Important Design Considerations for Clean Room

A clean room differs from an ordinary ventilated/conditioned room mainly in three ways.
1. Increased air supply. The increased air supply is an important aspect of particle control. Normal air-conditioning systems are designed for 0.5 to 2 air changes per hour essentially based on the occupancy level or as determined from the building exhaust levels. A clean room would have at least 10 air changes per hour and could be as high as 600 for absolute cleanliness. The large air supply is mainly provided to eliminate the settling of the particulate and dilute contamination produced in the room to an acceptable concentration level.
2. The use of high efficiency filters. High efficiency filters are used to filter the supply air into a clean room to ensure the removal of small particles. The high efficiency filters used in clean rooms are installed at the point of air discharge into the room. Room pressurization is mainly provided to ensure that untreated air does not pass from dirtier adjacent areas into the clean room.
3. Room pressurization. The clean room is positively pressurized with respect to the adjacent areas. This is done by supplying more air and extracting less air from the room than is supplied to it.