Using CO2 From Fermentation To Purge Serving Kegs

Back in September 2017, I published the results of an xBmt I performed comparing a New England IPA packaged in a manner to reduce cold-side oxygen exposure to one packaged with less rigorous methods. Up to that point, I’d been highly skeptical of the concerns many voiced about the perils of cold-side oxidation, in part because I’d racked hundreds of batches of beer to non-purged kegs that ended up being perfectly fine, at least in my anecdotal experience. However, as stubborn as my wife may say I am, both the results of that xBmt and my own evaluation of those beers had an impact.

I adopted the perspective that, even if past batches of beer were subjectively incredible, minimizing oxygen exposure on the cold-side was one way to reduce the risk of something potentially going wrong. After determining one of the main vectors of cold-side oxidation in my process was packaging, I began purging my kegs by using CO2 from a tank to push sanitizer out, a method used by many.

Based on my years of kegging, I reckoned I could purge about 15 kegs off of a single 10 lb/4.5 kg tank and accepted the cost of gas was worth the benefits of better beer. Then I blew through 30 lbs/13.5 kg of CO2, an amount that would usually last me half a year or longer, in just 2 months and spent $100 to fill those tanks up. A bit of simple math told me that my newfound zealotry would end up costing 3 times more than my previous ways.

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