Site Preparation Guide, Second Edition - HP Integrity cx2620 Server

not limited to raised floor tiles, worn air-conditioning parts, heating ducts, rotor brushes in
vacuum cleaners, or printer component wear. Because metallic particles conduct electricity, they
have an increased potential for creating short circuits in electronic equipment. This problem is
exaggerated by the increasingly dense circuitry of electronic equipment.
Over time, very fine whiskers of pure metal can form on electroplated zinc, cadmium, or tin
surfaces. If these whiskers are disturbed, they can break off and become airborne, possibly causing
failures or operational interruptions. For more than 50 years, the electronics industry has been
aware of the relatively rare but possible threat posed by metallic particulate contamination.
During recent years, concern has increased regarding metallic particulate contamination in
computer rooms, where these conductive contaminants are formed on the bottom of some raised
floor tiles.
Although this problem is relatively rare, it can be an issue within your computer room. Because
metallic contamination can cause intermittent or permanent failures on your electronic equipment,
HP strongly recommends that your site be evaluated for metallic particulate contamination
before installation of electronic equipment.
Cooling Requirements
Air conditioning equipment requirements and recommendations are described in the following
sections.
Basic Air Conditioning Equipment Requirements
The cooling capacity of the installed air conditioning equipment for the computer room should
be sufficient to offset the computer equipment dissipation loads, as well as any space envelope
heat gain. This equipment should include:
• Air filtration
• Cooling or dehumidification
• Humidification
• Reheating
• Air distribution
• System controls adequate to maintain the computer room within specified operating ranges
When calculating cooling requirements, include the heat generated by lighting and by personnel.
For example, a person dissipates about 450 BTUs per hour while performing a typical computer
room task.
At altitudes above 10,000 feet (3048 m), the lower air density reduces the cooling capability of
air-conditioning systems. If your facility is located above this altitude, you might need to modify
the recommended temperature ranges. For each 1,000 foot (305 m) increase in altitude above
10,000 feet (up to a maximum of 15,000 feet), subtract 0.83°C (33.5°F) from the upper limit of the
temperature range.
Air Conditioning System Guidelines
Use the following guidelines when designing an air-conditioning system and selecting the
necessary equipment:
• The computer room air-conditioning system should be capable of operating 24 hours a day,
365 days a year. It should also be independent of other systems in the building.
• Consider the long-term value of server availability, redundant air-conditioning equipment,
or capacity.
• The system should be capable of handling any future server expansion.
Environmental Elements 33