TL;DR
Hopper overflow means the discharge valve is stuck, the collection bin is full, or dust has bridged in the hopper cone. Correct it promptly to prevent dust backup into the filters.
What you might see
- dust building up around the base of the collector
- hopper level sensor alarm
- discharge valve motor running but dust not discharging
- dust backing up into the filter section
Likely causes
Collection bin or drum full, blocking discharge
Discharge valve (rotary airlock or flap valve) stuck or jammed with compacted dust
Dust bridging in the hopper cone, especially with hygroscopic or sticky material
Discharge valve drive motor overload or mechanical failure
Required tools
- Wooden or plastic rod (for clearing valve jam)
- Rubber mallet (for breaking hopper bridge)
- Replacement collection bin or drum
- LOTO kit
- Respiratory protection (appropriate for dust type)
Safety first
- If the collector handles combustible dust, never use metal tools or create sparks near the hopper or discharge valve. Dust suspended in air is an explosion hazard.
- Lock out the discharge valve drive motor before clearing any jam. An energized rotary airlock can cause severe hand injuries.
- Wear respiratory protection appropriate for the dust type when opening the hopper area.
Procedure
- 1
Stop the collector fan before opening any hopper access point. Airflow through an open hopper will spread dust into the workplace.
Warning: If the dust is combustible, follow your facility combustible dust procedures before opening the hopper. An ignition source near an open hopper is a fire hazard. - 2
Lock out the fan, pulse jet controller, and discharge valve drive motor.
- 3
Check the collection bin or drum. If it is full, replace or empty it before proceeding. This is the most common cause.
- 4
Inspect the discharge valve for jammed material. Use a wooden or plastic rod to clear any dust bridge at the valve inlet. Do not use metal tools that can create sparks.[1]
- 5
Check the discharge valve drive motor for a fault or overload alarm. Reset the overload only after the jam is cleared.
- 6
Inspect the hopper cone for bridging. Lightly tap the exterior of the cone with a rubber mallet to break up a dust bridge. Do not use a steel hammer.[1]
- 7
If bridging is a recurring problem with the current material, consider adding an aeration pad or vibrator to the hopper cone to prevent re-bridging.
- 8
After clearing the blockage, restart the discharge valve first, then restart the fan. Confirm dust is discharging before returning to normal operation.
Sources
Donaldson Torit Downflo Evolution Cartridge Dust Collector Installation and Operation Manual, Donaldson Torit
Donaldson Torit DFO Dust Collector Installation, Operation and Maintenance Manual, hopper and discharge system maintenance procedures (general)
View source
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