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Non-invasive and efficient

FLUXUS G831 ST-LT measures steam flow non-invasively from the outside of the pipe in hazardous areas. Non-invasive steam flow measurement means measuring without any interruption of operation and supply. Since clamp-on ultrasonic transducers are simply mounted on the outside of the pipe, it requires just minimal installation effort and no opening of the pipeline.

The acoustic measuring method proves to be impressive with its exceptionally high measuring dynamics, is highly sensitive even at very low flow velocities and functions independently of the flow direction. Due to this large flow range (flow velocities from 0.01 m/s up to 60 m/s), there is no need to reduce pipe diameter to fit an inline meter’s requirement of minimum flow velocity. Moreover, the non-invasive measurement does not cause any pressure loss. The transducer mountings can be completely insulated to reduce any heat loss to the environment.

With FLUXUS G831 ST-LT it is possible to capture all steam usage from very low to very high flow rates with one meter size.

Completely maintenance-free

Non-invasive steam flow measurement also means measuring without direct contact with the medium flowing in the pipe. FLUXUS G831 ST-LT has no moving parts. Therefore, FLUXUS ST-LT is not subjected to wear and tear and does not require any maintenance.

The addition of intrinsically safe process inputs for pressure and temperature at the meter location means the FLUXUS G831 ST-LT measures volume and mass flow of saturated and super­heated steam at temperatures up to 180 °C in hazardous areas.


  • Reliable, non-invasive steam measurement
  • High dynamic flow range even at low flow velocities
  • no pipe diameter reduction – zero pressure loss
  • Integrated mass flow measurement
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Technical Facts

Measurement uncertainty of the measuring system (volumetric flow rate)
±0,3 % of reading ±0.005 m/s
Measurement uncertainty at the measuring point (volumetric flow rate)
±1..3 % of reading ±0.005 m/s, depending on application
±0,15% of reading, ±0,01 m/s
Flow channels
1 or 2
saturated steam, superheated steam
Process temperature
max. 180°C non-Ex
max. 165°C ATEX Zone 2
max. 155°C ATEX Zone 1
Process pressure
min. 3 bar abs.
Pipe diameter range
Flow velocity range
0,01m/s…60m/s (depending an pipe size and transducer)
Explosion protection
ATEX / IECEx Zone 1
FM Class 1/Div1
Communication Protocol
Modbus RTU, Profibus PA, FF H1, HART
Digital communication
USB Interface
Advanced Meter Verification (AMV)
Additional Information
please have your specific application tested for feasibility