filter rotating the connection flange allows the direction in which a gas flows through the filter element located in the filter housing to be reversed in this way the filter can be operated as a coalescence filter or as a dust filter by simply rotating the connection flange application_number US 54823804 A description the filter 1 illustrated comprises a top part 2 and a bottom part 3 between which a connection flange 4 is arranged the top part 2 has two connection adaptors 5 6 by means of which the filter 1 can be introduced for example into a compressed air line not shown the loosely inserted connection flange 4 is clamped between an inner collar 7 of the top part 2 and a connection ring 8 of the housing bottom part with the aid of a union nut 9 the connection ring 8 is fixedly connected to a cylindrical center piece 10 of the housing which is adjoined by a bottom cap 11 the upper edge of a hollow cylindrical filter element 14 which is closed off at the bottom by a cover 13 is clamped in a sealed or adhesively bonded manner in a groove 12 in the connection flange 4 the cover 13 likewise has a peripheral groove 15 in which the lower edge of the filter element 14 is adhesively bonded or clamped the cover 13 bears a capacitive level sensor 16 with two annular electrodes 17 18 a condensate tube 19 extends as a riser line through a web 20 of the connection flange 4 the interior 21 of the filter element 14 and its cover 13 into the interior 22 of the housing bottom part 3 an electrical line not.