Conveying air demand: the evaluation begins with defined process conditions, material data and equipment boundaries. A pneumatic conveying blower should not be selected from pipeline diameter alone. Required airflow originates in the behavior of the material, then changes as the design accounts for the pipe route, gas expansion, feeder leakage, receiver venting and operating cases.
An effective airflow evaluation creates a traceable path from process requirement to blower inlet volume. That path allows the supplier and buyer to discuss the same duty rather than comparing catalogue figures stated at different conditions.
Step 1: Define the Loaded Conveying Requirement
Start with the material flow rate and a representative product description. Particle-size distribution, bulk density, moisture, temperature, cohesiveness, abrasiveness and friability influence the stable transport regime. A commercial material name is rarely sufficient.
The minimum practical conveying-air velocity should come from representative trials, reliable comparable data or a qualified system designer. The target then needs a controlled allowance for credible variation—not a large arbitrary multiplier.
This first step establishes the air required inside the loaded pipeline. It does not yet define the blower catalogue flow.
Step 2: Map Every Operating Route
Record actual internal pipe diameters, horizontal and vertical lengths, bends, transitions, valves, flexible hose, feeder and receiving equipment. For a multi-route system, evaluate each allowed destination. The longest route is not automatically the most restrictive; elevation, bore, bend count and receiver pressure can change the result.
The airflow must keep velocity above the stable limit at critical locations while avoiding excessive velocity after gas expansion. A stepped pipeline or another bore change may be required when the acceptable velocity window is narrow.
Step 3: Add Defined Air Consumers and Leakage
Useful blower flow is not limited to the air moving through the main pipe. The balance may include:
- Rotary-valve leakage.
- Venturi or feeder motive air.
- Vessel aeration or auxiliary injection.
- Purge and line-clearing air.
- Intentional branch flow.
- Credible system leakage.
Each contribution should be stated at a pressure and temperature condition. Adding unlike volume figures without conversion can overstate or understate the inlet duty.
Step 4: Establish the Pressure Budget
The blower must overcome air-only pipe friction, gas-solid conveying resistance, feeder loss, elevation effects, receiver pressure and filter resistance. Clean and maximum normal filter conditions should both be evaluated.
Airflow and pressure are coupled. Increasing flow can raise velocity and pressure loss, so adding more air may reduce the remaining pressure margin. A blocked line should be addressed through design and protection rather than a larger uncontrolled airflow allowance.
Step 5: Convert to One Quotation Basis
The project should state whether the required volume is free air, standard air or actual blower-inlet flow. It should also give reference pressure, reference temperature, humidity basis and site altitude. Article 088 explains these volume conditions in detail.
Mass flow is a useful common basis when comparing conditions, but the blower still displaces an actual inlet volume. The final quotation must therefore identify both the effective process requirement and the corresponding blower-inlet duty.
Step 6: Check Normal and Abnormal Cases
A complete evaluation normally includes startup, loaded conveying, product-rate changes, route changes, purge, clean filter, loaded filter and maximum ambient temperature. For each case, record required flow, expected pressure and acceptable control response.
The result should be validated by material testing or commissioning measurements where uncertainty is commercially important. Pressure, airflow, speed, current and receiver-filter differential pressure provide a useful operating baseline.
Selecting a Pasifik Roots Blower
Pasifik Blower manufactures two-lobe and three-lobe positive-pressure roots blowers within a published portfolio. These figures are portfolio boundaries rather than a per-model operating map.
Final selection uses the actual inlet volume, maximum differential pressure and applicable model performance and power diagrams. Speed, motor capacity and discharge temperature must be verified for every governing case. A structured airflow evaluation gives that selection a defensible technical basis and reduces costly changes after installation.
Glossary
Blower-inlet duty: Actual volume, inlet pressure, inlet temperature and required differential pressure at the blower connection.
Governing case: Operating condition that establishes a limiting flow, pressure, power or temperature requirement.
Loaded conveying: Operation with both conveying gas and bulk solid moving through the pipeline.
Operating route: Specific permitted path from feeder to receiver, including its fittings and destination pressure.
Process-air requirement: Gas flow needed within the process to achieve stable material transport and related functions.
Traceable duty: Equipment requirement whose inputs, conversions and design cases are explicitly documented.