Regular testing and validation of production environments is an accepted practice but, to date, similar testing of compressed air lines that run into clean rooms is not. Crowthorne Hi-Tec Services (CHTS) validates a large number of clean rooms 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:
Compressed air can contain a number of contaminants. A basic test will look at:
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:
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 clean room environment.