Features and Benefits
The porosity of a filter medium directly affects the filter performance. A higher porosity gives a lower pressure drop and a lower amount of voids for entrapment of solid particles. The porosity (density) of a sintered filter is determined by the compacting pressure. Typically density levels in sintered stainless steel filters are in the range 3,8-5,6 g/cm³ which corresponds to a porosity of 25-40%.
Filter density is a consequence of the press force, not of the particle size distribution.
The filter or "micron" rating is a comparative test result most commonly evaluated using the "bubble test method" (ASTM E128-61). This gives an indication of the solid particle size retained by the filter. A micron rating is highly dependant on the pore shape, i.e. predominantly a result of the chosen particle shape and size distribution. Note that besides the particle shape compacting also has an effect on the micron rating.