Going with (and accurately measuring) the flow: Part 1 of 2
Our modern way of life, punctuated by everyday conveniences like taking a shower or fueling a car, is underpinned by a silent army of technologies often taken for granted. Without these innovations, simple tasks and essential functions would revert to cumbersome and inefficient methods. Fortunately, a sophisticated infrastructure of pumps, pipes and processing equipment diligently transports vital fluids—water, chemicals and fuels—across the globe.
Within this network of technological marvels lies a crucial component ensuring the safe and accurate movement of these fluids: flow meters. These devices are specifically designed to quantify the flow rate of fluids—whether liquids, gases, or vapors—as they traverse pipelines, providing operators with essential, real-time data.
However, while flow meters perform this indispensable function, traditional technologies often present limitations. Some flow meters struggle to maintain accuracy when faced with fluctuations in a fluid’s handling characteristics, such as temperature, density and viscosity. These variations can lead to unreliable flow measurements, potentially compromising the integrity of the entire fluid-handling operation. Furthermore, the necessity for frequent calibration in other flow meter designs can result in significant and costly periods of operational downtime.
Addressing these inherent challenges is the Coriolis flow meter. This advanced technology delivers all the fundamental benefits of flow measurement while effectively mitigating the limitations of conventional designs. Its unique design and operational principle enable it to accurately measure a diverse range of fluids across numerous applications without compromising performance or requiring frequent recalibration.
This two-part series will delve into the intricacies of Coriolis flow meter technology, offering a comprehensive understanding of its functionality and an explanation of why it is exceptionally well-suited for demanding process and manufacturing environments within industries such as chemical, pharmaceutical, semiconductor, and oil and gas, among others.
HOW CORIOLIS FLOW METERS WORK
The name of the Coriolis flow meter originates from French engineer and mathematician Gaspard-Gustave de Coriolis, who discovered the concept of Coriolis force, the effect of motion on a rotating body. An example is the Coriolis effect, which states that any moving body on or above the earth’s surface, such as an ocean or air current, will tend to drift sideways from its course because of the earth’s rotation. This discovery played a key role in oceanography, meteorology and ballistics, and was later used as a primary element in measuring a substance’s mass flow rate.
The Coriolis flow meter directly measures mass flow rate by harnessing the principles of physics within its intricate design. Typically, a magnetic exciter induces oscillations in one or more flow tubes. In the absence of flow, these tubes vibrate uniformly, with the inlet and outlet oscillating in perfect synchronization (in phase). However, as fluid begins to flow, the Coriolis force comes into play. This force acts on the fluid, causing it to accelerate as it moves toward the point of maximum vibration and decelerate as it moves away, resulting in a subtle twisting of the flow tube(s). Highly sensitive sensors strategically positioned at the inlet and outlet precisely track this minute motion and quantify the phase difference between the oscillations at these two points. Crucially, the magnitude of this phase shift exhibits a direct and linear relationship with the mass flow rate of the fluid; a greater phase difference unequivocally signifies a higher mass flow rate. This elegant measurement directly yields the mass flow rate, a fundamental parameter in many industrial processes.
Other Coriolis flow meters follow a similar configuration. Fluid flows into the sensor, consisting of two flow-sensitive elements that are vibrated relative to one another, like the tines of a tuning fork. Fluid interacts with the sensor dynamically in such a way that the sensor’s response is immune to the fluid’s chemical and physical properties, flow regime, or variations in the flow-velocity profile. Fluid mass flow rate is determined by measuring the relative motion and frequency of the flow-sensitive elements.
BENEFITS OF CORIOLIS FLOW METERS
Coriolis flow meters offer several benefits compared to other types of flow meters thanks to its operating framework. One key advantage is accuracy. Coriolis flow meters provide the highest available measurement and control accuracy (±1 percent), thus ensuring the integrity and quality of a product batch, uptime and yield throughput.
Additionally, the accuracy of Coriolis flow meters is unaffected by changes in fluid characteristics, such as density, viscosity and temperature. Other flow meters can often struggle with fluctuations, leading to inaccurate measurements and, ultimately, batch inconsistency.
Another problem with non-Coriolis flow meters is calibration requirements. With Coriolis flow meters, frequent calibration is not necessary because fluid dynamics do not impact their accuracy. However, non-Coriolis flow meters are susceptible to accuracy drops depending on fluid conditions. To counteract this, operators must calibrate their flow meters when handling different fluids. If a variety of fluids are to be measured at different times, frequent calibration will take the flow meter offline constantly, leading to costly, compounding downtime.
A LOOK AHEAD
In next month’s conclusion to this series, we’ll take a closer look at the versatility of Coriolis flow meters. Then we’ll explore a number of real-world examples illustrating their benefits in the field, including Malema’s own CPFM-8800 Flow Meter family and the CMFC-5000 and CMFC-6000 Series of flow controllers.
Jay Rajagopalan is the senior director of engineering and product management for Malema, Boca Raton, Florida, and can be reached at jay.rajagopalan@psgdover.com. Malema is a product brand of PSG, a Dover company. PSG is the global pump, metering and dispensing-solution expert, enabling the safe and efficient transfer of critical and valuable fluids that require optimal performance and reliability in applications where it matters most. Additionally, PSG is a leading provider of flow meters designed to reduce waste and downtime while accurately measuring, monitoring and controlling the distribution of fluids. Headquartered in Downers Grove, Illinois, PSG is comprised of several world-class brands, including Abaque, All-Flo, Almatec, Blackmer, Cryo-Mach, Ebsray, em-tec, Griswold, Hydro, ipp, Malema, Mouvex, Neptune, PSG Biotech, Quantex, Quattroflow and Wilden. PSG products are manufactured on three continents—North America, Europe and Asia—in state-of-the-art facilities that practice lean manufacturing and are ISO-certified. PSG is part of the Pumps & Process Solutions segment of Dover Corporation. For more information, visit www.psgdover.com.
