Physical filtration through screen filters is performed by retaining suspended solids in the water in holes in the filter. The screen acts as a sieve that allows solids smaller than the sizes of its holes to pass through, while retaining larger solids.
There is a certain incorrect tendency to state the filtering capacity of a screen by making reference to the number of threads by unit of length, without mentioning its thickness. This means that the dimensions of the holes that retain suspended solids are not assessed. It is very common to hear screen characteristics expressed as a mesh value. However, LAMA emphasises the importance of naming the screen based on the dimensions of its holes in micrometres. The lower the screen value, expressed in mesh, the larger its filtering holes, and vice-versa.
All LAMA screen filter cartridges consist of a tubular polyamide for automatic filters or PVC for manual filters structure, with a stainless-steel screen. For self-cleaning filters, we use cartridges+screen form the injection; and for PVC cartridge surface is drilled using a CNC machining centre. The hole locations are geometrically studied to ensure that the maximum surface area of the filter cartridge is used, achieving a very high percentage of holes. The precision of the machine tool used to make the holes allows them to be placed close together to obtain an oversized filtering surface. We have a significantly greater number of screen openings in our polyamide and PVC cartridges, compared to screens 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 automatic filters (with an opening size of 0.190 mm for those supplied as standard).