Article Courtesy of Pipeline and Gas Journal
By: Jay Rajagopalan, Senior Director of Engineering and Product Management for Malema, part of PSG, a Dover Company
Coriolis flow meters use vibrating flow tubes to directly measure mass flow rate, unaffected by changes in fluid properties.
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 article 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 the oil and gas industry.
How Coriolis Works
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.
The Coriolis meter can measurement with control valves for fast and repeatable closed-loop fluid control.
Benefits of Coriolis
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%), 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.
Versatility is another attribute exclusive to Coriolis flow meters. When it comes to lower-viscosity fluids, traditional flow meters tend to excel. But, if you put those same flow meters, which include paddle wheel, vortex, differential pressure and ultrasonic, in intricate applications where viscosities are higher or viscosity dynamically changes during the process, their limitations become obvious.
For example, accurate flow measurement and control of slurry dispense in semiconductor polishing and lapping tools are critical to guarantee high throughput, reduced consumption and consistent quality.
Diamond slurries are particularly difficult to measure due to their high viscosity, which can exceed 500 cP. Traditional flow meters, such as paddlewheel and vortex meters, are not equipped to handle higher viscosities. Because Coriolis flow meters are not impacted by varying viscosities, it makes them an ideal technology for this type of application.
Another benefit of Coriolis flow meters is the ability to tolerate fluids that contain entrapped gases or bubbles. This may be a particular concern with slurries or solutions containing hydrogen peroxide.
During measurement, Coriolis flow meters can handle fluids with up to 30% bubbles. Traditional flow meters are sensitive to the presence of entrapped gases, with ultrasonic models unable to operate past 5%-10% of entrapped gases. The inability to measure fluids with these entrapped gas volumes leads to a loss of measurement accuracy and control, directly impacting process efficiency.
Real-World Examples
While Coriolis flow meters use the same operational principle to achieve results, not all are constructed the same way. Malema, part of PSG®, a Dover company, fabricates its patented CPFM-8800 Series Coriolis Flow Meters from Perfluoroalkoxy (PFA) polymeric material.
Semiconductor manufacturing applications, among many others, require all PFA-wetted surfaces for proper functionality, accuracy and chemical compatibility. The CPFM-8800 Series Coriolis flow meters are comprised of two assemblies: one containing the sensor and the other supporting electronics. The combination provides highly accurate measurements ±1%) of mass flow rate, total mass, and temperature.
The flow meters feature a measurement range of 50 g/min to 4,000 g/min, a fluid temperature range of 64.4°F to 122°F (18°C to 50°C) and a maximum operating pressure of 80 psig (5.5 bar). It is ideal for highly corrosive chemicals, ultra-high-purity chemicals, water, slurries or solutions with solids or entrapped gases, and fluids with varying density or viscosity.
Conclusion
Flow meters are essential technology for measuring the flow of fluids, gases and vapors, superseding traditional versions of this technology in applications with varying viscosities and characteristics.
The Coriolis flow meter features a versatile principle allowing it to measure a wide range of fluids with high accuracy without performance setbacks. Its fluid measurement performance is independent of a fluid’s properties, eliminating the need for calibration when switching to different fluids.
Accuracy is also unaffected by flow variations, meaning the flow meter will still provide the same accuracy measurements under laminar or turbulent flow conditions.
Even entrapped gases (up to 30%) are unable to impact the performance of a Coriolis flow meter. The versatility and superior accuracy of this technology deliver unparalleled performance in an abundance of challenging applications across growing industries.
This article originally appeared in the August 2025 issue of Pipeline and Gas Journal.