Book - School of Science and Technology

432 Air distributionFrameSpring clipConeFrameDomeEccentricConcentricFigure 15.32 Mushroom type wall ventilatorsCleanrooms have evolved into two major types, which are differentiated by theirmethod of ventilation and containment. These are conventional and undirectional flow.Conventional cleanrooms are known as turbulently ventilated cleanrooms or (US FederalStandard 209E) non-unidirectional. Undirectional flow cleanrooms are also known aslaminar flow or ultra clean rooms.Some clean and containment room applications are as follows:. electronics and opto-electronic manufacturing. biotechnology. pharmaceutical manufacture. food and drink production. hospitals.British Standard 5295 defines a cleanroom as:A room with control of particulate contamination, constructed and used in such a way asto minimise the introduction, generation and retention of particles inside the room andin which the temperature, humidity and pressure shall be controlled as is necessary.The American Federal Standard 209E describes air cleanliness classes related to thenumber of particles in each size category as follows:ClassMeasured particle size (m)0.1 0.2 0.3 0.5 5.01 35 7.5 3 1 N/A10 350 75 30 10 N/A100 N/A 750 300 100 N/A1 000 N/A N/A N/A 1 000 710 000 N/A N/A N/A 10 000 70100 000 N/A N/A N/A 100 000 700