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Within a chemical site, Sodium Hydroxide (NaOH) is produced by means of electrolysis and then distributed via piping to the respective production plants for further processing. A stable concentration of the Sodium Hydroxide is thus obligatory and has to be monitored very closely. Inline instrumentation, such as previously installed density meters, regularly failed due to the harsh conditions.

As of the good experiences the customer already made with FLEXIM's non-invasive ultrasonic FLUXUS flow meters as well as FLEXIM's non-invasive PIOX S process analyzer for the concentration monitoring of Sulphuric Acid, now also the online concentration measurement of Sodium Hydroxide should be carried out by PIOX S.

Conjointly with the customer, FLEXIM adapted the measurement device to the operators' needs and the individual concentration range it should be able to accurately cover.

Since PIOX S has been installed, it accurately and reliably monitors the NaOH concentration by measuring the liquid sound speed which stand in distinct relation to the liquids' concentration. Determination of the Sodium Hydroxide concentration values by PIOX S are transmitted to the process control center. If the measuring values deviate from the preset values, the process is automatically regulated.


  • Reliable, non-intrusive concentration and mass flow measurement with one measuring system
  • Installation without process interruption
  • No media contact, no wear on the instrumentation, no risk of leaks
  • Drift-free measurement and long term stable