Ensuring air quality in controlled areas is an essential precondition to avoid direct or cross contamination in sensitive environments - such as hospitals and testing or manufacturing of pharmaceutical, food, cosmetics, microelectronics, which require packaging or encapsulation of drugs or chemical components -, keeping them free from the presence of microparticles and pathogenic agents that can interfere with a desired result.
The concentration of these total particles suspended in the air, as a result of controlled measurement tests, is what classifies an environment as a clean room. That is why asepsis is so important and involves parameters of access, sterility, isolation and, especially, air filtration systems. These purification and climatization systems are related to the air flow in the inlet unit, the control of the humidity level, temperature and pressure.
Filtration stages
In cleanrooms, the system for achieving extremely high air quality through the filtration of solid particles requires several filtration stages, such as the use of coarse pre-filters, fine filters, and absolute filters (HEPA, or High Efficiency Particulate Arrestance – these filters retain contaminants such as fungi, bacteria, spores, and smoke).
Complementary steps can be added to this set of filtration equipment for the control and removal of suspended microscopic particles, with activated carbon filters for filtering gases and odors and silica filters for removing moisture from the air.
As for air capture, it can be atmospheric or enclosed and release in closed rooms or in the atmosphere. In addition to filters, there may also be a need for fans, boxes, ducts, air diffusers and air conditioning systems to determine the flow and quality of the air supplied in the clean room, in addition to the air flow, whether unidirectional or not.
Cleanroom filtration system
In practice, the filter elements are fixed in frames to accommodate the filter cells or mats, providing support for anchoring sealing and tightening devices. These devices will ensure that the fluid follows the desired path and is effectively filtered, without bypassing the filters.
This is necessary because in a fluid dynamic flow system, the least resistant path will always be the one traveled by the fluid. Another means of guaranteeing filtration is the installation of non-permeable barriers to gases, separating them from the filtering set upstream (dirty sides) and downstream (clean sides).
Monitoring of the filtering mechanism
The monitoring of the efficiency of the filtering set is up to the tests and resources necessary for its measurement. This should not be waived in a cleanroom design, otherwise it will not be possible to predict saturation or leakage of filter elements, frames, seals and barriers.
Changing filters and replacing pre-filtration elements are also points of attention, to maintain system performance and ensure cleanroom compliance throughout its lifetime.