What Is The Air Flow Pattern In A Clean Room?

In a Clean Room, there are two main types of air flow patterns: parabolic flow and turbulent flow. One is specially designed for use in desktops while the other is designed for portable systems.

Laminar Flow

Unidirectional and Parallel Flow: The laminar flow, or unidirectional airflow is the most used and desired air flow in clean room at high levels. Laminar flow is characterized by layered movement of air, without much intermixing of the layers, just as two layers of fluid move past each other in parallel. A relative stream velocity is maintained across the cross – section of the clean room.

Vertical and Horizontal Variants

Vertical Laminar Flow: In a vertical laminar flow clean room air is conditioned horizontally and then supplied from the ceiling and exhausted at the floor. This orientation is particularly useful where horizontal processes are inverted downwards and that includes semiconductor manufacturing where wafers are processed. The continuous downward flow enables removal of particle which may be produced during manufacturing process, therefore ensuring they do not deposit on delicate articles.

Horizontal Laminar Flow: In a horizontal laminar flow clean room, air is supplied from one of the side walls and exhausted at the opposite side wall. This type of flow is utilized in some assembly operations where long flat surfaces require frequent cleaning type services.

Particle Removal Efficiency: Laminar flow is the most effective in terms of removal of particles from the environment of the clean room. Concerning the idea that air moves in an unidirectional manner, particles are moved along with the direction of the air stream and are promptly cleared out of the working space. Thus, obtaining a very low concentration of particles in the Cleanroom, which will make a cleanroom appropriate for use in industries that require high degrees of cleanliness including the manufacturing of electronic devices, drugs, and aerospace components.

Turbulent Flow

Chaotic and Mixed Flow: Turbulent flow on the other hand is described by stochastic unsystemmatic air currents. In a turbulent flow clean room, the air being supplied to the room is not uniform; thus turbulence, eddies and swirls occur. There is an irregular distribution of air velocities in the room and considerable integration of various air flows.

Applications and Limitations: The turbulent flow clean rooms are also cheaper in terms of fabrication and operational costs than the laminar flow clean rooms. They are ideal for used in situation where the cleanness of the environment is not very high. For instance, in some carrying out of light assembly tasks, or in areas where the emission of particles is negligible. However, turbulent flow is not stable, the particles are more likely to stay in the air and may settle on the object and work-piece so it is not used in precision work or processes which are highly sensitive to contamination by particles.

Therefore, laminar flow is most common in clean rooms where high level of cleanliness is needed while turbulent flow maybe used in other clean rooms since it is cheaper despite the impracticalities of the air flow.