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The
World Market for Ultrasonic Flowmeters, 3rd Edition
(New
study, January 2008)
The
World Market for Ultrasonic Flowmeters, 2nd Edition
(2003)
- Provides historical perspective
The
World Market for Ultrasonic Flowmeters, 1st Edition
(2001) - Provides
historical perspective
There are
two main types of ultrasonic flowmeters: transit time and Doppler.
A transit time ultrasonic flowmeters 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.
Doppler
flowmeters also send an ultrasonic signal across a pipe.
Instead of tracking the time the signal takes to cross to the other
side, a Doppler flowmeter relies on having the signal deflected by
particles in the flowstream. These particles are traveling at the same speed as the flow.
As the signal passes through the stream, its frequency shifts in
proportion to the mean velocity of the fluid. A receiver detects the
reflected signal and measures its frequency. The meter calculates flow by
comparing the generated and detected frequencies. Doppler ultrasonic
flowmeters are used with dirty liquids or slurries.
They are not used to measure gas flow.
Ultrasonic
flowmeters were first introduced for industrial use in 1963 by Tokyo Keiki
(which later became Tokimec) in Japan.
Tokimec is located in Tokyo, Japan.
In 1972, Controlotron (Hauppauge, New York) became the first U.S.
manufacturer to market ultrasonic flowmeters in the United States.
In the late 1970s and early 1980s, both Panametrics (Waltham,
Massachusetts) and Ultraflux (Poissy Cedex, France) experimented with the
use of ultrasonic flowmeters to measure gas flow.
Initially, ultrasonic flowmeters were not well understood, and were
sometimes misapplied. Many
technological improvements have been made in the past 10 years, and the
limitations of ultrasonic meters are better understood.
Advances in transit time technology have broadened the types of
liquids that transit time flowmeters can be used on. Many transit time
meters today can handle liquids containing some impurities.
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