How are the material properties taken into account in the design of pneumatic transport?

The design of pneumatic transport always starts with the material. When the material to be transported is fine-grained dust, granular granulate, hot metallurgical slag, or wet sludge, the design solutions differ significantly from each other. The varying material properties are the most common reason why a pneumatic transport system either operates flawlessly or causes continuous operational disruptions. In this guide, we will go through the steps in detail how the material properties are taken into account in the design of pneumatic transport.

If you wish to explore pneumatic conveying solutions further, Read more about pneumatic conveying and see what kinds of applications we have implemented.

Find out the key properties of the material before planning

Before any piping is dimensioned or a device is selected, the actual properties of the material to be transported must be determined. This step forms the foundation of the entire design process, and failing to comply with it almost invariably leads to problems during commissioning or later in production.

The material properties influence all design decisions: the choice of transport method, piping sizing, pressure requirements, and equipment selection. The more variable these properties are during the process, the more flexibility and margin of safety is required in the design.

Find out at least the following characteristics:

• Particle size and particle size distribution as well as any variations between production batches
• Bulk density (bulk density) and its range of variation as humidity or temperature changes
• Moisture content and its effect on the material's flowability and tendency to clump
• Temperature, Especially for hot materials such as metallurgical pipes
• Consumability i.e., the material's abrasiveness, which directly affects the wear of equipment and piping
• Hygroscopicity i.e., the tendency to absorb moisture from the air
• Degradability that is, how much material is crushed during transportation

Checkpoint: Once all the features listed above have been documented and their ranges of variation known, you can proceed to selecting the transport method. If any information is missing, it is worth checking before proceeding, as incomplete initial data can lead to incorrect sizing.

Choose the transportation method based on the material's characteristics

Once the material properties are known, the next step is to choose the appropriate pneumatic conveying method. Pneumatic conveying is practically implemented using two main methods: dilute phase conveying and dense phase conveying. The choice between these methods is one of the most important decisions in design.

In the cargo transport The material flows through the pipeline as a dispersed stream at high air velocity. It is particularly suitable for lightweight materials that flow easily and are resistant to disintegration, as well as for shorter transport distances. Leaching transport is a simple and cost-effective solution when the mechanical stress of the material is not a problem.

In the tulip transport The material moves in the pipeline as smaller-speeded up tubes, and the transport gas consumption is significantly lower. This method is particularly suitable for:

• For fragile materials that easily break down due to mechanical stress
• For abrasive materials where high speed would wear out the piping quickly
• For heavier or denser materials
• For long travel distances where energy efficiency is emphasized

We prefer pneumatic transport whenever it is technically possible, because it consumes less compressed air and reduces the wear of pipes and equipment. This is reflected directly in operating costs and maintenance requirements throughout the entire system life cycle. However, there are cases where pneumatic transport works better in relation to the material or the transport distance. The good part is that the same equipment can often be configured to operate in both ways with minimal program modifications.

Checkpoint: The choice of transport method is made correctly when it is based on documented material characteristics and not solely on general practices. If the material is exceptional or its characteristics vary widely, it is advisable to proceed cautiously in selecting the method and to consider a material test before making a final decision.

Measure the piping and equipment according to the variation

After choosing the transport method, we proceed to the actual sizing. At this stage, the variability of material properties must be taken directly into account in the sizing parameters. Static sizing, which is based on only one ideal situation, easily leads to a system that does not function reliably under real conditions.

The calculation takes into account the following factors in particular:

1. Diameter and material of the pipeline: Choose the pipe size so that it functions reliably even at the extreme ends of the material’s particle size range. For abrasive materials, consider wear-resistant steel or other protection at critical points in the pipe.
2. Pressure and air volume: Measure the compressor and pressure system so that there is sufficient capacity even when the material properties deviate from normal. Variable humidity levels can significantly change the flow of the material.
3. Feeders and dosing equipment: Choose the feeding equipment based on the actual behavior of the material. A viscous or wet material requires a different feeding solution than a dry, free-flowing powder.
4. Separators and filters: Measure cyclons and filters according to the most demanding situation possible, not just based on normal usage.
5. Temperature resistance: With hot materials, such as metallurgical dies, ensure that all components withstand the variations in process temperature.

Special attention should be paid to pipe fittings and junction points where abrasive material consumes structures fastest. Replaceable wear protection can be designed for these points or reinforced materials can be used, which extends maintenance intervals and reduces unexpected downtime.

Checkpoint: The sizing is complete when each component has been selected based on the variation in material properties, not just the nominal value. Document the sizing criteria clearly so that the system can be modified later if the process or material changes.

Ensure the functionality of the solution through material testing

The sizing done on the design table is always based on certain assumptions about the behavior of the material. The more exceptional the material, the greater the risk that the reality will deviate from the calculated values. Material testing before final implementation is the most practical way to reduce this risk.

The test can help determine:

• How the material actually behaves in pneumatic transport at different speeds and pressures
• Which transportation method works best for this particular material?
• What kinds of clumping or clogging tendencies does the material have?
• How much material breaks down during transport
• With which parameters is the best energy efficiency and operational reliability achieved?

Testing is particularly important for the byproducts of circular economy projects and new process materials for which there are no ready-made references. For example, the slag from steel production, battery materials, and various metal dusts are materials whose behavior in pneumatic transport can surprise you without prior testing. You can learn about the solutions we have implemented on our reference page.

Based on the test results, the sizing can be refined before the final investment decision is made. This step pays for itself in reduced commissioning problems and improved operational reliability in production. Once the system has been properly sized based on the test results, uniform operation can be expected even as material properties fluctuate within the limits of normal process variation.

Checkpoint: The test is successful when the transport method and sizing parameters have been confirmed using real material and the results have been documented. If the test reveals significant deviations from the original assumptions, return to the sizing phase and verify the necessary changes before implementation.

The planning of pneumatic transport for handling varying materials is a process where each step builds upon the previous one. Careful consideration of the material’s properties, the selection of the correct transport method, dimensioning that takes variability into account, and material testing together form the foundation of a reliable system. At Kopra, we have nearly 50 years of experience in pneumatic transport of demanding bulk materials, and our own testing facility allows for testing of new materials before implementation. Explore our pneumatic conveying solutions or Get in touch, Then we discuss how to best take into account the properties of your materials in the design process.

More information about the transport needs of fine-grained materials can be found in the article what is the best pneumatic conveyor for fine materials.