When the entire body of air within the
cleanroom moves with a uniform velocity and direction, it is called "Laminar
Air Flow". Although a cleanroom may employ either a vertical or horizontal
airflow system, the vertical design is the most common. Laminar flow
is often referenced in cleanroom specifications as the percentage of
ceiling filter cover directing the vertical airflow towards the floor
(Class 100 rooms have filters, or air flow modules, installed in 70%
or more of its ceiling area).