Abstract: Several forms of surface impeller for aeration of liquids are disclosed. All of the forms are of the shrouded or closed turbine type. In one form, the impeller has a large-diameter flat steel horizontal upper disc adapted to be secured to the lower end of a vertically disposed rotatable drive shaft. Secured, as by welding, to the undersurface of the upper disc are a plurality, such as six or eight or other number, of vertical blades at uniform spacing. Each blade is curved in a retreating or backward direction relative to the direction of rotation of the impeller. Each blade has a long or deep vertical inner edge located forward of the center axis of rotation. The lower edge of each blade is inclined upwardly toward a relatively short or shallow vertical outer edge located near the outer periphery of the upper disc. The horizontal innermost portion of the otherwise inclined bottom edge of each blade is welded to a small lower tie plate.

Abstract: Several forms of surface impeller for aeration of liquids are disclosed. All of the forms are of the shrouded or closed turbine type. In one form, the impeller has a large-diameter flat steel horizontal upper disc adapted to be secured to the lower end of a vertically disposed rotatable drive shaft. Secured, as by welding, to the undersurface of the upper disc are a plurality, such as six or eight or other number, of vertical blades at uniform spacing. Each blade is curved in a retreating or backward direction relative to the direction of rotation of the impeller. Each blade has a long or deep vertical inner edge located forward of the center axis of rotation. The lower edge of each blade is inclined upwardly toward a relatively short or shallow vertical outer edge located near the outer periphery of the upper disc. The horizontal innermost portion of the otherwise inclined bottom edge of each blade is welded to a small lower tie plate.

Abstract: Several forms of surface impeller for aeration of liquids are disclosed. All of the forms are of the shrouded or closed turbine type. In one form, the impeller has a large-diameter flat steel horizontal upper disc adapted to be secured to the lower end of a vertically disposed rotatable drive shaft. Secured, as by welding, to the undersurface of the upper disc are a plurality, such as six or eight or other number, of vertical blades at uniform spacing. Each blade is curved in a retreating or backward direction relative to the direction of rotation of the impeller. Each blade has a long or deep vertical inner edge located forward of the center axis of rotation. The lower edge of each blade is inclined upwardly toward a relatively short or shallow vertical outer edge located near the outer periphery of the upper disc. The horizontal innermost portion of the otherwise inclined bottom edge of each blade is welded to a small lower tie plate.