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Maintaining the T4000 Air Filters



For optimum cooling, verify the condition of the air filters.

Air filters for both the front and rear fan trays help keep dust and other particles from entering the cooling system. To function properly, the entire cooling system requires an unobstructed airflow and proper clearance around the site, as described in T4000 Clearance Requirements for Airflow and Hardware Maintenance. See Figure 1.

Figure 1: Airflow Through the Chassis
Airflow Through the Chassis


Check the air filters regularly for dust and debris. As a general guideline, we recommended that you replace the filter elements every 6 months for routers operating in a typical environment. The filter elements degrade over time, and replacement intervals will vary by operating environment.

For procedures to replace the air filters, see the following topics:

The shelf life of polyurethane filter varies from two years to five years depending on the storage conditions. Store in a cool, dry, and dark environment. Wrap the media in plastic and store in an environment with relative humidity between 40%- 80% and temperature between 40°F (4° C) to 90°F (32° C). Note that if the material flakes, or becomes brittle when rubbed or deformed, it is no longer usable.


Always keep the air filters in place while the router is operating. Because the fans are very powerful, they could pull small bits of wire or other materials into the router through the unfiltered air intake. This could damage the router components.