Cleaning up: Compressed air lines may be a source of contamination
Compressed air is a very common, useful and non-disruptive power source for various types of process equipment, however the introduction of an external air source into a controlled environment is a potential source of contamination. Crowthorne Hi-Tec Services (CHTS) explains more
Regular testing and validation of production environments is an accepted practice but, to date, similar testing of compressed air lines that run into cleanrooms is not. Crowthorne Hi-Tec Services (CHTS) validates a large number of cleanrooms that contain compressed air systems but is only scheduled to test compressed air in about 15% of these environments. If you introduce air into a controlled environment that is not of the same standard, then you have degraded the facility and therefore the quality of the environment.
Apart from internal QA/QC practices there are a number of industry standards that set out parameters for the quality of compressed air. BS ISO 8573 ‘Compressed Air and Purity Classes’ is the foundation standard but users should note that compressed air standards are not rated in a comparable manner to that applicable for the background production environment; particle sizes and densities differ and this is an important factor. Other relevant standards are HSG 39 ‘Compressed Air Safety’ and BCAS (British Compressed Air Society) Guidance Note 102. In addition, the regular maintenance of compressed air equipment forms part of wider legislation covering a range of lab and production equipment.
As part of a controlled environment quality system, compressed air systems should be tested from a number of different perspectives:
- Product safety: Loss of environment integrity could prejudice product safety; CHTS has come across a persistent bio-burden contamination issue arising from the use of organic thread sealant in a compressed air unions rather than PTFE tape.
- Personnel safety: Ensuring that compressed air systems are clean and safe makes an important contribution to your labs health & safety compliance. Dampness or water vapour can cause particle agglomeration causing blocking of safety valves and pressurised oil or oil vapour can act as an incendiary risk.
- Quality integrity: In controlled production environments, compressed air may be viewed as a Critical Process Parameter which should be controlled as part of an overall quality regime.
Compressed air can contain a number of contaminants. A basic test will look at:
- Water vapour/Dew point test
- Hydrocarbons and oil mist
- Particles
- Bioburden
Testing regimes can then be customised to take into account the risk of contaminants particular to a specific plant or process.
Crowthorne customers who schedule the compressed air testing service, receive a five point plan to ensure that their compressed air utility provides pneumatic power and nothing else into their controlled environments:
- Basic testing to determine to what standard the compressed air is working to.
- Assistance and guidance to determine the correct level at which the system needs to work to maintain environment integrity.
- Identification of remedial action if necessary
- Development of a maintenance programme and periodic testing accompanied by a validation report.
- Assistance and advice on extending and/ or amending the compressed air network
All compressed air testing carried out by CHTS takes place using calibrated equipment that has been the subject of independent autoclave sterilisation before it is connected to a customer system, again with a view to retaining the integrity of the cleanroom environment.