IBM 7133 D40, Service Manual

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Full information about cooling requirements for the 7133 Model D40 is given in the 7133
Models D40 and T40 Serial Disk Systems: Hardware Technical Information. A summary
of that information is given here.
v
The recommended operating temperature is 22°C (72°F) or lower. At lower
temperatures, the risk of failure in the 7133 is reduced. If the operating temperature
is above 22°C (72°F) for long periods, the 7133 is exposed to a greater risk of failure
from external causes.
v
Each rack-mounted 7133 Model D40 requires an airflow of 2.5 m
³
per minute (87 ft
³
per minute). The input air temperature to all racks is recommended to be in the
range 20 through 25°C (68 through 77°F).
When racks containing many 7133s are to be installed together, the following
requirements must be met to ensure that the 7133s are suitably cooled:
– Air enters at the front of the rack and leaves at the back. To prevent the air that is
leaving the rack from entering the intake of another piece of equipment, racks
must be positioned in alternate rows, back-to-back and front-to-front. This
arrangement is known as “Cold Aisle / Hot Aisle.”
– Where racks are in rows, each rack must touch the rack that is next to it to
reduce the amount of hot air that can flow round from the back of the rack into the
intakes of the 7133s that are in that rack. It is recommended that Suite Attach Kits
be used to completely seal any gaps that remain between the racks. For details of
Suite Attach Kits, contact your marketing representative.
– Where racks are in rows front-to-front or back-to-back, a gap of at least 1220 mm
(48 in) must separate the rows across the cold aisle.
– Where cold air is supplied through perforated tiles or gratings in the floor, it is
recommended that the front of racks be located on floor-tile seams. A full line of
perforated tiles or gratings must be immediately in front of the racks. The
underfloor temperature must not exceed 15°C (60°F).
Air conditioners must be located where they can take their input from the hot
aisle, and supply cooled air to the underside of the cold aisle perforated tiles or
gratings. It is recommended that the air conditioners be located at the ends of the
hot aisles. This requirement ensures that hot exhaust air cannot flow over the top
of the racks and reenter at the front.
The perforated tiles or gratings must be able to supply a suitable airflow for all the
7133s that are present in a rack. For example, if a T42 rack contains ten 7133s,
and the air conditioners are located at the ends at the ends of the hot aisles, the
airflow required is 19.8 m
³
per minute (700 ft
³
per minute). If the air conditioners
are located in front of, or behind the racks, the airflow required for the example
T42 rack is now 25.5 m
³
per minute (900
³
per minute).
– To ensure correct airflow in each rack, the rack filler plates must be installed in
unused positions. Also, all the gaps in the front of the racks must be sealed,
including the gaps between the 7133s.
Chapter 1. Reference Information
39