In the air are contained fine dust, oil, smoke and metal powder,
which is visible, as well as particles which is invisible to the
naked eye. Their sizes range 0.01㎛ to 100㎛ and they are contained
in the air by about 1000000 widely
The naked eye can see 10㎛ or larger and these dusts are too large
to be removed from a clean room; they must be removed from an air
control unit. From a clean room, only 1㎛ or smaller particles can
be removed. FED defines 0.5㎛ as standard for the level of cleanliness.
The following figure shows sizes of particles contained in the
air: |
