The required breathing air quality for industrial application is stated in EN12021. This page is intended to provide information on the safe limits of potential contaminant gases within breathing air and to ensure that the life support gas of oxygen is of an adequate level.
Compressed air for breathing normally originates from a compressor system installed or operating at the place of use and there are various factors that can affect the quality and safety of this air.
- The air intake to the compressor can ingest airborne contamination from localprocesses and vehicle exhaust fumes which are not removed by standard breathingair filtration. Such air borne contamination may not be continuous but the pollutionof the air supply may persist for hours or days.
- Malfunctioning compressors, especially reciprocating type, can produce unsafelevels of both carbon monoxide and carbon dioxide.
- Breathing air filtration has a finite life and can fail causing high levels of oil and watercontamination to be present in the air.
- The performance of desiccant filters is dramatically affected by operatingtemperature. Infrequent validation may result in poor quality air being supplied foran extended period
- Failure of the compressed air aftercooling will result in air entering the filtration attoo high a temperature, this will cause the filtration to prematurely fail and passexcess levels of oil and water.
- Malfunctioning dryers can disturb the oxygen concentration to outside safe levelswithin the breathing air.
- High levels of water in breathing air can freeze within RPD demand valves causingthe air supply to fail.
- Insufficient air flow or pressure to the RPD will reduce the protection factor of theRPE and potentially expose the user to ingress of external contaminants.
- The effects of contaminants when breathed at elevated pressure can have a muchgreater effect on users than it would at normal pressure.
- Changes in the performance of compressor and filtration equipment are usuallyrapid in nature. Any failure affecting outlet air quality may injure users for anextended period if quality validation is infrequent.
- Odour alone is a poor indicator of air quality, toxic as asphyxiant gasses are oftenodourless, the limits for oil pollution are lower than the threshold detection levelthat most people will notice.
All employers have a duty of care to their employees to ensure that the breathing air they are supplied with is adequate for the RPD they are using and safe to breathe. The points raised above may form the basis of the risk assessment called for in the European guidance document for the selection and use of respiratory protective devices EN 529.