Site Preparation Guide, Fourth Editon - HP Integrity rx7620 Server

Appendix B
General Site Preparation Guidelines
Environmental Elements
39
If a ceiling plenum return air system or a ducted ceiling return air system is used, the return air grilles in the
ceiling should be located directly above the computer equipment cabinets.
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
perimeter of the system cabinets. Supply air emitted though the perforated floor panels is then available
near the cooling air intake vents of the computer system 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 perimeter 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 computer
system 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 perimeter of
the computer system cabinets. The supply air is then available near the cooling air intake vents of the
computer system 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.
Table B-1 Computer Room Environment
Parameter Operating Limits
Recommended
Operating
Range
Maximum Rate of
Change (per hour)
Non-Operating
Ranges
Temperature
a
a. The temperature ranges stated are at 0 to 5,000 ft. The maximum operating temperature must be
derated by 1° C/1,000 ft from 5,000 to 10,000 ft.
41° to 95° F
(5° to 35° C)
68° to 77° F
(20° to 25° C)
20° C/hr (no tape media)
10° C/hr (with tape media)
-40° C to +70° C
Humidity 15% to 80%
with no condensation
(40% to 55% recommended)
40% to 55% RH
non-condensing
30% RH/hour
non-condensing
90% RH
non-condensing
@ 65° C (149° F)