Pre-air filters can take out bigger particles for example dust and pet dander from indoor air, while medium-efficiency filters can more take away smaller particles like pollen and germs. Drip-proof filter plates (CGR) are applied specifically if the filter chambers needs to have a particularly high degree of tightness https://reidzmwfp.techionblog.com/31828817/a-secret-weapon-for-stainless-steel-plate-and-sheet-filter-press