Disclosed herein is a device for directing fish toward a preferred path in a water passageway. The device includes a base and a plurality of spaced bars coupled to the base and cantilevered from the base. The plurality of spaced bars are electrified in anode cathode pairs. The plurality of spaced bars can extend from the base to form a frustoconical shape such that the spaced bars direct fish toward a hydraulic turbine blade hub and away from a hydraulic turbine blade tip. Alternatively, the plurality of spaced bars can extend from the base to form a linear array.

A compressor (2) characterized by being equipped with: a rotary shaft (12); multiple impellers attached to the rotary shaft; a main flow path that guides a fluid from the prior-stage impeller to the latter-stage impeller; a chamber (31) that forms a circle centered around the axial line and connects to the main flow path; a suction nozzle (32) that guides the fluid from the outer circumferential side toward the inner circumferential side in the chamber; multiple movable vanes provided in the main flow path at intervals in the circumferential direction of the axial line and capable of moving and thereby adjusting the flow volume of the fluid passing through the main flow path; and a drive mechanism (42) that is provided at one side in the circumferential direction of the suction nozzle (32) within the chamber (31), and that changes the angle of the multiple movable vanes. In addition, of the one side and the other side in the circumferential direction within the chamber (31), the suction nozzle (32) is inclined toward the other side so as to increase the flow volume of the fluid toward the other side.

The disclosure relates to a degassing tank (1) comprising a first inlet (20) and a dip tube (4) extending between the first inlet (20) and a lower part (3) of the tank (1), in which the dip tube (4) is movable, when in use, relative to the first inlet (20) between a first position in which the dip tube (4) provides a fluid line between the first inlet (20) and the lower part (3) of the tank (1), and a second position in which the fluid communication between the first inlet (20) and the lower part (3) of the tank (1) is closed.