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Do non-dispersive-infrared (NDIR) gas sensors have advantages?

A core competence of m-u-t is the development and production of NDIR gas sensors, providing stable and reproducible measurement results due to their robust optical technology. Our optical NDIR gas sensors offer further advantages: selectivity (low cross-sensitivity to other gases), accuracy, long-term stability, sensitivity and resolution.

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Long-term Stability

m-u-t NDIR gas sensors are the best choice for processes where precise gas measurements are essential. Our NDIR sensors have a significantly higher long-term stability than electrochemical sensors. They can operate maintenance-free for over 10 years and be recalibrated if necessary. Electrochemical sensors must be tested and calibrated regularly - sometimes monthly - and replaced if the accuracy is outside the specified range.

Speed

NDIR results are quickly available. Other gas sensor types (e.g. electrochemical and semiconductor sensors) require time to reach saturation or heating time for precise measurement. Therefore, in high volume production, large quantities of off-spec products could be produced before any deviation is detected. By using our NDIR sensors such deviations can be avoided. Based on many years of extensive experience with NDIR gas sensors, m-u-t can provide unique solutions for many different applications.

Multigas Measurement

In many processes not only a single gas but a complex gas mixture and other parameters such as pressure, temperature and humidity also need to be measured. Instead of using several individual sensors, m-u-t develops your customized multigas sensor to measure all relevant gases and additional parameters in one compact unit. Once calibrated, the sensor gives you full process control over a long period of time. For the analysis of relatively small gas concentration mixtures, we offer extremely compact multigas measuring cells with folded beam paths. The compact gas measuring cells can be space-savingly integrated into your system. On request, the multigas measuring cells can be calibrated for all relevant gases over the respective concentration and temperature range; possible cross-sensitivities between the gases will be determined and compensated.

Restrictions

Only infrared active gases can be measured with NDIR technology. A gas is considered to be infrared-active if its molecular atomic arrangement allows asymmetric stretching and bending vibrations (e.g. CO2 as a dumbbell model).

Non-infrared active gases are e.g:

  • noble gases (He, Ne, Ar, Kr, Xe)
  • elementary diatomic gas molecules (H2, N2, O2 etc.)

Infrared active gases

With the NDIR technology the following typical gas groups can be measured:

  • Hydrocarbon compounds CxHx
  • Carbon dioxide CO2
  • Carbon monoxide CO
  • Water H2O
  • Anaesthetic gases, such as laughing gas N2O

Selectivity

All infrared active gases are detected by NDIR sensors due to their spectral fingerprint (absorption band). However, there are absorption bands of different gases which overlap and thus create cross-sensitivities ("false readings"). These can be detected and compensated by our intelligent multigas sensors.

For further questions or information, please call us at any time or send us an email.

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Advantages at one Glance

 ElectrochemicalNDIR
Reproducibility-+
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