Turbine meters were introduced for flow measurement by Reinard Woltman, an 18th century German inventor. Today many domestic water meters are called Woltman meters with a worldwide install base that perhaps numbers in millions of meters.  Turbine meters may be used both in liquid and compressed gas applications.  The turbine meter is comprised of a number of components that include the flow body, the rotating turbine element, the rotor support/axle, the bearing(s), and a a pickoff module to count the turbine’s rotation. The key component that provides the flow rate reading is the rotating turbine element which consists of a multi-bladed rotor mounted at right angles to the flow in a pipe with a free-spinning bearings. The rotors are slightly smaller than the flow tube and their speed of rotation is directly proportional to the volumetric flow rate of the fluid. The rotation of the blades can be detected by solid state devices (reluctance, inductance, capacitive and Hall-effect pickoffs) or by mechanical sensors (gear or magnetic drives)