Pneumatic conveying particle degradation should be measured under repeatable conditions. Representative sampling links the product result to the material rate, airflow, pressure and route that produced it.
The test should be planned around the customer’s acceptance criterion and the proposed roots blower operating window.
Write the Test Objective Before Selecting the Rig
Define the product-quality question: allowable fines increase, intact-particle fraction, coating loss, shape change or another functional property. State the production material rate, route severity and number of handling cycles the trial is intended to represent.
The objective determines whether a single-pass pilot line is sufficient or repeated circulation is required. Repeated passes can demonstrate cumulative damage, but they do not reproduce a long plant line automatically because the material changes after each circulation.
Qualify the Feed Sample
Record grade, batch, particle-size distribution, moisture, temperature, bulk density and previous handling. Store and condition all comparison samples consistently. If multiple production lots are credible, test the most damage-sensitive condition or establish separate acceptance ranges.
Take a baseline sample immediately before the test feeder. A sample from a remote storage bag may not represent material after plant handling and can distort the comparison.
Reproduce the Governing Route Features
The pilot should include representative pipe bore, bend geometry, feeder, conveying mode and receiver entry where practical. If exact replication is impossible, identify which impact events are over- or under-represented.
Report actual straight distance, vertical sections, bend count and number of passes separately. Do not collapse them into one equivalent-distance number for degradation because concentrated bend impacts and distributed wall contact can produce different damage.
Control the Gas-Solid Operating Point
Measure blower-inlet airflow, differential pressure, material rate, speed, inlet condition and gas temperature during each accepted run. The values must describe the same stable period. Record pressure fluctuation and line-clearing behavior so unstable points are not included as valid quality data.
Where the trial uses a positive-pressure roots blower, select a setting that represents the proposed plant velocity range. Excess test airflow can exaggerate damage, while insufficient flow can create sliding or blockages unlike the intended duty.
Build a Representative Sampling Plan
Samples should capture the complete material stream or use multiple increments distributed across the run. Collection from one side of a pipe or one moment in time can under-represent fines or coarse particles.
Reduce large samples with a recognized method that preserves particle distribution. Use the same equipment and procedure for baseline and post-conveying samples. Label every sample with run, location, time and cumulative cycle.
Protect the Mass Balance
Measure feed loss and receiver gain when possible. Unexplained mass can remain in the pipeline, filter or sampling equipment. Fines collected in the receiver filter may form part of product degradation and should be included or reported separately according to the agreed criterion.
Confirm line clearance between runs. Residual material can mix test conditions and make later samples appear more or less degraded than they are.
Analyze Distribution, Not One Average
Report movement between relevant size fractions and the amount of newly generated fines. Where particles are coated or polymeric, add surface or streamer analysis. Include measurement repeatability and sample-preparation uncertainty.
The report should link damage to airflow, pressure, solids rate, bends and cumulative handling. It should not claim a universal velocity threshold from one product.
Convert Results into Procurement Limits
The accepted test region becomes a maximum quality-related airflow or velocity boundary and a minimum stable transport boundary. The final blower duty must fit between them while covering route and filter pressure.
A representative pilot trial should record product degradation and the operating conditions that produced it. Repeatable sampling and a defined acceptance limit make the production design reproducible.
Glossary
Baseline sample: Representative material collected immediately before the tested conveying exposure.
Cumulative cycle: Total handling exposure accumulated through repeated passes or process transfers.
Full-stream sample: Sample collected from the complete material flow rather than a limited side stream.
Mass-balance closure: Agreement between measured feed, receiver, sampled, retained and lost material within stated uncertainty.
Sample reduction: Controlled method for creating a smaller laboratory sample without changing its distribution.
Segregation bias: Sampling error caused when coarse and fine particles separate before or during collection.
Size-fraction movement: Change in the proportion of product contained within defined particle-size ranges.