What Gases Will A Carbon Dioxide Monitor Detect?
At first glance, this might sound like a simple question with an obvious answer, but in reality, it’s something we’re asked surprisingly often.
At Analox, our sales and customer service teams regularly speak with customers who initially believe that an oxygen (O₂) or even a carbon monoxide (CO) monitor will be suitable for a carbon dioxide (CO₂) monitoring application.
Fortunately, those conversations usually end with the customer choosing the correct gas monitoring solution for their safety or gas analysis requirements.
In this blog, we’ll explain:
- The primary purpose of a carbon dioxide monitor
- How carbon dioxide behaves
- The difference between carbon dioxide (CO₂) and carbon monoxide (CO)
- Why using the wrong type of gas detector can create serious safety risks
By the end, you’ll understand why a dedicated CO₂ monitor is essential wherever carbon dioxide is used, stored, or produced.
What Do Carbon Dioxide Detectors Detect?
Put simply, carbon dioxide detectors detect carbon dioxide (CO₂), and nothing else. They are designed specifically to measure CO₂ concentrations and will not detect or monitor other gases.
This distinction is important because people sometimes use the wrong type of detector for certain gas hazards, which can create serious safety risks for those working in those environments.
Recently, an Analox employee discovered a carbon monoxide (CO) monitor being used where carbon dioxide monitoring was required. This is extremely dangerous because a CO monitor cannot detect CO₂. Fortunately, the issue was identified and corrected before it could lead to harm.
Why Is Carbon Dioxide Detection So Important?
Carbon dioxide is a hazardous gas that cannot be detected by human senses, you cannot see it, smell it, or taste it. This means CO₂ can build up in an area unnoticed until concentrations become dangerous.
When carbon dioxide leaks from a gas cylinder, it is denser than the surrounding air and will settle at low levels first. This is why fixed CO₂ sensors should typically be installed around 12 inches (30 cm) above floor level and positioned as close as possible to potential leak sources such as gas cylinders.
Correct sensor placement allows leaks to be detected early, before CO₂ concentrations rise into occupied breathing zones.
Carbon Dioxide Safety Tips
Carbon dioxide naturally occurs in the atmosphere at around 0.04%, but concentrations can rise quickly in enclosed or poorly ventilated environments. Even relatively small increases can begin to affect the body.
To help reduce risk, follow these key CO₂ safety practices:
- Install CO₂ monitors in areas where carbon dioxide is stored or used
- Ensure adequate ventilation in enclosed spaces
- Position sensors low to the ground, as CO₂ is more dense than air
- Regularly maintain and calibrate gas detection equipment
- Train personnel to understand the risks of CO₂ exposure
Be aware of the signs of elevated CO₂ levels, which may include:
- Nausea
- Vomiting
- Dizziness
- Headaches
- Rapid breathing and increased heart rate
- Confusion
- Loss of consciousness
Is CO₂ and Carbon Dioxide the Same Thing?
Yes. CO₂ and carbon dioxide are the same thing. CO₂ is simply the chemical formula for carbon dioxide and is commonly used as a shorthand name.
The science behind it is straightforward: one molecule of carbon dioxide is made up of one carbon atom (C) and two oxygen atoms (O₂), hence the formula CO₂.
How Can You Tell if You Have a CO₂ Leak?
CO₂ cannot be detected by human senses, you cannot smell it, taste it, or see it. The most reliable way to identify a leak is by using a dedicated carbon dioxide monitor.
CO₂ is classified as a substance hazardous to health by organizations including the Health and Safety Executive (HSE), which is why effective monitoring is so important.
Although carbon dioxide is naturally present in the air at very low concentrations, elevated levels can quickly become harmful and, in some situations, fatal.
There are various types of CO₂ monitors available, including portable and fixed systems, which use a range of gas sensing technologies such as:
NDIR - Non-Dispersive Infrared Sensing
NDIR (Non-Dispersive Infrared) sensing is a gas measurement technique that detects specific gases using their unique infrared absorption wavelengths.
In CO₂ monitoring applications, NDIR sensors identify and measure carbon dioxide concentrations by analyzing how CO₂ absorbs infrared light within a defined wavelength range.
GFC - Gas Filter Correlation
Gas Filter Correlation (GFC) is a specialized gas sensing technique designed to detect highly specific gas properties with excellent selectivity.
In simple terms, the analyzer is configured with the unique characteristics of CO₂, allowing it to monitor specifically for carbon dioxide while minimizing interference from other gases.
This helps filter out unwanted gasses and provide an even more safe and accurate measurement.
If you want to learn more about the different CO₂ sensing techniques visit our carbon dioxide detection page where we have more information on this subject.
Are Portable and Fixed CO₂ Detectors the Same?
At a basic level, portable and fixed CO₂ monitors perform the same function. Both continuously monitor carbon dioxide levels in ambient air and detect rising CO₂ concentrations that could become harmful or potentially fatal.
Both types of detector can trigger audible and visual alarms, such as sounders, LEDs, or beacons, to warn personnel of a potential carbon dioxide leak.
The main differences relate to how and where the monitors are used, depending on the specific application and level of protection required.
Fixed and Portable CO₂ Detectors
Fixed CO₂ detectors are designed to continuously monitor specific areas where carbon dioxide is stored or used, such as breweries, pubs, laboratories, and gas storage rooms.
Portable CO₂ monitors provide personal protection for personnel entering or moving between environments where CO₂ may be present. Typical users include gas delivery drivers, maintenance engineers, and personnel visiting multiple gas storage sites. Portable units are especially useful when workers cannot guarantee that fixed gas monitoring systems are already installed.
Both fixed and portable detectors use audible and visual alarms to warn users of rising CO₂ levels. Some portable devices, such as the Analox CO₂BUDDY personal monitor, also include vibrating alarms for use in noisy environments where hearing protection may be worn.
Fixed and portable systems each offer different features and advantages, making them suitable for different CO₂ monitoring applications.
Fixed CO₂ Monitor Features
- 4–20 mA output to trigger ventilation fans and help disperse CO₂ buildup
- Gas shut-off valve integration to isolate gas supply in the event of a leak
Connection to Building - Management Systems (BMS) using a Data Output Module (DOM) on the Ax60+ system
- Additional visual alarms and beacons for high-noise environments where audible alarms may be missed
Portable CO₂ Monitor Features
- Designed to be worn by personnel using belt clips and lanyard attachments to keep the monitor close at hand
- The Analox CO₂BUDDY can be calibrated onsite, removing the need to return the unit for calibration servicing
Is a Carbon Monoxide Detector the Same as a Carbon Dioxide Detector?
No. A carbon monoxide (CO) detector is not the same as a carbon dioxide (CO₂) detector. They monitor two completely different gases and use different sensing technologies.
Because the names sound similar, these gases are often confused. However, a carbon monoxide detector cannot detect carbon dioxide, and a carbon dioxide detector cannot detect carbon monoxide. Using the wrong type of detector can allow dangerous gas concentrations to go unnoticed, potentially putting people at serious risk.
The main similarity between the gases is that both can be hazardous and neither can be detected by human senses such as sight or smell.
More About Carbon Monoxide
Carbon monoxide (CO) is a toxic gas produced during the incomplete combustion of fuels, usually where there is insufficient oxygen present.
Symptoms of carbon monoxide poisoning can include:
- Headaches
- Dizziness
- Nausea or sickness
- Weakness
- Confusion
- Shortness of breath
These symptoms often worsen the longer a person remains in the affected environment.
If I Use Nitrogen, Should I Use a CO₂ Detector?
No. Nitrogen monitoring requires an oxygen (O₂) monitor, not a carbon dioxide (CO₂) detector.
Nitrogen is an inert gas, meaning it does not readily react with other substances. However, nitrogen can displace oxygen in the air if a leak occurs, creating a serious oxygen depletion hazard.
Because of this, areas where nitrogen is stored or used should be protected using an oxygen monitor designed to detect unsafe O₂ levels.
However, if both nitrogen and carbon dioxide are present, such as in pub cellars, laboratories, or industrial gas storage areas, a dual-gas monitoring solution is recommended. In these environments:
- CO₂ sensors detect toxic carbon dioxide buildup
- O₂ sensors detect oxygen depletion caused by gases such as nitrogen
It is important not to rely on an oxygen monitor alone to identify CO₂ leaks. Dangerous CO₂ concentrations can affect the body long before oxygen levels fall enough to trigger an O₂ alarm.
Learn more about our CO₂ monitoring solutions or explore our O₂ gas detection systems to find the right protection for your application.
Key Takeaway
If you are storing or using carbon dioxide, you should use a dedicated carbon dioxide detector. Analox offers a range of portable and fixed CO₂ monitoring solutions designed to suit a wide variety of safety applications.
If you need advice on selecting the right gas detection solution for your environment, please get in touch. Our team will be happy to help you identify the most suitable monitoring system for your application.