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.

Key Features

  • Single point ultrasonic measurement technology
  • Unaffected by traffic flow and sound reflections
  • No moving components providing maintenance free operation
  • Designed to withstand the harshest of tunnel environments
  • Measurement precision of +/- 0.1m/sec
  • Easy mounting system


SpecificationImagesDocumentationProduct Enquiry



Measurements Air flow and direction
Measuring units m/sec
Measurement Technique Ultrasonic
Ambient Temperature -20°C to +65°C
Power supply 12V DC @1.5A
Construction SS316L / Ti – Designed to IP67 (IP69K Optional)
Analogue outputs 2 x 4-20mA current outputs as standard, isolated, 500Ω maximum load, fully configurable
through TunnelTech software.
Relay Outputs 2 x volt-free SP contacts, 50V 400mA max, for flow direction and fault condition
Communications Port RS485 for local communication with laptop or modbus RTU protocol
Lang Filetype Document Size
English TunnelTech 305 Datasheet 400kb

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