Filtration

Filtration (also called filtering) is a process for separating or purifying substances, usually a suspension or an aerosol. Filtration belongs to the mechanical separation processes, which are exclusively based on physics. Contrary to popular belief, not only particles larger than the pore size of the filter are retained – this is only one mechanism among many. Other mechanisms include particle inertia, diffusion effects, electrostatics or barrier effect. Therefore, particles much smaller than the pore size of the filter are basically also separated. Especially in the field of gas filtration, filters have an area called filter gap, where particles are insufficiently separated – significantly larger (due to inertia and barrier effect) and also significantly smaller (due to diffusion) particles are completely retained.