Patent ID: 7284716

Claim:
An agitating device comprising: a first cover plate having a liquid inlet hole; a second cover plate disposed at a position spaced apart from said first cover plate in a direction orthogonal to a spreading surface of said first cover plate; a rotary impeller disposed at a position corresponding to said liquid inlet hole in a interplate space defined between said first and second cover plates; an approximately tube-shaped or tub-shaped stationary inner screen member disposed in said interplate space so as to surround said impeller and formed with a plurality of elongate first liquid communication holes in a peripheral wall thereof, each of said first liquid communication holes extending in the directional orthogonal to said an reading surface; and at least one approximately tube-shaped stationary outer screen member disposed in said interplate space so as to surround said inner screen member and formed with a plurality of elongate second liquid communication holes in a peripheral wall thereof, each of said second liquid communication holes extending the direction orthogonal to said spreading surface. wherein said elongate first and second liquid communication holes mostly eliminate a circumferential component of a flow vector of said mixture to allow said mixture to have substantially only a radial component.