On July 22, 1999, a day before the
Space Shuttle Columbia launched with the first female
shuttle Commander - Eileen Collins, the first SiloPatrol® SMU
level sensor was shipped out from Monitor Technologies’ Elburn,
IL facility. It was among the industry’s
first electronically controlled “smart” cable-based
level sensors. Ten years later, the SiloPatrol is still
an industry-leading continuous level sensor. Since
the original unit, the SiloPartol has evolved into
the Second Edition (SE) with product enhancements like
a sealed split compartment design, a serviceable wiper
seal compartment, enhanced motor control features,
and unique lock-out circuitry which if utilized prohibits
a sensor from making a measurement when activated.
The SiloPatrol® SE
is a rugged, reliable and accurate level measuring
system designed for the harshest and most dynamic
conditions. It is effectively used to improve material
inventory control of powder / bulk solids and many
liquids in storage silos, hoppers, vessels, etc.
The sensors measure the inventory level automatically
and on-demand without the need for your operator
or plant personnel to climb silos. The smart cabled-base
sensors automatically lower 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. A microcontroller
directs all of the functions of the sensor to ensure
the proper travel of the weight & cable, which
provides accuracy and reliability of the measurement.
These sensors are easy to install and are also virtually
maintenance free, requiring only a periodic inspection
usually once or twice per year. Once the material
level measurement is obtained, a variety of operator
interface devices is available to calculate and display
material volume, weight and more. A PC-based software
package is also available that can automate report
generation, send emails to suppliers or corporate
locations and allow remote viewing of material level
inventory. Please visit www.monitortech.com/product_c_c_sp.shtml for
Monitor Technologies LLC is a pioneering
supplier of level measurement instrumentation, solids
flow monitors, 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. Monitor is located
in Elburn Illinois.
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.