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Nitrogen is required in many processes of the chemical and pharmaceutical industry; predominantly as protective gas, to prevent the occurrence of explosive atmospheres, such as when handling dusty products or solvents. At many sites, nitrogen is provided centrally, as is compressed air. Tanks filled with liquid nitrogen ensure a continuous supply and the expanded gas feeds to a pipe system, from which consumers draw required amounts of nitrogen. While the amounts that are fed in are recorded using gearwheel meters, there are often no individual consumption measurements.

As in the described case, when the new production facility was constructed, engineers wanted to have the possibility of recording consumption rates in order to determine actual demand, to sound out any possible savings potential and to obtain empirical data as a basis for future plans.

Moreover, utmost cleanliness is required in pharmaceutical applications. The nitrogen fed into the ring system has the highest quality level 5.0, corresponding to a purity of 99.999%. Any possible contamination must therefore be prevented at all costs. If the pipeline has to be opened for any work, this means an extended shutdown of production in all connected systems. Once installation work has been completed, the nitrogen network must undergo a detailed sampling inspection by the department responsible for qualification and validation. Production can be resumed only after the required purity level has been certified.

The technicians in charge were therefore looking specifically for a non-invasive measuring method for carrying out consumption measurements. Non-invasive flow measurement with the FLUXUS G ultrasonic measuring system proved to be the ideal solution. Since clamp-on transducers are simply mounted on the outside of the pipe, there is absolutely no risk of contamination and modifications made to the measuring point do not have any effect on the production process. Now the individual consumers, which are supplied via six lines in the building, can be measured successively using non-invasive technology. Another positive side effect of the flow measurements is the simple determination of possible leaks: nitrogen is an odourless gas. That's why, smaller leaks in the network generally go unnoticed. If a flow rate is now measured in one line while there is no nitrogen being consumed and the system is in operating mode, a leakage can definitely be detected.


  • Reliable, non-invasive volume flow measurement for precise recording of individual consumers
  • External non-invasive measurement: absolutely no danger of contaminating the ultra pure gas flow
  • No plant shutdown for installation or subsequent extensive re-qualification of the plant
  • Simple, gradual recording of all consumers with just a single clamp-on measuring system
  • Determination of possible leakages