HP 9000 rp5400 Servers - Manual (Page 151)

Specifically, disk drives, tape drives, and some other mechanical devices can have bearing failures
resulting from airborne abrasive particles. Dust may also blanket electronic components like
printed circuit boards causing premature failure due to excess heat and/or humidity build up
on the boards. Other failures to power supplies and other electronic components can be caused
by metallically conductive particles, including zinc whiskers. These metallic particles are
conductive and can short circuit electronic components. Use every effort to ensure that the
environment is as dust and particulate free as possible. See the following heading titled "Metallic
Particulate Contamination" for additional details.
Smaller particles can pass though some filters and over a period of time, cause problems in
mechanical parts. Small dust particles can be prevented from entering the computer room by
maintaining the air conditioning system at a high static air pressure level.
Other sources of dust, metallic, conductive, abrasive, and/or microscopic particles can be present.
Some sources of these particulates are:
•
Subfloor shedding
• Raised floor shedding
• Ceiling tile shedding
These particulates are not always visible to the naked eye. A good check to determine their
possible presence is to check the underside of the tiles. The tile should be shiny, galvanized, and
free from rust.
The computer room should be kept clean. The following guidelines are recommended:
•
Smoking—Establish a no-smoking policy. Cigarette smoke particles are eight times larger
than the clearance between disk drive read/write heads and the disk surface.
• Printer—Locate printers and paper products in a separate room to eliminate paper particulate
problems.
• Eating or drinking—Establish a no-eating or drinking policy. Spilled liquids can cause short
circuits in equipment such as keyboards.
• Tile floors—Use a dust-absorbent cloth mop rather than a dry mop to clean tile floors.
Special precautions are necessary if the computer room is near a source of air pollution. Some
air pollutants, especially hydrogen sulfide (H2S), are not only unpleasant but corrosive as well.
Hydrogen sulfide damages wiring and delicate sound equipment. The use of activated charcoal
filters reduces this form of air pollution.
Metallic Particulate Contamination
Metallic particulates can be especially harmful around electronic equipment. This type of
contamination may enter the data center environment from a variety of sources, including but
not limited to raised floor tiles, worn air conditioning parts, heating ducts, rotor brushes in
vacuum cleaners or printer component wear. Because metallic particulates conduct electricity,
they have an increased potential for creating short circuits in electronic equipment. This problem
is exaggerated by the increasingly dense circuitry of electronic equipment.
Over time, very fine whiskers of pure metal can form on electroplated zinc, cadmium, or tin
surfaces. If these whiskers are disturbed, they may break off and become airborne, possibly
causing failures or operational interruptions. For over 50 years, the electronics industry has been
aware of the relatively rare but possible threat posed by metallic particulate contamination.
During recent years, a growing concern has developed in computer rooms where these conductive
contaminants are formed on the bottom of some raised floor tiles.
Although this problem is relatively rare, it may be an issue within your computer room. Since
metallic contamination can cause permanent or intermittent failures on your electronic equipment,
Hewlett-Packard strongly recommends that your site be evaluated for metallic particulate
contamination before installation of electronic equipment.
Environmental Elements 151