Table Of Contents
Installing Air Filters in Cisco 3825 Integrated Services Routers
This document describes how to install the optional air filter kit located on the side of your Cisco 3825 Integrated Services Router (ISR).
This document is intended for the air filter installer, who should be familiar with electronic circuitry and wiring practices and have experience as an electronic or electromechanical technician.
Note Use this document in conjunction with the Cisco 3800 series ISR hardware and regulatory compliance and safety information documentation for your router. You can find this documentation at the following URLs.
For the Cisco 3800 Series Hardware Installation Guide:
For the Cisco 2800 Series and Cisco 3800 Series Integrated Services Routers Regulatory Compliance and Safety Information document:
If you have questions or need help, see the "Obtaining Documentation, Obtaining Support, and Security Guidelines" section.
This document contains the following sections:
Follow these guidelines to ensure general safety:
•Keep the chassis area clear and dust-free during and after installation.
•Keep tools away from walk areas where you or others could fall over them.
•Do not wear loose clothing that may get caught in the chassis. Fasten your tie or scarf and roll up your sleeves.
•Wear safety glasses when working under conditions that may be hazardous to your eyes.
•Do not perform any action that creates a potential hazard to people or makes the equipment unsafe.
Safety with Electricity
Follow these guidelines when working on equipment powered by electricity:
•Locate the room's emergency power-off switch. Then, if an electrical accident occurs, you can quickly shut the power off.
•Before working on the system, turn off the power and unplug the power cord.
•Disconnect all power.
•Do not work alone if potentially hazardous conditions exist.
•Look carefully for possible hazards in your work area, such as moist floors, ungrounded power extension cables, and missing safety grounds.
•Never assume that power is disconnected from a circuit. Always check.
•If an electrical accident occurs, proceed as follows:
–Use caution, and do not become a victim yourself.
–Turn off power to the system.
–If possible, send another person to get medical aid. Otherwise, determine the condition of the victim and then call for help.
–Determine if the person needs rescue breathing or external cardiac compressions; then take appropriate action.
Preventing Electrostatic Discharge Damage
Electrostatic discharge (ESD) can damage equipment and impair electrical circuitry. It occurs when electronic printed circuit cards are improperly handled and can result in complete or intermittent failures. Always follow ESD prevention procedures when removing and replacing cards. Ensure that the router chassis is electrically connected to earth ground. Wear an ESD-preventive wrist strap, ensuring that it makes good skin contact. Connect the clip to an unpainted surface of the chassis frame to safely channel unwanted ESD voltages to ground. To properly guard against ESD damage and shocks, the wrist strap and cord must operate effectively. If no wrist strap is available, ground yourself by touching the metal part of the chassis.
Caution For safety, periodically check the resistance value of the antistatic strap, which should be between 1 and 10 megohms (Mohms).
Statement 1071—Warning Definition
Required Tools and Equipment
Installation might require some tools and equipment that are not provided as standard equipment with the router. The following tools and parts are required for a typical router installation:
•Number 2 Phillips screwdriver
•ESD-preventive wrist strap
Figure 1 shows a Cisco 3825 ISR.
Figure 1 Cisco 3825 Integrated Services Router
Figure 2 shows the hole cover to be used to block airflow on the front of the Cisco 3825 ISR.
Figure 2 Hole Cover
Figure 3 shows the Cisco 3825 air filter 23-inch rack mounts and air filter.
Figure 3 Air Filter Rack Mounts and Air Filter for the Cisco 3825 Router
Installing the Cisco 3825 Air Filter
This section contains the following content:
Warning Do not touch the power supply when the power cord is connected. For systems with a power switch, line voltages are present within the power supply even when the power switch is off and the power cord is connected. For systems without a power switch, line voltages are present within the power supply when the power cord is connected.
Warning Do not work on the system or connect or disconnect cables during periods of lightning activity.
Warning Network hazardous voltages are present in the BRI cable. If you detach the BRI cable, detach the end away from the router first to avoid possible electric shock. Network hazardous voltages also are present on the system card in the area of the BRI port (RJ-45 connector), even when power is turned off.
Warning Before working on equipment that is connected to power lines, remove jewelry (including rings, necklaces, and watches). Metal objects will heat up when connected to power and ground and can cause serious burns or weld the metal object to the terminals.
Figure 4 shows the airflow patterns for the Cisco 3825 air filter.
Figure 4 Airflow Diagram for Cisco 3825 Router with Air Filter Installed
Air flow through HWICs
Air flow across the CPU and AIMs
Router back panel
Router front panel
Air exhaust through rear-router faceplates
Air flow through NMEs
Follow these steps to install the air filter:
Caution To prevent damage to the router, do not attempt to pry off the plastic bezel.
Step 1 Power down the router and disconnect the power cord from the front of the router.
Step 2 Disconnect all network interface cables from the back panel of the router.
Step 3 Remove the router from the rack.
Step 4 Use the number 2 Phillips screwdriver to remove the rack-mounting brackets from the router.
Step 5 Place the router on a flat surface.
Attaching Brackets and the Air Filter Housing to the Router
Attach the mounting brackets and air filter housing to the router, using a number 2 Phillips screwdriver to install the screws provided with the brackets.
Caution Do not overtorque the screws. The recommended torque range is 10 to12 in-lb (1.1-1.4 N-m) for the Cisco 3825 router.
Caution Your installation must allow unrestricted airflow for router cooling. See Figure 4 for airflow requirements.
Step 1 Slide the hole cover (shown in Figure 2) between the plastic bezel and the metal chassis, with the solid side of the hole cover placed over the air holes on the front of the chassis under the bezel.
Note The clearance hole in the hole cover should align with the upper mounting ear screw hole.
Note Make sure that the hole on the hole cover is aligned with the top screw hole on the side of the Cisco 3825 ISR. (See Figure 5.)
Figure 5 Placing the Hole Cover in Position
Step 2 Attach the air filter housing and rack mount by using the 6 provided screws on the air filter side, and the 4 provided screws on the opposite side. (See Figure 6.)
Note Make sure that the upper right mounting screw of the filter housing mounting bracket passes through the hole in the hole cover shown in Figure 2.
Figure 6 Attaching the Air Filter Housing and Rack Mount
Step 3 Insert the air filter. (See Figure 7.)
Caution Based on air contamination levels published in NEBS GR-63, we recommend that you replace the filter every 6 months. However, if your air contamination levels are less than those published in NEBS GR-63 we recommend that you inspect the filter every 3 to 4 months and replace as necessary.
Note Cisco does not comply with R4-68 (Equipment shall have provision for fan-filter replacement with the fans shut down or blocked to prevent handling contamination. Some designs where the filters are withdrawn from the airflow for removal (for example, door-mounted filters) satisfy the intent of this requirement.). Because of this, we recommend changing the filter on the router when the office is less than 40C (optimal temperature is 32C) to ensure that the fans are operating at their low-speed setting.
Figure 7 Inserting the Air Filter
Installing the Router in a Rack
To install the router in the rack, see the Cisco 3800 Series Hardware Installation Guide:
Obtaining Documentation, Obtaining Support, and Security Guidelines
For information on obtaining documentation, obtaining support, providing documentation feedback, security guidelines, and also recommended aliases and general Cisco documents, see the monthly What's New in Cisco Product Documentation, which also lists all new and revised Cisco technical documentation, at:
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