By filter category, following is meant:

• the adjustment in a use category, application category (U,S,G,C,K)
• takes place through the BIA ( Berufsgenossenschaftliches Institut für Arbeitssicherheit)
• pursuant to the valid norms tRGS 519 / EN 60335-2-69
• additional request of explosion protection (B1) and
• certification of the residual dust content by awarding it a test mark H2, H3 respectively

A sufficient Art cleaning from wood dust is only given when:

• filter material with a passage <0,5% is used
• filter categories G,C,K are fulfilled when simultaneously the filter area load of 150m³/m²h will not be exceeded or
• the type examination concerning the residual dust content exists and has at least been certified the test mark H2 (see return air)