Filter body

Filter body with a self-supporting, open-pored composite body including a support body of coarse porosity consisting of extraneously or intrinsically bonded coarse grain and a diaphragm of fine porosity containing extraneously or intrinsically bonded fine grain which is bonded to an external surface of the support body, the improvement comprising

• the ratio of the coarse grain to the binder by volume percent is (80 to 90):(20 to 10), and
• the diaphragm contains, in addition to the fine grain and a binder, fibers which have an absolute diameter of between 0.5 and 3 microns and a length at least ten times greater than their diameter and which are in the range of 50 to 500 microns, in that the ratio of the fine grain, the fibers and the binder in percent by volume is (60 to 40):(40 to 20):(30 to 10), in that the ratio of the thickness of the support body to the thickness of the diaphragm is between 5:1 and 75:1, in that the absolute thickness of the diaphragm is between 0.2 and 2 millimeters, and in that the ratio of the specific permeabilities of the support body and the diaphragm for fluids in the laminar flow range is between 2:1 and 100:1.