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Gas monitor styles and knowing when to use them

Jul 7, 2017 8:49:00 AM / by Quad City Safety

Worker crouching over an open manhole holding a gas monitor

What kind of gas monitor do I need for my confined space?

You know there are areas that are high risk for workers, especially in the construction industry.We’re going to tackle them all and give you the information that workers need to stay safe, but today let’s zero in on the gas monitoring requirements for confined spaces.

Let’s cover the basics really quick. Any time you have to enter an area that isn’t made for long-term human occupancy, has limited access or egress, or the area has the potential for oxygen deficiency or toxic gases—you are in a confined space. Chemical plants, paper mills, refineries, gas underground mines and utility passageways are just a few places workers can find combustible or toxic gases.

Want a few examples of confined spaces?

  • Restricted entry or exit
  • Trenches
  • Vats
  • Ditches
  • Silos
  • Tunnels
  • Underground electrical vaults
  • Inside of boilers
  • Wells
  • Storage tanks
  • Manholes
  • Culverts
  • Cold storage

    confined space calibration and bump testing video

Alright, you get the picture now. So, what the heck are we trying to avoid in confined spaces?

Well, for starters, you need to make sure a worker isn’t entering or digging in a place where they can be overcome by invisible killers. Toxic gases or a shortage of oxygen is serious and the reality is that a worker may not come out alive. Whether the risk is asphyxiation, fire or explosion, it’s important to regularly and continuously monitor these areas for the presence and concentration of gas. There is a reason why confined spaces are dangerous and you need to take more than the minimum precautions to be safe.

One of the biggest mistakes that people make is thinking that they can tell if there is a deadly gas present based on a smell. OSHA says the only way to safely detect a hazardous atmosphere is with a “calibrated direct reading instrument”. Some gases have a paralyzing effect on your senses. Imagine making a safety decision that way. Can we say HR nightmare?



We aren’t just talking rural, out of the way areas either. Think about urban areas like New York City for a second. You think your shnoze is going to pick up on a gas leak in a manhole? Get real. You are likely going to catch a whiff of a dirty water dog long before you have a chance to stop the manhole explosion that happens every so often in the city.

Atmospheric Testing of Confined Spaces OSHA 29 CFR 1910.146 (c): Know the atmospheric conditions of your worksite!

  1. Oxygen content: The most common cause of death from atmospheric hazards in a confined space is due to asphyxiation from lack of oxygen. It’s also important to remember that too much oxygen can also have its own risks, as well.

  2. Flammable gases and vapors: Here’s just a few!
    1. Ammonia (NH3)
    2. Carbon monoxide (CO)
    3. Chlorine (CI)
    4. Hydrogen cyanide (HCN)
    5. Hydrogen sulfide (H2S)
    6. Methane (CH4)
    7. Nitric oxide (NO)
    8. Sulphur dioxide (SO2)
  1. Potential toxic air contaminants: Any unsafe levels of contaminants that could cause illness or injury to the worker’s health

Know the difference in gas monitor styles!

Portable: These guys can be designed for single or multiple gases and can be placed right on the worker so that they can be sure they aren’t entering a danger zone. Some of these devices are paired with tracking devices and software that can help safety manager instantly know of changes in gas status

Transportable: These devices are used for area monitoring that can continuously check for changes in the presence of gases or oxygen levels. Similar to portable monitors, in that they are lightweight and can run off batteries

Fixed: These bad boys can detect gas before workers are sent in to a potentially dangerous area. Mounted within an enclosed area, they have alarm capabilities, dependable sensors and transmitters. They can be configured for specific gases

Single Gas: Pretty self-explanatory. Designate these gas detectors to monitor a specific known gas or oxygen concentration. Single gas detectors are useful when you only need to monitor one gas

Multi-gas: With unknown or multiple hazards, a multi-gas detector is best. Measure multiple gases simultaneously following this sequence: Oxygen, combustible gases and toxic contaminants

Calibration systems: When you want to take human error out of the equation, these babies are what you need. They help safety managers by calibrating gas monitors, charging batteries, record keeping, create reports and communicate the results.

Bluetooth capability: Yep, that finally happened. Now, information can be relayed from the front-line worker to a remote host controller and back again. Now companies can have wireless connections without the expense of a private network. Apps and smartphones can also now help with constant visibility.

Click here to find out why gas detector calibration is king!

Reality can be more frightening than fiction

Want to hear a true story from the mid 70’s about an oil and gas facility in Texas? This company pumped gas into a well in the attempts to force out more oil. The gas contained about 40,000 parts per million (ppm) of hydrogen sulfide. The weather conditions that day allowed the gas to concentrate along the ground and travel. The gas killed 9 people that day, eight of which were at a farm about 150 yards from the well. It happened so suddenly, the victims had no chance at survival.

H2 S is one of the most deadly gases and can kill at small doses, stopping a person’s breathing and rendering them unconscious in seconds.

And they couldn’t smell it coming for them. This isn’t the only story, there are many, many more. Even though there have many regulations put in place over the years, workers need to constantly be on the lookout for dangerous levels of gases. And bosses need to track the exposure levels their workers have had over time.

Confined spaces aren’t the place for workers to “learn as they go”. Make sure workers are trained to know the dangers of confined spaces and give them the equipment they need to get the job done.


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Safety: It’s Your Life, It’s Our Business

Topics: Gas Detection, Confined Spaces

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