User's Manual

DRAFT 4
TB9400 Installation and Operation Manual Installation 65
© Tait Electronics Limited September 2011
5.1.5 Cabinet and Rack Ventilation
The cooling airflow for the base station enters through the front panel and
exits at the rear of the subrack. For optimum thermal performance, the
heated air that has passed through a base station must not be allowed to re-
enter the air intakes on the front panel. Any space at the front of the cabinet
not occupied by equipment should be covered by a blanking panel. Refer
to Figure 5.1 on page 66.
To allow enough cooling airflow through a cabinet-mounted base station,
we recommend the following:
■ an area of at least 23 in
2
(150 cm
2
) of unrestricted ventilation slots or holes
in front of the air intakes for the fans for each subrack; for example, thirty
0.25 x 3.3 in (6 x 85 mm) slots will allow the recommended airflow
■ a vent in the top of the cabinet with an area of approximately 23 in
2
(150 cm
2
) per subrack, or a similar area of ventilation per subrack at the
rear of the cabinet behind each subrack
■ a 2 U gap at the top of the cabinet.
Note The ventilation opening must be unrestricted. If the slots or holes
are covered with a filter, mesh or grille, the open area must be
increased to allow the same airflow as an unrestricted opening.
The maximum ambient temperature entering the cabinet must not exceed
+ 140°F (+ 60°C).
If you are installing multiple subracks in a cabinet, ensure that there will be
enough cooling airflow through the cabinet after the equipment has been
installed. For example, the recommended maximum number of subracks in
a 38 U cabinet is five, as shown in Figure 5.1 on page 66.
If the base station is installed in a rack or cabinet with other equipment with
different ventilation requirements, we recommend that the base station be
positioned below this equipment.
Auxiliary Extractor
Fans
The base station does not require auxiliary extractor fans mounted in the top
of the cabinet. If your cabinet is already fitted with fans, the following
procedures apply:
■ if there are six or more 4.75 in (12 cm) fans, each capable of extracting
94.2 ft
3
per minute (160 m
3
per hour), they must run continuously
■ if there are fewer than six fans, you must remove them and ensure the
vent in the top of the cabinet has an area of approximately 23 in
2
(150 cm
2
) per subrack.
If you have any other configuration, the performance of your system will
depend on how closely you comply with the base station airflow
requirements described above.