silo Archives - CRATUS Technology https://www.cratustech.com/tag/silo/ Physical | Digital | Connected Wed, 16 Sep 2026 15:29:58 +0000 en-US hourly 1 https://wordpress.org/?v=7.1.3 https://www.cratustech.com/wp-content/uploads/2023/09/cratus-site-icon-100x100.png silo Archives - CRATUS Technology https://www.cratustech.com/tag/silo/ 32 32 Accurate Volume Measurement for Silos https://www.cratustech.com/accurate-volume-measurement-for-silos/ Wed, 16 Sep 2026 15:29:58 +0000 https://www.cratustech.com/accurate-volume-measurement-for-silos/ Two silo failures hide behind instruments that look like they are working: an arch across the outlet and a rathole down the middle. Volume and peak pile height, read together through one drawdown, tell them apart before production stops.

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Go Beyond Single-Point Sensors to stop your silo lying to you

Here is the first one. The silo is full, the feeder is running, and nothing is coming out. Somewhere above the outlet the material has formed a stable arch across the opening, strong enough to carry its own weight, and the entire column above it is now standing on that arch instead of feeding the discharge. The second is worse, because it lies in the opposite direction. The material bores a narrow channel straight down the middle and empties through it, leaving the rest standing against the walls where it slowly hardens. Your level reading falls toward empty. Most of what you are storing never moved.

Exterior of a completed steel bulk storage silo, a sealed shell that gives no view of the material surface inside
Diagram of three silo states: healthy even draw-down, a bridge arching across the outlet, and a rathole chimney with material packed against the walls

Neither of these shows up on anything you already have installed, and the reason deserves precision, because it is not a quality problem with your instruments. A radar or ultrasonic gauge measures the distance to whatever surface sits under its beam. During a rathole that surface is the floor of the chimney, so the gauge reports a silo running empty while the perimeter is still packed. Load cells look like they ought to catch it, and they do not. A load cell gives you total mass and says nothing whatsoever about where that mass is sitting, so a ratholed silo and a properly draining one holding the same tonnage read identically. Every instrument in that list returns a single number, and what has gone wrong is a shape. One number cannot describe a shape.

Diagram showing a radar or ultrasonic level gauge reading empty down a rathole chimney while load cells report the same total mass for a ratholed and a normally draining silo
A printed number card beside a small pile of granular material, showing that a single level reading cannot describe the shape of the surface

Which means the first you hear about it is when production stops, or when somebody climbs up and looks. That is the point where the cost stops being about material. Clearing an arch, or breaking down material caked on the wall, means going in with a pole, and it gets scheduled blind because nobody can see whether it is necessary. Meanwhile the structure itself is paying. Jenike and Johanson, who have worked on this problem since the 1960s, are blunt about it: eccentric discharge develops non-uniform pressures around the circumference, “leading to circumferential bending and axial compression on the cylinder shell.” In thin metal silos that produces high membrane stresses which “may deform the shell and in some cases cause catastrophic failure.” In concrete it produces bending moments and serious cracking. Then they add the line that should keep an engineer awake, that the non-catastrophic failures “may be the prelude to a much larger event in the near future.”

Plan-view diagram of eccentric discharge in a silo, with the flow channel sitting off centre and the shell pushed out of round by circumferential bending

What actually reads both failures is the shape of the surface, and it turns out you need only two values off it to get the whole story: how much material is in there, and how tall the highest point is. Watch those two together through a drawdown and each failure signs its own name. Healthy discharge, both fall. An arch, both go flat while the feeder keeps running. A rathole, volume drops away while peak height sits exactly where it was, because the walls are holding it up. Two numbers moving against each other, and you know which problem you have well before anything downstream starves.

Chart of silo volume and peak pile height through one drawdown: both fall in healthy flow, both stay flat during a bridge, and volume falls while height holds during a rathole
Wiring and terminals inside an industrial control cabinet where silo volume and peak pile height registers are passed to SCADA over Modbus TCP

The CRATUS VMS-HS128 publishes both of them. LiDAR sensors mounted in the roof space scan the full surface on a schedule, and the compute unit puts volume in cubic meters and peak pile height in meters straight into your SCADA over Modbus TCP, as two ordinary registers. That detail matters more than it sounds, because the diagnostic above is not something you have to buy from us or wait for a release to get. Your own integrator can historize those two tags and write the divergence alarm in an afternoon, inside the control system you already run. Everything else the system does, inventory that is current rather than remembered and a reason to stop opening the roof, is worth having on its own. But the first time it tells you an arch is forming while the silo still reads full, it has paid for itself.

A closed and bolted silo roof hatch, the access point crews open to look inside for a manual level check
See the VMS-HS128

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