Site Preparation Guide, Second Edition - HP Integrity cx2620 Server

• Air conditioning equipment air filters should have a minimum rating of 45% (based on
“ASHRAE Standard 52-76, Dust Spot Efficiency Test”).
• Introduce only enough outside air into the system to meet building code requirements (for
human occupancy) and to maintain a positive air pressure in the computer room.
Air Conditioning System Types
The following three air conditioning system types are listed in order of recommendation:
• Complete self-contained package unit(s) with remote condenser(s). These systems are
available with up or down discharge and are usually located in the computer room.
• Chilled water package unit with remote chilled water plant. These systems are available
with up or down discharge and are usually located in the computer room.
• Central station air handling units with remote refrigeration equipment. These systems are
usually located outside the computer room.
Basic Air Distribution Systems
A basic air-distribution system includes supply air and return air. Refer to Table 2-4 (page 39)
for more information.
Configure the air-distribution system to deliver adequate supply air to the cooling air intake
vents of the server equipment cabinets. Maintain supply air temperature within the following
parameters:
Ceiling supply system From 55° F (12.8° C) to 60° F (15.6° C)
Floor supply system At least 60° F (15.6° C)
If you use a ceiling plenum return air (CPRA) system or a ducted ceiling return air system, place
the return air grills in the ceiling above the exhaust area or the exhaust row.
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 a plenum for the supply air.
Return air from an underfloor air distribution system can
be ducted return air (DRA) above the ceiling.
Locate perforated floor panels (available from the raised
floor manufacturer) 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 server
cabinets.
Ceiling plenum air distribution
system (CPRA)
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 airflow
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 server cabinets.
Direct the return air back to the air-conditioning equipment
though the return air duct above the ceiling.
34 General Site Preparation Guidelines