Patent ID: 7401572

Claim:
In an apparatus for providing a visual indication of a flow of fluid through an opaque hard walled tube, said apparatus comprising a tube defining a flow path, a turbine wheel mounted in the tube for rotation alongside an inside wall of the tube, said turbine wheel having a plurality of turbine blades, a cylinder mounted outside the tube for rotation alongside an outside wall of the tube, said cylinder being magnetically coupled to the turbine wheel through the sidewall of the tube so that rotation of the turbine wheel causes rotation of the cylinder, a plurality of magnets being mounted to the cylinder, and a visually observable pattern on an outside surface of the cylinder so that rotation of the cylinder can be visually ascertained, the improvement comprising a ring mounted peripherally around the plurality of turbine blades and forming a part of the turbine wheel, a plurality of magnets mounted to the ring, wherein the magnets are mounted to the ring and to the cylinder so as to magnetically couple the turbine wheel to the cylinder, and an annular recess formed in an inner wall of the tube for receiving the ring.