Filter Units

An extraction system should always be equipped with a filter unit. The filter unit separates coarse material in the cyclone body of the unit and fine dust in an internal arrangement of conical pleated cartridge filters. Pleated filters have very high filter areas in relation to their physical size. The filter units therefore have high capacity while maintaining compact overall dimensions.

Filters are cleaned with reverse pulse which results in very effective cleaning, long filter life and low maintenance.

Normally the filter units are equipped with a plastic bag or container for collection of the extracted material but other types of discharge arrangements can also be installed.


In the filter unit, dust is separated from the air in several steps:

• the cyclone will separate particles down to a size of 1/100 mm.
• the filter will separate particles which escape the cyclone effect.

The dust laden air is introduced into the cyclone at a high velocity. Through centrifugal force the dust particles, with higher relative mass than the air molecules, are forced outward toward the wall of the cyclone and drop to the bottom. The air flows toward the centre of the cyclone and through the filter.

Filter Loading

Permissible air flow determines the air velocity through the filter material, known as filter loading. Consider also inlet/outlet velocities. Permissible filter loading varies with dust type.

Permissable Filter Loading
Dust Type [m³/h/m²]
Stone 120
Concrete 120
Wood 160
Cement 120
Plastic 120
Graphite 60
Carbon black 60
Welding fume 60


For the extraction of welding fume, the maximum permissible flow in the S 34000 will be:

60 (m³/h)/m²  x  34 m² filterarea = 2040 m²/h

The velocity of the air through the inlet and outlet should not exceed 30 m/s. When one filter unit does not have sufficient capacity, several units can be connected in parallel.


For more detailed information, please read our


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Dustcontrol, Box 3088, Kumla Gårdsväg 14, 145 03 Norsborg, SWEDEN