The first turbine flow meter was invented by Reinhard Woltman way back in 1790. He came up with the idea in response to a need of studying loss of water flow velocity in open canals. Since then, the turbine flow meter has seen many innovations in terms of technology. However, the original design persists more or less and is still the preferred flow meter when it comes to measuring the flow of water in large quantities. It is known as the Woltman flow meter.
Later developments in the technology have resulted in the creation of eight different types of turbine flow meters. While some of the flowmeters have been named after the type of water wheels on which they are based, some others are named after the technology. Broadly speaking, following are the different types of turbine flow meters currently in use:
- Pelton Wheel
Based on the original Pelton wheel that was used to turn turbines using flowing water, the Pelton wheel has buckets attached to the outside of wheel. When water or liquid hits these buckets, the wheel starts rotating. The Pelton wheel turbine flowmeter has a similar setup in a more compact frame and is used to measure the flow of low viscosity liquids that are flowing at slow rates.
- Paddle Wheel
Paddle Wheel flow meters are again based on the design of a water wheel. These types of flowmeters have shafts that are placed at right angles to the flow stream. The shafts are attached to a lightweight paddle wheel that rotates as the flow moves the shafts. The speed of rotation of the paddle wheel is proportionate to the flow speed of the liquid. Paddle wheel flow meters are more effective for low-speed flows.
- Propeller
Propeller flowmeters are based on the principle of the propeller turbine, which is used in the generation of hydroelectric power. Invented by Forrest Nagler in 1916, a propeller turbine has between three and six blades and looks similar to the wooden propeller found in boats. The blades are fixed and rotate around a central axis. Propeller flowmeters have a major advantage in the form of their fewer blades, which makes them more immune to damage from debris. They are also extremely low cost and do not require any electric supply to measure the flow rate.
- Woltman
Woltman meters are the first turbine flow meters invented and continue to be used widely in municipal and industrial water applications for the measurement of flow rates of large volumes of water. These meters deliver highly accurate readings as their axis is aligned in line with the direction of flow.
- Single Jet
Single Jet flowmeters consist of a set of blades set directly in the path of a stream or jet of water within a pipe. The stream or jet is created using an orifice. Such types of meters are mainly used for billing purposes in residential and commercial water supply operations.
- Multi-jet
Based on the same principle as Single Jet flowmeters, multi-jet flowmeters direct water from multiple orifices onto blades to make them rotate around a central axis. Multi-jet water meters are also used for residential and commercial water supply billing purposes.
- Compound
A Compound flow meter is a cross between a regular turbine flowmeter and a positive displacement meter. It has both a turbine and a positive displacement component. When the flow rate is high, it is measured using the rotation speed of the turbine. Low flow rate on the other hand is measured using the displacement component. These types of hybrid meters are widely used for measuring water flow rates in apartment buildings that have varying flow rates during the day and night.
- Axial
Axial flowmeters have a turbine or rotor that rotates around the axis of flow, hence the name. These meters are mainly used for measuring the flow of petroleum products, industrial liquids, and gases. Depending on the substance for which they are used, axial flow meters have different designs for liquids and gases.
