Principally, filtration is divided into two different processes; deep-bed filtration and surface filtration.
During surface filtration, the solid particles are retained at the filter surface due to their size. Prerequisite for this mechanical separation is that the biggest pore sizes of the filter material are smaller than the smallest solid particles which need to be retained. The disadvantage of surface filtration is that the particles, which accumulate at the filter surface, form a filter cake, which raises the flow resistance distinctly, and accordingly decreases the filtration flux.
In deep-bed filtration, the filter effect is, on the one hand, based on a mechanical factor and, on the other hand, on an absorptive one. Thereby, a considerable portion of particles, which – due to the geometric proportions of pore openings and solid particles – normally could pass the pores, is retained in the three-dimensional structure of the filter material.
For applications with high demands regarding strength and corrosion behavior, our materials Siperm R and B Siperm are excellently suitable both as classical deep-bed filters and as surface filters. They offer a great range of pore sizes and permeability in combination with high strength and ductility. Depending on the application, our materials can also be produced as two-layer system.
Due to their food-safeness, our materials Siperm HP and Siperm R are suitable for applications in the field of drinking-water and manufacture of beverages.