Explosion sound and light alarm big-screen LCD, friendly interface, with automatic node search, software zero, software calibration, alarm set point function, using the RS-485 communication protocol to transfer data reliably. Explosion sound and light alarm basic technical indicators: (1) measuring range: 0-100% LEL (2) the basic error: ± 5% FS (3) Display: large-screen LCD, LED tube (4) Alarm: Sound light alarm (5) Alarm volume:> 65dB (6) Alarm response time: ≤30s (7) alarm action value: Low limit alarm 20% LEL (adjustable) high alarm 50% LEL (adjustable) (8) Equipment Failure Response Time: ≤100s (9) Chassis dimensions of: 440mm × 330mm × 98mm (10) Power: AC220V ± 15% (11) Working environment: Temperature -10 ℃ -50 ℃ Humidity ≤93% RH Atmospheric pressure 86kPa- 106kPa (12) Insulation resistance: normal environment ≥100MΩ when humidity is 93% RH ≥1MΩ (13) Working mode: Continuous (14) Power consumption: 10W (15) alarm output: 1A / 4 group contact output (16) power supply Node: 20 (node ??includes detectors and linkage module) (17) RS485 bus transmission distance of not more than 1200 meters (two-core shielded twisted-pair cable, diameter ≥0.75mm2)