Abstract: A conduit closure serving for the closure of a fluid conduit includes a closure element (4) which may be fastened on a conduit end. A securing element (30) is provided, which closes an opening (28) leading into the conduit inside. The opening (28) is on the closure element (4) or on the conduit (2). The securing element (30) is designed and arranged with respect to the closure element (4), in a manner such that securing element releases the opening (28) before the closure element (4) may be removed from the conduit (2).

Abstract: The invention relates to an aeration device (20) for aeration of a liquid. The aeration device comprises a plate (30) of a first material, said first material being permeable to air, said plate having inlet means (31) for inletting air into the plate and means for creating a flow of liquid across the plate of the first material, when said aeration device is immersed or submerged in a liquid. The plate of first material is stationary within the aeration device. The aeration device may moreover comprise a disc (12) arranged for being placed in parallel to the plate, but leaving a gap between the plate and the disc member, and the means for creating a flow of liquid across the plate of the first material may comprise means for rotating the disc member around a central axis through the disc member. Small or very small bubbles of air may be generated by the combination of air permeable material and creation of a flow across the plate.

Abstract: A centrifugal pump wherein a threaded ring is secured in its position by way of a pressure body which presses it against the axial abutment of a pump shaft and which is screwed axially to the end of the pump shaft. The threaded ring is seated loosely on the pump shaft and by a thread which is provided in a front hub region of the pump impeller and into which the thread of the threaded ring is screwed.

Abstract: A centrifugal pump wherein a threaded ring is secured in its position by way of a pressure body which presses it against the axial abutment of a pump shaft and which is screwed axially to the end of the pump shaft. The threaded ring is seated loosely on the pump shaft and by a thread which is provided in a front hub region of the pump impeller and into which the thread of the threaded ring is screwed.