It is the primary state, when the atmospheric air begins to interact with the filter system through a G class pre-filter. All the European norms ΕΝ 770:2012 are followed. They have applications in civil and industrial conditioning plants as well as pre-filters in larger air treatment unites where higher filtration efficiency is required.
Pre-filter or terminal filter made of polyester with efficiency up to 90%, with classification G3 and G4. The particular filter is most appropriate for high flow rate applications for both in civil and industrial building. It can also be used as a pre-filter of absolute filters.