Juniper QFX5240 - Page 40

The cooling system consists of the following components:
1. "Fan Modules" on page 33
2. "Airow" on page 35
3. "Power Supply Cooling System" on page 36
Fan Modules
The QFX5240 has four hot-insertable and hot-removable eld-replaceable fan modules (QFX5240-2U-
FANAO) installed at the rear of the switch. Each fan module houses two 80 mm x 80 mm counter-
rotang rotors.
The fan modules in a QFX5240 are FRUs designed for port-to-FRU airow, which is also known as
airow out (AFO) or front-to-back airow. The fan modules are numbered from 0 through 3. Each fan
module is 2-U high and has an associated LED to indicate its status. See Figure 18 on page 33.
Figure 18: Fan Module for QFX5240
NOTE: The fan speed varies based on the temperature of internal components, opcs modules,
and the ambient temperature. The maximum speed at which fans operate depends on the
congured ambient temperature. As the fan speed increases, the power consumed by the fans
increases. As a result, the device consumes more power when the temperature is high because
the fans run faster to maintain the operang temperature of the chassis within the congured
limits.
The QFX5240 switch must operate with all the four fan modules installed. If you need to replace a
faulty fan module, see "Remove a Fan Module from QFX5240 Switches" on page 90.
33