Backwashable filter apparatus

摘要

In a filter apparatus for flowing water, a backwash apparatus is provided which contains a backwash element (18) furnished with at least one slot-like inlet orifice (44), which backwash element can be connected on the outlet side to a backwash duct. The backwash element (18) is arranged to be axially displaceable within a filter element (16). The slot-like inlet orifice (44) pointing essentially radially towards the inner surface of the filter element (16) covers the entire raw water-side filter surface when the backwash element (18) is axially displaced, so that the filter element (16) is successively cleaned over its entire height by the water flowing from the clean water chamber (28) through the filter element (16) to the backwash element. The backwash element has a stepped piston (66) which, with the aid of a manually or automatically activatable control device, can be selectively impinged with various pressures which effect an autonomous axial displacement of the backwash element (18) between the two end positions. <IMAGE>