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Operator Activity
Human movement within the computer space is probably the single greatest source of
contamination in an otherwise clean computer room. Normal movement can dislodge
tissue fragments, such as dander or hair, or fabric fibers from clothing. The opening
and closing of drawers or hardware panels or any metal-on-metal activity can produce
metal filings. Simply walking across the floor can agitate settled contamination
making it airborne and potentially dangerous.
Hardware Movement
Hardware installation or reconfiguration involves a great deal of subfloor activity, and
settled contaminants can very easily be disturbed, forcing them to become airborne in
the supply air stream to the room's hardware. This is particularly dangerous if the
subfloor deck is unsealed. Unsealed concrete sheds fine dust particles into the
airstream, and is susceptible to efflorescence -- mineral salts brought to the surface of
the deck through evaporation or hydrostatic pressure.
Outside Air
Inadequately filtered air from outside the controlled environment can introduce
innumerable contaminants. Post-filtration contamination in duct work can be
dislodged by air flow, and introduced into the hardware environment. This is
particularly important in a downward-flow air conditioning system in which the
sub-floor void is used as a supply air duct. If the structural deck is contaminated, or if
the concrete slab is not sealed, fine particulate matter (such as concrete dust or
efflorescence) can be carried directly to the room's hardware.
Stored Items
Storage and handling of unused hardware or supplies can also be a source of
contamination. Corrugated cardboard boxes or wooden skids shed fibers when moved
or handled. Stored items are not only contamination sources; their handling in the
computer room controlled areas can agitate settled contamination already in the room.
Outside Influences
A negatively pressurized environment can allow contaminants from adjoining office
areas or the exterior of the building to infiltrate the computer room environment
through gaps in the doors or penetrations in the walls. Ammonia and phosphates are
often associated with agricultural processes, and numerous chemical agents can be
produced in manufacturing areas. If such industries are present near the data center
facility, chemical filtration may be necessary. Potential impact from automobile
emissions, dusts from local quarries or masonry fabrication facilities or sea mists
should also be assessed if relevant.
Cleaning Activity
Inappropriate cleaning practices can also degrade the environment. Many chemicals
used in normal or office cleaning applications can damage sensitive computer
equipment. Potentially hazardous chemicals outlined in the
Equipment"
or direct contact with hardware components can cause failure. Certain biocide
treatments used in building air handlers are also inappropriate for use in computer
rooms either because they contain chemicals, that can degrade components, or because
on page F-8 section should be avoided. Out-gassing from these products
Contaminant Properties and Sources
"Cleaning Procedures and
Controlling Contaminants F-3
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