Type EFST filter elements of filtration grades ZN, XN, XXN are mainly designed for separating liquid aerosols, i.e. smallest, nebulous liquid droplets (coalescing filtration, wet-type filtration) as well as for separating finest dust contaminants (fine dust filtration, dry-type filtration) from compressed air flows. Larger droplets or amounts of liquids are, of course, also separated during this process.

Type EFST filter elements of filtration grades ZN, XN, XXN consist of a pleated depth filter media and a separately located drainage media. The two functional layers are compactly located between the two stainless steel cylinders and therefore completely integrated in the filter element.

Thanks to the pleating technology the effective filter surface is increased many times resulting in a higher dirt holding capacity and a longer service life. At the same time the flow resistance and therefore differential pressure generated by the filter element is considerably reduced. Due to the separation of the two function units, filtration and drainage, which are both fundamental for the filter element, the function of the remaining layer is guaranteed even if one filter layer breaks. 

To avoid a breakthrough at an early stage, the pleated depth filter cylinder has two or more layers. In addition, it is provided with a pleated supporting fabric on the inside and outside. All media are located within the two stainless steel cylinders. In this way, breaking off completely or in parts of the filter layer used for filtration is impossi-ble. 

All the features mentioned above are a contribution to a filter ele-ment which has a high performance (high separation efficiency) com-bined with economic efficiency (low differential pressure) and maximum operating safety (integrated design).