Superdome Servers - I/O Expansion Cabinet Guide, Fifth Edition

Appendix B
Site Requirements
Environmental Requirements
221
CAUTION Low humidity contributes to undesirably high levels of electrostatic charges. This increases the
electrostatic discharge (ESD) voltage potential. ESD can cause component damage during
servicing operations. Paper feed problems on high-speed printers are usually encountered in
low-humidity environments.
Low humidity levels are often the result of the facility heating system and occur during the cold season. Most
heating systems provide air with a low humidity level, unless the system has a built-in humidifier.
Air Conditioning Ducts
Use separate computer room air conditioning duct work. If it is not separate from the rest of the building, it
might be difficult to control cooling and air pressure levels. Duct work seals are important for maintaining a
balanced air conditioning system and high static air pressure. Adequate cooling capacity means little if the
direction and rate of air flow cannot be controlled because of poor duct sealing. Also, the ducts should not be
exposed to warm air, or humidity levels may increase.
Dust and Pollution Control
Disk drives, tape drives, and some other mechanical devices require a dust-free environment for trouble-free
operation. Hewlett-Packard disk and tape drives are protected from dust particles by mechanical air filters
designed to trap large dust particles.
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 its air conditioning
system at a high static air pressure level.
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 (especially high-speed line printers) in a separate room to eliminate paper
problems.
• Eating or drinking—Establish a no-eating or drinking policy. Spilled liquids can cause short circuits in
equipment such as keyboards.
• Rugs—Use a tightly sealed vacuum cleaner to clean rugs.
• 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.
Electrostatic Discharge (ESD) Prevention
Static charges (voltage levels) occur when objects are separated or rubbed together. The voltage level of a
static charge is determined by the following factors:
• Types of materials
•Relative humidity
• Rate of change or separation