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In a vertical laminar flow clean room environment, vertical barriers are provided to isolate particle generating sources in a turbulence zone from the product(s) to be protected against contamination.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
77% of the total text.
Page 1 of 1
Particle Isolation in Clean Rooms
In a vertical laminar flow clean room environment, vertical barriers are
provided to isolate particle generating sources in a turbulence zone from the
product(s) to be protected against contamination.
Turbulence zones exist wherever the continuous flow of air is significantly
interrupted. This can occur when any obstruction is offered to the flow of air from
a H.E.P.A. filter or by lights, sprinklers or supports. In these turbulence zones,
there is considerable upward air flow, causing particles to be carried upward.
Because they are trapped in the zone, these particles tend to agglomerate and
form larger particles, until they become heavy enough to fall out of the turbulence
zone and on to the product(s).
It has also been found that air in a turbulence zone tends to travel along the
zone in a direction perpendicular to the cross section of the zone and
perpendicular to the primary air flow in the room. This presents a serious
problem in clean rooms because particles are carried throughout the room along
the turbulence zones. If a particle generator or filter leaks at one location in the
room, it may cause an increased particle count even though air in the room is
flowing downward with a velocity which otherwise would be adequate to preclude
horizontal travel of particles. Upwardly moving air in these turbulence zones may
also pick up particles from various unclean surfaces; and once captured in the
turbulence zone, the particles...