Not only the quantity of air (circulation multiple) and the type of filter determine the quality of the air and the qualification to be achieved. The amount of contamination from people and production are of great influence. How this contamination is removed is particularly important.
Once again, the importance of a good PoR (programme of requirements) is emphasised here. This should describe per cleanroom room what the contamination will entail during the production process, as well as any heat loads and extraction units, use of gases, number of personnel active, etc.
All these data help determine with which flow system the polluted air will be removed or recirculated in the system. These air flows can be divided into:
- Turbulent Flow
- Uni Directional Flow
- Cross Flow
In a Uni Directional Flow flow method, a raised floor is regularly deployed and the underlying space is used as a return duct. Such floor systems require a different construction method.