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Detecting High Sand Level in Settling Tank

A company that processes silica sand needed a point level indicator to monitor and indicate a high sand level in a settling tank. The slurry sand was fed into the settling tank where the sand and water would separate. The sand would settle to the bottom of the tank and the water would be decanted from the tank. If the sand level reached the decantation valve it would foul the valve and cause the process to be shutdown.

Interface level measurement usually presents challenges unseen in single material detection applications. In this case the level indicator needed to ignore the water and detect the presence of the sand. It had to operate in a liquid environment and detect the solid sand material. The company needed a device that would work, and work consistently. Many different level detection devices were tried without success. Some were not immune to water infiltration, while others could not differentiate between the water and the water-saturated settled sand.

Monitor recommended its Model KA rotary paddle bin level monitor with solid extension and guard and a paddle suitable for the target material. The unit was top mounted above the valve so that water could not penetrate into the unit through its paddle shaft seal. In addition, a stainless steel shaft and guard was used. The extension allowed the sensing alarm point to be adjusted to suit the application.

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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