3Temperature and humidityMaintain appropriate temperature and humidity in the equipment room.• Lasting high relative humidity can cause poor insulation, electricity creepage, mechanical propertychange of materials, and metal corrosion.• Lasting low relative humidity can cause washer contraction and ESD and bring problems includingloose captive screws and circuit failure.• High temperature can accelerate the aging of insulation materials and significantly lower thereliability and lifespan of the firewall.Table 1 Temperature and humidity requirementsAmbient temperature Ambient relative humidity• Operating0°C to 45°C (32°F to 113°F)• Nonoperating and storage–40°C to +70°C (–40°F to +158°F)• Operating10% to 95%, noncondensing• Nonoperating and storage5% to 95%, noncondensingCleannessDust 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 2 Dust concentration limit in the equipment roomSubstance Concentration limit (particles/cu m)Dust particles ≤ 3 x 104(No visible dust on desk in three days)NOTE:Dust particle diameter ≥ 5 μmThe equipment room must also meet strict limits on salts, acids, and sulfides to eliminate corrosion andpremature aging of components, as shown in Table 3.Table 3 Harmful gas limits in an equipment roomGas Max. (mg/m 3 )SO2 0.2H2 S 0.006NH3 0.05Cl2 0.01
