Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety
IN THIS ISSUE: Airline Respirators
When working in hazardous atmospheres for extended periods of time airline respirators are often the best choice to assure employee safety. OSHA defines these devices as atmosphere-supplying respirators, which allow users to breathe air from a source other than the ambient air in which they are working. They also include self-contained breathing apparatus (SCBA).
SCBAs have the highest assigned protection factor (APF) in the pressure-demand mode of 10,000 and can be used in Immediately Dangerous to Life and Health (IDLH) atmospheres. They have tanks that are rated for 30, 45, or 60 minutes but can be drained more quickly depending upon the amount of work being performed and the fitness of the individual. Because of their size, they can also inhibit entry into confined spaces with narrow entry openings.
Airline respirators, on the other hand, can have an unlimited supply of air from stationary sources such as tanks or compressors. They can be connected to a hose in lengths of 25 to 300 feet. They are available in demand, pressure-demand, and continuous flow configurations and use a facepiece, helmet, hood, or full-body suit. Airline respirators have an advantage over SCBAs since they have minimal resistance, and are lightweight with minimal bulk. The biggest drawback is that loss of air can be caused by damage to the airline (hose) or a compressor. Accordingly, they do not have an APF as high as an SCBA. If working in a dangerous atmosphere or in a confined space the entrant must have an escape bottle, which typically lasts from five to ten minutes.
Ensuring the quality of breathing air is most important in an airline respirator or SCBA. Compressed air must meet the ANSI/CGA 7-1 requirements for Type 1-Grade D breathing air. It includes:
- Oxygen content of 19.5 to 23.5%
- Hydrocarbon content of 5 milligrams per cubic meter of air or less
- CO content of 10 parts per million (ppm) or less
- CO2 content of 1000 ppm or less
- Lack of noticeable odor.
If a compressor is used to supply air, suitable in-line air purifying sorbent beds and filters must be present to meet the Grade D standard. These devices must be maintained and replaced or refurbished according to manufacture instructions. Several manufacturers offer airline filtration and monitoring systems.
As with any PPE, the employer and/or user must determine whether the choice of respirator will provide the protection needed to do the job and ensure the health of the worker. It is most important that airline respirator users receive specialized training and the equipment is maintained and monitored. All OSHA requirements including work procedures, respiratory cleaning and sanitation, medical monitoring, and fit testing must be met
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