Omega Tube Design Extends the
Usability of Coriolis Technology in
Mass Flowmetering Applications
Presented by
John Daly
NA Sales Manager
Rheonik USA
ISA–The Instrumentation, Systems, and Automation Society
Introduction
The objective of this session is to introduce Omega Tube
Coriolis technology, comparing it to conventional Coriolis
technologies currently available and describe why
challenging and extreme flow applications can be solved
using it
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Topics Covered:
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Coriolis technology in general
Working principles and design goals
Engineering elements of the Omega Tube Design
Features of the Omega Design
Examples and solutions of challenging applications
ISA–The Instrumentation, Systems, and Automation Society
Overview
Coriolis Mass Flowmeters have been available
commercially for about 20 years
Over the past decade, they have been one of the
fastest growing flow measurement technologies.
Growth has been driven by a unique ability to
directly measure mass as well as many other
general advantages
ISA–The Instrumentation, Systems, and Automation Society
Why is Mass so Good?
1 kg
In the Mountains
=
1 kg
On the Beach
=
1 kg
Out in Space
For most critical measurements, mass or
normalized volume is of interest – volume alone is
insufficient for many applications
ISA–The Instrumentation, Systems, and Automation Society
Advantages of Coriolis Meters

No flow profile issues like those seen with turbine,
ultrasonic and other “velocity” measuring meters
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No effect from changing viscosity
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No effect from density
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Easy to install

No moving parts – essentially no wear
ISA–The Instrumentation, Systems, and Automation Society
Different Coriolis Designs
Coriolis meter technology is offered by around a dozen
suppliers, each having their own design. Here is a sample
of some of the different types:
Cantilevered
Triangles
Parallel
Straight Tube
S-Shaped
Tubes
Torsional Loops
All work using the same Coriolis Principle but different
designs are more suited to specific applications; i.e.
straight-through designs may be more suitable for hygienic
applications
ISA–The Instrumentation, Systems, and Automation Society
Coriolis Meter Operating Principle
M
v
w
F
M
F
v
w
=
=
=
=
Mass of moving element (liquid or gas) in pipe
Coriolis force
velocity of mass moving
rotation speed / angular velocity
F=2*M*v*w
ISA–The Instrumentation, Systems, and Automation Society
Operating Principle - continued
Measured time difference / phase shift (t) is
proportional to flow
ISA–The Instrumentation, Systems, and Automation Society
Meter Design Goals
No ideal design possible –
simplified considerations:
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Preferred Design Features
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Long easily bendable pipe system
Large distance between oscillation and excitation point
Thin wall tube to keep spring constant small
High energy excitation to create large oscillation amplitudes
Conflicting Factors
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Long pipes may create unacceptable pressure drop
High pressure, abrasive and/or corrosive media requires thick wall
tubing
High energy input may be conflict with hazardous area requirements
Excessive excitation may lead to fatigue failure in tubing
ISA–The Instrumentation, Systems, and Automation Society
Omega Tube Design
Offers Some
Solutions
1
2
1. Semi-circular Measurement
Tube
2. Carefully balanced oscillation
system consisting of rods and
cross bar counter weight
3
flow
3. Flow Supply Section
ISA–The Instrumentation, Systems, and Automation Society
De-coupled Measurement Section
measuring tube
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flow
cross bar
No deformation at
increasing pressures
De-coupled from the
Process Flow Supply
Section
ISA–The Instrumentation, Systems, and Automation Society
Independent Tunable Oscillation
System

torsion rod
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cross bar
Stable and highly
energized oscillation
Large amplitude / great
signal to noise ratio
Adaptable to different
tube sizes, thicknesses
and materials
ISA–The Instrumentation, Systems, and Automation Society
Bitumen – High Pressure and
Temperature
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Process Conditions
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3” Line Size
1350psi / 93 bar
680°F / 360°C
Hazardous Area
Hot, viscous liquid
Thick wall tubing required to meet
pressure rating. Without Omega Tube
torsion rod/cross bar system, it would
not be possible to provide sufficient
oscillation for reliable meter operation
ISA–The Instrumentation, Systems, and Automation Society
Large Volume Fuel Oil Custody
Transfer Flow

Process
Conditions
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12” Line Size
Heated to
improve flow
Extremely
viscous liquid
Turbine and PD meters not ideal due to
abrasive nature of fuel oil
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Ultrasonic meters not accurate enough
due to flow profile issues
ISA–The Instrumentation, Systems, and Automation Society
Gas Flow at Extremely High Pressure
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Process Conditions
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900 bar / 13,000psi
Turndown of 100:1 required
H2 dispensing for alternative
automobile fuelling requires
very accurate metering over
a wide range of flowrates
Omega Tube Design can accommodate thick wall tube
to meet pressure requirements while providing high
accuracy across a range of 0.25 kg/min to 50 kg/min
ISA–The Instrumentation, Systems, and Automation Society
Flow Measurement of Highly
Corrosive Materials
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Process Conditions
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3” Line Size
HCl Flow
Highly corrosive to
Stainless Steel and other
Alloys
The Omega Tube Design lends itself to variations in
material of tube construction. Because of the torsion
rod/mass weight design, tubes manufactured from
exotic materials such as Tantalum can be accomodated
without requiring meter redesign
ISA–The Instrumentation, Systems, and Automation Society
Cryogenic Gas Flow Measurement

Process Conditions
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-425°F / -253°C
H2 Gas
Omega Tube
Design Mass
Flowmeters are
resilient to
extremes of
temperature due to
remote electronic
mounting
ISA–The Instrumentation, Systems, and Automation Society
Summary
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The Omega Tube Coriolis Mass Flowmeter design differentiates
from others by its unique construction with torsion rods and cross
bar.
With these design elements, the meters operate with large
oscillation movements (providing measurement performance)
without putting undesirable bending stress on the tubing.
The design allows for the accommodation of exotic materials and
thick wall tube without compromising performance.
Extreme applications with temperatures from -250°C up to 400°C
and pressures up to 900 bar can be solved, as well as high
volume/throughput requirements up to 1500 t/hr.
ISA–The Instrumentation, Systems, and Automation Society
the Mass Flowmetering Experts
For more information on Omega Tube Coriolis
Mass Flowmeters, please come to the South Fork
Instruments Table
www.rheonik.com
ISA–The Instrumentation, Systems, and Automation Society