Industrial Pneumatic Conveying Leak and Blockage Diagnosis

Pneumatic conveying moves powders or granules through pipelines using air or another conveying gas. A system may operate in dilute phase, dense phase, pressure conveying, or vacuum conveying, and each configuration has its own operating envelope. Leakage, material buildup, poor feed control, or an unsuitable gas-to-solids ratio can cause unstable throughput, product degradation, excessive energy use, and unplanned shutdowns.

A reliable diagnosis starts with operating data and a clear understanding of the conveying mode. Do not assume that every high-pressure alarm indicates a blockage or that increasing air supply is a safe universal remedy.

Map the system

Collect the system drawing, blower or compressor data, feeder type, pipeline route, bends, diverter valves, filters, receiver arrangement, material properties, normal throughput, and control limits. Identify changes made since commissioning, including new elbows, longer routes, altered material, or modified receiving equipment.

Record whether the system conveys continuously or in batches, and whether it uses pressure or vacuum. These details affect where pressure measurements are meaningful and what symptoms to expect. Review the design basis before comparing current operation with a historic pressure value.

Begin with trend evidence

Review conveying pressure or vacuum, gas flow where measured, blower current, feed rate, receiver filter differential pressure, cycle duration, and blockage alarms. Compare trends at a known throughput and material condition. A pressure increase with falling throughput can suggest growing resistance, but feed interruptions or a changed material bulk density can produce similar symptoms.

Listen for abnormal leakage only from a safe position. Never use hands to search for pressurised leaks, and do not open a pipeline while it contains pressure or hazardous dust. Noise alone does not identify the leak location.

Structured diagnostic workflow

1. Confirm the conveying mode, product, normal setpoints, and current operating state.
2. Compare pressure, flow, drive load, and throughput against a known stable baseline.
3. Check feed and discharge equipment for interruptions, bridging, or incorrect valve sequence.
4. Review receiver filter condition and differential pressure, where fitted.
5. Inspect accessible joints, flexible connections, seals, and diverter-valve areas for evidence of leakage or wear.
6. Compare pressure readings across available measurement points to help localise resistance.
7. Plan internal inspection only after isolation, depressurisation, dust-hazard assessment, and the required access controls.
8. Correct the confirmed cause and retest under comparable material and throughput conditions.

Recognising common patterns

Pressure rises while throughput falls. Possible causes include a developing plug, restricted filter, valve misalignment, or excess feed relative to available conveying gas. Follow the approved shutdown or clearing procedure rather than repeatedly forcing material through.

Throughput is low but pressure remains unexpectedly low. Check whether the feeder is delivering material, whether air is bypassing the intended route, and whether the pressure instrument is valid.

Blower load increases. Review operating point, inlet restrictions, filter condition, leaks, and changes in conveying resistance. Compare the motor current with the manufacturer's operating range.

Blockages recur at the same bend or branch. Inspect geometry, wear, material settling, and flow distribution. Confirm whether material characteristics or production rates changed. Repeated clearing without correcting the cause increases downtime and can damage equipment.

Vacuum conveying loses pickup performance. Investigate leaks on the suction side, filter loading, receiver seals, and the condition of the vacuum source. A leak may reduce effective pickup even if the equipment remains running.

Material properties matter

Particle size distribution, moisture, cohesiveness, bulk density, abrasiveness, and temperature influence conveying behaviour. A powder that flows well when dry may bridge after moisture ingress. A change in particle size or supplier can shift the system away from its original design point.

If the material changes, record the change and compare it with the design assumptions. Do not solve a persistent conveying issue solely by increasing air velocity; excessive velocity can increase wear, particle breakage, segregation, and filter loading.

Maintenance and verification

Inspect seals, flexible hoses, diverter valves, bends, feeder components, receiver filters, and pressure instruments according to the equipment supplier's instructions. For abrasive materials, look for wall thinning at elbows and impact zones. Replace components with suitable materials and ratings for the service.

After repair, verify that the system reaches stable throughput without abnormal pressure, drive load, or filter behaviour. Record the material and operating conditions so the new baseline is useful. If the fault remains, escalate to a conveying specialist with the trend data and layout rather than repeating the same intervention.

Reporting checklist

Include system type, material, throughput, pressure/flow trends, instrument details, inspected locations, suspected and confirmed defects, actions taken, and post-repair performance. Identify any uninspected sections or conditions that prevented confirmation.

Practical takeaway

Pneumatic conveying diagnosis is a process-and-equipment problem. Use correlated pressure, flow, load, and throughput data to narrow the fault, then inspect safely and verify the result under comparable operating conditions.