How To Choose A Confined Space Gas Monitor

The main aim of a gas monitor is to protect workers’ lives, and confined spaces may contain dangerous toxic and flammable gases.

It is very important to select the right confined space gas monitor; I share how to do so in this post.

What is a Confined Space?

A confined space is an area that’s not easy to enter or escape. There are limited ways to access confined spaces, and while they are appropriate sizes and configurations for employees to enter, they are not intended for continuous or long-term occupancy.

Why do we need a gas monitor before we enter into the confined space?

Confined spaces can potentially contain hazardous atmospheres and materials that can endanger workers’ lives.

The workers could be trapped, intoxicated, or asphyxiated, and other recognized health and safety risks. Entering and working in confined spaces requires additional safety measures.

What is the gas test in a confined space?

Oxygen, Hydrogen Sulphide, Carbon Monoxide, and Flammable gases or vapors are common in confined spaces.

Before entering a confined space, it is important to assess the atmosphere of space.

The assessment includes testing the atmosphere for oxygen, flammable gas, vapor or mist, combustible dust, or other hazardous atmospheres.

How to choose the right confined space gas monitor

When choosing the right confined space monitor, consider the gases you will detect, whether the monitor has a pump or diffusion one and whether it has sampling accessories.

The gases to be detected 

The most common gases in confined spaces are Hydrogen Sulphide (H2S), Carbon Monoxide (CO), Flammable gases and vapors, and Oxygen depletion.

I recommend choosing a monitor which will detect the following gases.

  1. LEL for flammable gases.
  2. CO for Carbon Monoxide.
  3. H2S for Hydrogen Sulphide.
  4. O2 for Oxygen depletion.

In some confined spaces, you might find Volatile Organic Compounds (VOC) or Ammonia (NH3).

In such cases, you might need a unit to detect the first gases and a PID sensor for VOC or NH3.

A built-in pump

There are two ways the gas monitor works: by diffusion, aka the monitor is passive and waits until the gases diffuse on the sensor plate so that it can detect them, or the active one that has a pump that can be used to draw the gas from a distance towards the monitor.

For confined spaces, I recommend choosing a monitor with a built-in pump so that you can sample the gases before entering the spaces.

If you already have the diffusion one, you can ask the manufacturer if they have a manual pump that can work with your unit.

Sampling accessories

Some confined spaces are deep, so you will need a sampling kit to detect gases from that deep. I recommend picking the monitor with a sampling hose of at least 20 ft.

What type of gas monitor should be used for confined spaces?

The BW MAX XT II confined space gas detector is the ideal, compact solution for monitoring confined space gases.

The confined space gas detector was designed to monitor the following gases simultaneously.

Gas Measuring range  Resolution
H2S 0-200 ppm 1 ppm
CO 0-1000 ppm 1 ppm
O2 0-30% Vol 0.1 %Vol
Combustible Gases 0-100 %LEL 1 %LEL

You can buy the Max XT II from any Honeywell distributor, or you can buy it on Amazon.

confined space

When is the right time to test the confined space?

Testing must be done less than 20 minutes before the worker enters the space and repeated if the space has been vacated for more than 20 minutes.

When should I calibrate the confined space gas monitor?

It depends on the manufacturer; most recommend calibrating it at least once per year, but if you are going to get the MAX XT II, Honeywell recommends calibrating it every 180 days.

Gas Detector Calibration

When should I bump-test the confined space gas monitor?

You should perform a functional test or bump test each day before using the monitor.

Before you use it, perform a quick bump test; if it passes, continue using it, and if it fails, perform a full calibration.

What Is A Bump Test In Gas Detection?

Final words

Confined spaces can contain toxic and flammable gases. It is important to choose a monitor that can detect those gases.

Pick the monitor with a built-in pump and sampling capabilities and draw the gas at least 20 ft.

I recommend BW MAX XT II from Honeywell, but any monitor with those characteristics should help you assess the confined space.

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