The aim of the air routing in both variants is to reduce the particle load by constantly exchanging the particle-rich air within the cleanroom with newly treated, low-particle air.
1. turbulent flow (turbulent dilution or mixing flow)
With turbulent flow, the air is introduced into the ceiling area with a swirl so that it is completely distributed with the room air in a swirling manner. This mixes the entire room volume evenly and also reaches areas under shelves and tables.
This flow variant is particularly suitable for cleanroom classes ISO 9-7. However, it should be noted that the turbulence of the air can stir up particles that have settled on surfaces and that the particle scattering from surfaces and especially from people is generally greater. Personnel must therefore be made aware of the potential hazards associated with their behavior.
2. low-turbulence displacement flow (laminar flow)
With low-turbulence displacement flow, the air is introduced almost vertically into the room through a laminar flow. Under this flow, the product is optimally protected and covered with filtered air. The particles contained in the air are displaced downwards by the flow and fed back into the ventilation system near the floor. This air flow minimizes the scattering of particles from surfaces or people and thus reduces the risk to the product and process. The displacement flow has a very high level of efficiency due to the low turbulence. It is suitable for all cleanrooms and is recommended by ISO-14644 in higher cleanroom classes from ISO 6.
The laminar flow should preferably be installed at the points where the critical processes are located. Alternatively, a higher cleanroom class can also be achieved at certain points with laminar flow cabinets or demarcated sub-areas.
