Troubleshooting / Silo / hopper

Silo / Hopper Troubleshooting

The most common silo / hopper problems on the plant floor, with the likely causes and the fix for each. Part of the OEE Lab troubleshooting directory.

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Problems on this page:

Bridging or arching over the outletRatholingFlooding or uncontrolled dischargeLevel measurement wrongFilter on the silo vent blockingProduct segregationStructural or safety concernsProduct build-up on the walls

Bridging or arching over the outlet

Hits OEE: Availability

Symptoms: Product stops flowing out although the silo is not empty.

Outlet too small for the product
Check the outlet size against the product flow properties.
Product compacted after long storage
Use the oldest product first and avoid long standing times.
Moisture causing caking
Keep the product dry and check the silo for leaks.
Flow aid not working
Check vibrators, air pads or the bin activator.

Prevention: Flow aid function checked weekly and product storage times kept short.

Ratholing

Hits OEE: Availability

Symptoms: Product flows only through a channel above the outlet and the rest stays put.

Hopper walls not steep or smooth enough
Fit a liner or insert designed for the product.
Cohesive product
Use flow aids or a different discharge device.
Silo emptied only partly before refilling
Empty the silo fully at intervals.
Outlet feeder drawing only from one side
Check the feeder design.

Prevention: Silo emptied fully on a planned schedule to clear stagnant product.

Flooding or uncontrolled discharge

Hits OEE: Quality

Symptoms: Fine powder rushes out like a liquid when flow restarts.

Aerated powder after filling
Let the product deaerate before discharge.
Rathole collapsing
Fix the cause of ratholing.
Feeder not able to hold the flow
Use a feeder that seals against flooding.
Too much aeration from flow aids
Reduce the aeration.

Prevention: Discharge settings reviewed for fine powders.

Level measurement wrong

Hits OEE: Availability

Symptoms: The silo runs empty or overfills because the level reading is wrong.

Sensor coated with product
Clean the sensor and choose one suited to dusty conditions.
Sensor not set for the product
Set the sensor for the product properties.
Product cone shape not allowed for
Check where the sensor measures on the cone.
High level switch failed
Test the high level switch regularly.

Prevention: High level switch tested before each delivery.

Filter on the silo vent blocking

Hits OEE: Availability

Symptoms: Filling slows, the silo pressurises, or dust escapes.

Pulse cleaning not working
Check pulse valves and air supply.
Filter elements worn or blinded
Replace the elements.
Delivery pressure too high
Ask the haulier to fill at the agreed pressure.
Moisture in the filter
Check for condensation.

Prevention: Vent filter checked after each delivery.

Product segregation

Hits OEE: Quality

Symptoms: The product leaving the silo changes in size or composition.

Filling from one point builds a cone
Use a filling device that spreads the product.
Funnel flow emptying the centre first
Convert to mass flow where segregation matters.
Mixed products stored together
Store one product per silo.
Dropping height too large
Reduce the fall height.

Prevention: Product samples taken at the start, middle and end of discharge.

Structural or safety concerns

Hits OEE: Availability

Symptoms: Cracks, dents, corrosion or a pressure relief event are found.

Overfilling or overpressure during delivery
Check the pressure relief and the high level switch.
Eccentric discharge loading the walls
Discharge from the central outlet as designed.
Corrosion at the base or roof
Inspect and repair.
Relief panel not maintained
Check the relief device.

Prevention: Structural inspection on the schedule your site sets; never enter a silo without the confined space procedure.

Product build-up on the walls

Hits OEE: Quality

Symptoms: Product sticks to the walls and drops off in lumps later.

Wall surface rough or corroded
Fit a liner or repair the surface.
Moisture or condensation
Insulate or ventilate to stop condensation.
Product too warm when stored
Cool the product before storage.
Cleaning not scheduled
Clean the silo on a schedule.

Prevention: Silo cleaning planned with the confined space procedure.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: screw conveyor · rotary airlock · bucket elevator · vibratory feeder · pneumatic conveying system · EPS moulding machine · level sensor · load cell · concrete batching plant

Stop the same fault coming back

Recurring silo / hopper stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

Book a Fabrico demo
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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary

Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover