Multipath Ultrasonic Meters
time ultrasonic flowmeters rely on ultrasonic transducers to send a signal
or “beam” at an angle from one side of a pipe to the other.
Often this signal is reflected back to the sending side of the pipe.
The flowmeter calculates flowrate by comparing difference between
the “transit time” of the signal when it travels with the flowstream
and when it travels against the flowstream.
about New Technology Flowmeters:
time ultrasonic flowmeters are distinguished according to the number of
“paths” they have. A path
is simply the path or track of the ultrasonic pulse as it travels across
the pipe and back again. Many
ultrasonic flowmeters are single or dual path, meaning that they send
either one or two signals across a pipe and back.
Typically there are two transducers for each path; one is a sender
and one is a receiver.
info on Transit
the past ten years, there has been a lot of research and development work
on multipath ultrasonic meters. Multipath
ultrasonic meters have three or more paths.
The benefit of having multiple paths is that flow is measured at
more points in the flowstream. This
enhances the accuracy of the measurement.
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.
main suppliers of ultrasonic flowmeters for custody transfer of natural gas
include Emerson Daniel, Elster-Instromet, Sick, and FMC Technologies.
More recently, KROHNE has also released the Altosonic V12, a 12
chord meter for custody transfer of gas applications.
Cameron, which has traditionally had petroleum liquid applications,
has released the LEFM 380Ci, an eight path ultrasonic meter for natural gas
ultrasonic multipath meters for custody transfer of natural gas have four,
five, or six paths. However, in
May 2011, Elster announced a new six-path ultrasonic gas meter that has six
paths and sixteen chords. The
additional number of chords enables the flowmeter to take into account flow
profile and turbulence, and provides additional diagnostic capabilities.
multipath flowmeters are also used to measure the custody transfer of
petroleum liquids. Two
companies that are prominent for these applications are Caldon (now a
division of Cameron) and Faure Herman (now a division of IDEX Corporation, faureherman.com).
Caldon used to have ultrasonic meters designed primarily for the nuclear
industry. However, in recent years, the company has expanded its
application range to include the oil and gas industry. Caldon has two-path,
four-path, and eight path meters for liquid applications. The company was
acquired by Cameron in January 2006. Caldon’s flowmeters are among the
most expensive ultrasonic meters made.
Herman, which is based in
France, is well known for its helical blade turbine flowmeters. However, it also
offers what it calls an 18-path ultrasonic flowmeter for custody transfer
of liquids. In addition to custody transfer, Faure Herman’s ultrasonic
flowmeter is designed for process applications. Faure Herman was acquired
by IDEX Corporation in February 2007.
is another company that has made its mark in custody transfer of liquids,
with its ALTOSONIC V and ALTOSONIC III offerings.
For further information, please see
www.FlowUltrasonic.com and www.UltrasonicFlows.com.