3-2
Cleanness Requirements
Dust concentration limits
Dust is hazardous to the operating safety of devices. Dust buildup on chassis may result in static
absorption, causing poor contact of metal components or points. When indoor humidity is extremely low,
this is more likely to happen, shortening the useful life of the devices and causing communication
failures.
Table 3-2 lists the dust concentration limits in the equipment room.
Table 3-2
Dust concentration limits in the equipment room
Diameter (
μ
m)
0.5
1
3
5
Concentration
limit (particles/m
3
)
1.4 × 10
7
7 × 10
5
2.4 × 10
5
1.3 × 10
5
Harmful gas concentration limits
Besides, the equipment room should meet the rigorous limits on salt, acid and sulfide to eliminate
corrosion and premature aging of some parts, as shown Table 3-3.
Table 3-3
Harmful gas concentration limits
Gas
Max (mg/m
3
)
SO
2
0.2
H
2
S 0.006
NH
3
0.05
Cl
2
0.01
Electrostatic Discharge Prevention
Sources and damages of static electricity
By design, a U200 series device is ESD preventative; but excessive buildup of static electricity can still
damage the card circuitry and even the entire device.
On the communication network connected to a U200 series device, static electricity is primarily
introduced from the outside electrical fields, such as the outdoor high-voltage power cabling and
lightning, and from the inside system, such as the indoor environment, floor materials and the chassis
frame.
Measures against ESD
To protect your device against electrostatic discharge (ESD), follow these guidelines:
Ensure that the device and the floor are well grounded.
Ensure that he equipment room is as dust free as possible.
Maintain adequate humidity and temperature.
Wear an ESD-preventive wrist strap and clothes before touching a circuit board.
Place removed cards (mini interface cards, MIM modules, or CF cards) upward on an antistatic
workbench or into a static shielded bag.
Содержание SECPATH U200-CS
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