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.

This filter with a thickness of 60mm is manufactured by fibers of glass. It is appropriate for the retention of dust and paint droplets with 89% efficiency. It is applied for dust filtering in industrial buildings but mainly paint booths where it is used to trap the droplets of paint.

The filter enclosed in a galvanized frame is fabricated by sheets of aluminium wire or galvanized metal. The particular pre-filters have applications in aggressive atmosphere with high velocity air streams in the ducts which results high flow rate.

Filtercels are synthetic filters of G2, G3 and G4 classes which are enclosed in a galvanized metallic frame between two also metallic grids for protection. Its applications as a pre-filter are in air treatment unites, filter walls as well as in paint booths.

The particular filter with a thickness of 65mm manufactured by two paper sheets can trap the cloud of paint droplets between them and due to air pressure difference between the two sheets, the separation of paint and clean air can be achieved with efficiency between 90% to 98%.

This pre-filter is manufactured by polyurethane and belongs to the G2 class. It has applications in air conditioning in fan-coils as well as in primary filtration of the air in cases of fabrication premises where special conditions are obtained.

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.