Process-related effects of trapped air

Due to pneumatic transportation, bulk materials such as cement, plastic powder or milk powder are often enriched with large quantities of air. When filling or bagging, this air leads to low bulk densities and thus to an increased bulk volume.

The consequences are:

• Greater space requirement for transportation and storage

• Unstable filling processes

• Increased dust formation

• Uneven filling of containers

Operating principle of venting and suction

During venting and suction, the trapped air is removed from the bulk material via porous venting elements. The pore structure is designed in such a way that gases prefer to flow through while the solids remain in the container.

Localized flow peaks are avoided thanks to the flat gas discharge via the porous structure. The bulk material is not whirled up, but can settle evenly. Depending on the bulk material and process control, the bulk volume can be significantly reduced, in suitable cases to up to 20 % of the original volume.

Typical designs and versions

Porous SIPERM® components in various geometries are used for venting and suction applications in order to adapt them to the respective process situation:

• Seamless, porous pipes for flat air extraction

• Venting inserts for sacks, big bags or containers

• Customized venting designs for integrated solutions

The design is chosen so that gas is discharged evenly over as large an area as possible.

Cleanability during operation

During the extraction process, fine powder particles can accumulate on the surface of the porous components. In such cases, gas permeability can be restored by applying a short pressure surge from the side facing away from the product.

This backwashing removes adhering particles and enables stable continuous operation without having to remove the venting element or clean it manually.