Troubleshooting / Pneumatic conveying system

Pneumatic Conveying System Troubleshooting

The most common pneumatic conveying system problems on the plant floor, with the likely causes and the fix for each. Part of the OEE Lab troubleshooting directory.

Not your exact symptom?

Describe it in the symptom finder and search the whole directory.

Open the symptom finder

Problems on this page:

Line blockagesConveying capacity fallingBend wear and holesProduct degradationReceiver filter blockingDiverter valves leaking or stickingStatic and dust explosion riskBlower or compressor faultsMoisture or condensation in the lineCross-contamination between products

Line blockages

Hits OEE: Availability

Symptoms: The conveying line plugs and has to be cleared by hand.

Air flow too low for the product
Check the blower or compressor output and the air supply valves.
Feed rate too high
Reduce the feed rate into the line.
Product damp or sticky
Check the product moisture.
Bends or joints catching product
Check for steps at joints and worn bends.

Prevention: Conveying pressure trended so a rising trend warns before a blockage.

Conveying capacity falling

Hits OEE: Performance

Symptoms: Less product reaches the destination per hour than before.

Blower or compressor wear
Check the air output against the design.
Air leaks in the line
Find and fix leaks at joints and diverters.
Filter on the receiver blocked
Clean or replace the receiver filters.
Rotary valve leaking air
Check the rotary valve clearances.

Prevention: Throughput recorded per batch or per hour.

Bend wear and holes

Hits OEE: Availability

Symptoms: Bends wear through and leak product.

Abrasive product at high velocity
Reduce the conveying velocity where the design allows.
Bend type not suited to the product
Use wear-resistant bends.
Line velocity too high at the end of the line
Check the design of the line.
No inspection of known wear points
Measure wall thickness at bends.

Prevention: Bend thickness checks on abrasive lines.

Product degradation

Hits OEE: Quality

Symptoms: Particles break, fines increase, or coatings are damaged in transit.

Conveying velocity too high
Reduce the air flow to the minimum that keeps the line clear.
Sharp bends
Use long-radius or gentle bends.
Too many bends
Simplify the route.
Dilute phase used for a fragile product
Consider dense phase conveying.

Prevention: Product size checked before and after conveying.

Receiver filter blocking

Hits OEE: Availability

Symptoms: Differential pressure across the receiver filter rises.

Pulse cleaning not working
Check the pulse valves and air supply.
Fine or sticky product
Use filter media suited to the product.
Filter bags worn
Replace the bags.
Moisture condensing in the receiver
Check the conveying air temperature.

Prevention: Filter differential pressure logged.

Diverter valves leaking or sticking

Hits OEE: Quality

Symptoms: Product goes to the wrong destination or leaks at the diverter.

Seals worn
Replace the diverter seals.
Actuator air supply low
Check the actuator.
Position sensors out of adjustment
Adjust the sensors.
Product build-up in the valve
Clean the valve.

Prevention: Diverter positions checked at each route change.

Static and dust explosion risk

Hits OEE: Availability

Symptoms: Static shocks or protection system alarms occur.

Line not earthed or bonded
Check earthing at every joint.
Non-conductive hoses
Use conductive hoses.
Explosion protection fault
Call the specialist; never run with protection disabled.
Dust leaks from joints
Fix leaks and keep areas clean.

Prevention: Earthing and bonding tests on the planned schedule.

Blower or compressor faults

Hits OEE: Availability

Symptoms: The air mover trips, runs hot or is noisy.

Inlet filter blocked
Replace the inlet filter.
Relief valve opening
Check the line for blockages that raise the pressure.
Bearings or belts worn
Service the blower.
Oil level low
Check the oil.

Prevention: Blower service on the maker schedule.

Moisture or condensation in the line

Hits OEE: Quality

Symptoms: Product cakes in the line or receiver and moisture is found in the conveying air.

Conveying air not dried or cooled
Check the aftercooler and dryer on the air supply.
Line passing through cold areas
Insulate or trace-heat the line where it passes cold areas.
Hygroscopic product
Use dried air for products that take up moisture.
Air supply drains not working
Check the condensate drains.

Prevention: Air dew point checked on lines carrying moisture-sensitive products.

Cross-contamination between products

Hits OEE: Quality

Symptoms: Traces of the previous product are found in the next product.

Line not purged between products
Run the purge cycle the changeover procedure sets.
Diverter leaking
Replace diverter seals.
Product trapped in dead legs or bends
Remove dead legs and check the bends.
Cleaning procedure not followed
Make the line clearance a signed step.

Prevention: Line clearance check signed at every product change.

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

Related equipment guides: rotary airlock · dust collector · fan / blower · silo / hopper · compressed air system · hammer mill · coffee roaster

Stop the same fault coming back

Recurring pneumatic conveying system 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
The directory stays free.

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