Pelton wheel Turbine Flow Meter.

A turbine flow meter operating on the Pelton wheel principle for low flow rate applications on low viscosity fluids. Conventional axial flow turbine meters become increasingly difficult to manufacture in very small sizes and bearing drag becomes more significant. The Pelton wheel on the other hand still retains a manageable diameter allowing close machining tolerances whilst being capable of handling very low flow rates with reasonable accuracy

Documentation

Nixon Pelton Wheel Technical Description