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Specification
Caution – If the system is to be operated at an altitude between 3280 ft. to 10,000 ft.
(1000 m to 3048 m) above sea level, lower the environmental temperature 3.3°F
(1.7°C) for every 3280 ft. (1000 m) above sea level.
Airflow and Heat Dissipation
The ideal method for cooling equipment in a cabinet is to control the room ambient
temperature and use rack cabinet doors that have a 63% or higher Free Air Ratio.
Under these conditions, additional fan packs on the rack cabinet are usually not
necessary. Recommended airflow ranges are listed below. Cabinet airflow should be
front to back. Allow at least 30 inches in front of the cabinet, and at least 24 inches
behind the cabinet, for service clearance, proper ventilation, and heat dissipation.
Caution – In order to achieve proper airflow, both the front and rear doors need
approximately 63% open-area perforations (holes). This percentage refers to the ratio
of open space, by way of holes or slots, to closed area within an airflow inlet or
outlet. This is commonly referred to as the Free Area Ratio, or FAR. 63% FAR
translates into approximately 33 holes in an area that is 25mm square.
Recommended Total System Volumetric Airflow per U
Most rack-ready equipment today requires front-to-back cooling, therefore, enclosed
cabinets should provide front-to-back cooling as well. While some racks have fans
mounted on the top of the enclosure, it's better to have them mounted directly to the
rear door so the air is pulled through the chassis from front to back.
18
Sun StorageTek 6540 Rack Ready Site Preparation and Installation Support Guide • July 2006
Operating
Transit range
Maximum dew point
Maximum gradient
1U 32 -36 CFM / U
2U 39 - 45 CFM / U
4U 38 - 40 CFM / U
5U 45 - 50 CFM / U
7U 25 - 43 CFM / U
Nonoperating
5% to 95%
79°F (26°C)
10% per hour
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