IL. — Monitor Technologies’ SecureCareSM
customer service will deliver “knowledge” this
fall. Monitor will conduct a two-part web seminar in November/December
2004, which will provide an overview of the advantages
and disadvantages of various technologies used for the
continuous measurement of bulk solids and powders. This
free seminar is designed to help you eliminate the waste
associated with misapplications, and eliminate a good deal
of frustration. This seminar will discuss:
• Weight & cable
and Through-Air Radar
• Load Cell and Strain-Gauge Weighing Systems
this seminar will not be an in-depth review of the principles
of operation of each technology, it will make it easier for
attendees to assess the compatibility of these technologies
with a specific application, estimate the “real world” performance,
and make cost effective decisions. Only generic information
will be presented, that will not reflect any particular manufacturer
Lewis, Monitor’s Vice President of Sales and Marketing,
will present this two-part seminar. Each broadcast will be
approximately 30 to 40 minutes in length. A white paper,
upon which the seminar is based, will be made available to
you are interested in attending Monitor’s Fall seminar,
just go to www.monitortech.com, click the “For Engineers” tab
on the home page, and follow the instructions to register.
You will receive your invitation for the seminar via email.
first web seminar for 2004 was held on June 28th. It was
titled “Accuracy of Continuous Level Measurement in
Dry Bulk Solids Applications”. If you missed this seminar,
you can download a copy of the Power Point presentation,
or download the seminar itself from the Monitor website.
IL. — Monitor’s capacitance-type proximity
switches are ideal for low cost level detection and for installation
in tight spaces. They are easy to install and calibrate.
devices are used to detect the presence or absence of bulk
solids and have round M30 threaded housings. The thermoplastic
polymer enclosures have an IP67 rating.
models are available. The Model PAC-30U accepts 20 – 265
VAC (45-65 Hz) power and is switch selectable for normally
open or normally closed operation. The Model PDC-30 accepts
10-40 VDC power and is available in PNP or NPN configuration.
capacitance-type proximity switches from Monitor offer adjustable
sensing distance from 4 to 25 mm, and carry Monitor’s
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.