DEPENDENCE OF FILTRATION PROPERTIES ON STAINLESS-STEEL MEDIUM STRUCTURE

Filtration properties including porosity, air permeability, minimum bu bble point, pore sire distribution, latex bead filtration efficiency a nd dirt-holding capacity were investigated for woven wire meshes and s intered nonwoven metallic fibre media, in order to understand the effe ct of their structural differences, When 165X1400 mesh and Fibermet(R) 20A0 fibre medium were compared, it was found that the basis weight a nd air permeability of the woven mesh and the nonwoven fibre medium we re similar. The porosity of 165X1400 (36.7%) was lower than that of 20 A0 (84.7%). However, the wire mesh had a much higher minimum bubble po int than the fibre medium (3553 Pa versus 1845 Pa). The 165X1400 had a narrower pore size distribution than 20A0, Between 5 and 20 mu m, the latex bead filtration efficiency of 165X1400 was lower than that of 2 0A0. At 20 mu m, both 165X1400 and 20A0 had a latex bead filtration ef ficiency of 98%. The lower latex bead filtration efficiency of 165X140 0 compared to 20A0 did not correlate with a higher minimum bubble poin t. A similar difference was also observed between 325X2300 wire mesh a nd Fibermet(R) 10A0, and both of them had a filtration efficiency of 9 8% at a latex bead diameter of 9 mu m. Analysis of the structure of al l four filter media showed that there were multiple filtration layers through the thickness in the depth filtration fibre media, and only a single filtration layer in the surface filtration wire meshes. The mul tiple filtration layers of interconnected pores and tortuous pore path s in the fibre media were more effective in catching rigid latex bead particles than the single filtration layer, and a nearly linear pore p ath in the wire meshes, The fibre media also had higher dirt-holding c apacities than the wire meshes.