What Is a CO2 Sensor?

Carbon dioxide is a deadly gas that can kill a person before they realize what is happening. Because it is odorless and colorless, you may not even know it is present without a detector. Exposure to carbon dioxide can cause headaches, nausea, vomiting and even death. A Co2 sensor (or carbon dioxide sensor) detects the presence of carbon dioxide in an area. This device indicates the quality of indoor air, and it is ideal for industrial and commercial applications.

How Co2 Sensors Operate

Carbon dioxide sensors have a wide range of applications. They are ideal for the HVAC industry to measure the quality of indoor air, as well as ventilation on air conditioning systems. They monitor the level of carbon dioxide in a building to tell the HVAC system when fresh air is needed to restore optimal airflow. They measure air quality in terrestrial and space applications, measure Co2 levels in greenhouses, and are useful in many other industries.

NDIR Co2 Sensors

Two basic types of Co2 sensors exist. The first is the non-dispersive infrared (or NDIR) Co2 sensor. A NDIR sensor is a spectroscopic sensor that uses a light tube, an infrared source, infrared detector and a wavelength filter. The highest quality of these devices measures gas with sensitivities between 20 and 50 PPM. Waves of light go through the tube towards an infrared light detector while the gas absorbs the light. All remaining light is absorbed, except that absorbed by the carbon dioxide. The detector reads the amount not absorbed by either the CO2 or the filter. The measured difference tells how many carbon dioxide molecules are in the air.

Chemical Co2 Sensors

The second type of carbon dioxide sensor is a chemical Co2 sensor. It uses as many as three electrodes and an electrolyte. The carbon dioxide passes through the chemical sensor to produce a measurable electrochemical reaction. One of the popular options in this category is the nanotechnology based chemical sensor. It is portable, and provides high sensitivity and low cost and power needs. Chemical Co2 sensors are valuable in space applications.

Calibrating a Co2 Sensor

Carbon dioxide sensors that measure air quality may need calibration to ensure accurate results. This requires using either outdoor air or a calibration gas. When calibrating with outside air, users must place the device away from objects that release carbon dioxide, such as running vehicles and heavy vegetation. Once the device has been calibrated, it is ready to use.

Top Brands of Co2 Sensors

Several manufacturers make CO2 sensors for various applications. Honeywell is renowned for HVAC sensors that ensure the correct quality of air for air conditioners and ventilation systems. They sell wall-mounted sensors that connect to the HVAC system. These infrared systems measure the air in a duct or an open area.

GE manufactures Co2 sensors for use in residential and industrial applications. They work with HVAC systems, and measure refrigerant in automobiles and commercial refrigeration systems. This company provides a range of products with many of them being self-calibrated. They are often wall-mounted with easy wiring installation. Buyers have the option to choose a water-resistant product for use in specific projects.

Extech makes desktop air quality sensors with NDIR technology. Some items come with warning alerts to let users know when the quality of air is insufficient and carbon dioxide levels are too high. Some of these products calibrate themselves and require almost no maintenance to ensure accurate results.

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