Digital fluid flow meter

Claim 1

A fluid flow meter, comprising; (a) a shallow block with first and second faces parallel to each other and separated by a thickness T, with a circular opening of selected radius R through said block; with axis perpendicular to said faces; (b) a first entrance conduit longitudinally through said block approximately midway between said first and second faces, intersecting said circular opening approximately tangentially; (c) a portion of said first face adjacent said circular opening depressed a depth D, forming a first channel of approximate width W, where W is slightly less than 2R, and depth D; (d) second exit conduit means connected to said first channel; (e) circular impeller means of radius slightly less than R in said circular opening, said impeller having a plurality of spaced substantially radial vanes, and having a first axial boss of length D extending from a first face, and a second axial boss extending from the second face of said impeller, the total thickness of impeller plus first and second bosses equal approximately to T, with said first face of said impeller approximately coplanar with said first channel; and (f) means on said first and second faces to at least cover and seal all openings on said first and second surfaces.