Site Preparation Guide - HP Integrity BL60p Server Blade

General Site Preparation Guidelines
Environmental Elements
Chapter 2
18
Although this problem is relatively rare, it may be an issue within your computer room. Since metallic
contamination can cause permanent or intermittent failures on your electronic equipment, HP strongly
recommends that your site be evaluated for metallic particulate contamination before installation of
electronic equipment.
Electrostatic Discharge (ESD) Prevention
Static charges (voltage levels) occur when objects are separated or rubbed together. The voltage level of a
static charge is determined by the following factors (refer to Table 2-1):
• Types of materials
• Relative humidity
• Rate of change or separation
Static Protection Measures
Follow these precautions to minimize possible ESD-induced failures in the computer room:
• Maintain recommended humidity level and airflow rates in the computer room
• Install conductive flooring (conductive adhesive must be used when laying tiles)
• Use conductive wax if waxed floors are necessary
• Ensure that all equipment and flooring are properly grounded and are at the same ground potential
• Use conductive tables and chairs
• Use a grounded wrist strap (or other grounding method) when handling circuit boards
• Store spare electronic modules in antistatic containers
Acoustics
Computer equipment and air conditioning blowers cause computer rooms to be noisy. Ambient noise level in a
computer room can be reduced as follows:
• Dropped ceiling—Cover with a commercial grade of fire-resistant, acoustic rated, fiberglass ceiling tile
• Sound deadening—Cover the walls with curtains or other sound deadening material
• Removable partitions—Use foam rubber models for most effectiveness
Table 2-1 Effect of Humidity on ESD Charge Levels
Personnel Activity
a
a. Source: B.A. Unger, Electrostatic Discharge Failures of Semiconductor Devices (Bell Labs, 1981).
Humidity
b
and Charge Levels (voltages)
c
b. For the same relative humidity level, a high rate of airflow produces higher static charges than a
low airflow rate.
c. Some data in this table has been extrapolated.
26% 32% 40% 50%
Person walking across a linoleum floor 6,150V 5,750V 4,625V 3,700V
Person walking across a carpeted floor 18,450V 17,250V 13,875V 11,100V
Person getting up from a plastic chair 24,600V 23,000V 18,500V 14,800V