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FLOW & LEVEL CONTROL
Titan Enterprises explains the working principles of the Pelton Wheel and other Turbine Flow Meters
urbine flow design has changed little since their invention in the eighteenth and nineteenth centuries due to the simplicity and power of these devices to extract energy from the movement of a flowing water source. Turbine flow meters are one of the most commonly used and simplest methods of measuring liquid flow, from water and beer to aggressive chemicals, including ultra-pure water. The variety of turbine flowmeters are based on the mechanics – the physical orientation of the turbine in relation to the fluid flow. They work in two primary ways: 1. Analogous to a propellor or windmill – Axial
T A JOURNEY INTO FLOWMETERS turbine 2. Analogous to a water wheel – Radial turbine Turbine flowmeters measure the flow rate of
a fluid within a pipe or process line by utilising a rotor or turbine that rotates on an axis as the fluid moves across its blades. As the turbine rotates, each blade of the turbine passes a sensor which outputs a pulse signal. The speed at which the turbine rotates is directly proportional to the volumetric flow rate and the number of pulses the total volume passed. In an axial turbine, the fluid flows along the rotation axis where the fluid enters and exits in
the same direction, the fluid striking the angled turbine blades. In contrast, fluid flowing through a radial turbine strikes the plain blade in the direction of the tangent or 90° to the rotational axis (hence also referred to as tangential flow). Titan Enterprises released its first flowmeter sensor in 1981, a turbine device based on the Pelton Wheel design and working principles of the radial turbine. Titan’s mini turbine flowmeter range uses the
radial flow principle based on the Pelton wheel technique. This well proven method is the ideal way of measuring low rates of flow of low viscosity liquids. For these mini flowmeters, a jet of fluid is directed at a turbine that is mounted on robust low friction sapphire spindle and bearings. The geometry of the turbine and the fluid chamber ensures that the rotational speed of the rotor is proportional to the flow
NON-INTRUSIVE METHOD IS PRECISE AND VERSATILE I
n the ever-evolving landscape of industrial operations, the need for accurate, reliable, and cost-effective flow measurement is paramount. One innovative solution gaining traction is the use of portable clamp-on ultrasonic flow meters, either as rental devices or as part of a comprehensive flow check service provided by skilled engineers. Attached to the outside of the pipe, these devices do not require any process interruption, making them ideal for temporary measurements or troubleshooting. By using ultrasonic waves to measure the flow of liquids through pipes, these meters offer a non-intrusive method that is both precise and versatile. The rental model for clamp-on ultrasonic flow meters presents a compelling proposition for industries that need periodic flow measurement, but cannot justify the expense of permanent installations. Renting allows companies to access advanced technology without significant financial investment, enabling them to conduct short-term projects or emergency diagnostics with minimal disruption and cost. Many service providers now offer a flow check service, where trained engineers bring portable clamp-on ultrasonic flow meters to the site. This service model combines the technological advantages of ultrasonic flow meters with the expertise of seasoned professionals. Engineers can not only perform accurate flow measurements, but also provide comprehensive analyses and actionable insights based on their findings. This integrated approach ensures that potential issues are identified early, and performance optimisation recommendations are grounded in real-world data. Emerson manufactures and supplies what is said to be the world’s only ATEX certified portable flow meter for use on sites with hazardous areas and flammable gases.
www.emerson.com
34 OCTOBER 2024 | PROCESS & CONTROL
rate through the device. The use of this radial arrangement allows more energy to be imparted into the turbine, so the bearing drag is far less important. Furthermore, because more energy is available the bearings themselves can be a lot stronger, increasing the life of the flowmeter. For larger flows, some of the liquid can bypass the turbine chamber, which then behaves as a “shunt” to the metered fluid. Accuracy is still maintained and the output remains linear. Axial flow turbines are typically larger and have a higher flow throughput. Generally more efficient at moving large volumes of air or fluid at lower pressures, they are more suitable for large-scale, high-speed applications where high flow rates and low pressure drops are of prime importance. As such conventional axial turbines are commonly used in thermal power plants, wind turbines, and HVAC systems. Complex designs, manufacture and maintenance of axial turbines can be costly and challenging, becoming increasingly difficult to manufacture as size is reduced and bearing drag becomes more significant. On the other hand, radial turbine flowmeters are better suited for applications requiring low flow rates, typically seen in medical applications and laboratory work. The one disadvantage of the turbine
flowmeter is it’s very sensitive to changes in liquid Reynolds Number; a product of viscosity and density, therefore temperature and, for gas fluids, pressure. To mitigate this, Titan use a hexagon-shaped chamber which permits the formation of vortices that reduce the drag and assist the linearity into the laminar flow region. Titan’s range of turbine flow meters offers numerous advantages, including: • Low cost compared to other flow measuring technologies
• Fast response time with high repeatability • Easy to install and maintain • Provide direct volumetric flow.
Titan Enterprises
flowmeters.co.uk/turbine-flow-meters/
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