PAL and Material Air Lock.
Air locks are provided with HEFA filtered air supply with pressure to prevent
the cross contamination.
Clean up time: Clean up time is the time period required in a clean room at
when a AHU is started air in the room starts getting filtered, and replaced
with HEPA filtered air so that the particle count in the clean room comes to
the rated count of the classification.
For an example, a class 10000 area is at rest in morning and before AHU is
started its count will be higher than the rated value, after AHU is started air
in the clean room starts getting filtered through HEPA filter the particles get
filtered and part of air is exhausted and part of fresh air is filtered and
supplied so that the particle count in the room drops and is maintained to
the level of acceptance as per rated class of the clean room, time period
required to attain this is called as Clean up time.
While describing the class of filter one must not use term as 3-micron filter or
5 micron or 10-micron filter As per WHO Guidelines On HVAC system, it may
lead to wrong filter getting installed.
Therefore, Filters nomenclature should be adapted as EN 779 and EN 1822
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