Feedback Gas Generator

Feedback gas generator is used to bubble the sea water inside of equilibrator. 4% CO₂-in-N₂ gas (750 mL min^-1) is bubbled through a glass frit from below the midpoint of the equilibrator body, also continuously. Part of the bubbling gas (--500 mL min^-1) goes to the analysis line; the other 250 mL min^-1 is vented to the atmosphere through the bypass line, ensuring atmospheric pressure in the equilibrator headspace. For the analysis path, gas is pumped (to provide sufficient pressure) through a dehumidifier (2^oC cooler) and flowmeter, then into the analyzer.

The bubbling gas is originally zero gas (air with zero CO2 concentration, generated by passing ambient air through a heatless air dryer (molecular sieve), and then a soda lime column.