Cleanrooms are special rooms or indoor environments where the number of particles and contaminants in the air, the temperature, humidity and pressure are all prescribed by strict standards, including the number of micron and tenthmicron particles. Cleanrooms are meant for controlling and maintaining the number of these particles on the same level.
Cleanrooms are used widely across several industries such as fine mechanics, pharmaceuticals, automotive and space technology. More and more industries have been discovering the benefits of using cleanrooms in their production. All these industries require a highly controlled environment provided by high-quality equipment.
The reason is different in each industry. Mostly, the goal is to create products that are completely protected from airborne contamination. For example, no one wants to see a small particle or dust behind the display of a new phone. There are many other reasons apart from this, why cleanrooms should be used in manufacturing. For the pharmaceutical and microbiology industries, it is critical to maintain sterility and extreme hygiene, while in laboratories, the main goal is to keep the samples protected from the lab environment.
The oldest, US FED STD 209E standard is no longer valid. However, several multinational companies still determine their requirements based on FED209E standards to this day.
| Class | maximum particles/ft3 | ISO equivalent | ||||
|---|---|---|---|---|---|---|
| ≥ 0,1 µm | ≥ 0,2 µm | ≥ 0,3 µm | ≥ 0,5 µm | ≥ 5 µm | ||
| 1 | 35 | 7,5 | 3 | 1 | 0,007 | ISO 3 |
| 10 | 350 | 75 | 30 | 10 | 0,07 | ISO 4 |
| 100 | 3 500 | 750 | 300 | 100 | 0,7 | ISO 5 |
| 1 000 | 35 000 | 7 500 | 3 000 | 1 000 | 7 | ISO 6 |
| 10 000 | 350 000 | 75 000 | 30 000 | 10 000 | 70 | ISO 7 |
| 100 000 | 3.5×106 | 750 000 | 300 000 | 100 000 | 830 | ISO 8 |
ISO14644-1 is the most widespread modern cleanroom standard that not only defines the design of clean rooms, but also provides guidelines for implementation and use. Many manufacturers base their requirement system on ISO-14644:
| Class | maximum particles/m3 a | FED STD 209E equivalent | |||||
|---|---|---|---|---|---|---|---|
| ≥ 0,1 µm | ≥ 0,2 µm | ≥ 0,3 µm | ≥ 0,5 µm | ≥ 1 µm | ≥ 5 µm | ||
| ISO 1 | 10b | d | d | d | d | e | |
| ISO 2 | 100 | 24b | 10b | d | d | e | |
| ISO 3 | 1 000 | 237 | 102 | 35b | d | e | 1 |
| ISO 4 | 10 000 | 2 370 | 1 020 | 352 | 83b | e | 10 |
| ISO 5 | 100 000 | 23 700 | 10 200 | 3 520 | 832 | d,e,f | 100 |
| ISO 6 | 1 000 000 | 237 000 | 102 000 | 35 200 | 8 320 | 293 | 1 000 |
| ISO 7 | c | c | c | 352 000 | 83 200 | 2 930 | 10 000 |
| ISO 8 | c | c | c | 3 520 000 | 832 000 | 29 300 | 100 000 |
| ISO 9 | c | c | c | 35 200 000 | 8 320 000 | 293 000 | Room air |
a The following concentrations are cumulative measures, i.e. maximum permissible levels in a certain category refer to all particles of a given size or smaller.
b When testing these values, a large volume of air is required for sampling, which the standard makes specific recommendations for.
c This value is not specified by a certain class, since the limit would not be significant because of the very high concentration values.
d Measuring such small concentrations is not practical due to technical difficulties, therefore, these values are not specified by the standard.
e Measuring the low concentration of particles larger than 1 μm is problematic because the meter itself absorbs a fraction of the particle, which is difficult to control. Thus, these values are not specified.
The GMP guidelines may be the strictest standards for cleanrooms, as they require an in-service qualification process, i.e. the cleanroom is tested during normal operations.
| Class | maximum particles/m3 | |||
|---|---|---|---|---|
| At Rest | In Operation | |||
| ≥ 0,5 µm | ≥ 5 µm | ≥ 0,5 µm | ≥ 5 µm | |
| Grade A | 3 520 | 20 | 3 520 | 20 |
| Grade B | 3 520 | 29 | 352 000 | 2 900 |
| Grade C | 352 000 | 2 900 | 3 520 000 | 29 000 |
| Grade D | 3 520 000 | 29 000 | Not defined | Not defined |
Nevertheless, cleanroom standards do not only include requirements referring to the number of particles in the controlled environment. Well-designed cleanrooms take into account the number of air exchanges required to stay within the boundaries, the required inflow and suction points, their positioning and coverage of the ceiling, and the direction of air flows.
Cleanroom standards therefore include complex technology guidelines that help you to create an environment with appropriate equipment that matches the specificities of your industry.
