Determining the bulk density of a material to improve accuracy
of material weight calculation
In
the event that an accurate weight calculation is desired,
it will be critical to first know the exact bilk density of the target
material. (An accurate weight calculation is useful when implementing
a continuous
level measurement / inventory management system.)
The bulk density of any given material will vary from delivery to delivery
even if the same grade / specification of material is purchased. Some
suppliers will not say this, but reality will prove otherwise. A program
of sample weighing should be implemented to determine actual bulk density. To Determine the Bulk Density of a Material:
-
Construct a sample container. This container can be of any
shape or size and should be made of dimensionally stable material (i.e.
not cardboard).
- Measure the volume of a sample container. This volume
measurement must be very accurate. Do not rely on measurements obtained
by a ruler or caliper as these are typically not of sufficient accuracy.
Rather, it is best to measure the sampling container volume by water
displacement method.
Obtain a graduated cylinder or other laboratory-quality calibrated
liquid dispensing vessel. Record the volume of liquid required to fill
the sampling container.
- Calculate Compensation
Factor. Bulk density
is most frequently measured in pounds per cubic foot. Chances of
obtaining a sample container that measures exactly one cubic foot
is near impossible. Consequently, it will be necessary to calculate
a compensating factor to allow precisely one cubic foot volume
to be ascertained.
Example:
Water displacement determined Sample Container
volume to be 904cc
As we discuss density in lb/ft3, we will need to convert cc to
ft3:
904cc (0.00003531cc/ft3) = 0.03192 ft3
Calculate Compensation Factor (i.e. how many sample containers
required to total 1.0ft3?)
1ft3 = (X)0.03192 ft3
X = 31.328 ft3
- Weight the sample
of material. Use of an
accurate scale is imperative. Postal scales are convenient, accurate,
and almost all offices have such. Be sure to subtract the weight
of the sampling container from the overall measured weight.
- Apply Compensation Factor to determine bulk
density.
Example:
Total Sample Container with Sample:
Sample Container (empty):
Material only Weight:
Please feel free to give Monitor Technologies
a call (800-601-6302) or e-mail (monitor@monitortech.com) and let us
put our creative solutions to work for you!
Spotlight: Inventory Control
Solids Flow Detection
Microwave solids flow detectors can
be used in a variety of applications including feed mills & grain processing,
consumer foods (cereal, sugar, cocoa, coffee), chemicals & pesticides
and more. For example, one company uses Monitor’s Model SFD-2
solids flow detector to verify the flow of feed pellets through their
various transport lines which involves a process where a horizontal
screw auger is conveying pellets over to a vertical gravity chute. The
chute then directs the pellets to a process down below. They have
carefully placed the SFD-2 so that it detects the pellets as they
fall directly across the sensor face. (See Below)
The Model SFI and SFD-2 line of solids flow detectors
from Monitor Technologies, LLC provide analog or relay outputs
to indicate the flow / no-flow condition of powder and bulk solids
materials in chutes and pneumatic conveying lines. Using
microwave Doppler radar technology these units are non-invasive
plus extremely reliable and rugged to withstand the rigors of the
installation and your process extremes. From automated systems
with pneumatic lines to gravity chutes, solids flow monitors can
help to improve process performance. They can assist in detecting
flow problems, as well as, enhance the level of automation at a
facility like turning a conveyor on or off.
For more information on Solids
Flow Detectors click here or contact Monitor Technologies LLC
at 800-766-6486 in the USA and 630-365-9403 worldwide.
