are two main types of ultrasonic flowmeters – transit-time and Doppler.
A transit-time ultrasonic flowmeter has both a sender and a
receiver. It sends two ultrasonic signals across a pipe at an angle – one
with the flow and one against the flow. The meter then measures the
“transit time” of each signal. When the ultrasonic signal travels with
the flow, it travels faster than when it travels against the flow. The
difference between the two transit times is proportional to flowrate.
info on Doppler meters:
technological improvements have been made in ultrasonic flowmeters over the
past 20 years. Because of improvements in electronic processing technology,
transit-time meters are better able to handle fluids that are not
completely clean. This has enabled transit-time flowmeters to 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 broader use of these meters in a wider variety of
about New Technology Flowmeters:
important technological improvement has been the development of multi-path
transit-time flowmeters, which use more than one ultrasonic signal or
“path” in calculating flowrate. 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
flowmeters have been particularly important in the use of transit-time
meters to measure natural gas flow. Suppliers
such as Daniel (www.daniel.com),
and FMC Energy Systems have introduced four-path, five-path, and six-path
transit-time meters, respectively, to measure natural gas flow. In June
1998, the American Gas Association (www.aga.org)
approved the use of multipath ultrasonic flowmeters for custody-transfer
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.
For further information, please see
www.FlowUltrasonic.com and www.UltrasonicFlows.com.