Dissolved Oxygen increases during carbonation
A CO2 purity meter can go a long way in solving these types of questions. We had the same thing happening randomly. Usually after having our CO2 receiver filled. We put an SOP in place and made sure a brewer was on hand to watch the trucker unload the CO2, taking him through the line purging steps. We also asked our CO2 supplier for a COA for the CO2 in the truck. The Oxygen spec for Beverage grade CO2 can be as high as 30ppm oxygen entrained. Your normal DO meter can’t read this, and a haphazard CO2 transfer can see the entrained O2 jump way up to the 100’s. We told our CO2 supplier that we would reject any shipment over 10ppm O2. Our normal base line for O2 in CO2 was about 8ppm.
Firestone Walker Brewing Co
Paso Robles, CA