The four principals of a mechanical filter
How a mechanical filter works is based on four principles:
A – Trapping:
If a particle is too big to pass through the fibres, it is trapped and captured. The more particles are trapped, the narrower the space between the fibres and the more efficient the filter becomes.
B – Resistance:
Depending on the shape, size and density of the particle, it has a certain resistance. The course of a small heavy particle in an air flow will change less rapidly than that of a large light particle. If an air flow changes course, the particle “flies” straight ahead and collides with the filter fibre, where it is restrained and captured.
C – Interception:
When particles pass through the gauze of the filter material, they touch the fibres of the filter material, ensuring that they are halted and captured.
D – Diffusion:
Ultra-small particles make irregular movements because they are colliding with air molecules all the time. Because they don’t follow the air flows through the filter, they collide with the fibres in the filter material and are halted and captured. This is an important mechanism that ensures that ultra-small particles such as nanoparticles are filtered.