A ventfilter is installed on a vessel or reactor to prevent micro organism (bacteria, virus, yeast) to enter the vessel or reactor.
The vent filter can be sterile for food applications, fermentation reactors of sterilisation needs.
The vent filter can also contain molecular sieves to absorb water and to exclude that water comes in the reactor.
The vessel and reactor need also to be protected for implosion in case the vent filter is blocked.
Filtration can help you to design the correct vent filter.