UNDERWATER AERATION DEVICE

摘要

[Object] To provide a submersible aerator which can improve its aeration action, reduce load at the time of startup, prevent clogging by foreign objects, reduce maintenance work, and lower production and running costs. [Means for solution] An impeller 4 including blades 4 having partition walls which separate liquid passages 4w and air passages 4a is accommodated within a guide casing 6 for rotation between a lower surface 5d of an intermediate plate having an air suction opening 5s and an upper surface 7u of a suction cover having a liquid suction opening 7s. The liquid passages 4w and the air passages 4a meet through communication portions 4h at radially outer ends of rear-side blade partition walls 4r. Intermediate blades 4m are provided at radially outer ends of the liquid passages 4w. A conical space is defined between the blade lower end surfaces 4d and the suction cover upper surface 7u such that the space, which is wide at a portion adjacent to the liquid suction opening 7s, becomes narrower toward a radially outward region including guide vane tongues. A plurality of support legs 8 and a plurality of straining projections 9 are integrally formed on the lower surface of a peripheral portion of a bottom wall 6d of the guide casing. Sloping surfaces are provided on the top wall upper surface 6o between air-liquid discharge passages such that the sloping surfaces are inclined downward and increase in width in the radially outward direction.