Electrostatic Discharge (Esd) Prevention; Acoustics - HP Rp3440-4 - 9000 - 0 MB RAM Manual

General Site Preparation Guidelines
Environmental Elements

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:
• Types of materials
• Relative humidity
• Rate of change or separation
Table 2-1 Effect of Humidity on ESD Charge Levels
Personnel Activity
Person walking across a linoleum floor
Person walking across a carpeted floor
Person getting up from a plastic chair
a. Source: B.A. Unger, Electrostatic Discharge Failures of Semiconductor Devices (Bell Laboratories,
1981).
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.
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
30
a
Humidity
26%
6,150V
18,450V
24,600V
b
and Charge Levels (voltages)
32% 40%
5,750V 4,625V
17,250V 13,875V
23,000V 18,500V
c
50%
3,700V
11,100V
14,800V
Chapter 2