September 2011: SiloPatrol®
SE Cable-Based
Level Sensor
SiloPatrol® provides
level measurement for lighter and fluidized materials
Elburn, IL - The SiloPatrol® cabled-based “smart” level
sensor from Monitor Technologies can be equipped with
the optional stainless steel inverted cone style plumb
bob in order to provide level measurement in lighter
powder & bulk solid materials (bulk densities greater
than 5 lbs/ft3 [80 kg/m3]). The inverted cone style
plumb bob will not penetrate lightweight or highly
aerated powders as likely as a standard plumb bob may
tend to do. A Teflon® coated version of this cone
is also available for corrosive or sticky materials.
The SiloPatrol SMU (silo monitoring unit) lowers a weight & cable into the
silo until it contacts the material surface. Upon contact the weight & cable
system is immediately retracted and the measurement is fed to the plant control
system or operator interface. Once the material level measurement is obtained,
a variety of operator interface devices including a PC-based software are available
to calculate and display material volume, weight and more. The sensor is also
equipped with a simple electrical lockout feature for those applications where
measuring during fill is not desirable. These sensors are easy to install and
are also virtually maintenance free.
SiloPatrol combines Hall Effect sensor technology, state-of-the-art sealed bi-directional
optical sensing, a split-compartment enclosure design, isolated outputs, SMT
(surface mount electronic technology) and other valuable features to produce
a rugged and reliable measuring system designed for the harshest and most dynamic
conditions. For more details please visit www.monitortech.com, e-mail monitor@monitortech.com or
contact 1-800-601-5953 (in USA) / 1-630-365-9403.
Monitor Technologies LLC, located
in Elburn, Illinois, is a leading manufacturer of level
measurement instrumentation, solids flow indicators,
particle emission monitors and aeration devices for
the worldwide powder and bulk solids markets. The experience
and market knowledge gained over 50 years of business
has earned Monitor a reputation for providing high
quality and reliable product solutions backed with
trusted customer service. For more information please
visit www.monitortech.com.
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,
etc.
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
level indication.
Principle of Operation for the TrueCap RF Capacitance Level
Probe:
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.