Non-unidirectional, semi-turbulent airflow
This type of enclosed, clean area also has air that is both conditioned and filtered, where the air comes in via a ceiling plenum. At that point, the air is diffused throughout the room by way of many “slots” in the flow-thru ceiling tiles. Then the air is pushed vertically at low velocities, and exhausts near or at the level of the floor. As with the conventional cleanroom, this style is able to make a Class 100,000 atmosphere to the specifications of Federal Standard 209C, and it also requires rigid personnel control, high-quality, specialized equipment, and a cleaning routine consistent with maintaining that level of cleanliness.
Type 3. Horizontal Uni-directional Flow Cleanroom