There are two standards that our users typically refer to; the old FS209E standard which contained six classes, and the international replacement ISO 14644-1 classification system which adds two cleaner standards and one dirtier standard
FS209E cleanroom classifications were rated according to how much particulate of specific sizes exist per cubic foot (see chart below). The “cleanest” cleanroom in FS209E is referred to as Class 1; the “dirtiest” cleanroom is a class 100,000.
ISO 14644-1 cleanroom classifications are rated according to how much particulate of specific sizes exist per cubic meter (see the second chart). The “cleanest” cleanroom is a class 1 and the “dirtiest” a class 9. ISO class 3 is approximately equal to FS209E class 1, while ISO class 8 approximately equals FS209E class 100,000.
Airborne Particulate Cleanliness Class Comparison
| ISO 14644-1 | Federal Standard 209E | EU GMP Annex 1 | |||
|---|---|---|---|---|---|
| ISO Class | English | Metric | |||
| ISO 1 | |||||
| ISO 2 | |||||
| ISO 3 | 1 | M1.5 | |||
| ISO 4 | 10 | M2.5 | |||
| ISO 4.5 | Grade A | ||||
| ISO 5 | 100 | M3.5 | |||
| ISO 6 | 1,000 | M4.5 | |||
| ISO 7 | 10,000 | M5.5 | Grade B | ||
| ISO 8 | 100,000 | M6.5 | Grade C+D | ||
| ISO 9 | |||||
Airborne Particulate Cleanliness Classes (By Cubic Meter):
| Class | Number of Particles per Cubic Meter by Micrometer Size | |||||
|---|---|---|---|---|---|---|
| 0.1μm | 0.2μm | 0.3μm | 0.5μm | 1μm | 5μm | |
| ISO1 | 10 | 2 | ||||
| ISO2 | 100 | 24 | 10 | |||
| ISO3 | 1,000 | 237 | 102 | 35 | ||
| ISO4 | 10,000 | 2,370 | 1,020 | 352 | 83 | |
| ISO5 | 100,000 | 23,700 | 10,200 | 3,520 | 832 | |
| ISO6 | 1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | 293 |
| ISO7 | 352,000 | 83,200 | 2,930 | |||
| ISO8 | 3,520,000 | 832,000 | 29,300 | |||
| ISO9 | 35,200,000 | 8,320,000 | 293,000 | |||
Airborne Particulate Cleanliness Classes (By Cubic Meter):
| Class | Number of Particles per Cubic Meter by Micrometer Size | |||||
|---|---|---|---|---|---|---|
| 0.1μm | 0.2μm | 0.3μm | 0.5μm | 1μm | 5μm | |
| ISO1 | 10 | 2 | ||||
| ISO2 | 100 | 24 | 10 | |||
| ISO3 | 1,000 | 237 | 102 | 35 | ||
| ISO4 | 10,000 | 2,370 | 1,020 | 352 | 83 | |
| ISO5 | 100,000 | 23,700 | 10,200 | 3,520 | 832 | |
| ISO6 | 1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | 293 |
| ISO7 | 352,000 | 83,200 | 2,930 | |||
| ISO8 | 3,520,000 | 832,000 | 29,300 | |||
| ISO9 | 35,200,000 | 8,320,000 | 293,000 | |||
In cleanrooms, particulate concentration changes over time — from the construction and installation of equipment to its operational status. ISO delineates three cleanroom classification standards: as-built, at-rest and operational. As instruments and equipment are introduced and particulates rise, an “as-built” cleanroom becomes an “at-rest” cleanroom. When people are added to the matrix, particulate levels rise still further in the “operational” cleanroom.
ISO 14644-2 describes the type and frequency of testing required to conform to certain standards. The following tables indicate mandatory and optional tests.
Required Testing (ISO 14644-2)
Schedule of Tests to Demonstrate Continuing Compliance
| Test Parameter | Class | Maximum Time Interval | Test Procedure |
|---|---|---|---|
| Particle Count Test | ≤ ISO 4 | 6 Months | ISO 14644-1 Annex A |
| > ISO 5 | 12 Months | ||
| Air Pressure Difference | All Classes | 12 Months | ISO 14644-1 Annex B5 |
| Airflow | All Classes | 12 Months | ISO 14644-1 Annex B4 |
Optional Testing (ISO 14644-2)
Schedule of Additional Optional Tests
| Test Parameter | Class | Maximum Time Interval | Test Procedure |
|---|---|---|---|
| Installed Filter Leakage | All Classes | 24 Months | ISO 14644-1 Annex B6 |
| Containment Leakage | All Classes | 24 Months | ISO 14644-1 Annex B4 |
| Recovery | All Classes | 24 Months | ISO 14644-1 Annex B13 |
| Airflow Visualization | All Classes | 24 Months | ISO 14644-1 Annex B7 |