Measuring device with self-powering annular turbine

A flow measuring device that has:

• a non-metallic housing that has an inner surface through which a fluid flows along an axis of a central waterway;
• an annular turbine that is arranged at an axial position along the central waterway, surrounds the central waterway, and rotates about the axis of the central waterway;
• a set of vanes that extend inwardly from a circumferential wall of the turbine into the central waterway, and are set an angle at which the flow of liquid through the central waterway causes the turbine to rotate without reducing the pressure of the fluid through the pathway by more than 10%;
• a set of magnets that are spaced circumferentially about the turbine;
• a set of coils that are mounted to the housing, have coil axes that are radial to the axis of the central waterway, and are spaced circumferentially about the central waterway at an axial position that is radially outward from the magnets on the turbine;
• and
• a set of circumferentially spaced reinforcing arms, one for each coil, the circumferential width of each reinforcing arm near the axial position of the turbine being no more than the radius of the coil.