Why do I need an Air Shower?
Air showers can greatly enhance your cleanroom’s
performance by removing surface contamination from clothing and cleanroom
garments. Gowning/changing room areas are the interface between a dirty
"street clothes" environment and a clean room environment.
Unfortunately, the changing or gowning process itself releases contaminants
from street clothes that can settle onto the "clean" garments. Air
showers blow off and remove much of this contamination preventing it from entering
the clean space. For more specific information on different air shower
applications, see the Engineers Guide to Air Showers section on the website.
How does an Air Shower Work?
The air shower produces high pressure air, filters
this air through a HEPA/ULPA filter, then flows the air through adjustable
nozzles which exit at a high velocity, so air is directed towards the
individuals waiting to be cleaned. This high-velocity air removes surface
particles and also "flaps" the garments to dislodge more firmly attached
particles. After cleaning, the air is re-circulated back to the high-pressure
blower, where it is prefiltered, then HEPA/ULPA filtered and then ducted back
to the adjustable high-velocity cleaning nozzles. The air shower utilizes an
adjustable microprocessor controller to allow easy on-site adjustment of the
cleaning cycle time and other critical process controls.
How does Garment Type Influence
Cleaning Effectiveness?
The cleaning effectiveness of the air shower is
affected by the type of garments, the size, shape and type of contamination.
Large light particles such as lint, hair, dander, and skin flakes are the
easiest to remove. Particulate contamination adheres to garments in two basic
ways: Either by mechanical entrapment or by an electrical attraction.
Mechanical bonds between the garment and particulate contamination are reduced
when smooth surface garments are utilized. These include
"cleanroom-designed" garments and those made from synthetic materials
such as Tyvex, Gortex, polyester, and nylon – to name a few. These materials
are low-shedding and minimize the mechanical bond, making it easier to blow the
surface contamination off the garments. Natural fibers, such as cotton, tend to
shed particles and their surface finishes tend to have a higher mechanical bond
with particles, making them harder to clean. Synthetic garments can develop a
static charge. This charge can "hold" particles to the surface of a
garment. To help reduce this charge, garments can be laundered with an "anti-static"
agent in the final rinse. This will help reduce the level of static charge on
the garments, allowing particles to be more readily removed. Some garments are
available with special built-in conductive fibers that can assist in keeping
the surface charge to a minimum. Consult your garment supplier for details.
Point Ionization (static neutralization) can be installed on the inside walls
to dissipate some of the charge on the garments, helping to reduce the holding
charge (force) of the garment, making it easier for the air to blow the
particles off. In many cleanroom applications, much of the contamination in the
room is carried in on the garments of the individuals working within the room.
Typically they bring it to the most critical area. Without using an air shower,
individuals are often cleaner when they leave the clean space because a large
portion of the contamination they had on their garments will have fallen off
within the clean space. Using an air shower is an effective way to remove much
of the contamination that would otherwise come off within the clean space.