ISO 14644 is the international standard for the classification of air purity in cleanrooms and the test methods for monitoring them.
ISO 14644 is composed of:
- ISO 14644-1: (2016) Classification of air cleanliness based on particle concentration
- ISO 14644-2: Monitors to demonstrate that the air cleanliness in the cleanroom meets the set particle concentration limit
- ISO 14644-3: Test method
- ISO 14644-4: Design, construction and start-up
- ISO 14644-5: Processing
- ISO 14644-6: Vocabulary
- ISO 14644-7: Separation devices (clean air hoods, glove boxes, insulators and Environmental conditions
- ISO 14644-8: Classification of molecular contaminants in air
- ISO 14644-9: Classification of cleanliness of surface particles
After years of being under revision, a new final version of ISO 14644-1, titled ‘Dust- and germ-free rooms and environments - Part 1: Classification of air cleanliness based on particle concentration' was finally published in 2016. The standard has not changed since 1999. However, revision of the standard had already started in 2007. Many drafts were published, e.g. in 2011, 2012, 2014 and 2015, but not some of these drafts could reach final status.
The new version essentially contains the following changes:
- The number of measurement points is defined in a table and no longer needs to be calculated as the square root of the area.
- No statistical Upper Confidence Level (UCL) calculation.
- No limit for >5 µm particles for ISO 5.
| Classification numbers Numbers (N) | Recommended limits for microbial contamination (a) | |||||
|---|---|---|---|---|---|---|
| 0.1µm | 0.2µm | 0.3µm | 0.5µm | 1µm | 5.0µm | |
| ISO 1 | 10 | |||||
| ISO 2 | 100 | 24 | 10 | |||
| ISO 3 | 1 000 | 237 | 102 | 35 | ||
| ISO 4 | 10 000 | 2 370 | 1 020 | 352 | 83 | |
| ISO 5 | 100 000 | 23 700 | 10 200 | 3 520 | 832 | |
| ISO 6 | 1 000 000 | 237 000 | 102 000 | 35 200 | 8 320 | 293 |
| ISO 7 | 352 000 | 83 200 | 2930 | |||
| ISO 8 | 3 520 000 | 832 000 | 29 300 | |||
| ISO 9 | 35 200 000 | 8 320 000 | 293 000 | |||