Filter membranes of the type heterogeneous and comprising at least one first membrane has a structure of the pores asymmetrical

摘要

The invention relates to a filtering element. / p & & p & the filtering element consists of at least one filtering membrane as the first filter 2 and at least one filtering membrane as a terminal filter 3. In order to reach the time of use for a safety device is identical with respect to the filters with a membrane, the first filter 2 has pores of a truncated cone 4 with a decreasing diameter in the direction of flow and the terminal filter 3 has pores cylindrical 5. The first filter 2 and the terminal filter 3 have different chemical compositions. The diameter y of the pores 5 is less than the smallest diameter x2 of the pores 4. The first filter 2 may consist of an aromatic polyamide, polysulfone, and in a cellulose derivative and the terminal filter 3 may consist of an aliphatic polyamide, polysulfone or polyvinylidene fluoride.