3
Temperature and humidity
Maintain appropriate temperature and humidity in the equipment room.
•
Lasting high relative humidity can cause poor insulation, electricity leakage, mechanical
property change of materials, and metal corrosion.
•
Lasting low relative humidity can cause washer contraction and ESD and bring problems
including loose captive screws and circuit failure.
•
High temperature can accelerate the aging of insulation materials and significantly lower the
reliability and lifespan of the firewall.
For the temperature and humidity requirements of the firewall, see
Table1-1 Temperature/humidity requirements
Item
Specification
Ambient temperature
•
Operating: 0°C to 45°C (32°F to 113°F)
•
Storage: –40°C to +70°C (–40°F to +158°F)
Ambient humidity
5% RH to 95% RH, noncondensing
Cleanliness
Dust buildup on the chassis might result in electrostatic adsorption, which causes poor contact of
metal components and contact points, especially when indoor relative humidity is low. In the worst
case, electrostatic adsorption can cause communication failure.
Table1-2 Dust concentration limit in the equipment room
Substance
Concentration limit (particles/m
3
)
Dust particles
≤ 3 × 10
4
(No visible dust on desk in three days)
NOTE:
Dust
particle diameter ≥ 5 µm
The equipment room must also meet strict limits on salts, acids, and sulfides to eliminate corrosion
and premature aging of components, as shown in
Table1-3 Harmful gas limits in an equipment room
Gas
Max. (mg/m
3
)
SO
2
0.2
H
2
S
0.006
NH
3
0.05
Cl
2
0.01
NO
2
0.04
Cooling system
The firewall uses natural cooling. For adequate cooling of the firewall, follow these guidelines:
•
Reserve a minimum clearance of 100 mm (3.94 in) around the outlet air vents.
•
Make sure the installation site has a good cooling system.
