Nitrogen dioxide (NO2) tunnel sensor
TunnelCraft III Codel International

Nitrogen dioxide (NO2) is fast becoming the most important measurement in tunnels and will eventually replace nitric oxide (NO) as the key measurement. The TunnelCraft III NO2 Air Quality Monitor (AQM) uses a high-power blue LED to measure the attenuation of UV/blue light by NO2 in the tunnel atmosphere.
The AQM consists of a transceiver that projects the light beam to a reflector within a stainless steel tube mounted 1m away. Sintered filters in the measurement chamber allow gases from the tunnel atmosphere to diffuse into the chamber while inhibiting the passage of particulates.The NO2 sensor can be used as a stand-alone instrument or as part of a multi-point monitoring system.

› High accuracy and stability
› Zero maintenance
› Simple operation - no moving components
› Output in ppb (parts per billion)
› High reliability
› Span verification by span gas injection
› Fully configurable current and relay outputs
› RS232 or RS485 - Modbus output optional