The Feasibility of Differential Flow Velocity Dividing Working Areas in a Cleanroom

The possibility of dividing working areas by airflow velocity differences in a cleanroom with fan-filter unit (FFU) systems was investigated. Without physical partitions, the cleanroom area was divided into working and non-working areas defined by the FFU exit flow velocities, which were maintained at constant value in the working areas and reduced in the non-working areas. As uniform micro-sized particles were released from a particle generator in the non-working area, the concentrations of particles in the working area were monitored by a particle counter. The results showed that high downward flow velocity in the working area can effectively prevent particles from spreading. The results also suggested an optimum velocity ratio of 20% between adjacent flow regions, in terms of the balance between energy savings and the effective partition insulation.