Confined spaces

Responding is John Onuska III, training specialist, Industrial Scientific Corp., Pittsburgh.

Although confined spaces can be found in a variety of applications, identifying them can be a challenge. By nature, confined spaces constitute hazards: Atmospheric hazards (in that certain gases will displace breathable air); toxic hazards (with the accumulation of flammable materials); and physical hazards (in that confined spaces limit the ability to avoid contact with electricity, moving mechanical components or unstable substances).

Per OSHA, a confined space is large enough for an employee to enter fully and perform assigned work, is not designed for continuous occupancy by the employee, and has a limited or restricted means of entry or exit.*

As you walk through most facilities, you will see signs designating the confined spaces. Some simply say “confined space,” while others read “permit-required confined space.” Permit-required confined spaces are defined as having one or more of the following characteristics:

• Contains, or has the potential to contain, a hazardous atmosphere
• Contains a material with the potential to engulf someone who enters the space
• Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross-section

But what about those spaces that aren’t clearly marked as confined spaces? Storage tanks, sewers, boilers, manholes, ship voids, tunnels, silos, vats and wells are things that we commonly consider confined spaces. But there are also trenches on a worksite and pits used to house control valves. Such areas can contain many hidden dangers. Just because it isn’t marked as a confined space doesn’t mean that you shouldn’t exercise caution prior to entering it.

When you’ve identified a confined space or even an area you believe has the potential to be a confined space, you want to test the area appropriately before you go in and make sure that you perform continuous monitoring to keep yourself safe. Always remember that the gases within confined spaces will have their own molecular weight and will be found at different levels. That is why it is important to test the top, middle and bottom before entry is made.

Also, don’t get tunnel vision to get the job done quickly. It is just as important to get the job done safely. After reading this, I hope that the next time you walk down the street and take a look around, you see a few confined spaces you might not have noticed before.

*Source: OSHA OSHA3138-01R2004

Editor's note: This article represents the independent views of the author and should not be construed as a National Safety Council endorsement.