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Charcoal Manufacturer Improves Inventory Accuracy & Reliability

“We used a cable running up the side of the silo through the top and down inside with a weight attached to the end inside the silo. The end on the outside was attached to a hand winch.  We would release the winch, lower the cable until it appeared it had hit the material surface.  Then we would take a reading from a marker on the cable on the outside.” There were a total of eight silos of various heights.

This type of measurement was made on silos containing wood chip and wood flour.  These are ingredients in the charcoal manufacturing process. There were a total of eight silos of various heights.  Wood chip and wood flour are processed into briquettes and fired.  This is a simplification of the process and may not be a completely accurate description, but the actual process is proprietary to each manufacturer.

The problem that was created was measurement error and inconsistency due to the manual method employed and human error in making this manual measurement.  It was very frequent that they were way off in readings and the measurement of the cable outside the silo was always an “eyeball guess”.

The charcoal manufacturer wanted to eliminate the human element in making these measurements and improve accuracy of measurement and reliability of data.  The solution was the SiloPatrol® inventory monitoring system from Monitor Technologies.  The SiloPatrol inventory monitoring system is a smart weight & cable based sensor system.  This state-of-the-art weight & cable system is a proven problem solver.  Wood chips have a bulk density of about 20-30 lbs/ft3 and wood flour is even lighter at about 15-20 lbs/ft3.  In addition, the dielectric constant was very low, running around 1.7 or lower.  The local Monitor representative arranged a demonstration and to date eight silos have been equipped with the system, including an HMIHMI that operators and users read data from.  The lightweight nature of the material was no problem and the low dielectric constant has no effect on the performance of this smart cable-based sensor system.  The SiloPatrol system eliminated the manual measurement process, the time taken to make the manual measurements, improved accuracy of measurement and overall reliability.  The charcoal manufacturer realized savings in time and material.  The system has been in use successfully for the past four years.

Give Monitor Technologies a call and let us put our creative solutions to work for you!


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Spotlight: RF Capacitance Level Sensor
TrueCap Level SensorsTrueCap Light  
TrueCap® MK-2
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, 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.

Click here for more information on the TrueCap MK-2 Level Sensor or contact Monitor Technologies LLC at
Tel.: 800-766-6486 in the USA and
Tel.: 630-365-9403 worldwide.


>>Download TrueCap Product Bulletin #413

>>Click here to learn more about other Point Level Switches from Monitor Technologies


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