7
11.0 Troubleshooting
11.1 High Pressure Drop Reading
• Improper Timer Operation
Check the wiring, fuses, and setting of pulse duration
and interval.
Do not adjust the pulse duration on time without consulting
an AAF representative.
• Insufficient Compressed Air
Check the air supply to be sure the compressor is providing 90-
100 psig. Check for a plugged filter in the compressed air line.
• Solenoid Pilot Valve Malfunction
Listen to be sure the solenoids are firing. Check for momentary
air venting each time each solenoid fires. Clean and replace, if
necessary.
• Leaky Dust Discharge Device
A leaking rotary lock, screw conveyor, slide gate, etc., can
overload the collector by preventing dust discharge. This will
cause high pressure drop, reduced airflow, and shorter filter life.
Follow manufacturer’s recommended service procedures.
• Condensation
High humidity will create blinded filter cartridges which results
in excessive pressure drop. Run the cleaning mechanism with
the fan off and timer activated to release the dust cake. If
condensation is a recurring problem, pre-processing warm-up
and post-processing purge periods of 15 to 20 minutes may help.
Exterior insulation may also be necessary. Sources of moisture
may come from leaky process ductwork, moisture in the process
gas stream, or moisture in the compressed air system. Try
blow-down of the compressed air reservoir(s) to eliminate
condensation and verify the dryer system is operating properly.
• Collector Overloads
Too much air or too much dust will create high pressure drops
across the collector. Check the fan speed, system design, pre-
cleaners and the damper position. Be sure the dust load and air
volume are those the system was designed to handle.
11.2 Visible Discharge
• Improper Cartridge Installation
Check that the access covers are securely fastened and sealed
and that the filters are installed correctly with the gasket-end first.
• Improper Sealing of Cartridge
Check sealing gasket on cartridge.
• Insufficient Dust Cake
The unit could be pulsing too frequently resulting in over-
cleaning. Increase pulse interval or raise the high setting on the
optional demand pulse switch to increase pressure drop slightly.
• Cartridge Replacement Required
Eventually the filter cartridge will wear out. Normally this results
in excessive pressure drop. However, if the dust is very abrasive,
leaks can occur.
11.3 Insufficient Hood Control
• Incorrect Fan Rotation
The incorrect rotation of the fan will not provide the system static
pressure or volume required.
• Fan V-belt Slippage
Tighten the v-belts if necessary. Replace worn, broken, or
stretched belts.
• Leaks
Leaking ductwork, access doors, explosion vents, dust discharge
devices, or housing will cause insufficient suction at the pick-up
point. Seal all leaks. Follow manufacturer’s recommended
procedures for service on discharge devices.
• Clogged Air Passages
Clogged ducts, closed dampers, or closed gates will shut off
airflow.
• Undersized Ducts
Undersized ducts will create excessive pressure losses for which
the fan may not have been sized.
(12 pages)
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