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The probe MF420-IR-CO2-AL is the robust version of our air quality signal, which visualizes the air quality with a traffic light function. With the integrated changeover relay at levels above the thresholds e.g. a fan can be controlled.

Measuring Ranges and threshold values

The MF420-IR-CO2-AL is available with a standard measuring range of 0-5000 ppm CO2.

The Standard threshould values are configured as follows:

< 1,500 ppm CO2 LED green
1,500 ppm to < 5,000 ppm CO2 LED yellow
> 5,000 ppm CO2 LED red

When exceeding the first threshold value (1500 ppm) two short beeps are heard and the LED traffic light turns from green to yellow. If the second threshold value (5000 ppm) is exceeded, the LED traffic light turns from yellow to red and the device triggers an audible permanent alarm. If the CO2 concentration falls below the first threshold, the device goes back to the ground state and the green LED lights up again.

Relais Connections

The product MF420-IR-CO2-AL has a relay with changeover contact, when exceeding the threshold it is triggered and thus e.g. a fan relay can be controlled.


The device complies with the generic standards EN 61000-6-2 and EN 61000-6-4 and thus the EMC Directive 2004/108/EC.

Maintenance and Service

The device thanks to its NDIR-Technology is low-maintenance - we recommend at least an annual inspection.

For more details, please refer to the technical data or ask our contact person.


Product NameProduct FeaturesProduct Code
MF420-IR-CO2-AL Carbon Dioxide
Measuring range: 0 - 5,000 ppm


Principle of Measurement NDIR (two-beam infrared photometer)
Power Supply Voltage 24 V DC ± 5%
Current approx. 100 mA
Ambient Temperature -10°C to +50°C  
Air Pressure 900 hPa to 1100 hPa  
Permissible Humidity 15 to 95% relative humidity non condensing
Output Change Over Relays max. 50 V
Optical Display green LED [CO2] < 1.500 ppm
yellow LED 1.500 ppm < [CO2] < 5.000 ppm
red LED [CO2] > 5.000 ppm
Malfunction Hard- und Software yellow LED flashing
Housing Alloy red  
Protection class IP 54
Weight approx. 500 g
Dimensions (L x W x H) 90 x 85 x 65 mm
Connecting cable 3 x 1.52 Cu shielded cable

Pin Assignment:

For more details, please ask our contact person.