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MDI (Methylene diphenyl diisocyanate) is an important intermediate product for the formation of polyurethanes, which are known as a foam structure for mattresses, car seats, insulation and many other end products.

One of the pre-products of MDI are isocyanates. An MDI plant operator was looking for a high temperature solution for flow rate monitoring of the isocyanates entering a heat exchanger. As the degree of fouling within the heat exchanger depends on the flow rate, an accurate monitoring is of crucial importance.

Previously installed inline flow meters frequently failed due to the enormous thermic stresses (> 220°C). As the measurement point is located within a hazardous area (ATEX Zone 1) and safety is a big concern, the operator was looking for a non-intrusive flow metering solution.

FLEXIM was the answer! The hazardous area approved FLUXUS clamp-on ultrasonic flow meter in conjunction with the high temperature WaveInjector transducer mounting fixture, allowed the customer to accurately and reliably measure the volume streams at such demanding conditions with the highest degree of safety and plant availability possible. For installation no pipe work or even process shut downs are necessary and maintenance efforts are kept to an absolute minimum.


  • High-temperature, non-intrusive flow measurement - no more thermal resistance failures
  • No production stop for the installation, virtually no maintenance required, no risk of leakages
  • Fully ATEX Zone 1 certified for usage in hazardous areas