25For the temperature and humidity requirements of different switch models, see Table 1.CleannessDust buildup on the chassis may result in electrostatic adsorption, which causes poor contact of metalcomponents and contact points, especially when indoor relative humidity is low. In the worst case,electrostatic adsorption can cause communication failure.Table 20 Dust concentration limit in the equipment roomSubstance Concentration limit (particles/m³)Dust ≤ 3 x 104 (no visible dust on the tabletop over three days)NOTE:The dust diameter is greater than or equal to 5 μm.The equipment room must also meet strict limits on salts, acids, and sulfides to eliminate corrosion andpremature aging of components, as shown in Table 21.Table 21 Harmful gas limits in the equipment roomGas Maximum concentration (mg/m 3 )SO2 0.2H2 S 0.006NH3 0.05Cl2 0.01EMIAll electromagnetic interference (EMI) sources, from outside or inside of the switch and applicationsystem, adversely affect the switch in a conduction pattern of capacitance coupling, inductance coupling,electromagnetic wave radiation, or common impedance (including the grounding system) coupling. Toprevent EMI, take the following actions:• Use a single-phase three-wire power receptacle with a protection earth (PE) to filter interferencefrom the power grid.• Keep the switch far away from radio transmitting stations, radar stations, and high-frequencydevices.• Use electromagnetic shielding, for example, shielded interface cables, when necessary.• Route interface cables only indoors to prevent signal ports from getting damaged by over-voltageor over-current caused by lightning strikes.Laser safetyThe H3C S5820X Switch Series is a line of Class 1 laser devices.
