement
using dust penetrating technology to
provide unsurpassed bin volume accuracy. Its unique 3D mapping capabilities
provide a visual representation of bin
contents, detecting irregular material
surfaces, cone up or down conditions, as
well as sidewall buildup."
Unlike single point devices, it works
by measuring multiple points within the
bin simultaneously and determining the
average material top level.
Even with accurate measurement to
the top of the material in a bin, the actual
weight of product in the bin is still determined by the volume the material oc-

cupies in the bin and its presumed density. The density varies by the pressures
in the material. Most densities used are
what I describe as "loose densities."
This is the density determined by using standard procedures where a known
rial and the top struck off level. Experiments show, however, that the density
increases as the container is vibrated
so that same mass of material now occupies less volume in the container and
density check box.
A second change in density occurs
when the material in the test box is
subjected to pressure from above,
simulating the vertical pressure on
materials deep within a bin. Again, the
density increases.
Thus the best density to use in determining the weight of the material in
a bin is some value between the loose

GEAPS

and compacted densities. This density can be determined by accurately
bin and determine the actual volume of
would then give a reasonably accurate
density to use at given depths resulting
in closer accuracy and control of inventory amounts.
cles where we will look at additional
points that might be upgraded in an
existing facility.
Fred Fairchild is feed science professor emeritus
in the Department of Grain Science at Kansas
State University. Prior to coming to Kansas State
in 1994, he worked in the industry designing,
constructing and commissioning numerous mill
facilities. He is a licensed professional engineer.
He can be reached by e-mail at fjf@k-state.edu.
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