Safe Area Visibility/Fog Detector


Measures atmospheric visibility (meteorological optical range) by determining the amount of light scattered by particles (smoke, dust, haze, exhaust fumes) in the air that pass through the optical sample volume. A 42° forward scatter angle is used to ensure performance over a wide range of particle sizes. MOR is calculated by converting the received signal strength (extinction coefficient, σ) using Koschmeider’s formula, MOR (Km) = 3/σ.

Performance in all weather conditions is achieved with an integrated sensor design that keeps all sensor cabling internal to the sensor for complete Protection against dust and water intrusion. Based on the proven field experience, the sensor uses a “look down” geometry to reduce window contamination. The optical windows have continuous duty anti-dew heaters. All power and signal lines to the Visibility/Fog detector are protected with surge and EMI filtering to help guarantee uninterrupted service for the life of the sensor.

  • Optimal tunnel measurement range
  • Road & rail tunnel applications
  • Proven 42° forward scatter angle
  • Preferred “look down” geometry
  • Compact, light weight package
  • Simple installation & maintenance



Technical Details

Model Safe Area Visibility/Fog Detector
Measurement range 15 – 0.03 km-1 Extinction (EXCO)
200 m – 100 km Visibility
Time Constant 60 sec
Scatter Angle 42° nominal
Source 880 NM LED
Operating Humidity 0 up to 100 %
Output 4 – 20 mA single ended output standard
Housing UV-resistant fiberglass
IP Rating IP66 (NEMA-4X)
Ambient temperature -40 °C up to +60 °C
Voltage range 100 – 240 Vac, 24V A Nominal or
10 – 36 Vdc, 6V A Nominal
Mounting Nominal 40 mm ISO pipe, 48 mm OD max.
Weight 8 kg
Dimensions 889x292x305 mm WxHxD


Model Safe Area Visibility/Fog Detector
Output 4 – 20 mA isolated output
Relays Control (up to 2) Diagnostic

Order Details

Article Code Dimensions Weight
602.002 889x292x305 mm 8 kg