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4.2 Confined Spaces
The first step to a safe entry is to recognise that the space is dangerous. OSHA defines a confined space as one that is large enough for a worker to enter and do the job, has limited or restricted means of entry or exit, and is not designed for continuous occupancy.
- A non-permit confined space has no hazard that could cause death or serious physical harm.
- A permit-required confined space is a confined space with one or more of these features:
1. It contains, or could contain, a hazardous atmosphere. 2. It contains a material that can engulf an entrant. 3. Its inside shape could trap or suffocate an entrant, for example walls that converge inward or a floor that slopes down to a smaller section. 4. It contains any other recognised serious safety or health hazard.
Key terms
| Term | Meaning |
|---|---|
| Acceptable entry conditions | The conditions that must exist in the space for entry to be safe. |
| Attendant | A person outside the space who monitors the authorised entrants and carries out the duties in the permit space program. |
| Authorised entrant | A worker whom the employer authorises to enter. |
| Entry supervisor | The person responsible for the entry, who decides whether to start or end it. |
| Entry permit | The written document that allows and controls entry. |
| Emergency | Any event inside or outside the space, including a failure of controls or monitoring, that could endanger entrants. |
Hazards in a confined space
- Atmosphere. OSHA names four hazardous atmospheres: oxygen deficient, flammable, toxic, and irritant or corrosive. Most confined space deaths and injuries come from asphyxiants, flammables and toxics.
- Configuration. Poor ventilation lets gases and vapours collect. Test near the bottom of the space as well, because gases heavier than air settle in the low areas.
- The work itself. Scraping, painting, sanding, and welding or brazing with certain metals can produce toxic vapour, and some cleaning and degreasing solvents give off highly toxic vapours.
- Outside sources. Fumes from nearby work can drift in. Continued exposure to an irritant may dull a person's sense of it, so they do not notice that exposure is increasing.
- Physical hazards. Extreme heat or cold; engulfment by loose granular material, one of the most common physical hazards; noise that is amplified and makes communication difficult; wet surfaces and sloping floors that cause falls; and falling objects at top openings.
- Mechanical hazards. Rotating or moving equipment and energy sources inside the space must be identified.
What OSHA requires
- The employer must evaluate the workplace to find permit-required spaces and tell all employees of their existence, location and danger. Danger signs at entrances are used for this.
- If a space is too dangerous to enter, the employer must take effective steps to keep employees out.
- If entry is necessary, the employer must have a written permit space program, available to employees.
- Before entry, the entry supervisor completes and signs an entry permit, which confirms that all preparations are done and that the space is safe. The permit is posted at the entrance or made available to entrants.
- Everyone who works in a permit space must be trained so that they can recognise hazards and carry out their duties.
- Entrants, attendants and entry supervisors each have duties set out in the standard.
Rescue
The employer must make sure that rescue people are trained and equipped, have the same training as authorised entrants, and are trained and certified in first aid and CPR. OSHA advises practice rescues every year, with rescuers entering the space, and rescuers should know all the hazards of the space.
A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.