The Codel TunnelTech 201 Air-Quality Monitor from HMA Instrumentation is an essential part of any road or rail tunnel safety system. It monitors the atmosphere within the tunnel, ensuring that the tunnel ventilation system provides sufficient clean air to protect tunnel users’ health and for drivers to clearly see the road ahead.

The Codel TunnelTech 201 Air-Quality Monitor from HMA Instrumentation uses well-proven infrared techniques to determine CO and NO concentrations and optical attenuation to monitor Visibility levels. As there is only one moving part, reliability levels are very high and maintenance requirements are extremely low.

Key features include continuous measurement of CO and NO and Visibility in road and rail tunnels; class-leading accuracy, repeatability and resolution; rugged, corrosion-resistant construction; minimal maintenance requirements; and optional RS 485 (Modbus) output.