Researching the requirements
11
Environmental factors
Temperature and humidity
High temperatures tend to increase the rate of deterioration of most
materials. Temperature fluctuations can cause temporary or permanent
changes to equipment which can affect the grade of service. Low humidity
conditions can increase the build up of static electricity, while high
humidity can have an adverse effect on the performance of disks, tapes, and
printers.
Static electricity
Microelectronic circuits are extremely sensitive to static discharge. Static
discharge can cause permanent damage to any circuitry and/or interruptions
in system operation and the loss of data. Static electricity could be the
result of physical vibration, friction, and separation of materials. The most
common collectors of static electricity are people.. Other common causes of
static electricity build-up are low humidity, certain types of carpeting, the
use of wax on equipment room floors, and plastic-soled shoes.
Plastic-soled shoes, for example, are noted for generating large amounts of
static electricity. The insulative nature of the shoes, and certain flooring
materials and levels of humidity, can cause the wearer to accumulate and
carry body charges in excess of 15 kV.
Note:
IEEE Standard 142-1982 recommends that flooring resistance
should be more than 25,000
Sz
and less than 1 million megohms,
measured by two electrodes 3 feet (0.91 m) apart on the floor. Each
electrode must weigh
5
lb (2.2 kg) and have a dry flat contact area of
2.5 inches (63.5 mm) in diameter.
Some products that prevent static discharge include sprays, anti-static mats,
and wrist straps.
Vibration
Vibration can cause slow deterioration of mechanical parts and, where
severe, can cause serious disk errors. Structure-borne vibration and
consequent noise transferred to the equipment room should be avoided.
Raised floors should have extra support jacks at strategic places to prevent
the transmission of vibration.
Installation planning 553-3001-l 20