Cooling With The Fan Tray - Cisco Catalyst 6840 Series Hardware Installation Manual

Preparing for Installation
If you are installing your switch in an enclosed or partially enclosed rack, we strongly recommend that you
verify that your site meets the following guidelines:
• Verify that there is a minimum of 6 inches (15 cm) of clearance between the sides of the rack and both
• Verify that the ambient air temperature within the enclosed or partially enclosed rack is within the chassis
• If the ambient intake air temperature is less than 104°F (40°C), the rack meets the intake air temperature
• Verify that the enclosed or partially enclosed rack allows an adequate flow of air through the switch
• Plan ahead. Your switch that is installed in an enclosed or partially enclosed rack might currently meet

Cooling with the Fan Tray

The chassis fan tray provides cooling air for the switch chassis and components. If an individual fan within
the fan tray fails, the Fan Status LED turns amber. Individual fans within a fan tray cannot be replaced; you
must replace the entire fan tray.
Refer to your software configuration guide for information on environmental monitoring.
the chassis air intake grill and the chassis air exhaust grill.
operating temperature limits. After installing the chassis in the rack, power up the chassis and allow the
chassis temperature to stabilize (approximately 2 hours). Measure the ambient air temperature at the
chassis air intake grill and at the chassis air exhaust grill by positioning an external temperature probe
approximately 1 inch (2.5 cm) away from the grills.
criterion.
• If the ambient intake air temperature exceeds 104°F (40°C), the system might experience minor
temperature alarms and is in danger of overheating.
• If the ambient intake air temperature equals or is greater than 131°F (55°C), the system will
experience a major temperature alarm and shut down.
chassis as follows:
• If the difference between the measured intake air temperature and the exhaust air temperature does
not exceed 10°C, there is sufficient airflow in the rack.
• If the difference in air temperature exceeds 10°C, there is insufficient airflow to cool the chassis.
Note
The 10°C temperature differential between the intake and the exhaust must be
determined by taking measurements using external digital temperature probes.
Do not use the chassis internal temperature sensors to measure the temperature
differential.
ambient air temperature and air flow requirements. However, if you add more chassis to the rack or you
add more modules to a chassis in the rack, the additional heat generated might cause the ambient air
temperature within the rack to exceed 104°F (40°C) and can cause minor alarms.
Catalyst 6840-X Switch Series Hardware Installation Guide
Cooling with the Fan Tray
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