Coriolis compared to turbine, pd and USM.pdf

Coriolis Meter Comparison

1. Operation of Coriolis Meter /
Advantageous over other
meter technologies

2. www.rheonik.com –the mass flowmeter experts
The popular Metering technologies –
particular for custody transfer
■PD Meters ( Positive Displacement)
■Turbine Meters
■CMFM (Coriolis Mass Flowmeter)
■USFM (Ultrasonic Flowmeter)
■Ultrasonic and Coriolis are the fastest growing technologies.
We will soon see why and then have a close look at them.
■There is no best technology for all applications. The suitability in
terms of cost, accuracy and provability needs to be considered case
by case.

3. www.rheonik.com –the mass flowmeter experts
The PD Meter
■Very popular from 1- 4 inch
■Capable of producing results of 0.1 to 0.3% accuracy if well
applied and maintained.

4. www.rheonik.com –the mass flowmeter experts
Series 2 DN 80 to 300
The Turbine Meter
■Very popular, particularly for bigger sizes 4 to 16 inch
(bigger sizes available)
■Capable of producing results of 0.1 to 0.3% accuracy if well
applied and maintained.

5. www.rheonik.com –the mass flowmeter experts
The Coriolis Mass Flowmeter (CMFM)
■Different makers offer a wide range of models. All measure a phase shift
generated by an oscillating pipe system and flow going through. Fundamental
difference beside the operating principle is the direct measurement of mass.
■Increasing use (worldwide by nearly 10% p.a.). More and more popular due
to its reliability.
■Capable of producing results of 0.1 to 0.3% accuracy at varying conditions.

6. www.rheonik.com –the mass flowmeter experts
The Ultrasonic Flowmeter (USFM)
■There are different types of ultrasonic
meters. They are based on the Doppler
principle or on the Transit Time principle.
For custody transfer you would only use
the Transit Time based system, spool
piece type.
■The ultrasonic meter primarily measures
the velocity of the flow and outputs
volume. The faster the flow the big the
run time difference tDN to tUP which is
measured.
■Becomes more and more popular on
larger sizes – typically 6 to 16 inch
(larger possible).
■Capable of producing results of 0.15 to
0.3% accuracy if well applied.
Multibeam
USFM

7. www.rheonik.com –the mass flowmeter experts
■Beside a Total Cost of Ownership it is important to consider the sensibility of
the technology to "external" effects like:
Installation
conditions /
flow profile
Wear and
need for re-
calibration
Provability
on site
flow profile very
viscous media
flow profile low
viscous media
larger changes of velocity
over the diameter
flater distribution of
velocities over diameter
Changes in the fluid regarding
density & viscosity
More than a datasheet is need to select a
technology!

8. www.rheonik.com –the mass flowmeter experts
+ + + (not sensitive)
+ + (sensitivity possible)
+ (sensitive – care needs to be taken)
PD Meter
Turbine Meter
Coriolis Meter
Ultrasonic
Meters
Installation Conditions / Flow profile
very insensitive to installation – shuffling of defined
volume does not need special conditioning
flow profile and straight run needs to be considered with
care – low Reynolds Numbers and asymmetries in flow
profile disturb
very tolerable to various installation conditions, no straight
run requirements, however firm and robust mounting
required to avoid heavy tensions/vibration from inlet and
out piping
similar to turbine meter – flow profile sensitive. If not
compensated with multiple beams and corresponding
software, even more sensitive than turbine
+++
+
++
+

9. www.rheonik.com –the mass flowmeter experts
+ + + (not sensitive)
+ + (sensitivity possible)
+ (sensitive – care needs to be taken)
PD Meter
Turbine Meter
Coriolis Meter
Ultrasonic
Meters
Fluid Conditions / Changes of fluids at
metering point
very insensitive to installation – shuffling of defined
volume does not need special conditioning
sensitive, particularly to high viscosities – limited
compensation by special constructions possible
very tolerable to various conditions, no influence of
viscosity and density
similar to turbine meter – flow profile sensitive. If not
compensated with multiple beams and corresponding
software, even more sensitive than turbine
+++
+
+++
+

10. www.rheonik.com –the mass flowmeter experts
+ + + (not sensitive)
+ + (sensitivity possible)
+ (sensitive – care needs to be taken)
PD Meter
Turbine Meter
Coriolis Meter
Ultrasonic
Meters
Maintenance and Wear
seal surface can suffered in case of non- clean liquid–
shuffled volume may change
rotating parts and baring may suffer from severe
application conditions
no moving parts – no wear
no moving parts – no wear
+
+
+++
++

11. www.rheonik.com –the mass flowmeter experts
+ + + (offers all)
+ + (offers some benefits)
+ (offers no additional benefits)
PD Meter
Turbine Meter
Coriolis Meter
Ultrasonic
Meters
Self diagnostics, pro-active maintenance
and multi variable information
basically none
basically none
measures additionally the density, analysis functions
available
measures additionally the sound velocity, analysis
functions available+
+
+++
+++

12. www.rheonik.com –the mass flowmeter experts
■In particular those advance functions and the friendliness towards
maintenance (at similar accuracy) made the Coriolis and Ultrasonic
the fastest growing flow technology. A closer look to them in the
flowing charts:

13. www.rheonik.com –the mass flowmeter experts
The USFM measures basically a medium flow velocity in the pipe along the beam. By
multiplication with the known square area of the pipe the volume flow can be computed.
A closer look to the Ultrasonic Flowmeter
(USFM) and its operating principle
(t
up – t
dn)
t
up * t
dn
A * L
2 * cosΘ
(t
up – t
dn)
t
up * t
dn
*
* Geometry Factor = K
Q = K
Reality however is more sophisticated since the K factor depends on flow itself,
viscosity and symmetry of the flow profile.
Q volume flow L length of beam path
K calibration factor D diameter of pipe
A square area of pipe Θ Angle between pipe axis and beam

14. www.rheonik.com –the mass flowmeter experts
Q = v
a A
v
a= 1/D * v(x) dx
D = Pipe Diameter
v(x) = velocity at position x
v(x) depends on:
- symmetry of flow profile
- position in pipe
- Reynolds Number, hence viscosity and flow rate
∫
–D/2
D/2
■Average velocity V
a over the whole pipe
area is needed and it is a major challenge
to derive the average velocity by the time
measurement

15. www.rheonik.com –the mass flowmeter experts
Consequently it is essential that:
–a fully developed and symmetrical flow profile is available (to make it predictable and
computable) multi beam configuration (different planes) with powerful compensation
computer is in place
–(to precisely calculate the none constant K factor for changing flow profiles).
Flow Profile compensation over Reynolds
Number for a diametrical beam
Flow Profile may change significantly on
some applications
Reynolds number (Re) defines the profile
shape (assuming enough straight run, no
swirls)
Re =
(Hence a change in viscosity from 1 to
200 cSt will change the Reynolds Number
by factor 200)
v * D
kin. visc.

16. www.rheonik.com –the mass flowmeter experts
Important consideration when applying
Ultrasonic Meters
■Straight Run – undisturbed flow profile
■Multi Beams through different planes needed to compute correct
compensation factors
■Changes in viscosity / Reynolds Number is a challenge for the
meter
■Measured volume needs to be further corrected by temperature
and pressure to have it normalized to standard conditions for
custody transfer (V15, V60)

17. www.rheonik.com –the mass flowmeter experts
Most suitable applications for Ultrasonic
Flowmeters
■Installation places which offer good possibilities for flow profile
conditioning (straight run)
■Application with very high throughput (ultrasonic becomes more
cost effective on large sizes)
■Stable flow profile i.e.
–single light liquid
–no significant changes in viscosity
–gas applications as naturally very high Reynolds Number
■Availability of additional instrumentation / computers to perform
volume corrections to standards