How does the filter collect particles?

How does the filter collect particles?


Diagram illustrating the filtration mechanisms of inertial impaction, interception, diffusion, and electrostatic attraction. In each case, fibers are shown filtering particles.

This photo shows the four filtering mechanism.

This photo cr. https://blogs.cdc.gov/niosh-science-blog/2009/10/14/n95/



Inertia Impact: With this mechanism, particles with excessive inertia due to size or mass cannot follow the gas flow because it steers around the filter fibers. This mechanism is responsible for collecting larger particles.


Interception: When particles are close to the filter fibers, they may be intercepted by the fibers. Again, this mechanism is responsible for collecting larger particles.


Diffusion: Small particles are constantly bombarded by air molecules, causing them to deviate from the airflow and come into contact with the filter fibers. This mechanism is responsible for collecting smaller particles.


Electrostatic attraction: The oppositely charged particles are attracted to the charged fibers. This collection mechanism is not conducive to a certain particle size.