What is Filtration?
Filtration refers to the removal of particles and aerosols from a fluid, either partially or completely. It is not simply a sieving effect; if it were, it would not be possible to explain how a filter with a micron-level porosity can capture particles with diameters as small as 0.3 μm.
The porous structure of filters is designed to divide the airflow into many microflows when it passes through a gas stream. This allows the particles carried by the airflow to change direction multiple times until they are captured. This phenomenon is independent of the type of material that constitutes the filter’s porous structure but arises from the fact that the particle follows a path up to 300 times longer than its diameter. Particles can be captured by three different forces:
- Inertia
- Diffusion
- Interception
The capture mechanisms affect the overall efficiency of the filter to varying degrees: the effects of interception and inertia increase as particle size increases, while the diffusion force decreases.
Why Filtration?
Greater comfort, economic savings, and good preservation of premises and machinery are just a few of the benefits of an efficient filtration process. While the economic savings may not be immediately measurable, the reduction in contamination levels is.
Particles that contribute to contamination are very fine and are naturally present in the air, measured in micrometers (μm). 1 μm is equal to 10^-6 meters, or one millionth of a millimeter. From here, we can classify the particles as follows:
- Dust – Solid particles dispersed in the air, with sizes no smaller than 100 microns.
- Aerosols – Very small solid and liquid particles generated by sublimation, condensation, or combustion.
- Smoke – Mixtures of solid particles and fluid and gaseous products. These are particles in both solid and liquid form, ranging from 0.1 to 0.3 micrometers in diameter, generated by incomplete combustion of organic substances like coal, wood, petroleum products, etc.
- Clouds – Water particles generated around condensation nuclei.
- Mists and Fogs – Suspended droplets in the air, generated by condensation of vapors or liquid atomization.
- Viruses – Sizes ranging from 0.005 to 0.1 micrometers, often grouped in larger particles formed by colonies or accumulations with other materials.
- Vegetal Spores – Sizes ranging from 10 to 30 micrometers, with pollen ranging from 10 to 100 micrometers.
These naturally occurring particles are further augmented by particles from industrial processes, which increase dust levels.
Airborne impurities impact human health as they can cause serious health issues—silicosis, asbestosis, chronic bronchitis due to toxic gases.
Applications of Filters
Improving air quality and maintaining cleanliness in environments is possible through filtration, which removes harmful or irritating contaminants that are small enough to reach the lungs.
In certain sectors, filtration is mandatory. The electronics industry, for example, requires it due to the precise tolerances in its processes, where contaminant particle sizes can be even larger than the components themselves.
The food and pharmaceutical industries also require high-level filtration to increase product shelf life; rather than using preservatives, filtration can stop the germs responsible for fermentation.
Types of Filters
- Activated carbon filters
- Cartridge filters
- Bag filters
- ATEX filters
- ATEX cartridge filters
- Dust collector filters
- ATEX bag filters
- Cyclone filters
- Electrostatic filters
For more information on our products and their use and application, visit the section dedicated to air extraction systems.
