To unclog a blocked silo safely, work from outside only. Diagnose whether you have a bridge, a rathole, or wall buildup; then clear it in order of risk—outlet-side agitation, poking rods or air lances from designed top access points, and professional no-entry cleaning equipment. Never send a person inside, and never work below the blockage.
A blocked silo turns into a production emergency fast: the kiln, boiler, or batch plant downstream isstarving while hundreds of tonnes sit right there. That urgency is exactly when bad decisions happen.
SAFETY RED LINES
Before any clearing method – four non-negotiable rules
Never enter the silo to clear a blockage. Flowing material can trap a standing adult in seconds and bury them in under half a minute; about half of documented entrapments are fatal.
Never work below the blockage. Hung-up material releases without warning.
Lock out the feeder and discharge equipment before anyone works at any opening.
Control ignition and dust – a collapsing blockage aerates fines; in coal, biomass or grain that is an explosion risk.
Step 1: Diagnose Before You Poke
Symptom
Likely problem
Where it sits
Flow stopped abruptly; level reads normal
Bridge (arch)
Across the outlet or lower cone
Flow declined gradually; level reads high
Rathole
Vertical channel above the outlet
Slow, erratic discharge for weeks
Wall buildup
Annulus along the walls
Step 2: Clear It from Outside — Ranked by Risk
Method
Works best on
Risk
Notes
Outlet-side agitation (jog feeder, run discharger)
Fresh, thin bridges
LOW
Try first; stop if no result in minutes
Poking rods / air lances from top access
Ratholes; bridges reachable from above
MEDIUM
Fall protection; work above the blockage only
Professional no-entry cleaning (whips, pneumatic augers)
Hardened, consolidated masses
MEDIUM
Top-port work, 1–3 days downtime
Air cannons fired into the stagnant zone
Recurring bridges & ratholes
LOW–MED
Retrofittable live; usually the permanent fix
Sledgehammer · water · man entry
—
DON’T
Dents breed buildup; water sets it; entry kills
Blocked right now? Send a photo and your silo drawing—we respond with a no-entry clearing plan.
Clearing treats the symptom. The cause—a funnel-flow silo storing a cohesive material—is still there, and the week after a clearing is the best time to install prevention: the silo is empty, access is arranged, and the cost of the outage is fresh in everyone’s mind. See the prevention table and our guide to preventing ratholing, or go straight to silo air cannons.
Only as a formal, permitted confined-space entry by a trained crew with rescue provisions—and only after every no-entry method is exhausted. As a routine operations decision: no.
Sometimes once, on a thin fresh bridge. The dents become anchor points for future buildup, turning an occasional blockage into a chronic one.
No-entry equipment worked from the top port: whip machines that flail buildup off walls, and pneumatic augers or lances that cut consolidated cores.
Bridge: abrupt stop, normal level reading. Rathole: high level, dwindling discharge; a probe from the top drops into an open pipe.
Flow aids (sequenced air cannons) for cohesive buildup; liners, steeper hoppers or larger outlets where the flow pattern is wrong; FIFO and scheduled clean-outs in every case.
Blocked silo? Get help now.
Photo + silo drawing + material → a no-entry clearing plan and a prevention layout, from our engineers.
