2-3
Temperature/Humidity Requirements
To ensure the normal operation and service life of a switch, a certain level of temperature and humidity
should be maintained in the equipment room. If the humidity in the equipment room is too high for a long
time, it will lead to bad insulation of the insulating material or even creepage. Sometimes, the
mechanical performance changes of material, the rustiness and corrosion of some metal parts are also
likely to occur. If the relative humidity is too low, the captive screws may become loose due to the
shrinkage of the insulation washers. Meanwhile, the electrostatic is likely to be produced in the dry
environment, which will jeopardize the CMOS circuit of the switch. The higher the temperature, the
greater the damage it will do on the switch. High temperature for a long time will speed up the aging
process of the insulation materials, greatly lower the reliability of the switch and therefore affect its
service life seriously.
Table 2-1
Temperature/humidity requirements
Temperature
Relative humidity
Working condition
Idle condition
Working condition
Idle condition
0
0
C to 45
0
C (32
0
F to
113
0
F)
–40
0
C to +70
0
C (–40
0
F
to +158
0
F)
10% to 95%,
noncondensing
5% to 95%,
noncondensing
Cleanness Requirements
Dust is a big harm for the normal operation of the switch. The indoor dust accumulated on the chassis
can cause electrostatic adsorption, resulting in the poor contact of the connector or metal contact point.
This happens more frequently when the relative indoor humidity is low, which will not only shorten the
service life of the switch, but also cause communication failure.
The required specifications on dust content and particle diameter in an equipment room are shown in
Table 2-2
.
Table 2-2
Dust concentration limit in the equipment room
Physical active substance
Concentration limit (particles/m³)
Dust particle
≤
3 x 10
4
(No visible dust on desk over three days)
Note: Dust particle diameter
≥
5µm
Except the requirements on dust, rigorous requirements on ingredient of salts, acids and sulfides of air
in an equipment room are also set. These harmful gases will speed up the metal corrosion and the
aging processes of certain parts. The equipment room should be protected from the invasion of harmful
gases such as SO
2
, H
2
S, NO
2
, NH
3
and Cl
2
, the value limits of which are shown in the following table:
Table 2-3
Limits on harmful gases in the equipment room
Gas
Maximum concentration (mg/m3)
SO
2
0.2
H
2
S 0.06
NH
3
0.05
