One is that Coriolis mass flowmeters remain the most accurate mass flow meter, and they are highly reliable with little need for maintenance. Coriolis meters do not place any obstruction in the flowstream, although bent-tube meters can slow down flow velocity. Straight-tube meters have been developed to address this effect and to suit the needs of sanitary applications, which pose an issue for bent-tube meters, which can accumulate material building at their bending points. 

The most important recent advance in the Coriolis market is the development of Coriolis meters for line sizes above 6 inches. Rheonik, now part of GE Measurement, used to be the only company offering large line-size Coriolis meters. Coriolis mass flow meter are primarily targeting oil & gas applications. Many of them, though not all, are designed for custody-transfer applications. 




Rheonik Messgeräte GmbH has more than twenty years of experience in the field of Coriolis Mass Flow meter design and development. Beginning in 1984, Karl Küppers began the design of a mass flow meter based upon the Coriolis effect that later became the patented Omega tube Coriolis Mass Flow meter manufactured by Rheonik today. 


After the exhaustive testing of many different designs, the Omega tube meter with torsion rods and mass bars was granted a patent based upon its unique operation and construction feature. Compared to other meter designs, the Rheonik Omega tube design offers outstanding performance and mechanical reliability


Rheonik was founded in 1986 by Mr. Küppers to commercially produce the Rheonik Mass Flowmeter range. Based initially in the town of Maisach near Munich, the company grew quickly due to the widespread  success of the Rheonik design in the field. 


To accommodate in creased demand, Rheonik Messgeräte GmbH relocated to a modern facility in Odelzhausen with increased production and office space.Today, Rheonik manufactures the largest range of Coriolis mass flowmeters in the world for customers in more than 30 countries. With more than twenty years experience in the field, Rheonik Messgeräte GmbH is one of the world leaders of Coriolis Mass Flowmeter development and manufacture.



All Rheonik coriolis mass flow meters are based on a patented Omega tube design with increased signal-to-noise ratio, for excellent performance and reliability. The combination of a patented torsion rod swinger with the Omega shape and support bars results in high accuracy measurement independent of pressure, even at very low flow velocities.



RHM coriolis flow sensors offer direct mass flow rate for liquids, sludge, and gases, all with high accuracies. These sensors are extremely resistant to gas bubbles entrained in the process stream, and are unaffected by viscosity, density, extreme temperatures, and pressure changes.There’s a Rheonik RHM flowmeter for nearly any flow application range :




RHM Coriolis Sensors Overview from Rheonik Messtechnik GmbH :

Model
Qmin
Qmax
Qnom
pmax @ 120°C
typical size of process connection
kg/min
kg/min
kg/min
bar(g)
thread
flange
0.002
0.6
0.6
700
1/4″
DN15, 1/2″
0.038
5.0
5.0
870
1/4″
DN15, 1/2″
0.05
10
10
870
1/4″
DN15, 1/2″
0.15
20
20
510
1/2″
DN25, 1″
0.30
50
50
1,185
1/2″
DN25, 1″
0.75
100
75
960
3/4″
DN25, 1″
1.00
200
150
815
3/4″
DN40, 1 1/2″
2.25
300
300
700
1″
DN50, 2″
5.0
750
600
700
DN80, 3″
12.5
1,500
1,250
290
DN80, 3″
45
3,000
2,500
430
DN100, 4″
130
8,000
5,000
215
DN150, 6″
200
12,000
10,000
150
DN200, 8″
600
30,000
23,000
50
DN300, 12″
Our Technology 
The typical Omega shaped Rheonik Coriolis mass flowmeter. All Rheonik meters are principally based on the design shown beside. No other design offers this degree of versatility and rangeability:
  • Measurement of liquid and gaseous fluids 
  • Flow rates from 0.002 to 30,000 kg/min (0.004 to 66,000 lbs/min) 
  • Diameters up to 12 inch / DN 300
  •  Pressure over 1,000 bar (14,500 psi) 
  • Temperature from -196°C to +395°C (-320°F to +743°F) 
  • Hazardous area certified versions available (ATEX, CSA etc.) 
  • Available in stainless steel, Alloy C22, Duplex, Tantalum and others
The Advantages Summary
Omega design is the basis for one of the most advanced Coriolis flowmeters available:
  • No change of accuracy with changing pressures – active measurement section is half round and maintains its exact shape at any pressure
  • Active measurement section of the Omega is de-coupled from process connections via mass bars. Vibrations have less influence on measurement than with conventional Coriolis meters
  • Tensions from the process side cannot disturb active measurement section of Omega since it is de-coupled (straight tube shaped meters are very vulnerable in this regard)
  • Mass bar and torsion rods (rods work as a spring) form a harmonically oscillating system, resulting in great stability and little energy needed (therefore intrinsically safe)
  • Mass bar – torsion rod system provides very big amplitudes, hence excellent signal to noise ratio. Even smallest rates can be measured reliably.
  • Straight tubes have low signal to noise ratio
  • Torsion oscillator allows bigger wall thickness, hence higher pressure ratings, increased safety, and extreme temperature possible
  • Torsion movement instead of bending creates less stress in tubes – longer life time
  • Torsion movement is less affected by pipe vibrations since the vibrations are horizontal or vertical. Operational movement (torsion) is not in the same plane as the vibration movements – less cross talk
  • Compact form. Shorter face-to-face length than straight tube shaped meters
  • Separate transmitter for flexibility – easy to integrate into systems
  • Extreme applications
  • Sensor models rated over 1,000 bar are available
  • Temperatures from -196°C to +395°C
  • Highest accuracy under real-life conditions
  • Units available for fiscal duties
  • Low energy usage
  • EEx ia IIC sensors available (ATEX and CSA)
  • Flexible configuration
  • Diameters from ½” to 12″
  • Wetted parts materials available: stainless steel, Alloy C22, (Super) Duplex, Tantalum and others
APPLICATIONS
  • Suitable for virtually any mass flow application, such as: Batching, Dosing, General flow control, Injections, Filling
  • Loading of boats, vessels, rail tank wagons
  • High temperatures and other challenging applications
  • Highly viscous media (low pressure drop and excellent performance at low flow conditions)
  • Properly used for corrosive liquids and Low Flow 
  • Properly used for beverages that require  food grade instrument
FEATURES
  • The outstanding features include :  Suitable for pressure up to 450 bar
  • Size : 1/4″ – 12 ” : 
  • Measuring ranges : 0.002  kg/min to 25.000 kg/min ( depending on pipe size ) 
  • Accuracy   : 0.1% and better
  • Repeatability : better than 0.05%
  • Optimised solutions for your batching operation
  • Extra compact design with minimal space requirement
  • EEx Approvals (i.e. ATEX, CSA, …)
  • Custody Transfer Approvals (i.e. PTB, NMI, …)
  • As heavy duty version available (increased wall thickness of measuring pipes for additional safety – 250 bar)

Specification : 
  • Typical measuring ranges : 0.002  kg/min to 25.000 kg/min
  • Flow Accuracy :  0.1% and better
  • Repeatability  :  better ± 0.05% of rate
  • Density         :  better than  ± 0.001 g/cc
  • Temperature   : -200 to +350°C 
  • Pressure range : Measuring Loops max. 93 bar – max CL 600 / PN 40
  • Material of Wetted Parts :
  • 1.4571 / SS 316Ti (standard), 
  • 1.4539 / SS 904L on request, 
  • Hastelloy C22 on request
  • Tantalum and Other material on request
  • Housing : 
    • Stainless Steel: 1.4301 / SS 304 ( standart) and  others on request
    •  Protection class: IP 65 (Nema 4X) and higher on request 
  • Electrical connection
    • Junction box / aluminium coated (standard) IP 65 (Nema 4X) (Junction box in SS optional)
    • Cable entry M25 x 1.5 (M20 x 1.5, ½” and ¾” NPT optional)
    • Max cable length between RHM and RHE :
    • 100 m (330 ft)
    • 200 m (660 ft) only with factory approval
  • Approvals
    • ATEX (CESI 02 ATEX 053 X) : Ex II 1 G, EEx ia IIC T6-T1
    • CSA (220705) Class I, Div 1 and 2, Groups A, B, C and D;Type 3
    • Custody Transfer Approvals (PTB 1.32-97027224 and NMI TC 3382)
    • PED according to directive 97/23/EC available
    • 3A Sanitary Approvals
  • Transmitter and Display mounting : wall mounting, Pannel Mounting, Rack Mounting
  • Outputs :
    • 2 analog outputs, 
    • 1 frequency/pulse output 
    • 3 digital outputs (Lt, +/-, error…)
  •  Inputs :   2 inputs (hold, reset, zero)
  • Power supply :   
    • 230 VAC +/- 10% or
    • 115 VAC +/- 10% or    
    • 24 VDC 
    • Cable entries:   4 x M25 x 1.5 – others optional
  • Interface :  
    • RS 422/485/232 – optional
    •  HART – optional 
  • Power consumption : < 15 W