Abstract: A turbo-engine guard (2) for mounting on the air inlet (1) side of a turbo-engine, particularly of airplanes, comprises guard elements (3) possessing an optimum aerodynamic design. Advantageously the center lines or their extensions of the guard elements intersect or do not intersect each other in one plane. Preferably the guard elements (3) are helically mounted, preferably along several helical lines. Appropriately the guard elements (3) are kept under a tension so that these elements return to their original position after collision. Suitable materials for the guard elements are plastics of the poly-p-phenylene terephtalamide type, carbon fibres, metal or parts being held together by a binder being resistant to temperatures comprised between +150.degree. C. and -50.degree. C.

Abstract: Apparatus for continuous filtration of a fluid, for example water containing solids, comprising a plurality of filter cells partially filled with mobile filtering material, each cell having an inlet and an outlet, means being provided for continuously supplying fluid to the inlets, a drain element for filtered solids being connectible to a limited number of cell inlets without interrupting the fluid supply to the other cell inlets, the drain element lowering the fluid supply pressure prevailing at the limited number of cell inlets to a value lower than the filtrate pressure prevailing at the cell outlets so that these cells are backwashed with filtrate such that the mobile filtering material only partially filling the cells is swirled in the turbulent filtrate flow within the cells and is thoroughly cleaned from adhering solids.