Air Quality and Cleanrooms

"Filtration removes microorganisms. In cleanrooms, this is achieved through HEPA filters, which are designed to remove up to 99.997% of particles from air. HEPA filters are protected from blockage by prefilters, which remove up to about 90% of particles from the air. Therefore, if air contains about 3 x 108 particles per m3, and there is one prefilter and one HEPA Filter, the prefilter removes a sufficient number of particles to leave about 3 x 107 per m3 as a challenge to the HEPA filter. The terminal HEPA filter will leave about 103 per m3 to enter the cleanroom. In EU GMP, this relatively low number is within the limits for Grade A / ISO Class 5 and Grade B / ISO Class 7 “at rest” (Annex 1.4)."

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Air Quality and Cleanrooms

The performance of a cleanroom is defined by a set of complex interactions between the airflow, sources of contamination and heat, position of vents, exhausts and any objects occupying the space. Consequently changes to any of these elements will potentially affect the operation of the cleanroom and could invalidate aspects of the room design.

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