Physical filtration occurs in screen filters due to the retention of solids in suspension in water between the holes of the sieve. The screen behaves like a sieve that allows dirt with a smaller particle size than its holes to pass through, and retains grains larger than the holes.
It is common to hear the filtering capacity of a screen being expressed incorrectly, using the length of the number of threads and ignoring its thickness. Therefore, no reference is made to the true dimensions of the filter hole or its precise capacity to stop solids from passing through. It is common to hear screen qualities expressed as a mesh value. However, LAMA emphasises the need to name the screen based on the dimensions of its hole, expressed in micrometres. The lower the mesh value, the larger its filtering holes, and vice-versa.
All LAMA screen filter cartridges consist of a robust cylindrical polyamide or PVC structure, with a stainless-steel screen. We use polyamide cartridge+screen from the injection for automatic filters and we use PVC-screen for manual filter, the surface of the structural tube is drilled using a CNC machining centre. Hole locations are geometrically planned to ensure that the entire filter cartridge space is used, thereby obtaining the highest possible percentage of holes. The accuracy of the machine tool used to make the holes allows them to be made closer together to achieve a very balanced filtering surface. Our polyamide and PVC cartridges have a significantly higher number of mesh openings, compared to those manufactured entirely from stainless steel.
LAMA manufactures screen filter cartridges with different opening sizes: from 3 mm to 0.02 mm for manual filters (with an opening size of 0.130 mm for those supplied as standard), and from 1.5 mm to 0.02 mm for self-cleaning filters (with the standard being 0.190 mm).