Cisco 4490 - Manual (Page 71)

5-3
Cisco Global Site Selector 4490 Hardware Installation Guide
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Chapter 5 Maintaining the Cisco Global Site Selector 4490
Maintaining Your Site Environment
Adequate ventilation is particularly important at high altitudes. System
performance may not be optimum when the system is operating at high
temperatures as well as high altitudes.
• Make sure that all slots and openings on the system remain unobstructed,
especially the fan vent on the back of the system.
• Clean the system at regular intervals to avoid any buildup of dust and debris,
which can cause a system to overheat.
• If the system has been exposed to abnormally cold temperatures, allow a
2-hour warm-up period to bring it up to normal operating temperature before
turning it on. Failure to do so may cause damage to internal components,
particularly the hard disk drive.
Humidity
High-humidity conditions can cause moisture migration and penetration into the
system. This moisture can cause corrosion of internal components and
degradation of properties such as electrical resistance, thermal conductivity,
physical strength, and size. Extreme moisture buildup inside the system can result
in electrical shorts, which can cause serious damage to the system.
Each system is rated to operate at 8 to 80 percent relative humidity, with a
humidity gradation of 10 percent per hour. 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 system 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 components with internal
pressure, such as electrolytic capacitors, to fail or perform at reduced efficiency.
Each system is rated to operate at a maximum altitude of 6500 feet (2000 meters)
and can be stored at a maximum altitude of 15,000 feet (4570 meters).