Dissolved Gas Extraction System

The Dissolved Gas Extraction Unit (DGEU) allows continuous concentration measurements of dissolved gases in water and other liquids in real time*. The DGEU extracts gas from a liquid stream through an internal hydrophobic micro-porous membrane (comprised of polypropylene hollow fibers). Internal water and gas pumps and mass flow controllers allow precise control of flow rates and pressures of the liquid in the DGEU and the strip gas which is sent to the gas analyzer. By accurately controlling the water flow rate through the membrane, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the DGEU is able to generate precise and reproducible results.

Measuring the gas flow rates in and out of the DGEU, allows the gas-phase concentrations (parts per million) to be easily converted into dissolved gas concentrations (nanomolar). The Unit is controlled via software on selected LGR analyzers to provide autonomous measurements in the field. An internal multi-channel data logger records all parameters reported by the DGEU and can also record analog signals from other instruments in a single data file.

This novel tool, when combined with one or more LGR trace gas analyzers, can replace time consuming head-space equilibration processes and complex shower-head systems. This allows new research opportunities, including measuring gas seepages from ocean floor; monitoring water quality of oceans, lakes, rivers, and fish-farms; quantifying surface-gas exchange processes in lakes and monitoring dissolved gases in wastewater treatment plants.