ND-Infrared Sensor
NDIR - nondispersive Infraredspectroscopy
NDIR – operating principle:
A non-dispersive infrared sensor is used to measure concentrations. The missing infrared radiation absorbed by the respective gas through physical interaction of the radiation and the molecules is determined. Non-dispersive in this context means that radiation energy is absorbed.
Many gases have a specific wavelength range in the infrared range in which they absorb infrared radiation. The gas to be analysed is filled into a cuvette of defined length and irradiated with infrared light. The length of the cuvette is selected so that the requirements for the measuring range can be met.
An infrared sensor is located at the other end of the cuvette. To prevent the sensor from responding to all wavelengths, a bandpass filter suitable for the respective gas is connected upstream. Ideally, only this gas should absorb the light of this wavelength and no other gas contained in the gas mixture.
- Benefits at a glance
- Cost-optimized measurement method due to its modular and compact design
- Quick and continuous measurement up to high concentrations
- High quality cell made of electro-polished stainless steel
- Heatable cuvette to prevent condensation
- Long-term stable measurement signal by evaluating a reference channel and additional temperature and pressure compensation
- Detection of up to four different gases
- Cost-optimized measurement method due to its modular and compact design
- NDIR Options
- Measurement of other IR-active molecules
- Mounting on base plate
- Analog measurement output (e.g. 4 - 20 mA)
- Communication via CAN or RS232
- Corrosion-resistant material selection (Stainless Steel, PTFE etc.)
- Heatable cuvette
- Input for electrochemical sensor
- Execution Examples
CO2/CO2/H2O CO/CO2/CH4 CO/CO2/SO2 Measuring range 0 – 2,5%
0 – 20%
0 – 15%0 – 40%
0 – 30%
0 – 10.000 ppmv0 – 1.000 ppmv
0 – 20%
0 – 1.000 ppmvLimit of detection (LOD) < 25 ppmv
< 200 ppmv
< 150 ppmv< 400 ppmv
< 300 ppmv
< 10 ppmv< 1 ppmv
< 200 ppmv
< 1 ppmvRise time (t90) < 1 s < 10 s < 1 s Highlights Heatable cuvette to prevent condensation
Extremly high densitiy of the cuvette
Can be used under strongly fluctuating environmental conditions
