In theory, for an entire room to reach ISO 6 air cleanliness, you need to enter the cleanroom via an ISO 8 (ante-room), then go through an ISO 7, to finally get into the ISO 6, as shown in the image.
In reality however, you can reach an ISO 6 cleanroom with 1 (recommendation is 2) airlock. Again, it depends of the size of the room, the process taking place inside the cleanroom, the number of people working inside, the equipment inside, etc.
Unidirectional air flow is sometimes recommended to reach ISO 6 classification. For a room of less than 4–6 meters in width (depending on the activities taking place inside the cleanroom), air returns can be positioned on the side of the walls instead of in the floor. Installing air returns in the floor is more expensive.
ISO 6 zone | 90–180 air changes per hour
ISO 7 zone | 30–60 air changes per hour
ISO 8 zone | 15–25 air changes per hour (ante-room)
Main Features
(1) Assembly structure designed, easy installation and easily moved
(2) Directional wheels can be installed, suitable for small building and high cleanliness area;
(3) Modular design: clean booth can be as small as several square meters and can be as large as hundreds of square meters
(4) It has large useful and effective area; while compared with traditional clean room, it has such features like low investment, high return and stable.
The basis of cleanroom standards is the micrometer, or micron for short (µm), which is the size of the particles to be filtered. As stated before, cleanrooms are classified by how clean the air is, according to the number of particles and size of particles per volume of air. The cleanroom classification table below shows the maximum concentration limits (particles/m3 of air) for particles equal to and larger than the considered sizes shown.
Some classifications do not require certain particle sizes to be tested because the respective concentrations are too low or too high to be tested, but they should not be zero.