How Does a CO2 Detector Work? (2023)

How Does a CO2 Detector Work? (1)

A CO2 detector contains a carbon dioxide sensor that measures the CO2 gas level in the air and sends an electrical signal back to a control and/or display.

The first CO2 detectorwas designed in 1815 to measure carbon dioxide concentrations in the atmosphere. Common applicationsfor a CO2 detector include monitoring indoor air quality, process control, horticulture, food and beverage, and landfills.

How does a CO2 detector measure CO2?

Most modern carbon dioxide detectors usenon-dispersive infrared (NDIR) sensorsthat measures infrared light in a sample of air. This technology is useful as the amount of light that passes through the sample is inversely proportional to the number of carbon dioxide molecules in the air.

As IR light passes through a sample tube of air, the CO2 gas molecules absorb a single band of IR light while letting other wavelengths of light pass through. At the other end of the tube, the remaining light hits an optical filter that absorbs every wavelength of light except the wavelength absorbed by the CO2. The remaining CO2 molecules are counted by an IR detector which sends an analog voltage to the sensor's circuitry. In this way, a carbon dioxide sensor can be said to "count" the number of CO2 molecules in the air.

Learn more about how a CO2 sensor works here.

Do I need a CO2 detector?

Depending on your industry, environment, and use of stored gases, you may need a carbon dioxide detector.

(Video) What Does a Carbon Monoxide Detector Do?

For those that store, produce, or use carbon dioxide - exposure to high levels of CO2 can be fatal. High levels of CO2 can lead to severe negative health effects like headaches, dizziness, fatigue, asphyxiation, and even fatality. Because of injuries in buildings that do not have proper monitoring in place, theOccupational Safety and Health Administration (OSHA) has established a permissible exposure limit (PEL) for CO2 of 5,000 ppm averaged over an 8-hour work day.

Overall, if you are using carbon dioxide and working in or around the gas, CO2 safety detectors should always beused in order to initiate an audible or visual alarm to alert individuals in the room where potential CO2 levels could be dangerous to their health.

CO2 detectors are also used in the home as a measurement of indoor air quality. High levels of CO2 indicate poor air exchange.

Learn more about carbon dioxide detectors in the home.

Is a carbon dioxide detector the same as a carbon monoxide detector?

No. While both carbon dioxide (CO2 detectors) and carbon monoxide (CO detectors) are important when discussing hazardous gases, they are very different. One of the most common misconceptions is that a carbon monoxide detector can detect carbon dioxide, and vice versa. And, while both CO and CO2 gases have a lot of similarities they could not be more different.

The most critical differentiator is that carbon dioxide is natural andnon-flammable,while carbon monoxide is the product of incomplete combustion andflammable.While carbon dioxide can be naturally found in the earth's atmosphere, carbon monoxide is not.

(Video) Carbon Monoxide Detector Functionality

In addition, carbon dioxide detectors use infrared sensors to detect levels of gas in the atmosphere, whereas carbon monoxide detectors primarily use electrochemical sensors as well as gel sensors and metal oxide semiconductors.

Note that the density of both gases is also very different. CO2 is heavier than CO. For this reason, a CO2 detector should be near the floor while a CO detector should be placed near the ceiling to ensure proper detection.

Will a CO2 monitor detect carbon monoxide?

No. A CO2 monitor is not designed to detect the presence of carbon monoxide. Conversely,a CO detector will not detect CO2

A CO detector sounds an alarm if it senses elevated levels of carbon monoxide in the airneara furnace or gas burning appliances.

In addition, both CO and CO2 detectors use different sensing technologies. CO2 detectors oftenuse infrared sensors to detect levels of gas, while CO sensors mainly use electrochemical sensors.

Learn more about the difference between carbon monoxide and carbon dioxide here.

What are signs of CO2 in the house?

While carbon dioxide is in the air naturally, in large quantities (> 1,000ppm) elevated levels can effect your health. For instance, excess CO2 can cause individuals to experience headaches, fatigue, nausea, asphyxiation, or convulsions.

(Video) Understanding Smoke and Carbon Monoxide Detectors | Ask This Old House

Fortunately, being aware of carbon dioxide concentrations in your home can help prevent negative health effects from occurring and create healthier lifestyles.

Here are 4 sources of carbon dioxide in the home and how to lessen their impact:

  1. HVAC systems:HVAC systems are designed to control the atmosphere in a given environment by recycling air. But without proper ventilation, CO2 can build up. A CO2 sensor can warn against this
  2. Fireplace:Carbon dioxide is one of several gases produced by combustion, which means indoor fireplaces can produce gas buildup if they are not ventilated properly. Installing CO2 monitors in your home and annual inspections can mitigate this.
  3. Crowds: Humansexhale approximately 1 liter of CO2 with each breath. More occupants in an enclosed area creates higher CO2 levels. This can be mitigated by opening windows to regulate ventilation and airflow, as well as have indoor air quality monitors in place to measure when CO2 levels exceed normal threshold.
  4. Smoking:CO2 levels in cigarette smoke are 200 times the levels in the atmosphere. Regular smoking indoors can also create consistent overexposure to carbon dioxide concentrations. By ensuring smoking is done outdoors you can be mitigate individual exposure.

Is there a way to check your CO2 levels at home?

How Does a CO2 Detector Work? (3)

By using a carbon dioxide detector or indoor air quality monitor like the Aranet4 HOME you can easily and affordably measure carbon dioxide levels.

These devices also use a quality NDIR sensor that gives the device the ability to quickly measure the amount of CO2 in the air in real-time.

Should levels exceed the normal threshold the device will show instant visual/audible indication so you are alerted to ventilate the space and mitigate from harmful CO2 exposure. When it comes to CO2 levels in a home, many individuals also look to ASHRAEwhich sets standards in place for recommended indoor air CO2 concentrations.

Below we have included a list of CO2 levels perASHRAEto provide guideline when you read your CO2 monitor so you can understand the levels in your home.

(Video) Does your Carbon Monoxide Detector really work?

In summary, ASHRAE recommends that levels in your home be between, maintained at, or below 1,000ppm in schools and 800ppm in offices.

Here are 3 benefits to improving indoor air quality with CO2 monitoring:

  1. Occupant Comfort-By utilizing an indoor air quality monitor, you can eliminate potential contaminants that directly influence poor IAQ. This includes CO2, CO, and particulate matter (PM2.5/10).
  2. Increase in Productivity-Studies have shown, that with less CO2 buildup many people find that they gain back productivity, focus, and energy - three main areas where poor indoor air quality often influences.
  3. Energy Efficiency-Utilizing CO2 monitors or CO2 air quality sensors when occupying space can provide you with proper ventilation indicators, making energy costs significantly lower!

Where should C02 detectors be placed?

This depends on your application:

  • Safety - Carbon dioxide detectors should always be placed 12 inches (30cm) off the floor.
  • Indoor Air Quality - Placement is less important, but is typically placed at 36 - 60 inches ( 90-150cm) from the floor.

What makes a good C02 detector?

When it comes to purchasing or selecting your first carbon dioxide (C02) detector there are a few things to keep in mind to ensure the best quality product for your industry or application.

For starters, you want to have a detector that includes quality features and should look at C02 detectors similar to purchasing a car. Not only do you want a quality product, you want an affordable cost, easy operation - and above all else the ability to ensure safety or air quality analysis.

Below are the top 5 features customers look for prior to purchasing any CO2 detector:

  1. Accuracy (including a high quality NDIR CO2 Sensor)
  2. Audible/Visual (instant audible or visual alarms that appear when CO2 levels exceed threshold)
  3. Installation (easy operation and installation procedure with thorough documentation)
  4. Meets Codes/Regulation(a detector that can meet code compliance around CO2 safety or meet specific ASHRAE IAQ standards)
  5. Resolution(clear and easy visual display of CO2 concentrations from a large LCD screen)

For more information on CO2 sensing technologies or to speak to a CO2Meter expert, contact us at or 877-678-4259

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