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.
- 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
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.
Water displacement determined Sample Container
volume to be 904cc
As we discuss density in lb/ft3, we will need to convert cc to
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
Total Sample Container with Sample:
Sample Container (empty):
Material only Weight:
Please feel free to give Monitor Technologies
a call (800-601-6319) or e-mail (firstname.lastname@example.org) and let us
put our creative solutions to work for you!
Spotlight: RF Capacitance Level Sensor
Advanced RF Capacitance Level Probe
The TrueCap® Model MK-2
RF Capacitance point level probe is designed to provide a superior
and stable sensitivity threshold making it suitable for a variety
of powder / bulk solids and some liquid or slurry applications.
Advanced features of the Model MK-2 include: > Automatic immunity to material build-up on
the probe by its driven shield design > Push-button calibration > Enhanced temperature compensation > Maximized reliability via smart sensing algorithms
like “self-validating” fail-safe protection > Visible status LED on ordinary location units > Versatility through a variety of configuration
options including: hazardous location version, split architecture
design, quick-connect process connection, stub probe, cable extensions,
solid extensions, Nylon® probes, Ryton® - equiv. probes,
A practical application for the TrueCap would be to use this level sensor where
a residual material build-up on a different sensor would cause a false material
Principle of Operation for the TrueCap RF Capacitance Level
The vessel wall and the active probe element establish an impedance reference
between each other when exposed to air which has a dielectric constant of 1.
When materials with a dielectric constant greater than 1 are in close proximity
to the probe, the impedance of the sensing field between the sensor and the vessel
wall will change. Once the amount of change exceeds a threshold that was electronically
determined during the calibration process, an output relay will either be energized
or de-energized depending upon the position of the fail-safe selector on the
probe’s electronic circuit board. A change of as little as .5 pico-farad
is all that is necessary for the probe to sense the presence of material.