6 | Measurement Basics
G 1910-02
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B-H90.0.01.DB2-2.1
6
Measurement Basics
6.1
NDIR CO
2
sensor
6.1.1
Explanation
The sensors are based on non-dispersive infrared sensor technology, NDIR. This is
the most widely used sensor technology for CO
2
measurement.
The principle of the NDIR sensor is that an IR light source is focusses so that an opti-
cal beam is created, which passes through the existing gas, including CO
2
. After an
optical band pass filter is passed, an IR sensor measures the level of IR light, wherein
the CO
2
values in the optical path are displayed.
6.1.2
Design
1.
Gas inlet
2.
Gas outlet
3.
IR lamp
4.
Optical filter
5.
Thermopile detector
IR detectors
A sensor module with single-channel detectors is used for the product.
A micro light bulb is used as an IR radiation source. It emits a broadband spectrum.
The sensor is long-lasting and maintenance-free. In order to be able to maintain the
specified accuracy for many years to come, regular adjustment must be carried out
depending on the required accuracy.
IR radiation source
