HP 9000 Superdome SX2000 Generic Site Preparation Guide - Edition 6 - Page 22

• Humidification • Reheating • Air distribution • System controls When calculating cooling requirements, include the heat generated by lighting and personnel. For example, a person dissipates about 450 Btus per hour while performing a typical computer room task. At altitudes above 10,000 feet (3,048 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 (4,572 m)), subtract 0.83 °C (1.49 °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 product availability, redundant air-conditioning equipment, or capacity. • The system should be capable of handling any future product expansion. • 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 descending order of preference: 1. Complete self-contained package units with remote condensers. These systems are available with up or down discharge and are usually located in the computer room. 2. 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. 3. 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. See Table 1-5: "Typical Environments of Customer Installations" (page 27) for more information. Configure the air-distribution system to deliver adequate supply air to the cooling air intake vents of the product equipment cabinets. Maintain supply air temperature within the following parameters: • Ceiling air supply system-From 12.8 °C (55 °F) to 15.6 °C (60 °F) • Floor air supply system-At least 15.6 °C (60 °F) 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 systems are listed in descending order of preference: 22 General Site Preparation Guidelines