1) The system can work as a pressure-type system, with dust or particles moving through the fan (typical of wood industries / workshops).
2) The system can work as a depression-types system, where particles are eliminated either through a simple kiln where the fan is often directly mounted on top of the cyclone, or through a more complex system with compartments inside the filter, relayed by the introduction of air to eliminate airborne particles.
The technical characterises
In pressure-type systems, like in the wood industry, as all particles travel directly through the fan, the impeller must be equipped with radial blades (T-type Blades), and very often mounted without any shroud, to avoid particles becoming attached within the fan. Robustness of the fan and material thickness are important elements of fan design. Fans located after the cyclone and/or within filtering systems, can have backward inclined, airfoil or flat blades due to the clean air environment. The most important characteristics of the fan are low noise levels and high efficiency so users get the best performance from the installation, avoiding the use of silencers or acoustic insulation.