Cooling System Components; Airflow Through The Chassis - Juniper Internet Router M160 Hardware Manual

M160 Internet Router Hardware Guide

Cooling System Components

The cooling system has the following components. All are hot-removable and
hot-insertable, as described in Field-Replaceable Units (FRUs) on page 4.
CAUTION: Do not remove the air filter for more than a few minutes while the
router is operating. The fans and impellers are powerful enough to draw in foreign
material, such as bits of wire, through the unfiltered air intake, which could damage
router components.

Airflow through the Chassis

Figure 20 shows airflow through the chassis and the location of
the impellers and fan tray.
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Cooling System
Air intake vent, air filter, and intake cover—Provide an opening for room air to
enter the router. They are located at the bottom of the chassis front, below the
cable management system, as shown in Figure 1. The air filter is removable
and covers the air intake vent, preventing dust and other particles from
entering the cooling system. For maintenance and replacement instructions,
see "Maintaining the Air Filter" on page 128. The nonremovable air intake
cover is located behind the air filter and provides EMC shielding.
Front cooling subsystem—Cools the FPCs, PICs, and midplane. It includes a fan
tray located behind the cable management system and a large, central impeller
behind the craft interface. For replacement instructions, see "Replacing the Fan
Tray" on page 148 and "Replacing the Front Impeller Assembly" on page 150.
Rear cooling subsystem—Cools the SFMs, host module, PCGs, and power
supplies. It includes one impeller located at the upper right of the chassis
rear and another at the lower left, as shown in Figure 2. The upper and
lower impellers are not interchangeable. For replacement instructions, see
"Replacing the Rear Lower Impeller Assembly" on page 154 and "Replacing
the Rear Upper Impeller Assembly" on page 156.