Ultrasonic flowmeters are relatively new to the market. They were first introduced for industrial use in 1963 by Tokyo Keiki in Japan.  In 1972, Controlotron became the first U.S. manufacturer to market ultrasonic flowmeters in the United States. In the late 1970s and early 1980s, both U.S.-based Panametrics (now GE Panametrics) and the French Ultraflux experimented with the use of ultrasonic flowmeters to measure gas flow. 

Initially, ultrasonic flowmeters were not well understood, and were sometimes misapplied.  It was not until the 1990s that ultrasonic flowmeters began to be widely used for industrial applications. 

Technological improvements expand use

Technological improvements over the last two decades have continued to expand ultrasonic meter use.

Advances in transit time technology in particular have broadened the types of liquids that can be measured. Improvements in electronic processing technology means many transit time meters today to handle liquids containing some impurities. Because of improvements in electronic processing technology, transit time meters are better able to handle fluids that are not completely clean. Transit time flowmeters can now be used for applications that could previously only be handled by Doppler flowmeters. These improvements have also increased the accuracy of ultrasonic meters, which has led to a broader use in a wider variety of conditions.

Transit time meters send two ultrasonic signals across a pipe at an angle and tracks the time the signal takes to cross to the other side. They are distinguished according to the number of “paths” they have. Multipath ultrasonic meters have three or more paths. By using more than one path, the flowmeter measures flow at more than one location in the flowstream, leading to greater accuracy. Some ultrasonic flowmeters now have up to 18 paths.

Doppler ultrasonic flowmeters also send an ultrasonic signal across a pipe but rely on measuring  frequency shifts caused by particles in the flowstream. Doppler ultrasonic flowmeters are used with dirty liquids or slurries. They are not used to measure gas flow. 

Meter of choice for custody transfer

In 1998, the American Gas Association (AGA) approved the use of ultrasonic flowmeters for custody transfer applications. Since that time, suppliers have researched multipath meters and brought out new products. 

Ultrasonic meters have become a top meter of choice for custody transfer of natural gas. Their large diameter makes them a natural choice for the large line sizes required for transporting natural gas over long distances, giving them an advantage over Coriolis meters.The high accuracy and reliability of the multipath ultrasonic meters used for this purpose gives them an advantage over the DP flow and turbine meters they compete against for this application.

Multipath flowmeters have been especially important for measuring natural gas flow. Suppliers such as Daniel (now an Emercon brand),  Elster (now Honeywell Elster) and TechnipFMC  have introduced four-path, five-path, and six-path transit time meters, respectively, to measure natural gas flow. The market for inline ultrasonic meters for custody transfer of natural gas is one of the fastest growing niches in the entire flowmeter market.

Learn more about New Technology Flowmeters:

Most manufacturers target liquid petroleum ultrasonic applications  Full-bore design is an important technical characteristic, as throughput is not diminished by obstructions in the liquid fluid flow. Inline ultrasonic flowmeters are certified for use in liquid custody transfer applications and now include features that minimize measurement uncertainty, reduce the potential for process downtime, and are able to identify upstream blockages or abnormal flow profiles in real time.
These features are very beneficial to efficient and economical petroleum liquids production 

Caldon (now part of Schlumberger/Cameron) and KROHNE have introduced ultrasonic flowmeters for custody transfer of petroleum liquids.

Check metering

Another important application for ultrasonic flowmeters is check metering -- verifying another flowmeter's readings. Some clamp-on meters are used for this purpose since they can be conveniently moved from one meter to another. (Clamp-on technology is unique to ultrasonic meters.) Inline ultrasonic flowmeters are also used for check metering.

For further information on ultrasonic flowmeters, including our detailed market reports, please see www.flowultrasonic.com.