Confined Space Classification Decision Tree

Use this Decision Tree to help you determine if a confined space is a permit-required confined space or a non-permit confined space.

Do You Have Any Confined Spaces in Your Workplace? [ ] Yes [ ] No

Explanation: A space is considered a confined space if:

It’s big enough and so configured that a worker can enter it bodily and perform work inside;
It has limited or restricted means of entry or exit, e.g., tanks, vessels, silos, storage bins, hoppers, vaults and pits; and
It’s not designed for continuous occupancy.

Instructions: If there aren’t any spaces like this in your workplace, the standard doesn’t apply to you and you don’t have to go any farther. But if you do, keep going.

Are any of the Confined Spaces You’ve Identified Permit Confined Spaces? [ ] Yes [ ] No

Explanation: Evaluate the confined spaces in your workplace and classify them as either:

Non-permit confined spaces, i.e., those that don’t contain or potentially contain hazards capable of causing death or serious harm to an entrant which you can allow workers to enter; or
Permit confined spaces, i.e., spaces that do contain actual or potential hazards that require additional safety measures to prevent entry or ensure it’s safe. To be considered a permit space a confined space must have at least one of the following characteristics it/its:
- Contains or potentially contains a hazardous atmosphere, i.e., one that may cause death, incapacitation or impairment of self-rescue including:
  - Flammable gas, vapor or mist above 10% of its lower flammable limit (LFL);
  - Airborne combustible dust at a concentration at or above its LFL
  - Oxygen concentration of below 19.5% or above 23.5%;
  - Concentration of a substance above or potentially above its Permissible Exposure Limits (PELs) or dose limit; or
  - Any other atmospheric condition immediately dangerous to life or health (IDLH).
- Contains a material that could engulf an entrant;
- Configuration could result in trapping or asphyxiating an entrant by inwardly converging walls or a floor that slopes downward and tapers to a smaller cross-section; or
- Contains any other recognized safety or health hazard.

Instructions: If you have only non-permit spaces, skip Section 3 and proceed to Section 4 of the Assessment. If you have permit spaces, go to Section 3.

If You Have Permit Confined Spaces, Have You Implemented the Proper Safety Measures? [ ] Yes [ ] No

Explanation: You have 2 options for dealing with permit spaces:

Seal them off so that nobody can enter them; or
If you allow entry, implement a confined spaces entry program to ensure safety measures are taken before and during each entry.

Instructions: Use the 10 Steps to Creating a Confined Space Entry Workplan to find out what safety measures are required and how to implement each of them.

Do You Reassess and, if Necessary, Reclassify Confined Spaces? [ ] Yes [ ] No

Explanation: The rules vary depending on how the confined space is currently classified.

Confined Spaces Currently Classified as Permit Spaces: If workers enter any confined spaces you classified as non-permit confined spaces, reassess the confined space when there are changes to the configuration of the confined space or the work done inside it. You then must decide based on the reassessment whether to reclassify the non-permit space as a permit space.
- Don’t reclassify the space as a permit space if it still doesn’t contain or have the potential to contain hazards of death or serious bodily injury to entrants.
- Reclassify the space as a permit space if you determine that the confined space contains or has the potential to contain hazards of death or seriously bodily harm upon entry. In this situation, you must immediately bar entry unless and until you establish a confined spaces entry program for the space.
Confined Spaces Currently Classified as Non-Permit Spaces: A permit space can be reclassified as a non-permit space if you can demonstrate that entry hazards, including hazardous atmospheres have been eliminated. You must create written certification documenting the basis for this determination that lists.
1. The date
2. The location of the space
3. The signature of the person making the determination