United States
Hong KongConfined space entry
A confined space is large enough to enter, has limited means of entry or exit, and is not designed for continuous occupancy. It becomes permit-required if it has a hazardous atmosphere, engulfment risk, entrapping configuration or another serious hazard.
A category where the rules are strict because the failure mode is so consistent: somebody enters, is overcome, and a colleague goes in after them.
What makes a space confined
Three conditions, all required: large enough for an employee to enter and perform work, limited or restricted means of entry or exit, and not designed for continuous occupancy.
A crawl space, a manhole, a tank, a pit, a sewer. Not a room with a door.
What makes it permit-required
Any one of four additional characteristics.
- A hazardous atmosphere, actual or potential
- Material with the potential to engulf an entrant
- An internal configuration that could trap or asphyxiate
- Any other recognized serious safety or health hazard
Somebody collapses in a space with an oxygen-deficient atmosphere. A colleague goes in to help without testing or equipment and collapses too. This is why an attendant stays outside and does not enter, and it is the most tested principle in the whole topic.
The three roles
| Role | Does |
|---|---|
| Entrant | Enters and performs the work |
| Attendant | Remains outside, monitors, and never enters to rescue |
| Entry supervisor | Authorizes entry, verifies conditions, terminates when required |
The permit
Documents the space, the hazards, the atmospheric test results, the personnel, the equipment and the rescue arrangements. It is canceled when work is complete or conditions change.
Testing order
Oxygen first, then flammable gases, then toxics. Oxygen first because the other readings depend on it and because it is the fastest killer.
Common questions
What makes a space confined?
It is large enough to enter, has limited entry or exit, and is not designed for continuous occupancy. All three.
What makes it permit-required?
A hazardous atmosphere, engulfment potential, an entrapping configuration, or another recognized serious hazard.
Can the attendant enter to rescue somebody?
No. The attendant remains outside, because the rescuer is usually the second casualty.
What order are atmospheres tested in?
Oxygen first, then flammable gases, then toxics.
What are the three roles?
Entrant, attendant and entry supervisor.