View around flow indicator

Apparatus for providing a visual indication of a flow of fluid through an opaque hard walled tube, said apparatus comprising:

• a housing having an inside surface defining a flow path, said flow path having a longitudinal axis, the inside surface of the housing forming a generally circumferentially extending annular recess,
• a turbine wheel mounted in the housing for rotation around the longitudinal axis of the flow path, said turbine wheel comprising a hub positioned on the longitudinal axis, a ring positioned in the annular recess, a plurality of radially extending turbine blades connecting the hub with the ring, and a plurality of magnets carried by the ring,
• a cylinder mounted on an outside surface of the housing for rotation around the longitudinal axis of the flow path, said cylinder carrying a plurality of magnets which are magnetically coupled to the plurality of magnets carried by the ring, and
• a visually observable pattern on an outside surface of the cylinder so that rotation of the cylinder can be visually ascertained.

In a method for providing a visual indication of a flow of fluid through an opaque hard walled tube comprising positioning a turbine wheel having a plurality of turbine blades in the tube for rotation alongside an inside wall of the tube,

• positioning a cylinder on the outside of 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, and
• providing a visually observable pattern on the outside surface of the cylinder so that rotation of the cylinder can be visually ascertained,
• the improvement comprising
• flowing the fluid through a diverging section of tubing just prior to flowing said fluid through the turbine wheel, said tubing diverging at a half-angle of divergence, as measured between a tube axis and the inside wall of the tube, in the range of from 3 to 30 degrees, wherein the turbine wheel is positioned in an enlarged section of the tube.