A stepped-bore roots blower conveying line has two distinct acceptance questions: whether the package meets its declared airflow-pressure duty and whether the material travels reliably through the installed route. The test plan should define both before commissioning.
A structured site acceptance test compares measured performance with the approved velocity map, pressure budget and product criteria. It also separates roots blower package performance from the behaviour of the complete gas-solid system.
Agree the Acceptance Matrix Before Start-Up
The matrix should list each approved material, route and operating case. Include normal production, maximum credible production, minimum-rate or turndown operation and purge. For multi-destination systems, the longest or most restrictive branch should be tested, along with any branch that creates a different pressure or velocity profile.
Define tolerances and measurement methods in advance. A target such as “good conveying” is not auditable. Delivered solids rate, blower-inlet airflow, differential pressure, speed, electrical input, discharge temperature, receiver-filter differential pressure and purge result are practical measured outputs.
Verify the Installed Geometry
Before loaded testing, confirm actual internal diameters, transition orientation, valve lineup and route. Check for gasket intrusion, misalignment, fabrication ledges, unexpected flexible hose and changes made during construction.
These details matter because the velocity map is based on effective area. A small obstruction near a transition can create local acceleration or a material collection point even when the nominal pipe sizes are correct.
Establish the Air-Only Baseline
Operate the cleared route at planned blower settings and record airflow and differential pressure. Compare the result with the calculated clean-line resistance. A significant difference should be resolved before material is introduced.
The test also confirms control-valve position, pressure instrumentation, filter condition and the empty-line pressure that later purge cycles should approach. Pressure relief should remain inactive throughout normal acceptance points.
Run Loaded Production Tests
Introduce material at a controlled rate and allow the system to reach stable operation. Record synchronized airflow, pressure, feeder rate and receiver mass. Confirm that the required throughput is delivered without continuing pipeline accumulation or unacceptable pressure fluctuation.
Where direct section airflow measurement is impractical, use validated pressure points and the accepted gas balance to confirm that the installed condition remains consistent with the velocity map. Pay special attention immediately after each enlargement and near the receiver.
Repeat the normal point. Repeatability is essential because a single successful run may hide feeder variation or progressive buildup. Then test the defined maximum and minimum operating points without exceeding the blower’s approved speed, power, pressure or temperature limits.
Check Product and Component Outcomes
If staging was justified by reduced degradation, take representative inlet and receiver samples using the same sampling method. Compare the relevant quality measure, such as fines fraction, intact pellets or coating condition. If wear reduction was the objective, establish inspection locations and a baseline for future thickness or condition measurements.
Noise, vibration and receiver-entry behaviour should also be observed. Lower calculated velocity does not guarantee that a transition or bend avoids concentrated impacts.
Prove the Purge Cycle
Stop feed and execute the approved purge recipe. Verify that the largest downstream section clears and that the receiver filter handles the air volume. Use the agreed residual-material or empty-line-pressure criterion rather than time alone.
An abnormal-stop recovery test may be appropriate when the process consequence of retained material is severe, but it must follow the site’s safety procedure and material hazard assessment.
Close the Test with Two Responsibilities
The roots blower package is accepted against declared inlet conditions, airflow, differential pressure, speed, absorbed power, motor rating, temperature and protective functions. The conveying system is accepted against material rate, stability, product condition, purge and component performance.
Acceptance should verify both package duty and material performance against declared tolerances. Document test conditions and responsibility before commissioning so findings can be assigned to the correct system boundary.
Glossary
Acceptance matrix: Schedule linking every test case to measurements, tolerances and pass criteria.
Air-only acceptance: Verification of cleared-route airflow and pressure before solids are introduced.
Installed-geometry check: Confirmation that actual bores, transitions, fittings and route match the approved design.
Loaded acceptance point: Stable test condition with material feed used to verify throughput and pressure performance.
Performance boundary: Verified continuous operating limits for the selected equipment, including pressure, speed, power and temperature.
Site acceptance test: Structured field test confirming installed equipment meets agreed measurable requirements.
Witness point: Test stage observed or approved by designated project parties before work proceeds.