Contaminant Effects
B-4 StorageTek SL150 Modular Tape Library Installation Manual
designed to be used in the airstream of a re-circulating air system. The use of push
mops or inadequately filtered vacuums can also stimulate contamination.
It is essential that steps be taken to prevent air contaminants, such as metal particles,
atmospheric dust, solvent vapors, corrosive gasses, soot, airborne fibers or salts from
entering or being generated within the computer room environment. In the absence of
hardware exposure limits, use applicable human exposure limits from OSHA, NIOSH
or the ACGIH.
Contaminant Effects
Destructive interactions between airborne particulate and electronic instrumentation
can occur in numerous ways. The means of interference depends on the time and
location of the critical incident, the physical properties of the contaminant and the
environment in which the component is placed.
Physical Interference
Hard particles with a tensile strength at least 10% greater than that of the component
material can remove material from the surface of the component by grinding action or
embedding. Soft particles will not damage the surface of the component, but can
collect in patches that can interfere with proper functioning. If these particles are tacky
they can collect other particulate matter. Even very small particles can have an impact
if they collect on a tacky surface, or agglomerate as the result of electrostatic charge
build-up.
Corrosive Failure
Corrosive failure or contact intermittence due to the intrinsic composition of the
particles or due to absorption of water vapor and gaseous contaminants by the
particles can also cause failures. The chemical composition of the contaminant can be
very important. Salts, for instance, can grow by absorbing water vapor from the air
(nucleating). If a mineral salts deposit exists in a sensitive location and the
environment is sufficiently moist, it can grow to a size where it can physically interfere
with a mechanism or can cause damage by forming salt solutions.
Shorts
Conductive pathways can arise through the accumulation of particles on circuit boards
or other components. Many types of particulate are not inherently conductive, but can
absorb significant quantities of water in high-moisture environments. Problems caused
by electrically conductive particles can range from intermittent malfunctioning to
actual damage to components and operational failures.
Thermal Failure
Premature clogging of filtered devices will cause a restriction in air flow that could
induce internal overheating and head crashes. Heavy layers of accumulated dust on
hardware components can also form an insulative layer that can lead to heat-related
failures.
Room Conditions
Maintain a high level of cleanliness on all surfaces within the controlled zone of the
data center. Trained professionals should clean all surfaces periodically, as outlined in
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