Symptoms, Likely Causes and First Checks for Cement and Dry Powder Conveying
Introduction
Common problems of air slide conveyors usually appear as changes in material flow, fluidization, air leakage or conveying capacity. The same symptom can have several possible causes, so troubleshooting should begin with the operating condition rather than immediately increasing blower pressure or replacing components.
Typical causes include changes in powder condition, insufficient or uneven fluidizing air, blocked or damaged air slide fabric, inlet overfeeding, outlet restriction, air leakage and poor venting.
This guide provides a first-level troubleshooting process for the most common operating symptoms. Detailed blockage removal and preventive maintenance procedures are covered separately in the related LVRUI technical guides.
For the basic conveying mechanism and fluidization principle, see the Air Slide Conveyor Working Principle guide.
Quick Troubleshooting Guide
The common problems of air slide conveyors can usually be narrowed down by checking the symptom, likely causes and operating conditions in a logical order.
| Problem | Likely Causes | First Checks |
|---|---|---|
| Poor or No Material Flow | Low airflow, fabric restriction, wet powder, overfeeding, outlet restriction | Check material condition, blower operation, fabric condition and outlet |
| Dust or Air Leakage | Damaged seals, loose flanges, excessive internal pressure, poor venting | Inspect joints, covers, vent path and dust collection |
| Material Build-Up | Moisture, agglomerates, poor fluidization, restricted discharge | Check powder condition, fabric, air supply and outlet |
| Uneven Fluidization | Partial fabric blockage, damaged fabric, uneven air distribution | Compare flow across the conveyor width and inspect fabric/air chamber |
| Reduced Capacity | Partial restriction, material change, unstable feeding, insufficient fluidization | Compare current operating conditions with normal baseline |
| Abnormal Blower Pressure | Fabric restriction, air-line restriction, leakage or operating changes | Check pressure trend, air path, fabric condition and open valves |
1. Poor or No Material Flow
Symptom
Powder moves slowly, intermittently or stops before reaching the outlet.
Likely Causes
✓ Insufficient or uneven fluidizing air
✓ Blocked or damaged air slide fabric
✓ Moisture or agglomeration in the powder
✓ Excessive feeding at the inlet
✓ Partial blockage or restriction at the outlet
✓ Changes in material properties
✓ Loss of the required downward conveying profile
First Checks
Start with the simplest operating checks:
- Confirm that the blower is running normally and air is reaching the lower chamber.
- Check whether the material has become damp, compacted or agglomerated.
- Inspect the outlet and downstream equipment for restriction.
- Check whether material is being fed faster than the conveyor can discharge.
- Inspect the air slide fabric if the problem remains localized or persistent.
Do not increase blower pressure automatically. Poor flow can also be caused by wet powder, fabric blockage, overfeeding or downstream restriction.
2. Dust or Air Leakage
Symptom
Dust or air escapes from flange joints, inspection covers, transfer points or discharge connections.
Likely Causes
✓ Damaged or compressed sealing gaskets
✓ Loose flange or inspection-cover connections
✓ Excessive pressure in the upper conveying space
✓ Restricted venting at the receiving point
✓ Excessive fluidizing air for the actual operating condition
✓ Poor dust-collection connection at transfer points
First Checks
Inspect the visible leakage point first, but do not assume that the seal itself is always the root cause.
If several joints begin leaking at the same time, check whether venting or downstream dust extraction has become restricted. Increasing internal pressure can force dust through joints that previously operated normally.
Repair damaged seals and loose connections, then confirm that the receiving equipment and vent path allow fluidizing air to leave the system correctly.
3. Material Build-Up or Blockage
Material buildup is usually a symptom of another operating problem rather than an isolated failure.
Common causes include:
✓ Moisture or caking in the powder
✓ Agglomerates or coarse contamination
✓ Partial loss of fluidization
✓ Fabric blockage or damage
✓ Excessive feed rate
✓ Restricted discharge
Before changing blower settings, check where the buildup begins. Material accumulating near the inlet may indicate overfeeding or poor initial fluidization, while buildup near the outlet may indicate restricted discharge.
For step-by-step blockage diagnosis and clearing procedures, see How to Troubleshoot Air Slide Conveyor Blockages in Cement Plants.
4. Uneven Fluidization Across the Conveyor
Symptom
Powder moves faster in one area of the conveyor while another area shows slow flow, buildup or poor fluidization.
Likely Causes
✓ Partial blockage of the air slide fabric
✓ Local fabric damage or incorrect installation
✓ Uneven air distribution in the lower chamber
✓ Blocked or restricted air inlet
✓ Air leakage from one section of the lower chamber
✓ Uneven material loading across the conveyor width
First Checks
Compare the powder behavior across the conveyor width and identify whether the problem remains in one location.
If the same area repeatedly shows poor fluidization, inspect the fabric, support area, lower air chamber and nearby air inlet. A local problem is more likely to involve fabric condition, sealing or air distribution than overall blower capacity.
5. Reduced Conveying Capacity
Symptom
The conveyor still operates, but the actual powder transfer rate is noticeably lower than its normal operating level.
Likely Causes
✓ Partial fabric blockage
✓ Reduced or uneven fluidizing air
✓ Change in powder moisture or flow behavior
✓ Partial buildup inside the conveying route
✓ Unstable or restricted feeding
✓ Outlet or downstream restriction
✓ Air leakage from the lower chamber or air-supply system
First Checks
Compare the current operating condition with a known normal baseline.
Check whether anything has changed in:
✓ Material condition
✓ Feed rate
✓ Blower operation
✓ Pressure trend
✓ Outlet condition
✓ Dust or air leakage
✓ Blockage frequency
A capacity drop should not be corrected by increasing airflow or changing conveyor inclination before the actual cause is identified.
6. Abnormal Air Pressure or Blower Load
Symptom
Blower pressure, airflow or motor load changes significantly compared with normal operation.
Possible Causes
✓ Increasing resistance through blocked fabric
✓ Restricted air piping or partially closed valves
✓ Air leakage in the supply system
✓ Changes in material or feeding condition
✓ Downstream restriction affecting system pressure
✓ Incorrect operating adjustments
First Checks
Compare the current pressure or blower load with previous normal operating records.
A gradual increase can indicate increasing resistance or fabric contamination, while an unexpected decrease may indicate air leakage or an open connection.
Pressure values should be interpreted together with powder flow and material condition rather than used as a standalone diagnosis.
Research on a full-scale industrial air-slide conveyor also shows that conveying performance is influenced by interacting operating conditions such as air-chamber pressure, upstream loading and downstream suction.
For blower sizing and power relationships, see the Air Slide Conveyor Power Calculation Guide.
A Practical Troubleshooting Sequence
When the cause of common problems of air slide conveyors is not immediately clear, check the material, feeding, discharge, fluidizing air, fabric condition, sealing and venting in sequence.
When the cause is not obvious, check the system in this order:
1. Check the Material
Has moisture, fineness, temperature or agglomeration changed?
2. Check Feeding and Discharge
Is the inlet overloaded or is downstream discharge restricted?
3. Check Fluidizing Air
Is the blower operating normally and is air reaching the affected section?
4. Check the Air Slide Fabric
Look for localized blockage, damage or evidence of uneven permeability.
5. Check Sealing and Venting
Inspect flange joints, covers, lower-chamber leakage and the vent path at the receiving equipment.
6. Compare With Previous Operating Data
Pressure, throughput and blockage history can help distinguish a gradual deterioration from a sudden operating change.
Change one condition at a time where possible. Adjusting several variables simultaneously can make the real cause harder to identify.
For routine preventive checks and inspection intervals, see the Air Slide Conveyor Maintenance Checklist.
Common Problems of Air Slide Conveyors FAQs
What should be checked first when an air slide conveyor stops flowing?
Start with the material condition, outlet restriction, feeding rate and blower operation. If these appear normal, inspect the air slide fabric and air distribution in the affected section.
Should blower pressure be increased when powder flow becomes poor?
Not automatically. Poor flow may be caused by moisture, blocked fabric, overfeeding, outlet restriction or air leakage. Increasing blower pressure without identifying the cause may not solve the problem.
How can I tell whether the air slide fabric is causing the problem?
Localized poor fluidization, repeated buildup in the same area, increasing air resistance or visible fabric damage can indicate a fabric-related problem. The material and air supply should also be checked before replacement.
Why does air slide conveyor capacity decrease over time?
Possible causes include fabric contamination, material buildup, air leakage, changes in powder condition, feeding instability and downstream restriction. Comparing current conditions with previous operating records can help identify the change.
When should a blockage be treated as a separate troubleshooting problem?
If material flow stops because of a localized or persistent accumulation that cannot be corrected by normal feeding, airflow or discharge checks, inspect the blockage directly and follow a dedicated blockage troubleshooting procedure.
Conclusion
Common problems of air slide conveyors should be diagnosed from the operating symptom rather than corrected by changing blower pressure or conveyor settings immediately. Poor flow, dust leakage, uneven fluidization and reduced capacity can each result from several different causes.
A practical diagnosis should check material condition, feeding, discharge, fluidizing air, fabric condition, sealing and venting in a logical sequence. Once the actual cause is identified, detailed blockage repair or preventive maintenance can be handled through the appropriate specialist procedure.
Need Help Diagnosing an Air Slide Conveyor Problem?
Send LVRUI the material name, operating symptom, when the problem started, current conveying capacity, blower pressure or airflow information if available, photos of the conveyor, and details of any recent changes in material or operating conditions.
Based on this information, LVRUI can help identify the likely problem area and determine which equipment or operating conditions should be checked before replacement parts or configuration changes are considered.
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