construct, factory, machines
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October 16, 2019 |
Fire & Safety
CONFINED SPACES AND CONFINED SPACE VENTILATION
WHAT IS CONFINED SPACE?
- An area large enough for an employee to enter and perform work.
- Has limited or restrictive means of entry or exit.
- Is not designed for continuous human occupancy.
PERMIT-REQUIRED CONFINED SPACE
- Contains, or has the potential to contain, a hazardous atmosphere.
- Contains material with the potential for engulfment.
- Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging wall, or a floor which slops and tapers to a smaller cross-section.
TYPICAL CONFINED SPACES
- Storage tanks
- Pump waste wells
- Degreasers
- Manholes
- Tunnels
- Underground vaults
- Boilers
- Railcar tanks
- Silos
- Vessels
- Grain elevators
- Mixers
- Water tanks
- Bottom access enclosures
- Chemical process tanks
- Centrifuges
WHAT MAKE S CONFINED SPACE DANGEROUS?
- By-products of previously stored or processed materials and/or chemicals
- Accidental leaks or spills
- Chemical reactions
- Oxidation
- Mechanical operations
- Atmospheric hazards
ATMOSPHERIC HAZARDS
Atmospheric hazards are often the most dangerous hazards in confined space work. An atmosphere which exposes the employee to risk of heath, incapacity, injury and/or acute illness can result from any of the following:
- Oxygen deficiency, below 19.5%.
- Oxygen enrichment, above 23.5%
- Flammable or combustible gases and/or vapors.
- Dusts that obscures vision at 5 ft. or less.
- Any IDLH atmosphere, poses immediate threat to life or severe health effects which could impair escape.
HAZARDOUS ATMOSPHERE ONLY CONFINED SPACE
If the only hazard posed by a confined space is an actual or potentially hazardous atmosphere, and it can demonstrated that forced air ventilation alone is sufficient to maintain a safe atmosphere, then the full requirements of a Permit-Required Confined Space do not have to be met.
The air must be monitored before and during the occupation of the confined space –
Oxygen content (19.5% – 23.5%)
Flammable gases and vapors (less than 10% LEL)
Potential toxic air contaminants (less than PEL)