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Non-invasive flow measurement of cryogenic fluids

For many years, FLEXIM’s unique non-invasive ultrasonic flow meters have been running in various LNG and other cryogenic applications at temperatures down to -200 °C: from 3” lines in peak shaving plants to 36" pipes for tanker off-loading to storage tanks.

The non-invasive ultrasonic flow meters provide the ideal solution for all cases where reliable and trouble-free flow measurement of cryogenic fluids is required. With its huge measurement range FLUXUS Cryo is ideally suited to cover the highest flow rates of loading / off-loading processes as well as very low flow rates at when lines start or stop.

As the system measures from outside the pipe wall, installation does not require any pipe cutting or extensive pipe work. Further, FLUXUS Cryo is virtually maintenance free, does not cause any pressure drops and can never be the source for potential leaks.

With its unrivalled accuracy and reliability, FLUXUS Cryo meets all requirements for regular monitoring, control as well as SIS (Safety Instrumented Systems) purposes. The meter’s diagnostics can be used to detect the beginning and end of the cryogenic liquid flows in batch processing.


  • Highly accurate flow measurement of LNG, Liquid Ethane, Liquid Air, Nitrogen and Oxygen without any pressure drops
  • Highly reliable:
    - Maintenance-free. No moving or vibrating parts
    - Dual-beam redundant measurements
  • Operationally safe:
    - No gaskets, No leakage points
  • Economic:
    - No pipework modification necessary
    - One-man-installation without the need for lifting gear
    - No pressure loss - no chance for flashing


Retrofit Applications:

  • No pipework necessary
  • No lifting gear required – independent of pipe size
  • FLUXUS Cryo can be mounted at limited space conditions, e.g. at FLNG loading arms
  • Installation is done within a few hours when the pipe is not cooled down
  • The measuring system is fully integrated into the insulation

New Plants:

  • Highly cost-effective - only standard piping needs to be planned – FLUXUS Cryo fits
  • Late design changes aren‘t a problem! One equipment type fits many pipe sizes
  • No pressure-loss and thus no energy loss
  • No risk of flashing
  • Significantly reduced CAPEX, especially for large diameters
  • Global installation and support by FLEXIM


Industry Applications

Technical Facts

Flow channels
1 ( optional 2)
Quantities of measurement
Volume flow, mass flow, flow velocity
Cryogenic Fluids (LNG, Liquid Ethane, Liquid Air, Nitrogen, Oxygen and others)
Flow velocity range
0.01m/s ... 25 m/s
Measurement accuracy
±1.2% of reading, ±0.01 m/s (standard)
Measurement accuracy
±0.5% of reading, ±0.01 m/s (field calibration)
±0.15% of reading, ±0.01 m/s
Media temperature
-200°C ... +80°C
Operating temperature of the transmitter
-40°C ... +60°C
Pipe diameter range
70 mm to 1000 mm
Degree of protection
Transmitter: IP66, Transducers: up to IP68
Available Hazardous Area Classification (optional)
ATEX / IECEx Zone 1 / 2; FM Class I, Div. 1 / 2
Communication Protocol
HART, Modbus RTU/TCP, RS485, Profibus PA, Foundation Fieldbus

USB and Ethernet interface for communication available
Depending on Transmitter: Up to 4 Inputs (temperature Pt100/Pt1000), current, voltage, binary
Depending on Transmitter: Up to 4 Outputs: (active/passive) current, voltage, frequency, binary