UltrasonicFlow Meters:

Maintaining Performance in
Unstable Conditions

More than 40 years after work began to develop ultrasonicflow meters to measure the movement of liquids throughpipelines, the technology is being steadily more utilized.
The technology’s wide range of applicability is expected
to further drive its adoption in the growing chemical andpetrochemical industries as well as water and wastewater
treatment sectors.
Growth across multiple industries is fueling the need foraccuracy and reliability in measuring volumes of transported
liquids. But the variability in product composition, viscosity,and pipelines present puzzles in finding the right technology.
Difficulties in measuring crude petroleum products, inparticular, are not new. When research began on applicationof ultrasonic flow technology for that task, the challenge wasgaining the necessary acoustic resistance between pipeline
product and ultrasonic transducers. This obstacle wassurmounted when technology pioneers acoustically coupled
ultrasonic transducers to various liquids. The impact wasgroundbreaking.
“That invention,” Panametrics engineers wrote in a2005 paper, “was the cornerstone of ultrasonic flow
measurement....”
Other long relied upon measurement technologies posean array of difficulties amid the rigors of pipeline operation.
Turbine meters cause extra pipe line pressure drops requiring
compressors to restore it. This results in increased operatingcost. Rotors and bearings for turbine meters periodicallymust be replaced, making the meters vulnerable as thoseparts break down. Grit and other contaminants in liquids
contribute to reduced accuracy.
Coriolis meters offer advantages over turbine meters. The
devices are accurate and low-maintenance, with no internalmoving parts. But the cons are significant. Relying on asensor, transmitter, and bent tubes, the technology causespressure drops, is expensive, and unwieldy on lines larger
than 4 inches in diameter, and it is challenged under low
density conditions. More than three-fourths of Coriolis meters

are used on pipelines 2 inches in diameter or smaller.
Turbine and Coriolis metering technologies cannot meet thecurrent demand with 239 active petroleum pipeline projects
being tracked by the U.S. Energy Information Administration,
which will transport record production in the United States.
Laterals running from mainlines are made at diameters of
6 to 16 inches. Major interstate pipelines typically reach 48
inches with liquids flowing through at high pressure.

Rugged meters delivering thehighest standards in accuracy
are required for the essential jobof measuring, and ultrasonic flow
technology has a demonstrated
record of meeting the need.
How Ultrasonic Meters WorkUltrasonic flow meter technology, based on transit timemeasurement, tracks the time elapsed for ultrasonic pulses
traveling a fixed distance between ultrasonic transducers.
Mounted through valves into the pipeline, the transducers
acoustically communicate with one another, meaning each
receives ultrasonic signals transmitted by the other in thepair. Multipath ultrasonic flow meters increase accuracy
by measuring the paths of multiple pulses simultaneously.
A path refers to the track of an ultrasonic pulse as it
travels back and forth across a pipe. Multipath ultrasonicflow meters feature three or more paths. This allows formeasurement at more points in the flowstream, which boosts
accuracy.

The time between the transmission and reception of pulses
to and by the transducers is measured in both directions.
If no liquid is flowing, the transit times in either direction isequal. If liquid is flowing, transit times in the direction of flow
will be less than transit times in the opposite direction. The
difference is proportional to the velocity of the flow.
Measuring high viscosity products with lighter hydrocarbons
is difficult, but lower frequency transducers in ultrasonicmeters can allow sound to travel through more readily.
Meters equipped with powerful, high-speed electronics
churning out reams of diagnostic data can ensure problems
are identified earlier, resulting in maximum uptime andminimal maintenance.
While delivering high accuracy and high data volume,
ultrasonic meters also deliver on the bottom line.
The devices have no moving parts and fewer limitations thanother meters. Concerns common in other technologies areeliminated, including drifting, pressure drop, pipe restrictions,and meter maintenance. A single ultrasonic meter canmeasure flow through a large pipe. Other technologies
require a metering station with numerous differential
pressure meters to handle high flow in large lines.
Relying on the strength of their technology and the quality of
their design and manufacture, ultrasonic meters handle highdemand as well as the need for greater overall efficiency.

Validating Ultrasonic Meters
In 2005, Panametrics’ Mike Scelzo, Steve Milford, Nick Mollo,
and Jed Matson wrote: “Use of ultrasonic flow meters willcontinue to grow as users continue to become familiar withthe technology and achieve success with its use.”Those words have proved true over the last 15 years as
ultrasonic flow meters have emerged among the fastestgrowing technologies for pipeline applications.

Meters should demonstrate the followingattributes:

aAccuracy: The flow measurement provided bya meter can only be trusted if the meter can be
successfully calibrated against a known reference.
How closely the calibrated meter matches thereference is the accuracy of the meter. Ultrasonic flow
meters with properly designed path configurations canmeet the stringent accuracy requirements of custodytransfer applications.

aRepeatability: The flow rate measurement must

not only be accurate, but it must also be stable. Proper
ultrasonic signal processing and modern electronics
yield readings in very rapid succession that areconsistent with the behavior of the fluid. If the fluid
properties are stable, users can be sure the reported
flow rate will also be stable and repeatable over time
under the same conditions.

aTurn-down Ratio: The range of flow rates and fluid
properties of many applications can be considerably
broad. Petroleum products flow through a single
pipeline can shift from heavy, viscous crude oil one
day to low viscosity refined product the next. A highturn-down ratio means a single meter can accurately
and repeatably measure large swings not only in
velocity, the traditional meaning of the term, but also awide range of Reynolds number.

Custody Transfer
Powered partly by spikes in oil and gas production in theUnited States’ shale basins in 2019, more than 32,000 milesof pipeline were planned or under construction in North
America at the start of this year, according to UndergroundConstruction magazine. “[I]t’s a pretty good time to be apipeliner,” the magazine’s Jeff Awalt wrote.
Behind the trends, the work of extracting and moving
resources is more daunting than ever, requiring transmission
over vast expanses, varied terrain, and in vastly differing
climatic conditions to get products to buyers.
Large terminals and refineries wait at the ends of the lines.
But simply getting products to those places is not enough.
Accurately measuring the amount of the product being
moved is both difficult and essential.
Oil pumped from the earth varies widely in viscosity, fromlight crude at API gravity of 31 to heavy crude at API of lessthan 10. It’s not just the ability to handle varying viscositythat matters. Pressure, temperature, flow rate and range,
fluid composition, quality, accuracy, and redundancy all are
critical considerations in finding the right meters.
Other technologies suffer under scrutiny for these attributes.
Turbine meters with their various moving parts have been
known to fail when faced with wide fluctuations in pressure,temperature, flow, and fluid composition and quality. Coriolis
meters are impractical for large pipes.
Getting accurate measures as products are moved tocustomers is based on calibration and verification at thepoint of custody transfer. A variation of even tenths of apercent can translate to significant financial gains or losseson either side.

Ultrasonic metering at terminus
points assures spot-on accuracy
and consistent reliability in custodytransfers.
The absence of moving parts means the meters do notdegrade mechanically, providing a durable performancebase that gives peace of mind to companies and customers
alike.

Remote Flow Detection
The stakes are high for pipeline operators. When meters failto deliver accurate measurements, they can trigger false
alarms that send expenses needlessly soaring. Or they canfail to detect leaks, however small. Accurate measures are
critical with revenue, the environment, and reputations allon the line. Add to all this the varying conditions inherent inpipelines.
When multipath ultrasonic flow meters are employed,operators get better visibility into their pipelines and more
information for decision-making, which reduces risks. Inaddition, multiple measurement paths can cancel the effectsof swirl (provided the paths are orthogonal to one other)and other flow disturbances resulting from viscosity change.
Even in the face of poorly developed changing flow profiles,
without flow conditioners, measurements can be accurate.

Using the right algorithms, ultrasonic flow meters do not
require recalibration when fluids change, maintaining strong,reliable, accurate performance throughout.
Beyond accuracy, ultrasonic meters work faster, expediting
the process of monitoring and analysis. That lowers
downtime for yield management and asset protection. When
there are problems, the meters provide valuable information
to allow operators to act swiftly and decisively.
Sweeping technological improvements since Panametrics
revolutionized ultrasonic flow has propelled the meters pastcompetitors to the forefront of the market. Their accuracy,reliability, versatility, efficiency, and adaptability make themthe smart buy for anyone seeking the highest standards inmeasurement.
But the strength of the concept must, as in any case, beequaled by the quality of the company producing them.
When those two factors match, decision-makers know they
are on the path to the right call when deciding where toinvest money in measurement technology.

Copyright 2023 Baker Hughes Company. This material contains one or more registeredtrademarks of Baker Hughes Company and its subsidiaries in one or more countries. All
third-party product and company names are trademarks of their respective holders.
BHYM0820

About Panametrics
Panametrics, a Baker Hughes business, has been a pioneerin the sensor technology industry for more than 50 years.
With an innovative culture, we continue to develop solutions
for moisture, oxygen, liquid flow, and gas flow measurement.
Our proven technologies are widely known across manyindustries including, oil & gas.
Our Sentinel line of high-accuracy ultrasonic flow meters
deliver custody transfer-level measurement, easy
integration, rugged construction, and reliable performance– even in the unstable conditions of typical pipelines. To
learn more about our Sentinel high-accuracy ultrasonic flow
meters visit:https://www.bakerhughes.com/panametrics/flow-meters/
custody-transfer-allocation-leak-detection

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