Whitenair Laminar air flow is used when low airborne concentrations of particles or bacteria are required. This air flow pattern is in one direction, usually horizontal or vertical at a uniform speed of between 60 to 90 ft/min. and throughout the entire space. the typical air flow patterns in a laminar air flow cleanroom. The air velocity is sufficient to remove relatively large particles before they settle onto surfaces. Any contaminant released into the air can therefore be immediately removed by this laminar flow of air, whereas the turbulent air flow ventilated system relies on mixing and dilution to remove contamination. In an empty room with no obstructions to the airflow, contamination is removed faster by air velocities much lower than those mentioned above. However in practical situations there are obstructions and people moving in the space. Obstructions will cause the laminar air flow to be turned into turbulent air flow around the obstructions. Higher contamination concentrations will be established in the turbulent areas. Therefore, it has been found that the cleanliness of a laminar air flow cleanroom is directly proportional to the air velocity. Air changes per unit of time are related to the volume of the room and are many times greater than those supplied to a turbulent air flow cleanroom.