NDIR Technique DIA

The technique NDIR (Non Dispersive Infra Red) uses radiation from a broad band IR-light source which is absorbed by the rotational/vibrational modes of the gas to be measured. The integral absorption is detected without a dispersive element. In contrast to laser techniques, the selectivity is achieved by the sensitivity of the detector, which is filled by a pure gas of the species to be measured adjusted to a known concentration. It is also known as opto-acoustic technique, since the pressure change in the detector is measured like in a microphone.

Diagram Uras 26


Gas Flow Diagram

  • ABB analyser Uras26, one beam instrument sensitive for 12CO2 and 13CO2.
  • Gas management with stainless steal tubes and high-precision valves via 4 inlet ports for simultaneous sample and reference inlet.
  • Sample drying with integrated nafion element and Mg(ClO4)2 magnesium perchlorate.
  • Active temperature stabilization.

Mode of Operation

  • Online display of 12CO2, 13CO2, CO2, δ-13C, temperature and pressure.
  • Measure Wizard: Define a sequence of measurements from different ports and selected delay and measurement intervals with arbitrary amount of repetitions.
  • Build-in zero and end point calibration procedure.

Analysis of Data

  • Plot time course and Allan variance/deviation.