The ISO Standard 14644-1/2:2015 is an internationally accepted standard of Cleanroom and the associated controlled environments. ISO 14644 consists of the following parts under the general title Cleanrooms and associated controlled environments:
Part 1: Classification of air cleanliness by particle concentration
Part 2: Monitoring to provide evidence of cleanroom performance related to air cleanliness by particle concentration
Part 3: Test methods
Part 4: Design, construction and start-up
Part 5: Operations
Part 6: Terms and definitions
Part 7: Separative devices (clean air hoods, gloveboxes, isolators and mini-environments)
Part 8: Classification of air cleanliness by chemical concentration (ACC)
Part 9: Classification of surface cleanliness by particle concentration
Part 10: Classification of surface cleanliness by chemical concentration
Attention is also drawn to ISO 14698, Cleanrooms and associated controlled environments — Biocontamination control:
Part 1: General principles and methods
Part 2: Evaluation and interpretation of biocontamination data
Selected ISO 14644-1 airborne particulate cleanliness classes for cleanrooms and clean zones
| ISO Classification Number | Maximum concentration limited (particles/m3 of air) for particles equal to and larger than the considered sizes shown below | |||||
| ≥0.1µm | ≥0.2µm | ≥0.3µm | ≥0.5µm | ≥1µm | ≥5.0µm | |
| ISO Class 1 | 10 | |||||
| ISO Class 2 | 100 | 24 | 10 | |||
| ISO Class 3 | 1 000 | 237 | 102 | 35 | ||
| ISO Class 4 | 10 000 | 2 370 | 1 020 | 352 | 83 | |
| ISO Class 5 | 100 000 | 23 700 | 10 200 | 3 520 | 832 | |
| ISO Class 6 | 1 000 000 | 237 000 | 102 000 | 35 200 | 8 320 | 298 |
| ISO Class 7 | 352 000 | 83 200 | 2 930 | |||
| ISO Class 8 | 3 520 000 | 832 000 | 29 300 | |||
| ISO Class 9 | 35 200 000 | 8 320 000 | 293 000 | |||
Comparison between selected equivalent classes of FS 209 and ISO 14644-1
| ISO 14644 Classes | Class 3 | Class 4 | Class 5 | Class 6 | Class 7 | Class 8 |
| FS 209 Classes | Class 1 | Class 10 | Class 100 | Class 1 000 | Class 10 000 | Class 6 100 000 |
If a room is empty, a very low particle concentration can be achieved, this closely reflecting the quality of air supplied. If the room has production equipment in it that is operating, these should be greater particle concentration, but the greatest concentration occurs when the room is in full production. This classification of the room may therefore be carried out in these different occupancy states.
The occupancy states defined in ISO 14644-1 are as follows:
As built: the condition where the installation is complete with all services connected and functioning, but with no production equipment, materials or personnel present.
At-rest: The condition where the installation is complete with equipment installed and operating in a manner agreed between the customer and supplier, but with no personnel present.
Operational: The conditional where the installation is functioning in the specified manner, with the specified number of personnel present and working in the manner agreed upon.