Facility cooling requirements, Figure 2-19 – Cisco CRS-1 User Manual

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Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Site Planning Guide


Chapter 2 Power and Cooling

Facility Cooling Requirements

Figure 2-19

Airflow Through the 8-Slot Line Card Chassis

The 8-slot LCC airflow volumes are as follows:

Chassis airflow: Up to 900 cubic feet (25,485 liters) per minute

Power system airflow: Up to 240 cubic feet (6800 liters) per minute

Facility Cooling Requirements

The 8-slot line card chassis dissipates considerable power that generates much heat. In large
configurations, additional air cooling is required to maintain correct operating temperatures. The room
air must be cooled by external cooling units that are installed as part of the routing system.

Heat dissipation and external cooling requirements for the 8-slot line card chassis are as follows:

Heat dissipation (fixed configuration): 28,720 BTUs per hour

Heat dissipation (modular configuration): 32,570 BTUs per hour

External cooling requirements: 2.3 tons

To ensure that the site provides the proper air circulation for the system:

Make certain that the site is as dust free as possible. Dusty environments can clog the air filter or
power supply intake vents, reducing the cooling airflow through the system.

Allow sufficient airflow by maintaining a minimum of 6 inches (15.2 cm) of clearance at both the
inlet and exhaust openings on the chassis and the fixed configuration power modules. If airflow is
blocked or restricted, or if inlet air is too warm, an over-temperature condition can occur. Under
extreme conditions, the environmental monitoring system shuts down the power to protect the
routing system components.



Air enters

PLIM side

Power system


Air exits MSC and
fabric card side



Air filter