SCBA & Supplied-Air Respirators
Filter respirators clean the air around you. They cannot help where there is too little oxygen or the air is immediately dangerous. For those cases, workers use respirators that bring clean air from another source.
- Respirator Users
- Confined Spaces
- Emergency Response
Two main types
- Self-contained breathing apparatus (SCBA): the wearer carries a cylinder of compressed air on their back. It is used for emergency entry, firefighting and short high-hazard jobs. It gives freedom to move but only limited time.
- Supplied-air respirator (SAR, airline): clean air comes from a compressor or cylinders through a hose. It lasts as long as the supply and is common in abrasive blasting, painting and confined spaces. Some have a small escape bottle.
When they are required
- In oxygen-deficient atmospheres (below 19.5 percent oxygen).
- In atmospheres immediately dangerous to life or health (IDLH), or where the contaminant level is unknown. IDLH work needs a full-facepiece pressure-demand SCBA, or a combination SAR with an escape bottle (29 CFR 1910.134(d)).
- Where the exposure is too high for an air-purifying respirator.
- Some jobs, like abrasive blasting, require a supplied-air hood or helmet.
Air quality
- Breathing air must meet Grade D specifications, from CGA G-7.1: for example, 19.5 to 23.5 percent oxygen, very low carbon monoxide and limited oil mist.
- A compressor must have air-purifying filters and a carbon monoxide monitor or high-temperature alarm if it is oil-lubricated. Never use plant air that is not tested.
- Do not connect SAR hoses to oxygen or other gas lines.
Requirements before use
- A written respiratory protection program
- Medical evaluation and a fit test for tight-fitting facepieces
- Training on the equipment, its limits, donning and emergency use
- Inspection before each use and after cleaning: cylinder gauge, hose, regulator, alarms, facepiece
- Know the cylinder duration and end-of-service alarm; leave before the alarm sounds
- A standby person for IDLH entry, with rescue ability
Warning: Facial hair that breaks the seal makes a tight-fitting mask unsafe. See Beards & Respirators. Supplied-air hoods without a tight seal do not need a fit test, but still need training and clean air.
Standards & references
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