HP Integrity rx7620 Site Preparation Guide, Fourth Editon - HP Integrity rx762 - Page 54

General Site Preparation Guidelines Environmental Elements 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 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 might also blanket electronic components, like printed circuit boards, causing premature failure from 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. These metallic particles are conductive and can short circuit electronic components. Use every effort to ensure that the environment is as dust- and particulant-free as possible. Smaller particles can pass though some filters and, over a period of time, can cause problems in mechanical parts. Small dust particles can be prevented from entering the computer room by maintaining its air conditioning system at a high-static air pressure level. Other sources of dust, metallic, conductive, abrasive, or microscopic particles can be present. Some sources of these particulants are: • Subfloor shedding • Raised floor shedding • Ceiling tile shedding These pollutants are not always visible to the naked eye. Check the underside of the tiles to determine the presence of these pollutants. The tile should be shiny, galvanized, and free of rust. The computer room should be kept clean. The following guidelines are recommended: • Establish a no-smoking policy. Cigarette smoke particles are eight times larger than the clearance between disk drive read/write heads and the disk surface. • Locate printers and paper products in a separate room to eliminate paper particulate problems. • Establish a no eating or drinking policy. Spilled liquids can cause short circuits in equipment such as keyboards. • Use a dust-absorbent cloth mop rather than a dry mop to clean tile floors. Special precautions are necessary if the computer room is near a source of air pollution. Some air pollutants, especially hydrogen sulfide, are not only unpleasant but corrosive as well. Hydrogen sulfide damages wiring and delicate sound equipment. The use of activated charcoal filters reduces this form of air pollution. 40 Appendix B