VLux FuelPro


5-in-1 MiniSonde for detection and monitoring of fuel in the environment


VLux FuelPro is the latest advancement in in situ fluorometers from Chelsea Technologies, measuring 5 key parameters in one compact sensor. The miniature, high quality VLux FuelPro provides integrated environmental corrections for environmental interference from turbidity & absorbance.


Features & Applications


Chelsea’s miniature, high quality VLux FuelPro provides integrated environmental corrections for contamination.


  • 5 key parameters including:
    • BTEX
    • CDOM
    • Chlorophyll a & c
    • Absorbance
    • Turbidity (ISO 7027:1999 compliant)
  • Highly sensitive for detection of contaminants at the sub-ppb level
  • Integrated correction for turbidity and absorbance
  • Integral biofouling protection using both UV light and copper bezels
  • Compact and robust design, measuring 194 mm (H) x 50 ± 0.05 mm (D)
  • Ideal for standalone fieldwork or system integration including: CTDs, AUVs, ROVs and gliders
  • 6000 m depth rating
  • Integrated logging as standard, battery packs available on request
  • Compatible with Hawk and Watchkeeper for data display in the field


  • Pollution monitoring
  • Contamination of groundwater and other natural sources
  • Identification of leaks in underground pipes
  • Monitoring leaching from landfill
  • Monitoring pre and post- groundwater remediation work
  • Water treatment legislation



VLux In-depth


What is BTEX?

  • BTEX is a term used to describe 4 chemical compounds – Benzene, Toulene, Ethylbenzene and Xylene. They are all Volatile Organic Compounds (VOCs).
  • BTEX compounds are found in the natural environment in crude oil and in gas emissions from volcanoes. However, they are among the most abundantly produced chemicals in the world, through the processing of petroleum products and consumer goods, and car and aircraft emissions.

Why measure BTEX?

  • BTEX is often monitored as an indicator of VOCs as a whole. Individual compounds may be below the detection limits, so monitoring a group can be useful.
  • BTEX compounds can have harmful effects on people – benzene is a known carcinogen.
  • Monitoring BTEX can be used to identify leaks from industry into the natural environment, monitor fuel spills and their impact and identify health and safety concerns.

Why measure CDOM and Chlorophyll as well as BTEX?

  • Measuring CDOM and chlorophyll as well as BTEX allows the interfering background signals to be separated from the BTEX signal, improving accuracy and specificity of PAH measurement.

Why correct for absorbance and turbidity?

  • As the concentration of BTEX increases, the compounds themselves absorb light, resulting in a non-linear response of fluorescent signal against concentration.
  • Increased turbidity also has an impact, as light is scattered by particle and other matter in the water. Errors due to turbidity can be significant – adding the correction minimizes errors at even high turbidities.
  • In more challenging and dynamic environments such as rivers and estuaries, the impact of environmental factors cannot be ignored. VLux FuelPro measures turbidity and absorbance, applies the correction within the sensor and outputs environmentally corrected data.