HP 9000 rp5400 Servers - Manual (Page 150)

The following three types of air distribution system are listed in order of recommendation:
•
Underfloor air distribution system—Downflow air conditioning equipment located on the
raised floor of the computer room uses the cavity beneath the raised floor as plenum for the
supply air.
Perforated floor panels (available from the raised floor manufacturer) should be located
around the front of the system cabinets. Supply air emitted though the perforated floor
panels is then available near the cooling air intake vents of the hp server cabinets.
• Ceiling plenum air distribution system—Supply air is ducted into the ceiling plenum from
upflow air conditioning equipment located in the computer room or from an air handling
unit (remote).
The ceiling construction should resist air leakage. Place perforated ceiling panels (with down
discharge air flow characteristics) around the front of the system cabinets. The supply air
emitted downward from the perforated ceiling panels is then available near the cooling air
intake vents of the hp server cabinets.
Return air should be ducted back to the air conditioning equipment though the return air
duct above the ceiling.
• Above ceiling ducted air distribution system—Supply air is ducted into a ceiling diffuser
system from upflow air conditioning equipment located in the computer room or from an
air handling unit (remote).
Adjust the supply air diffuser system grilles to direct the cooling air downward around the
front of the hp server cabinets. The supply air is then available near the cooling air intake
vents of the hp server cabinets.
Air Conditioning System Installation
All air conditioning equipment, materials, and installation must comply with any applicable
construction codes. Installation of the various components of the air conditioning system must
also conform to the air conditioning equipment manufacturer's recommendations.
Air Conditioning Ducts
Use separate computer room air conditioning duct work. If it is not separate from the rest of the
building, it might be difficult to control cooling and air pressure levels. Duct work seals are
important for maintaining a balanced air conditioning system and high static air pressure.
Adequate cooling capacity means little if the direction and rate of air flow cannot be controlled
because of poor duct sealing. Also, the ducts should not be exposed to warm air, or humidity
levels may increase.
Humidity Level
Maintain proper humidity levels at 40 to 60% RH. High humidity causes galvanic actions to
occur between some dissimilar metals. This eventually causes a high resistance between
connections, leading to equipment failures. High humidity can also have an adverse affect on
some magnetic tapes and paper media.
CAUTION: Low humidity contributes to undesirably high levels of electrostatic charges. This
increases the electrostatic discharge (ESD) voltage potential. ESD can cause component damage
during servicing operations. Paper feed problems on high-speed printers are usually encountered
in low-humidity environments.
Low humidity levels are often the result of the facility heating system and occur during the cold
season. Most heating systems cause air to have a low humidity level, unless the system has a
built-in humidifier.
Dust and Pollution Control
Computer equipment can be adversely affected by dust and microscopic particles in the site
environment.
150 General Site Preparation Guidelines