Dry Bulk Solids Point Level Sensing

Looking for a sensor to sense the presence of fertilizers of varying dielectrics held in storage bins. Have tried capacitance sensors with limited success. Any others reco's? Thanks.

In the powdercaoting field they use vibration sensors that vibrate 2 rods and if the ends are in the powder they won't vibrate.

These were needed as the power in the spray chamber feed was aerated to be able to flow and floats would fall into the powder.

http://www.momentum-automation.com/tekstovi i reklame/Vibro i Mikrovawe tdoctb028__usa.pdf

Have you tried Rotary Bin Level indicators like the BMRX model from www.binmaster.com. We have used these for Grains like Wheat, Barley Peas and Canola.

The "O3D" sensor from IMF has some cool features for that type of measuring.
Not too expensive either.

Perhaps also the "TIM" from SICK.. I have not played with this one yet but it looks cool. I'm waiting on a demo.

https://w3.siemens.com/mcms/sensor-...int-level/vibrating/pages/sitrans-lvs100.aspx

This is what we use for a wide range of density materials. It works fairly well as long as it is oriented properly. Mounting it vertically when possible helps prevent bridging that comes with changes in humidity and density.

Levi G said:

Have you tried Rotary Bin Level indicators like the BMRX model from www.binmaster.com. We have used these for Grains like Wheat, Barley Peas and Canola.

Click to expand...

I agree, we've used rotary bindicators with great success in grain bins.

http://bindicator.com/product-category/roto-category/

+1 for Binmaster.

We used the tuning fork vibration sensors for detecting high/low limits on alumina.

Our final products can be conductive solids, and have found guided wave radar to be the most trustworthy for actual level indication. Setup allows varying bin configurations, and you can set null zones to cancel some reflected waves that may give a false reading.
The existing level transmitters have been there for over a decade without failures.

https://www.vega.com/en/Products/Product-catalog/Level/Guided-Wave-Radar/VEGAFLEX-82

We use tuning forks, pressure switches as well as the rotary indicators for low level and high level detection in bulk point level detection. Fertilizers are harsh on most materials, including sensors. Use stainless steel (plastic/composite tends to be weaker from a mechanical point of view) or a detection mechanism that does not come into contact at all with the product. Then there is still dust built up to cope with, as fertilizer handling is a dusty business.

An advanced level detection mechanism is through weight, by putting the storage bins on load cells. There are some mechanical points to keep in mind, and the load cell cables are susceptible to EMC interference due to the very low voltage differences that are to be detected. Probably somewhat over the top for straight forward point detection purposes.


dburnum, can you elaborate a bit on the guided wave radar units? I have not worked with these before. Are these immersed in the product, or rather hanging above the high level?

We use an ultrasonic detector - LU83-5101 by Flowline.

(We are detecting ink levels in a large storage tank.)
MadPoet.

It would be helpful to know how large the bins are. I work at a place that uses a lot of powders and pellets of varying density in our processes. I have used vibrating rod, fork, paddle wheel, capacitive and ultrasonic sensors. If the bins you are using are shaped properly and the material flows out consistently (without rat-holing or bridging), you could use any one of the above sensors if mounted properly. I try to avoid capacitive due to changes in ambient humidity in Michigan which can affect proper readings. The rod, fork and paddle sensors detect material at one place in the vessel, but are very sensitive to the angle they are mounted. If mounted horizontal, then bridging of the material on the sensor can occur. I have used and like the Bindicator and Binmaster products for these type of sensors. For ultrasonic sensors, I have had good luck with the Ranger and Ranger One sensors from Flowline. I have been intrigued by the 3D radar sensors that are offered by Endress + Hauser, but have not used them yet. These are ideal for large bins or silos that do not empty or fill evenly.

Toine,

The guided wave radar units we have installed, are installed on the top-side of our bins into a welded threadolet. we use a stainless-steel cable that hangs down through the product, and is physically attached to the bottom of the bin. It doesn't have to be attached, but our level transmitters sit off-center from the bin, and product fill can push the guide cable to the side of the bin. Anything that contacts or comes near the cable, causes a reflected radar signal that is used to continuously monitor the level.
We use guided wave radar units, because of dusts that can cause faulty reading on those bins. Our product can also "bridge" and bindicators don't work well for final product. They aren't trustworthy on detection due to our final product's properties.

IFM sell a 3D camera that can average the level of your bin. Partial dust can apparantly be filtered out, but you will need to keep it mostly clean.

I haven't used one yet, so contact IFM for suitability.

I think this is the O3D that I referred to.

This site has a cool demo of a tank fill monitoring with both the collapsed center situation as well as all the different contours that can happen in a tank.
I'm using it to monitor the level of sliced fruit in a large square shape hopper, it measures out to different points (thousands) on the surface and gives a measurement, basically building a 3D map of the contour.

its pretty sweet