Clean Room Integrity: Are Your Compressed Airlines Safe?

Is your compressed air supplied to the same quality as your clean room?

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.

If you haven’t tested, then you won’t know:

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.

Why should you test?

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.

What needs to be tested?

Compressed air can contain a number of contaminants. A basic test will look at:

    • Water vapour/ Dew point test
    • ydrocarbons 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.

    How does the CHTS compressed air testing service go beyond the standard?

    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 – Typical measures might include:
            1. Fitting of terminal filters at point of use
            2. Audit of compressor type and filters
            3. Audit of compressor maintenance programme
            4. Analysis of ‘dead legs’ within the system
            5. Analysis of pipe composition
          • Development of a maintenance programme and periodic testing accompanied by avalidation 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 clean room environment.

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