The market for ultrasonic flowmeters totaled $632 million in 2011 and is projected to grow at a compound annual growth rate of 9.6 percent through 2016, according to a report by Flow Research. Growth in this market is being driven by the use of ultrasonic flowmeters for custody-transfer applications and the resulting product development of multipath meters. Inline ultrasonic flowmeters account for two-thirds of revenues, with the remainder divided between clamp-on and insertion meters.  In addition to gas flow, ultrasonic flowmeters are used to measure the flow of petroleum and non-petroleum liquids.
Flow Research says flowmeter manufacturers are focusing a great deal of attention on ultrasonic flowmeters, as suppliers have made significant progress in enhancing the accuracy and reliability of the technology. This has mainly been done by increasing the number of paths, thereby increasing the number of measurement points, and also by adding greater diagnostic capability. The enhanced diagnostic capability can reduce the need for upstream piping, as well as increase the ability of the ultrasonic meter to determine sources of error. Recently, Flow Research says new and more accurate meters have been developed for custody transfer of petroleum liquids, as well as for custody transfer of natural gas.
Ultrasonic flowmeters are also being more widely used to measure process gas and flare gas, notes Flow Research. The use of wetted sensors provides greater accuracy, and insertion meters are used to measure flare gas in stacks, and ultrasonic flowmeters are used more widely in the chemical and refining industries. 

VIDEO: How Transit-Time Ultrasonic Flowmeters Work

While the growth of ultrasonic meters to measure process and flare gases is not as rapid as is the growth of multipath meters for custody transfer of natural gas, Flow Researchs says process and flare measurement are an important factor in the overall growth of ultrasonic meters.
The development of multipath transit time flowmeters, which use more than one ultrasonic signal or “path” in calculating flowrate, has been important for ultrasonic flowmeters. Each path requires a pair of sending and receiving transducers.  By using more than one path, the flowmeter measures flow at more than one location in the flowstream, leading to greater accuracy.  Multipath flowmeters have been especially important in the use of transit-time meters to measure natural gas flow.  In June 1998, the American Gas Association approved the use of multipath ultrasonic flowmeters for custody transfer of natural gas applications.  Since that time, there has been a substantial increase in the use of these meters for natural gas measurement, especially for custody transfer.
Flow Research has released a series of three studies on the worldwide ultrasonic flowmeter market.  The series is called The World Market for Ultrasonic Flowmeters, 4th Edition. One study focuses on inline meters, while the second study includes both clamp-on and insertion meters.  The third study provides data on the entire ultrasonic flowmeter market, including market size, forecasts, and market shares.

For more on Flow Research's work in the area of Ultrasonic Flow Measurement, see