The appearance of CO, CH₄, H₂S, NO, NO₂, VI tunnel air quality detector is shown in the figure. It is mainly composed of a visibility chassis, transmitting and receiving terminals, internal integrated circuits, and reflecting prisms. The circuit mainly consists of MCU controller, infrared transmitter, infrared receiver, gas sensor, RS485 communication module, power conversion module and so on. This technology uses infrared technology to measure visibility. The measuring device consists of a light source capable of emitting infrared rays, an infrared receiving probe and a reflector 3 meters away. The reflected light beam is received by the infrared receiving probe and the light attenuation parameters are measured, The concentration measurement of H₂S, CO, CH₄, NO, NO₂ uses electrochemical sensor technology. The amount of CH₄ concentration uses catalytic combustion technology.

Technical index

VI Measuring Range: K=0～15x10^-3m^-1

NO₂ Measuring Range: 0～20ppm

NO Measuring Range: 0～100ppm

H₂S Measuring Range: 0～10ppm

CH₄ Measuring Range: 0～5%Vol (0～100%LEL)

CO Measuring Range: 0～500ppm

VI Measurement Accuracy: ±0.1x10^-3m^-1 or 0.7 transmittance

NO₂ Resolution: 0.1ppm

NO Resolution: 0.5ppm

CH₄ Resolution: 0.05%Vol

H₂S Resolution: 0.05ppm

CO Resolution: ±0.1ppm

Communication Interface: 1 RS485

Analog Output: 5 channels 4～20mA current isolation output

Switch Output: 4 relay contact outputs, configured as limit value alarm

Power Supply Voltage: 85～264VAC

Working Temperature: -40～75℃

Working Humidity: 0～100%RH