| 摘要 |
1. Backwashable filter comprising a housing (1) which in its lower part has a filtrate chamber and in its upper part a bed (4) of granular filtering agent resting on a filter bottom (3, 3'), the filter bottom (3, 3') being furnished with nozzles (2, 2') consisting each of a tube (10) penetrating the filter bottom (3, 3') and having at least one through opening at its upper end at a distance from the filter bottom (3, 3') and of a cup-like hood (11, 11') covering the end of the tube (10) standing out of the filter bottom (3, 3') and forming an annular space (16, 16') between the lower edge of the hood and the filter bottom (3, 3') characterized by the height h of the annular space (16, 16') being larger than the particle diameter of the adjacent filtering agent (17) and the annular cross section between the tube (10) and the inner surface of the hood (11, 11') being at least half the size of the annular space surface (16, 16') - as measured from the lower edge of the hood - the radius r and the annular slot surface (16, 16') being measured from the inner lower edge of the hood (11, 11'). |
