H2SO4 – Sulphuric acid & Oleum

H2SO4 – Sulphuric acid & Oleum


Sulphuric acid is a very important raw material in the chemical industry and is used in may different processes. Oleum is produced by dissolving SO3 in H2SO4. Sulphuric acid is produced by dissolving water
in oleum. This is the so called double contact process.

To follow the process of dilution, an accurate and reliable real time in line analyser is needed. We have developped a very accurate analyser, based on density and speed of sound, to determine its concentration in parts or in the full range. The concentration of aqueous solutions of sulphuric acid or oleum is reported as %w/w H2SO4.


Sulphuric acid or oleum are used in several industries either in concentrated form or in dilutions down to a few ppm. In practice, the product can be measured with high accuracy in a well equipped laboratory using density meters. But above 90% saturation, density analysers does not give the accuracy that is needed for reliable process control. Other sensors, like conductivity sensors, refractive index meters or coriolis meters, simply lack sensitivity for specific applications, or do not seem to respond anymore at larger concentrations.

Rhosonics has developped a new method for controll of the full range. It is the combined density and speed of sound analyser in one sensor. Now, the full range from 0 to 120%w/w H2SO4 can be monitored with the ternary analyser Model 9580. This is the most accurate insitu real time process analyser on the market.


For this application our UMP probes are suitable, but also the new hybrid ultrasonic technology can be used for the determination of oleum. The benefits is that the temperature is measured based on ultrasonic
technology; we measure the speed of sound and we also determine the density of the liquid.

Other benefits are:

  • Very low price and cost of ownership
  • High accuracy and reproducibility
  • Maintenance free
  • No cleaning needed
  • No moving parts
  • No reagents
  • Insitu, spool and wafer sensor technology
  • High-end software technology, easy to operate
  • Colour graphics touch screen display
  • Datalogging
  • Various communication protocols, like Modbus