CO2 sensorCO2 sensor technical description

NDIR-based* CO2 sensor which achieves long-term stability

Unique calibration curve algorithm
Automatic calibration feature based on a unique dual wavelength (for measurement and reference) NDIR system (patent registered)

Because it adopts a calibration method which does not use atmospheric concentration (approximately 400 ppm), it can be used in fields such as “agriculture (greenhouses)” and “BEMS (building ventilation control)” where atmospheric concentration cannot be accurately measured.

*NDIR: Non-Dispersive Infrared

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on Murata CO2 sensors

Principles and problems with typical CO2 sensors (NDIR system)

Principles behind typical NDIR-based CO2 sensors: They calculate the CO2 concentration based on the light absorption according to the concentration of CO2.
Problems with typical NDIR-based CO2 sensors: Calibration is required, because the characteristics drift due to several factors.

CO2 sensor calibration methods and drift characteristics

Comparison with dual wavelength CO2 sensors

Initial characteristics

The productization of a high-accuracy CO2 sensor with superior temperature stability is achieved with a unique automatic calibration feature.

Reliability testing

Load test in a high temperature, high humidity environment (acceleration test) [Installation environment: 50°C, 95% RH]

Typical CO2 sensor

Primarily affected by the degradation of the optical path reflecting surface and the change in sensitivity of the photodetector, drifts significantly

Murata CO2 sensor

Suppresses degradation with a high-performance optical path and reflecting surface design
Suppresses changes in the sensitivity using a unique photodetector design and signal processing technology
Maintains stable performance due to its ability to automatically calibrate the impact of the reflecting surface degradation and changes in the sensitivity of the photodetector using automatic calibration

Actual long-term stability test in the field (drift amount measurement) [Installation environment: building ventilation duct]

Method to measure the drift amount: measured using a reference gas with a CO2 concentration of 1,000 ppm (including measurement error)

Drift of 50 ppm or less over a long period of time
Product lifetime of ten years (design life)
Maintains long-term stability and high measurement accuracy with a unique automatic calibration feature
Promises to improve maintainability
When used in building ventilation, it is able to control CO2 levels close to the upper limit of the CO2 concentration established under the Building Management Law
→For example, you can set it to 950 ppm to provide a 50 ppm margin near the upper limit of 1,000 ppm to help reduce ventilation energy usage

Check that it is ±50 ppm/year at 1,000 ppm in the duct installation environment