Filters sequence for classified cleanrooms
The correct classification of the rooms is achieved if proper filtration is combined with correct air recirculation and also diffused distribution. If one of these items are not satisfied the overall result will be below expectation and validation could be problematic.
Furthermore a correct balance of the overpressure is essential. Consequently, the air escaped by leaks, pass-through and so on, must be replaced with fresh air that must be equal or above the amount required by the personnel working in the clean room.
Here below you can find a table where room classification, air recirculation and filters sequence are related.
For more information refer to manufacturers brochures.
| ISO Class | Clean room Class F.S. 209 | Air Recirculation
(Vol/h) |
Pre Filter | Bag Filter 1 | Bag Filter 2 | HEPA
Filter |
ULPA
Filter |
Ceiling air distribution % |
| 3 | 1 | 360-600 | G4 | F8 | H12 | U17 | 90-100 | |
| 4 | 10 | 300-540 | G4 | F8 | H10 | U16 | 90-100 | |
| 5 | 100 | 240-480 | G4 | F7 | F9 | U15 | 20-50 | |
| 6 | 1000 | 40-120 | G3 | F7 | F9 | H14 | 10-20 | |
| 7 | 10000 | 20-40 | G3 | F6 | F8 | H14 | 10-20 | |
| 8 | 100000 | 10-20 | G3 | F6 | F8 | H12 | 5-10 |