HP Integrity rx7620 Site Preparation Guide, Fourth Editon - HP Integrity rx762 - Page 53

General Site Preparation Guidelines Environmental Elements 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. Table B-1 Computer Room Environment Parameter Operating Limits Recommended Operating Range Maximum Rate of Change (per hour) Non-Operating Ranges Temperaturea 41° to 95° F (5° to 35° C) 68° to 77° F (20° to 25° C) 20° C/hr (no tape media) -40° C to +70° C 10° C/hr (with tape media) Humidity 15% to 80% 40% to 55% RH 30% RH/hour with no condensation non-condensing non-condensing (40% to 55% recommended) 90% RH non-condensing @ 65° C (149° F) 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. 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. Appendix B 39