HP Integrity rx2620 Site Preparation Guide. First Edition - HP Integrity rx262 - Page 26

General Site Preparation Guidelines Environmental Elements Return air from an above ceiling ducted air distribution system may be ducted return air (DRA) above the ceiling, or ceiling plenum return air (CPRA). Adjust the supply air diffuser system grilles to direct the cooling air downward around the front of the hp Integrity rx2620 Server cabinets. The supply air is then available near the cooling air intake vents of the hp Integrity rx2620 Server cabinets. Air Conditioning System Specifications 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 55% 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. Specifically, disk drives, tape drives, and some other mechanical devices can have bearing failures resulting from airborne abrasive particles. Dust may also blanket electronic components like printed circuit boards, causing premature failure due to excess heat and/or humidity build up on the boards. Other failures to power supplies and other electronic components can be caused by metallically conductive particles, including zinc whiskers. These metallic particles are conductive and can short circuit electronic components. Use every effort to ensure that the environment is as dust- and particulate-free as possible. See the following heading titled Metallic Particulate Contamination for additional details. Smaller particles can pass through some filters, and over a period of time, cause problems in mechanical parts. Small dust particles can be prevented from entering the computer room by maintaining the air conditioning system at a high static air pressure level. Other sources of dust, metallic, conductive, abrasive, and/or microscopic particles can be present. Some sources of these particulates are: • Subfloor shedding 26 Chapter 2