The FLUXUS G831 ST-HT is our smart solution for high-temperature steam flow measurement in hazardous areas.

Non-invasive and efficient

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

This unique flow solution is based on the correlation flow measurement principle. The acoustic measuring method has exceptionally high measuring dynamics and functions independently of the flow direction. The FLUXUS G831 ST-HT offers precise bidirectional flow measurement over a wide turndown ratio up to 10:1.

Completely maintenance-free, robust and safe in operation

Non-invasive steam flow measurement also means measuring without direct contact with the medium flowing in the pipe. FLUXUS G831 ST-HT has no moving parts. Its ultrasonic transducers are fixed to the pipe with broad stainless-steel straps or our patented high-temperature mounting system WaveInjector and secured in robust stainless steel housings.

Therefore, FLUXUS ST-HT is not subjected to wear and tear and does not require any maintenance. No more venting and draining of inline flow equipment is necessary, which ensures a totally safe operation of our flow measurement solution.

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 400 °C in hazardous areas.


  • Reliable and non-invasive steam measurement
  • No pressure loss, no pipe modification, no process interruption
  • High dynamic flow range
  • Easy and cost-efficient retrofit


Technical Facts

Measurement uncertainty (volumetric flow)
±3% of reading*
Saturated steam and superheated steam
Measuring quantities
Volume flow, mass flow, flow velocity
Process temperature
100 - 630°C
Process pressure
1 -100 bar abs.
Pipe diameter range
±1% of reading*
Explosion protection
transmitter ATEX/IECEx Zone 1, FM Class I / Div 2
transducers ATEX/IECEx Zone 1/Zone 2, FM Class I / Div 2
Additional Information
please have your specific application tested for feasibility
* turbulent flow with Reynolds ≥ 60.000