Air flow in modular cleanroom environment
Air filtration is used in cleanrooms to minimize particulate in the cleanroom environments’ air. Particulate removal is achieved by transporting the particles with air through highly efficient particulate air (HEPA filters) or ultra low particulate air (ULPA) filters. The filters remove up to 99.99% of the particulate in the air. The classification of a modular cleanroom environment is largely based on the amount of particulate in the air. The particulate is measured in microns. The amount of microns in your environment is typically determined by the criticality of the production or process that is happening in the modular cleanroom environment.
The main variable that determines the type of cleanroom air pressure is whether the sample is to be protected from the surrounding environment, requiring positive pressure isolation, or whether personnel and the surrounding environment are to be protected from a harmful sample, requiring negative pressure containment. A positive pressure cleanroom maintains a uniform laminar flow (Figure 1), in which air is forced through filters located in the ceiling, and exits vents at the base of cleanroom walls. A negative pressure cleanroom removes hazardous chemicals or powders either by exhausting room air through the ceiling (Figure 2) or along the base of the wall (Figure 3).
Air flow and pressure are important to consider because they influence the physical space and energy consumption of your cleanroom. You may be subject to building permits or regulations, especially if the cleanroom design alters the structure of your facility or risks releasing harmful fumes into the environment.