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Methylene diphenyl diisocyanate (MDI) is an important intermediate product for the production of polyurethanes. During industrial production of MDI from diaminodiphenylmethane, a complex compound MDI oligomer mixture is formed at first and then purified by distillation in several distillation columns. In order to ensure safe and reliable processing, the various product flows must be measured continuously. This also includes the mass flow of MDI which is returned from the bottom area of the distillation column. In this case, high temperatures (> 200 °C) and highly viscous media place high demands on the reliability and efficiency of the flowmeters in use.

Non-invasive flow measurement with FLUXUS and in conjunction with the WaveInjector transducer mounting fixture for extreme temperatures proved to be the measurement system of choice for the bottom product of the MDI distillation.
FLEXIM's non-invasive flow measurement technology distinguishes itself with a number of advantages: unlike vortex meters which were previously used at this point for flow measurement, clamp-on flow transducers, which are attached to the outside of the pipe, are not subject to wear and tear by the medium and do not cause any pressure loss. In addition, the measuring system is attached simply during ongoing operation without any pipe work.


  • Acurate, reliable and virtually maintenance free flow measurement solution
  • No wear and tear by the medium
  • Simple attachment and set-up of non-invasive measuring system without pipe work or any interruption of production
  • No risk of hazardous medium leaking
  • No pipeline contraction, no pressure loss
  • Reliable control of the distillation column reflux ratio