Sun Oracle StorageTek SL150, System Assurance Manual

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Contaminant Effects
42 SL150 Systems Assurance July 2012
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
“Cleaning Procedures
and Equipment” section should be avoided. Out-gassing from these products 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 they are not 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, applicable human exposure limits from OSHA, NIOSH
or the ACGIH should be used.
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 in size 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.