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Engineering ToolBox > Clean Rooms - ISO Standard 14644
Clean room maintained virtually free of contaminants, such as dust or bacteria, are used in laboratory work and in the production of precision parts for electronic or aerospace equipment.
In the clean room standard ISO 14644-1 "Classification of Air Cleanliness" the classes are based on the formula
Cn = 10N (0.1 / D)2.08 (1)
where
Cn = maximum permitted number of particles per cubic meter equal to or greater than the specified particle size, rounded to whole number
N = is the ISO class number, which must be a multiple of 0.1 and be 9 or less
D = is the particle size in micrometers
| ISO Class | Maximum Number of Particles in Air (particles in each cubic meter equal to or greater than the specified size) | |||||
| Particle size | ||||||
| > 0.1 μm | > 0.2 μm | > 0.3 μm | > 0.5 μm | > 1 μm | > 5 μm | |
| ISO Class 1 | 10 | 2 | ||||
| ISO Class 2 | 100 | 24 | 10 | 4 | ||
| ISO Class 3 | 1000 | 237 | 102 | 35 | 8 | |
| ISO Class 4 | 10,000 | 2,370 | 1,020 | 352 | 83 | |
| ISO Class 5 | 100,000 | 23,700 | 10,200 | 3,520 | 832 | 29 |
| ISO Class 6 | 1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | 293 |
| ISO Class 7 | 352,000 | 83,200 | 2930 | |||
| ISO Class 8 | 3,520,000 | 832,000 | 29,300 | |||
| ISO Class 9 | 35,200,000 | 8,320,000 | 293,000 | |||
ISO Cleanroom Standards