HERDING®-sinter plate filter for surface filtration grant clean gas values of < 1 mg/m³, even with dusts of D50 < 1µm. The matrix consists of sintered polyethylene PE. An additional PTFE-coating gets into the pores of the PE-basic body and forms a micro-porous, non-sticking. This combined material is most extensively chemical resistant. The HERDING®-sinter plate filters are extremely stable in structure, rigid, water resistant and only need low-maintenance. The average useful life of a Herding ® filter can even exceed 10 years. HERDING® sinter plate filters show a very high efficiency of separation and environmental compatibility. The filters can be recycled without any problems, no toxic waste has to be disposed off. By using these filter elements in HERDING® HSL-units there is an optimum combination of positive attributes like: compactness, optimum flow behavior, ideal dust emission and an extensive operational safety, resulting from the rigidity of the matrix and of no wear and tear against abrasive media. At regular intervals or at pre-determined differential pressure the filter elements are cleaned on-line by a jet-pulse. The filter elements are fixed only by a single screw – which makes maintenance easy and saves times. On request antistatic or even special design, e.g. for using cooling lubricants or aerosoles are possible. HERDING®-DELTA-filter are future-oriented; already today they meet what tomorrow’s environment and legislation will require. So in fact the separation efficiency shows a much better value than required by the BIA-certificate, regarding dust classification M.