TL;DR
Reduced suction on the Torit DFO is most often clogged filter cartridges or a blockage in the ductwork. Check differential pressure first; if it is normal, inspect the duct and fan.
What you might see
- capture velocity at hood drops below spec
- dust visible at capture points
- static pressure at fan inlet lower than baseline
- filter differential pressure reading normal or low
Likely causes
Clogged filter cartridges with accumulated dust cake reducing airflow
Ductwork blockage from settled dust or debris in a horizontal duct run
Fan belt slipping or worn drive sheaves reducing fan speed
Duct system air leak allowing unfiltered air to bypass the capture hood
Required tools
- Magnehelic differential pressure gauge
- Pitot tube and manometer (for duct traverse if needed)
- Flashlight (for duct inspection)
- Replacement filter cartridges (Donaldson OEM spec)
- Belt tension gauge
- LOTO kit
Safety first
- Lock out and tag out the collector fan and pulse jet controller before opening any access panel or entering the hopper area.
- If this collector handles combustible dust, follow your facility's combustible dust program before any filter maintenance. Never use tools that create sparks inside the collector.
- Do not inhale collected dust. Wear an N95 respirator or supplied-air respirator appropriate for the dust type during filter replacement.
Procedure
- 1
Read the filter differential pressure gauge on the DFO. A reading above the Donaldson maximum specification confirms filter restriction.[1]
- 2
If differential pressure is high, initiate a manual pulse cleaning cycle from the control panel. Allow the cycle to complete and re-read differential pressure.
- 3
If pulse cleaning does not reduce differential pressure, the filter cartridges have exceeded their service life. Replace them per Donaldson DFO procedure.[1]
- 4
If differential pressure is normal but suction is low, inspect the ductwork for blockage. Open cleanout access points and check for settled dust in horizontal runs.
- 5
Measure fan inlet static pressure with a Magnehelic gauge and compare to the DFO fan curve at the current system resistance.
- 6
Check the fan belt tension and drive sheave alignment. A slack belt reduces fan RPM and suction.
- 7
Walk the entire duct system and check all flexible connections and access door seals for air leaks. Leaks reduce capture velocity at the source.
- 8
After any filter or duct repair, re-measure static pressure at the capture hood and confirm it meets the specification on the Donaldson system design sheet.
Sources
Donaldson Torit Downflo Evolution Cartridge Dust Collector Installation and Operation Manual, Donaldson Torit
Donaldson Torit DFO Dust Collector Installation, Operation and Maintenance Manual, filter differential pressure and maintenance procedures (general)
View source
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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.
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