REFERENCE
ISO 14644 classification and GMP grades
Two systems, one room. This is how they line up.
particles ≥0.5 µm per m³
Maximum particles per cubic metre
| Class | ≥0.5 µm | ≥1.0 µm | ≥5.0 µm | Former US FS 209E |
|---|---|---|---|---|
| ISO 5 | 3,520 | 832 | — | Class 100 |
| ISO 6 | 35,200 | 8,320 | 293 | Class 1,000 |
| ISO 7 | 352,000 | 83,200 | 2,930 | Class 10,000 |
| ISO 8 | 3,520,000 | 832,000 | 29,300 | Class 100,000 |
Limits per ISO 14644-1:2015. FS 209E was withdrawn in 2001 and is shown only because it is still in daily use.
GMP grade to ISO class
| GMP grade | At rest | In operation |
|---|---|---|
| A | ISO 5 | ISO 5 |
| B | ISO 5 | ISO 7 |
| C | ISO 7 | ISO 8 |
| D | ISO 8 | Not predefined |
Per PIC/S and EU GMP Annex 1. A room that meets its grade at rest can still fail in operation, which is why both states are stated.
Typical design values
| Class | Air changes per hour | Filtration |
|---|---|---|
| ISO 6 | 90–180 | HEPA, terminal |
| ISO 7 | 30–60 | HEPA, terminal |
| ISO 8 | 15–30 | HEPA or high-efficiency |
Differential pressure between adjacent classified areas is commonly designed at 10 to 15 Pa.
These are indicative ranges for early planning. Actual values are set by the room's heat load, occupancy, process and recovery requirement.
ISO Class 7 in practice
ISO Class 7 is where most regulated assembly and packing work sits in Malaysia. It permits 352,000 particles of 0.5 µm or larger per cubic metre, typically runs at 30 to 60 air changes per hour, and needs terminal HEPA filtration throughout. Stepping up from ISO 8 to ISO 7 roughly doubles the air you move, and that difference stays on your energy bill for the life of the room.
Choosing a class
Work backwards from the product. Ask what is exposed, for how long, and what the regulator expects for that product type. Over-specifying by one class raises air change rates and runs up energy cost for the life of the room.
Talk it through with us