What is the best kind of gas detector to use in confined spaces?

By Chad Schmidt | Last updated: June 5, 2024

It can only take seconds to succumb to a hazardous atmosphere in a confined space. That’s why investing in high-quality gas detectors is one of the most important steps you can take to protect workers. But selecting the appropriate monitor for a confined space isn’t a piece of cake; it depends on the space being entered and the type of work being performed.

Unfortunately, there is no one type of gas detector I can recommend to fit every situation. You need to carefully review the needs of your workers and pick the best detector for your confined space.

(Learn more in Working in Confined Spaces? You Need the Right Training)

With a wide variety of products to choose from, let’s take a look at the features you must consider when selecting a gas detector for used in confined spaces.

Sensor Selection

You must know what you need to measure before you can decide on a detector. If you don’t have an idea of the risks your workers face, it’s time to conduct a hazard assessment.

The types of sensors on your chosen detector should reflect the known and possible atmospheric hazards posed by the confined space it will be used in. Every confined space gas detector must, at the very least, have Hydrogen Sulfide (H2S), Lower Explosive Limit (LEL), Carbon Monoxide (CO), and Oxygen (O2) sensors.

For confined spaces where a specific gas is common, you may want to consider substance-specific sensors. These are available for a wide range of gases including:

For confined spaces where contaminants can vary widely (e.g., in sewers), using both a chemosorption (MOS) sensor that responds to a wide range of contaminants and several substance-specific sensors may be the safest approach.

Intrinsically Safe

Most instruments are classified for intrinsic safety. This means that their design prevents the possibility of ignition. While many devices are certified for use in Class I hazardous locations, some confined spaces require devices carry the classification for use in Class II locations, as well. Class II groups refer to “combustible dusts” and may be necessary for applications like in grain silos.

Ease of Operation

If a device is too complicated for a worker to easily use, it will likely be neglected. Gas detectors should be simple and straightforward. Confined spaces often have little room to maneuver in, so it’s critical that workers can use the device without adjusting settings or trying to figure out how to use complex features.


Confined spaces can be dark and noisy, so it’s essential that gas detector alarms be sufficient to get the attention of the user – this means loud and highly visible. Look for buzzers, flashing lights, explanatory messages, and built-in vibrator alarms.


Taking the above factors into consideration, infrared sensors are often a good choice for use in confined spaces. These instruments consist of a gas cell through which infrared radiation passes, thereby allowing an atmosphere to be tested somewhat remotely. Since infrared sensors cannot detect hydrogen, some applications may necessitate the use of a catalytic sensor as well.

I highly recommend trying a device prior to purchase. While performance information and feature descriptions are helpful, nothing truly replaces trying a gas detector out under similar conditions to the ones where it will be used.

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Written by Chad Schmidt | Business Development Manager - Western Canada

Chad Schmidt

Please check out my Professional Profile here. This is where you can see all the other content I've written.

I moved from Saskatoon to Edmonton in 1997 for an education and what I thought would be a quick pit stop on route to a life golfing in Kelowna. Priorities changed when I met my beautiful wife of 16 years, and proceeded to have 2 incredible children.

What also changed is my desire to succeed in the business world. I now have over 13 years in the very dynamic industry of outside sales. I have learned both in my personal and professional life that honesty, integrity, and patience are extremely important to have sustained success. I am a consultant who is focused primarily on making my clients job as painless as possible by helping them find solutions that best fits their organization.

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