CO₂ – CARBON DIOXIDE SENSOR FOR UNDERWATER APPLICATIONS

The CONTROS HydroC® CO₂ sensor is a unique and versatile subsea / underwater carbon dioxide sensor for in-situ and online measurements of dissolved CO₂. The CONTROS HydroC® CO₂ is designed to be used on different platforms following different deployment schemes. Examples are moving platform installations, such as ROV / AUV, long-term deployments on seabed observatories, buoys and moorings as well as profiling applications using water-sampling rosettes.

INDIVIDUAL ‘IN-SITU’ CALIBRATION

All sensors are individually calibrated in a water tank which simulates the deployment temperature. A sophisticated reference detector is used to verify the p CO₂ concentrations in the calibration tank.
The reference sensor is recalibrated with secondary standards on a daily basis. This process ensures that the CONTROS HydroC® CO₂ sensors achieve unmatched short and long-term accuracy.

OPERATING PRINCIPLE

Dissolved CO₂ molecules diffuse through a custom made thin film composite membrane into the internal gas circuit leading to a detector chamber, where the partial pressure of CO₂ is determined by
means of IR absorption spectrometry. Concentration dependent IR light intensities are converted into the output signal from calibration coefficients stored in firmware and data from additional sensors
within the gas circuit.

ACCESSORIES

A wide range of available accessories ensures that each of the CONTROS HydroC® CO₂ sensors can be adapted to meet customers’ requirements. The optional pumps with the different flow heads are the most popular options that ensure very fast response times. An anti-fouling head is used under conditions with significant biofouling pressure. The internal data logger can be used in conjunction
with the HydroC’s flexible power management features and the CONTROS HydroB® battery packs to conduct unattended long-term deployments.

HydroC® CO₂ data sheet

FEATURES

  • High accuracy
  • Very robust, depth rating up to 6000 m (profiling)
  • Very fast response time
  • User-friendly
  • Versatile – easy integration into almost every oceanographic measurement system and platform
  • Long-term deployment capability
  • ‘Plug & Play’ principle; all required cables, connectors and software are included

OPTIONS

  • Analogue output: 0 V – 5 V
  • Internal data logger
  • External battery packs
  • ROV and AUV installation packages
  • Profiling and mooring frames
  • External pump (SBE-5T or SBE-5M)
  • Easy deployment together with a CONTROS HydroFlash® O₂
  • CO₂ flow through sensor for underway (FerryBox) and lab applications

  REFERENCES

THE CONTROS HYDROC CO₂ ON A PROFILING FLOAT
“This study showcases the utility of floats as a novel tool for combined gas measurements of CO₂ partial pressure (pCO₂) and O₂.”

JOURNAL OF ATMOSPHERIC AND OCEANIC
TECHNOLOGY, DOI 10.1175/JTECH-D-12-
00043.1

QUALITY ASSESSMENT OF THE CONTROS HYDROC CO₂
The in depth assessment of the CONTROS HydroC CO₂ sensor is conducted in this study giving an insight into the capabilities of the sensors functionality as well as the data quality that can be achieved.

JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY, DOI 10.1175/JTECH-D-13-00083.1

EXTREME VARIATIONS OF CO2 AND PH IN A MACROPHYTE MEADOW OF THE BALTIC SEA
Insightful attempt of high resolution continuous measurement of the carbonate system in the highly variable environment that is the Baltic Sea’s nearshore.

PLOS ONE, DOI 10.1371/JOURNAL.PONE.0062689