An example of DREF 2000 usage in the filter sector is the use of friction spun yarns for drinking and industrial water, pure water and activated carbon filters. A specialist manufacturer employs DREF products for over 20 types of cartridge that require compatibility with FDA foodstuffs legislation. The yarns employed generally consist of PP fibres in the 3.3 dtex, 40 mm range, which are highly resistant to micro-organisms and have a wide scope of chemical applications
Friction spun yarns offer 20-40% more air volume in the yarn and less flow resistance than flyer yarns, as well as up to twice the service life. The fibre structures are relatively random and subject to high degree of twist. The yarns offer great regularity and increased strength, while their round yarn cross-section ensures limited deformation under transverse load. In addition, production costs are cut by up to 50% through reduced preparation, spinning and personnel expenses. The knot-free, uniform quality of the yarns guarantees fault-free filters and constant micron values, with the layered structure creating a hairy surface that is ideal for filtering purposes.