Juniper Networks MX480, MX240 User Manual

MX240 and MX480
Ethernet Services Router
Fan Tray Installation Instructions

13 February 2008
Part Number: 530-022145-01
Revision 1

This document describes how to remove and replace the fan tray on a Juniper
Networks MX240 and MX480 Ethernet Services Router. The fan tray and the air filter
make up the cooling system.

Contents

Cooling System ...............................................................................................2

Replacing the Fan Tray ....................................................................................4

Removing the Fan Tray .............................................................................5

Installing the Fan Tray ..............................................................................6

Electrostatic Discharge Point ...........................................................................7

Preventing Electrostatic Discharge Damage ....................................................9

List of Technical Publications ..........................................................................9

Requesting Technical Support .......................................................................16

Revision History ............................................................................................17

■ 1

MX240 and MX480 Ethernet Services Router Fan Tray Installation Instructions

Cooling System

The cooling system consists of the following components:

■ Fan tray

■ Air filter

The cooling system components work together to keep all router components within
the acceptable temperature range (see Figure 1 on page 2, Figure 2 on page 2,
Figure 3 on page 3, Figure 4 on page 3, Figure 5 on page 4, and
Figure 6 on page 4). The router has one fan tray and one air filter that install
vertically in the rear of the router. The fan tray contains three fans on an MX240
router and six fans on an MX480 router.

The air intake to cool the chassis is located on the side of the chassis next to the air
filter. Air is pulled through the chassis toward the fan tray, where it is exhausted out
the side of the system. The air intake to cool the power supplies is located in the
front of the router above the craft interface. The exhaust for the power supplies is
located on the rear bulkhead power supplies.

Figure 1: Airflow Through the MX240 Chassis

Figure 2: Airflow Through the MX480 Chassis

2 ■ Cooling System

The host subsystem monitors the temperature of the router components. When the
router is operating normally, the fans function at lower than full speed. If a fan fails
or the ambient temperature rises above a threshold, the speed of the remaining fans
is automatically adjusted to keep the temperature within the acceptable range. If the
ambient maximum temperature specification is exceeded and the system cannot

Cooling System

be adequately cooled, the Routing Engine shuts down the system by disabling output
power from each power supply.

Figure 3: Fan Tray in an MX240 Router

Figure 4: Fan Tray in an MX480 Router

Cooling System ■ 3

MX240 and MX480 Ethernet Services Router Fan Tray Installation Instructions

Figure 5: Air Filter on an MX240 Router

Figure 6: Air Filter on an MX480 Router

Replacing the Fan Tray

The router has one fan tray that installs vertically in the rear of the chassis. The fan
tray contains three fans on an MX240 router and six fans on an MX480 router. The
fan tray is hot-removable and hot-insertable.

The fan tray is located in the rear of the chassis on the right side. The fan tray weighs
about 6.8 lb (3.08 kg).

NOTE: To prevent overheating, install the replacement fan tray immediately after
removing the existing fan tray.

4 ■ Replacing the Fan Tray

To replace the fan tray, use the following procedures:

■ Removing the Fan Tray on page 5

■ Installing the Fan Tray on page 6

Removing the Fan Tray

To remove the fan tray (see Figure 7 on page 5 and Figure 8 on page 6):

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and

2. Loosen the captive screws on the fan tray faceplate.

3. Grasp the fan tray handle and pull it out approximately 1 to 3 inches.

WARNING: To avoid injury, keep tools and your fingers away from the fans as you
slide the fan tray out of the chassis. The fans might still be spinning.

Replacing the Fan Tray

connect the strap to one of the ESD points on the chassis. For more information
about ESD, see “Preventing Electrostatic Discharge Damage” on page 9.

4. Press the latch located on the inside of the fan tray to release it from the chassis.

5. Place one hand under the fan tray to support it and pull the fan tray completely

out of the chassis.

Figure 7: Removing the Fan Tray from an MX240 Router

Replacing the Fan Tray ■ 5

MX240 and MX480 Ethernet Services Router Fan Tray Installation Instructions

Figure 8: Removing the Fan Tray from an MX480 Router

Installing the Fan Tray

To install the fan tray (see Figure 9 on page 7 and Figure 10 on page 7):

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and

2. Grasp the fan tray handle and insert it straight into the chassis. Note the correct

3. Tighten the captive screws on the fan tray faceplate to secure it in the chassis.

connect the strap to one of the ESD points on the chassis. For more information
about ESD, see “Preventing Electrostatic Discharge Damage” on page 9.

orientation by the this side up label on the top surface of the fan tray.

6 ■ Replacing the Fan Tray