Cleanroom Classification
Cleanrooms are classified as 'ISO Class 1' through to 'ISO Class 9' according to the international standard ISO 14644-1.
An 'ISO Class 5' cleanroom, for example, is allowed a maximum concentration of 100,000 particles not larger than 0.1 µm in diameter within the cleanroom (particles/m3 of air).
The table below shows the selected airborne particulate cleanliness classes for cleanrooms and clean zones:
ISO 14644-1 Cleanroom Standards:
| ISO Classification Number | Maximum concentration limits (particles/m3 of air) for particles equal to and larger than the considered sizes shown below | |||||
| 0.1 µm | 0.2 µm | 0.3 µm | 0.5 µm | 1 µm | 5 µm | |
| ISO 1 | 10 | 2 | ||||
| ISO 2 | 100 | 24 | 10 | 4 | ||
| ISO 3 | 1,000 | 237 | 102 | 35 | 8 |
|
| ISO 4 | 10,000 | 2,370 | 1,020 | 352 | 83 | |
| ISO 5 | 100,000 | 23,700 | 10,020 | 3,520 | 832 | 29 |
| ISO 6 | 1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | 293 |
| ISO 7 | 352,000 | 83,200 |
2,930 | |||
| ISO 8 | 3,520,000 | 832,000 | 29,300 | |||
| ISO 9 | 35,200,000 | 8,320,000 | 293,000 | |||
This table shows a comparison of the various classes that are used internationally:
Cleanroom Class Comparison:
| ISO Classification Number | US FED 209E | BS 5295 | cGMP (operational) |
| ISO 1 | |||
| ISO 2 | |||
| ISO 3 | M1.5 (1) | 'C' | |
| ISO 4 | M2.5 (10) | 'D' | |
| ISO 5 | M3.5 (100) | 'E' or 'F' | A (B*) |
| ISO 6 | M4.5 (1,000) | 'G' or 'H' |