Keg purging chart

[Nemanach]

A couple months ago I saw a chart for how many times to purge a keg of CO2 after filling with beer based on the pressure at the regulator. I'm kegging my first batch this weekend but can't find it by searching. Anyone know where this is at?

 

[kev211]

This one?

That will do a pretty good job of getting the O2 level down. It's not because of diffusion however. The reduction in O2 (and N2) is strictly due to dilution. The purge pressure affects how many purge cycles you need to get to a particular O2 level. The table and chart below shows how pressure and number of cycles affects the O2 levels. The values are percent of original remaining, not mass of remaining. The mass remaining depends on the headspace volume.

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[Nemanach]

That's the one, thanks! How much o2 is generally considered acceptable?

 

[kev211]

That's the one, thanks! How much o2 is generally considered acceptable?

Beats me haha. 0? I push with Co2 now, but before I started doing that, I purged 3-4 times and never had any issues. Is that the best option? Probably not... But it worked for me

 

[Nemanach]

Fair enough. The kegerator is in the dining room and I brew in the basement so pushing with co2 will be tough unless I buy any other regulator and tank. Gotta let the finances settle first.

 

[kev211]

Fair enough. The kegerator is in the dining room and I brew in the basement so pushing with co2 will be tough unless I buy any other regulator and tank. Gotta let the finances settle first.

Ya I bought another co2 tank and regulator. Justified them to SWMBO as "backups" or "travel setup" for when I take beer outside of the home

 

[Nemanach]

I'm going to justify it as backup soon enough I think. What if I run out of co2 on a Friday night and I want another beer?! That would be some scary stuff.

 

[kev211]

I'm going to justify it as backup soon enough I think. What if I run out of co2 on a Friday night and I want another beer?! That would be some scary stuff.

Exactly. Gotta be prepared for the worst case

 

[doug293cz]

Here are the newer versions of the purge table and chart. Instead of giving O2 as percent of original remaining, the new ones give ppm (parts per million) of O2 in the headspace. The ppm values are independent of the headspace volume, as that's the way gas dilution works.





As far as how much O2 is tolerable, that depends on what type of beer you have, how fast you drink it, and whether you keep it cold all the time or not. Hop compounds are more susceptible to oxidation degradation than other components of beer, so IPA's, etc. will degrade faster than non-hoppy beers. And, the higher the O2 concentration, the faster they will degrade. According to this reference: http://www.craftbrewersconference.com/wp-content/uploads/2015_presentations/F1540_Darron_Welch.pdf, page 21, when total packaged oxygen is over 150 ppb (0.15 ppm), flavor changes in IPA's are detectable after 3 weeks of room temp storage, but not until after 4 months of cold storage. Every brewer has to determine for themselves how stringent they need to be about O2 control in packaging.

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