8
1.6
Installation Environment
This section describes the installation environment of the base cabinet.
1.6.1 Dust
Suspended Particles
Suspended particles in a computer room should not exceed 0.15mg/m
3
. A computer is designed in such a
way that it withstands the suspended particles. This value is permissible in an ordinary office. However, this
value can be maintained in the ordinary computer room if there is less outdoor air infiltration having
suspended particles like dust and if there is no smoke of cigarettes.
Dust Removal
The suspended particles like dust are collected in the filter of an air conditioner. The dust should be removed
from the computer room by cleaning floor surfaces and underfloor periodically. Cleaning is necessary in the
following cases.
When the computer room is ready, and before bringing in the computers
At the time of repairing the computer room
At the time of shifting the computers and re-arranging the devices
1.6.2 Corrosive Gas
Corrosive gas and salty wind cause corrosion, malfunctioning, and damage of the device, and reduce life of
the device remarkably.
Corrosive gas should be removed by providing suitable air cleaning equipment. In addition, positive clear air
pressure in the room prevents an entering of the corrosive gas from the outside. The chemical factory area,
thermal water/ volcanic zone etc. are considered as a source of corrosive gas.
TABLE 1.3 Permissible Level of Corrosive Gas
Name of gas
Permissible level
Hydrogen sulfide (H
2
S)
7.1ppb or less
Sulfur dioxide (Sulfur oxide)(SO
2
)
37ppb or less
Hydrogen chloride (HCL)
6.6ppb or less
Chlorine (CI
2
)
3.4ppb or less
Hydrogen fluoride (HF)
3.6ppb or less
Nitrogen dioxide (Nitrogen oxides)(NO
2
)
52ppb or less
Ammonia(NH
3
)
420ppb or less
Ozone(O
3
)
5ppb or less
Fluid vapor
0.2mg/m
3
or less
1.6.3 Sea Water (Salt Damage)
A large number of sea-salt particles are suspended in air by the salty wind near the sea-coast. If the sea-salt
particles remain in the computer, moisture and chemically condensed substances cause insulation failure,
and corrosion degradation of the components. Therefore, the computer should be installed at a place which
is far from the sea-coast.
Installation standards to prevent damage due to sea salt particles are shown below.
Standards: The computer should be installed at a place which is at least 0.5km away from the sea-coast
(Excluding the case having air-conditioner which prevents an entering of air from outside)
