Surface aeration impeller

An impeller for aerating a liquid and adapted to be affixed to a rotating shaft, comprising:

• a. a support disk having a circular outer edge and upper and lower surfaces;
• b. means for affixing said support disk to said rotating shaft so that said support disk is maintained in a substantially perpendicular relationship with said shaft;
• c. a plurality of impeller blades;
• d. cover means for creating an air intake opening above said upper disk surface and for reducing the amount of splashing caused by the rotation of said impeller near the surface of said liquid;
• e. means for adjustably securing said impeller blades to said support disk so that said impeller blades extend outwardly from said circular outer edge, extend above said upper disk surface and below said lower disk surface, and so that the degree of radial extension is adjustable, wherein each of said impeller blades has an upper edge which lies in a plane substantially parallel to said support disk and each impeller blade being tapered causing said blades to be widest at the portion closest to said rotating shaft and progressively more narrow as said blade extends outwardly from said support disk, and wherein each of said impeller blades includes a flow inducing fin along the lower edge of the blade, said fins being tapered so as to be widest at the portion closest to said rotating shaft and progressively more narrow as said blade extends outwardly from said support disk;
• and
• f. means for adjustably securing said cover means to the upper edges of said impeller blades so that said cover means is spaced from said upper disk surface and so that the degree of radial extension of said blades remains adjustable, wherein each of said impeller blades includes a flange portion along the upper edge thereof and wherein said means for adjustably securing said cover means to the upper edges of said impeller blades includes a plurality of radially aligned mounting holes in one of said cover means and said flange portions and fastener means adapted to be inserted into one of said mounting holes to thereby adjustably secure said cover means to the upper edges of said impeller blades.