NEC EXPRESS800, Service Manual

Page: 25 / 78

Planning Your Site 2-9
Air Conditioning
A properly sized air conditioning system ensures stable and reliable operation of
your servers by performing the following tasks:
!
cooling the system
!
preventing the generation of static charges
!
preventing the formation of corrosion causing condensation within the
system.
The system rack’s temperature and humidity requirements are listed in
Table 2-2.
Table 2-2. Temperature and Humidity Requirements
Item Operating Non-operating
Temperature 16 - 30°C 0 - 45°C
Relative humidity 40 - 70%
(non-condensing)
10 - 80%
Temperature and humidity should be measured 19.5 inches (50cm) from the
system and 3.3 ft (1m) above the floor.
To satisfy temperature and humidity requirements, an air conditioner should be
capable of heating, humidifying, and dehumidifying.
Heat is needed to precisely control temperature, increase computer room
temperature in winter to the system’s operating conditions, and to control
humidity.
Humidifying is required to combat low humidity, which allows static charges to
build-up.
If the system is operated in high-humidity conditions where condensation can
occur, long term reliability may be affected.
Cooling Capacity
The cooling capacity of an air conditioner is determined by the following
factors:
!
90% of the total calorific value of the system (allowing for expansion)
!
calorific value from the ceiling, walls, and windows
!
calorific value generated by personnel
!
calorific value of lighting and additional machines
!
humidity control effects.