Humidity; Altitude; Dust And Particles; Corrosion - Dell 4100 User Manual

•
Make sure that all slots and openings on the com-
puter remain unobstructed, especially the fan guard
on the back of the computer.
•
Clean the system at regular intervals to avoid any
buildup of dust and debris, which can cause a system
to overheat.
•
If the system is exposed to abnormally cold tempera-
tures, allow a 15-minute warm-up period after it is
turned on before attempting to read from or write to
the hard-disk drive.
•
If intermittent system failures are noticed, try reseat-
ing any socketed chips, which might have become
loose due to temperature fluctuations.

Humidity

High-humidity conditions can cause moisture migration
and penetration into the computer. This moisture can
cause corrosion of internal components and degradation
of properties such as electrical resistance, thermal con-
ductivity, physical strength, and size. Extreme moisture
buildup inside the computer can result in electrical shorts,
which can cause serious damage to the computer.
Each Dell system is rated to operate at 8 to 80 percent rel-
ative humidity, with a humidity gradation of 10 percent
per hour. In storage, a Dell system can withstand from 8
to 95 percent relative humidity.
Buildings in which climate is controlled by air-
conditioning in the warmer months and by heat during the
colder months usually maintain an acceptable level of
humidity for computer equipment. However, if a system is
located in an unusually humid location, a dehumidifier can
be used to maintain the humidity within an acceptable
range.

Altitude

Operating a system at high altitude (low pressure)
reduces the efficiency of forced and convection cooling
and can result in electrical problems related to arcing and
corona effects. This condition can also cause sealed com-
ponents with internal pressure, such as electrolytic
capacitors, to fail or perform at reduced efficiency.
Each Dell system is rated to operate at altitudes from -16
to 3048 meters (m) (-50 to 10,000 feet [ft]) and can be
stored at altitudes of -16 to 10,600 m (-50 to 35,000 ft).

Dust and Particles

A clean operating environment can greatly reduce the
negative effects of dust and other particles, which act as
insulators and interfere with the operation of a system's
mechanical components. Also, in addition to regular
cleaning, you should follow these guidelines to deter con-
tamination of the computer equipment:
•
Do not permit smoking anywhere near the system.
•
Do not permit food or drink near the system.
•
Use dust covers when the system is not in use.
•
Keep all diskettes in a closed diskette box when not
in use.
•
Close windows and outside doors to keep out air-
borne particles.

Corrosion

The oil from a person's fingers or prolonged exposure to
high temperature or humidity can corrode the gold-plated
edge connectors and pin connectors on various devices in
the computer. This corrosion on computer connectors is a
gradual process that can eventually lead to intermittent
failures of electrical circuits.
To prevent corrosion, you should avoid touching contacts
on cable connectors. Protecting the system from corro-
sive elements is especially important in moist and salty
environments, which tend to promote corrosion. Also, as
a further deterrent to corrosion, the system should not be
used in extreme temperatures, as explained in "Tempera-
ture" discussed earlier in this appendix.
Electromagnetic and Radio Frequency
Interference
Electromagnetic interference (EMI) and radio frequency
interference (RFI) from a computer can adversely affect
devices such as radio and television (TV) receivers oper-
ating near the computer. Radio frequencies emanating
from a computer system can also interfere with cordless
and low-power telephones. Conversely, RFI from
Maintaining the System C-3