Juniper EX4400 - Page 88

NOTE: You must install all the fan modules and they must be operaonal for opmal funconing
of the switch.
Leave at least 4 in. (10.16 cm) clearance in front and 2 in. (5.08 cm) behind the chassis for airow.
If the switch is operaonal while you are replacing fan modules, you must remove only one fan module
at a me. The switch connues to operate for 60 seconds without thermal shutdown while you are
replacing a fan module.
CAUTION: Do not mix:
• Fan modules with dierent airow direcons in the same chassis.
• Power supplies with dierent airow direcons in the same chassis.
• Power supplies and fan modules with dierent airow direcons in the same chassis.
If you install power supplies or fan modules with dierent airow direcons, Junos OS
raises an alarm.
Under normal operang condions, the fan modules operate at a moderate speed.
Temperature sensors in the chassis monitor the temperature within the chassis.
If a fan module fails or if the ambient temperature inside the chassis rises above the
acceptable range, Junos OS raises an alarm. If the temperature inside the chassis rises
above the threshold temperature, the system shuts down automacally.
EX4400 Switches with Front-to-Back Airow
In the EX4400 switch models that have front-to-back airow, cold air enters the chassis through the
vents on the front panel and hot air exhausts the chassis through the vents on the rear panel.
• Figure 60 on page 81 shows the front-to-back airow through an EX4400-24T switch.
• Figure 61 on page 81 shows the front-to-back airow through an EX4400-24P switch.
• Figure 62 on page 82 shows the front-to-back airow through an EX4400-24MP switch.
• Figure 63 on page 82 shows the front-to-back airow through an EX4400-24X switch.
• Figure 64 on page 83 shows the front-to-back airow through an EX4400-48T switch.
• Figure 65 on page 83 shows the front-to-back airow through an EX4400-48P switch.
80