A turbine flow meter is constructed with rotor and blades that use the mechanical energy of the fluid to rotate the rotor in the flow stream. Blades on the rotor are angled to transform energy from the flow stream into rotational energy. The rotor shaft spins on bearings: when the fluid moves faster, the rotor spins proportionally faster. Shaft rotation can be sensed mechanically or by detecting the movement of the rotor blades. Rotor movement is often detected magnetically, where movement of the rotor generates a pulse. When the fluid moves faster, more pulses are generated. Turbine flow meter sensors detecting the pulse are typically located external to the flowing stream to avoid material of construction constraints that would result if wetted sensors were used. The RPM of the turbine wheel is directly proportional to the mean flow velocity within the tube diameter and corresponds to the volume flow over a wide range.