Jose always sang during work hours. Although no one could tell what Jose was singing about, his musical improvisations were a welcome sound echoing through the mine. Then one day, just a few hours after lunch, Jose stopped. The unsolicited silence prompted one miner to check on Jose. What he found was startling. Jose was lying motionless on his side, unable to move or breathe. In an instant, tools were dropped and the miners ran for the exit. No one tried to resuscitate Jose or help him to safety. He was left to his fate in the mine.
You can relax. Jose was a sentinel canary. His sole job was to provide miners with an early warning of harmful gas buildup. Like it or not, canaries sacrificed themselves to save the lives of countless miners well into the 20th century.
Nowadays, electronic gas detectors have replaced canaries and mines have been defined by OSHA as permit-required confined spaces. But technically speaking, what is a confined space? And what is a permit-required confined space? Keep reading. You are about to get a straightforward definition for both.
Let’s start with confined spaces
According to 29 CFR 1910.146(b), if three conditions are true, your space is a confined space:
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The space must be large enough for an employee to completely enter it. Placing a bucket over your head does not put you in a confined space, but crawling into the basement does.
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The space must have limited or restricted means for entry or exit. Hiding out in the restroom at work does not mean you are dodging work in a confined space, but going to the extreme of crawling into the attic does. It also means you have some real work-avoidance issues.
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The space in question must not be designed for continuous occupancy. A ship’s ballast tank is a confined space for obvious reasons, but a submarine is not. This is because a submarine is designed for continued occupancy, while you won’t find human-centric accommodations in the ballast compartment of an oil tanker.
When do they become permit-required confined spaces?
Much like the saying, “all apples are fruit, but not all fruit are apples”, not all confined spaces qualify as permit spaces. For an area to be considered a permit-required confined space, all of the above criteria must be true as well as one of the following:
The space may contain potentially hazardous atmosphere such as carbon monoxide or other dangerous gasses.
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The space contains material that may engulf an entrant. This can be a liquid or solid. If there is a substance that can fill or plug the respiratory system, this is an engulfment hazard. The risk of capture, constriction or crushing is also considered engulfment. Note that the leading cause of death associated with grain silos is suffocation from engulfment.
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The area has walls that converge inward or a floor that slopes downward, tapering into a smaller area. Wood shaving hoppers fit this description perfectly.
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It may contain other serious hazards. This last point covers everything else hazardous. Charged electrical wires or unprotected machinery would be an example of this broad category.
Example scenario
Now that we have the technical stuff out of the way, let’s take a look at a real life confined space scenario.
Grain silo
A grain silo meets the criteria for being a permit-required confined space. When an employee must enter a grain silo, the following precautions must be in place.
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Because this is a permit-required confined space, the employer must issue a permit to the employee certifying that all applicable precautions (see below) have been implemented. This permit must be issued in each instance where the employee must enter the silo.
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Turn off and lock-out all equipment inside the silo. Remember that the auger may create a suction that can engulf the worker in a matter of seconds.
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Sample and monitor the air inside the silo before entry. Perform this monitoring with the Gas Alert MicroClipXT. It is a compact monitor that measures O2, CO, H2S and LEL.
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If the atmosphere inside the silo is not safe, one option is to ventilate the space until it is within safe limits. Facilities with silos may keep ventilating equipment on site for situations like this. You should use a ventilator that features an explosion proof motor on a grain silo. Conductive hose will also prevent the dangerous buildup of static electricity during ventilation
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Post an observer to continually monitor the entrant while inside the silo. Reliable communication, such as a two-way radio, between the observer and entrant must be provided.
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The entrant will need to wear a body harness and be attached to a personnel hoist to ensure that he can only sink waist high in grain. The Pelsue PH07C hoist not only meets this need but also allows an attendant to hoist the entrant to safety if needed. This kind of rescue is called a “non-entry” rescue because the attendant can retrieve the entrant without entering the confined space himself.
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Once work is completed in the silo, the permit must be revoked.
Each confined space needs to be evaluated by an employer to determine if it is a permit space. This will dictate how entry into these spaces will be handled. Organizing proper communication, training, permitting and contingency planning takes attention to detail and a commitment to employee safety. It is, however, well worth the effort to ensure that everyone goes home safe at the end of the day. To dive into the specific requirements for permit-required confined spaces, check out 29 CFR 1910.146(b). Be safe!