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TunnelTech 305

Air Flow Monitor

The TunnelTech 305 Air Flow Monitor (AFM) is CODEL’s industry proven tunnel air flow monitor.


The TunnelTech 305 Air Flow Monitor, is an essential part of any road or rail tunnel safety system. Firstly, it monitors the air flow measurement as well as the direction of flow inside the tunnel and ensures that the tunnel ventilation system provides sufficient clean air to protect tunnel users health and for drivers to clearly see the road ahead.


The TunnelTech 305 uses dual path ultrasonic technology to ensure high accuracy and having no moving parts, reliability levels are very high and maintenance requirements are very low. The sensor is constructed using stainless steel for ultimate protection against the harsh environments found in tunnels.


Fully configurable analogue and alarm outputs are provided. An RS485 link can be utilised to deliver via MODBUS protocol to a SCADA system located in the tunnel control centre.

Features & Benefits

Product Specification

MeasurementsAir flow and direction
Measuring Unitsm/sec
Measurement TechniqueUltrasonic
Ambient Temperature-20°C to +65°C
Power Supply12V DC @1.5A
ConstructionSS316L / Ti – Designed to IP67 (IP69K Optional)
Analogue Outputs2 x 4-20mA current outputs as standard, isolated, 500Ω maximum load, fully configurable
through TunnelTech software
Relay Outputs2 x volt-free SP contacts, 50V 400mA max, for flow direction and fault condition
Communications PortRS485 for local communication with laptop or modbus RTU protocol

Related Products

TunnelTech 700 - Gas Monitor
TunnelTech 205 - N02 Monitor

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