Why and how does an air diffuser clog over time?


A textile diffuser can more or less quickly become dirty depending on the conditions in which it  operates.
 
Two types of clogging are possible:

Internal clogging

Mainly due to poor filtration, i.e. a filter that is saturated or of insufficient filtration class.For porous ducts for example, the minimum filtration quality to be installed upstream is G4/F7. Without proper filtration, unwanted particles are blown into the duct, become trapped and stick to the walls, clogging the blow holes.

External Clogging

A very humid ambient air, loaded with dust or pollutants, favors a quick clogging of the duct walls. Moreover, the particles will more easily stick and cling to a humid duct via the Venturi effect. Humidity will also favor the growth of molds and the bacteria proliferation.

Finally, if the maintenance is not regular, dust will naturally settle and accumulate on the topoftheducts.
External clogging due to venturi effect in a dusty environment.
External clogging due to venturi effect in a dusty environment.