// Medidor MÁsico

The World’s Largest Range of Mass Flowmeters

Coriolis Force and the Rheonik Range


The Coriolis effect was discovered by physicist Gustave Gaspard Coriolis during the 1830’s, and is described as “the inertial force exerted on an object as a result of movement relative to a rotating frame of reference.” This science has been applied to many
technologies: hydraulics, machine performance, missiles, ergonomics, ocean and atmospheric circulation and, of course, mass flow metering.
The use of the Coriolis effect as a technique for liquid and gas mass flow measurement was firmly established over 20 years ago. Since then, a number of different designs have been produced. With the tremendous electronic signal processing technology advances that have been made, Coriolis mass flowmeters have become highly accurate and reliable instruments.
Rheonik remain at the forefront of this technology and now produce the world’s largest and most comprehensive range of meters. Only the Rheonik range has all of the following features:-

At the factory and in regional offices, Rheonik maintains a team of expert application and service engineers, offering best fit technology identification and specification all the way through to on-site commissioning and in-depth application troubleshooting and resolution. A factory trained sales and service network provides local service and support worldwide.
The Rheonik range with its unique Omega tube design allows the most challenging mass flow metering applications to be solved. The Omega tube has a torsional oscillation movement rather than the bending motion associated with other, more conventional Coriolis meter designs. The unique mechanical arrangement of the Omega tube meter allows the use of tubing with heavier wall thickness giving higher pressure ratings, combating abrasion and erosion and eliminating the requirement for the secondary pressure containment found with conventional designs.

· Liquid, sludge and gas measurement capability
· Models to measure flow rates from as low as 0.03 kg/h up to 1,500,000 kg/h (0.07 lb/h to 3,300,000 lb/h)
· Sizes up to 12” / DN300
· Pressure ratings up to 900bar / 13,050psig
· Temperature ratings from -255°C to +400°C / -425°F to +750°F
· Fiscal/custody transfer approvals (OIML R117 / NTEP)
· ATEX and CSA hazardous area approvals covering most of the world
· Extreme resistance to gas bubbles entrained in the process stream when compared to conventional Coriolis meters
· Unaffected by viscosity, density or pressure changes
· Multifunction measurement capability includes density and temperature
· Available with stainless steel, hastelloy, monel and tantalum wetted materials as standard. Other materials on request

Coriolis in action at an olive oil canning factory Highly accurate truck filling station with
RHM 60 FNT for custody transfer

Operating Principle

The flexibility of the Rheonik range in terms of applicability and accuracy is due to the patented mechanical arrangement of each meter. Each flowmeter has two
measuring tubes parallel to one another and formed into the unique Omega shape, oscillating in opposing directions.
The oscillating system is driven with two high mass cross bars mounted on vertical torsion rods:-
i) The high mass cross bars stabilize the torsional movement, either eliminating or greatly reducing interference from external vibration and providing continued, reliable operation with the presence of oscillation dampening factors such as entrained gas
bubbles or non-homogeneity in the process stream.
ii) The torsion rods minimize stress on the tubing, guide tube movement and help “energize” the torsional motion.
This rugged mechanical arrangement is energy conserving and requires very little power input (typically less than 300mW) to maintain oscillation amplitude.
The design provides for an exceptionally well balanced mechanism that approaches perpetual motion once energized, with a natural frequency that is tuned by
the mass of the cross bars and the elasticity of the torsion rods.
Amplitude is controlled by a pair of electromagnetic coils mounted at each side of the Omega tubes. The whole mechanism is symmetrical, ensuring that internal
acceleration forces from the measured process are counterbalanced. Whenever mass (either liquid or gas) flows through the oscillating Omega shaped tubes,
a Coriolis force is generated, causing a “bending” or “deflection” in the top of the tubes. This deflection is sensed as a phase shift between two electronic pick
ups mounted on the tubes. The degree of phase shift is directly proportional to the mass flowing within the tubes.
This can perhaps be better understood by imagining that the oscillation of the meter measuring tubes (the upper semi-circle of the Omega tubes) is taking place
on an imaginary disc with points “a” and “b” on the circumference of the disc. Process material, starting at point “a” and moving across the imaginary disc to point “b” (the path of “effective massflow”) will pass through a range of differing velocities along the way.
The Coriolis force (“FC”) generated from the oscillations of the disc and the effective mass flow vector is perpendicular to the movement of the mass across the disc and is proportional to the mass flow. In the meter, this force causes the deflection that is sensed by the two pick-up coils.

Sensor Construction Detail

All Rheonik Coriolis mass flow meters are manufactured to strictly controlled procedures and quality standards.
Vacuum brazing is used for the final assembly of Rheonik Omega tube meters. Each meter is closely inspected to ensure all joints are sound and defect free. Meters with removable cases are sealed with an O-ring, creating an IP65 / NEMA 4X joint preventing
the ingress of foreign material into the housing.
Process connections can be either a removable manifold style or welded directly to the Omega form tubing to create a truly sealless meter, ideal for processes with hazardous materials.
The pick-up coils and drive coils installed in the meter are constructed of polyimide insulated wire encapsulated in epoxy resin. High temperature versions have
ceramic insulated wiring. Depending upon the size of the meter, up to four PT-100 temperature sensors are installed in the meter for temperature compensation.
There are three main parts to Rheonik's patented Omega tube meter, each of which has a distinct function.
When added together, they ensure that the meter produces accurate and repeatable results (see facing page for additional details):-

Omega Form
· Design permits increased tube wall thickness
· Active measurement section is entire top half of omega tube and totally decoupled from the process piping
· No deformation of half round measurement section with changing pressure gives repeatable measurement
· Requirement for secondary pressure containment eliminated!
Patented Torsion Rod
· Helps energize torsion oscillation
· Guides tube movement
· Minimizes stress
· Produces large oscillation amplitudes and extremely good signal to noise ratio for best accuracies at low flow conditions
High Mass Cross Bar
· Reduces susceptibility to external vibration and processborne dampening conditions · Stabilizes torsion movement
· Works in conjunction with torsion rods to generate harmonic oscillation – tuning fork perpetual motion

Technical Data for Sensor Units


Typical Measuring Range(2)

Nominal Rate

Pressure Rating in psig(7)

Standard process





 For temperatures
up to 248ºF

 Threaded (1,3)






0.005 0.66(5)


4350 (5800)

¼” NPT

½” / DN15


0.22 - 11

0.11 - 5.5


4350 (2175)

¼” NPT

½” / DN15


0.44 - 22

0.22 - 11.0


2175 (3625)

¼” NPT

½” / DN15


1.1 - 55

0.55 - 27.5


5510 (2755)

½” NPT

1” / DN25


2.3 - 110

1.15 - 55


4205 (13050)

½” NPT

1” / DN25


4.5 - 220

2.25 - 110


2755 (4205)

¾” NPT

1” / DN25


9 - 440

4.5 - 220


2175 (4350)

¾” NPT

1” / DN25


13 - 660

6.5 - 330


1595 (3260)

1” NPT

2” / DN50


33 - 1650

16.5 - 825


1885 (5800)


2” / DN50


66 - 3300



1770 (3625(6))


3” / DN80


130 - 6610

65 - 3305


1450 (2900(6))


4” / DN100


350 - 17635

175 - 8820


1450 (2320(6))


6” / DN150


530 - 26455



1450 (3190(6))


8” / DN200


1100 -55115



580 (870(6))


12” /DN300

(1) ISO G threads available
(2) Typical range for standard meter.
Special ranges available
(3) Different sizes available
(4) Types RHM007 / 01 replaced by RHM015
(5) Optional fine tuning:
parallel 0.005 - 1.32 lb/min
serial 0.0025 - 0.66 lb/min
(6) Maximum pressure rating of tube.
Process connection may derate overall
meter pressure rating
(7) Pressure rating (in brackets) refers to
optional heavy duty or special versions

For the selection of the most suitable meter for your application, including assessment of pressure drop, please contact us with full process details.


Standard Models
Range 1:20 ±0.20% of rate or better
Range 1:50 ±0.50% of rate or better
Repeatability: Better than ±0.10% of rate
Optional Gold Line Models fine tuned to your application
Range 1:10 ±0.10% of rate or better*
Range 1:20 ±0.12% of rate or better*
Repeatability: Better than 0.05% of rate*
*Not all models are available with
optional Gold Line performance –
please consult factory

Accuracy and Repeatability (including zero drift) are stated at a reference condition of H20, 14.7psig, 68°F. Range is turn down from nominal flow rate. Optional special calibration and fine tuning for enhanced accuracy in customer specified ranges (including 10w flow) is available.

General Technical Specifications:


Ratings stated in the table above refer to meter tubes up to 120°C / 248°F.
Pressure ratings are lower for meters with higher temperature range.
Most meters are available with higher pressure ratings.

Temperature range
Extended 1
Extended 2
Very high

RHM type       Temp. in ºF       Temp. in ºC      Temp. Class (for EEX ai IIC version)
NT                 -4 to +248         -20 to +120     T4 – T6
ET1            -328 to +122       -200 to +50       T6 (Ex approval for T > -45ºC only)
ET2              -49 to +410         -45 to +210     T2 – T3
HT                 32 to 662              0 to 350        T1 – T3
VHT               32 to 752              0 to 400        No EEx approval

Wetted materials parts

Standard material of construction is 316Ti/1.4571 Stainless Steel.
Optional materials include Hastelloy, Tantalum, Monel and Inconel. Consult factory for others. PTFE is used in meters requiring seals.

The above tables are a summary of the standard meter range. Special and custom version meters are available on request.
All hazardous area meters carry ATEX and/or CSA/NRTL approvals. All standard versions comply with EU PED and ASME standards.

The RHE14 ¡s low cost, compact and ideal for OEM applications. I/O includes 4-20mA, pulse, flow direction and RS232 serial data. Programming and configuration by SensCom software.
The RHE06 is ATEX approved for hazardous area installation and offers pulse output and Error and Flow Direction. *The RHE06F+ has double pulse outputs with 90º phase shift for custody transfer applications.

All other Rheonik transmitters have clear, easy to read local displays and intuitive, menu driven set-up and configuration functions. All include diagnostics for fault finding and tuning. Features include low flow cutoff, response time, multiple I/O, selectable units and full scaling capabilities. All settings are stored in non-volatile memory and I/O is galvanically or optically isolated.

RHE 07/08/11

Programming: Programmable via 3 buttons
Analogue outputs: 2 assignable and scalable 0/4-20mA for flow, density, temperature or volume, galvanically isolated, max. load < 500 Ohm.
Digital outputs: 1 frequency / pulse output (0-10kHz, max. 30V / 50 mA), 3 status outputs (limit, error/alarm, flow direction etc.)
Digital inputs: 2 status inputs (remote zero, hold totalizer, tot. reset, quit error/alarm) RS232/422/485: Serial interface or HART options available. For details see individual    datasheet.
Display: 2 line, 16 character backlit LCD display
Features: Includes built-in single and dual stage batch controller

RHE07C has double pulse output for custody transfer

RHE 12

Programming: Programmable via 2 sensors behind the glass cover.
Analogue outputs: 1 programmable 0/4-20 mA output, galvanically isolated (intrinsically safe optional)
Digital outputs: 1 frequency / pulse output (intrinsically safe optional), HART Error / Alarm condition output (22 mA) RS232 / 485 options available.
Display: 2 line, 16 character backlit LCD display.

Profibus PA / Foundation Fieldbus in development  

General Data for alI Transmitters:

Ambient temperature: -40 to 60°C
Power consumption: < 15 Watt
RHE12 < 5 Watt
RHE14 < 1 Watt
RHE 06, RHE 06F+, RHE07, RHE 08 and RHE 14 transmitters to
be installed outside of hazardous area (RHE 08 can be installed in
Cl. 1, Div. 2 area).
RHE 11/12 can be installed in the hazardous area.
RHM can be installed in hazardous area (ATEX EEx ia IIC T6-T1 /
CSA Cl. 1, Div.1, Gr. ABCD) if connected to approved RHE unit.

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Av. Rivadavia 11088 P.6° Dto.”B” (C1408AAX) Capital Federal - Argentina
Tel. /Fax (+54) 011 4644-0825 / 4644-1376