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You are here: Home --> Forum Home --> Brewing Forum --> Brewing Discussion --> a couple of new stupid kegging questions

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homebrewdad
Charter Member
Birmingham, AL
2480 Posts


But then, I remove the lid and rack, which is going to increase the O2, right?




Posted 34 days ago.

mchrispen
Bastrop, TX
485 Posts


Yep

Sent from Outlook Mobile








Posted 34 days ago.

homebrewdad
Charter Member
Birmingham, AL
2480 Posts


And so, I'm back to square one, only with less CO2 in my tank. Yes?

Or have I reduced the available O2 enough to make it worth my while?




Posted 34 days ago.

Necropaw
Charter Member
Central WI
608 Posts


I guess the way i see it is: even without any kind of purging im exposing my beer to far, far, FAR less O2 vs bottling, so im really not going to fret about not wasting a ton of CO2 to purge the kegs multiple times.

I charge it with some CO2 to push sanitizer out, maybe give it a few seconds with the lid off, and call it good.




Posted 34 days ago.

flapjackcarl
Houston, TX
608 Posts


So Olan, my purge calculation was for post filling the Keg, assuming you didn't do any type of CO2 purge prior to racking to the keg. 

I personally don't CO2 purge my kegs beforehand. I would only start doing this if I was going to be doing a completely closed transfer (meaning I pushed beer into a purged keg with CO2). Closed transfers can be done on carboys if you use those orange carboy caps. I haven't bothered with this as of yet and I have not seen any issues with oxidation in my beers.

What I would recommend doing is to clean and sanitize your keg by whatever method you choose. Transfer from carboy to keg as gently as possible (similar to bottling). Then close the keg up, set your regulator to 30 psig and let it sit for ~3-5 minutes. Then bleed the pressure down (using either the relief valve, or by pressing the poppet down with a scredriver (make sure you do this on the gas side). Repeat the process of purging 4 or 5 more times to ensure there is very little O2 remaining in the keg (I'll double check my numbers, but I think 4 purge cycles should get you down to ~0.18 wt % O2).

Then carbonate by whatever means suits your fancy (low and slow, shaking, etc.)

Hope this helps.




Posted 34 days ago.

flapjackcarl
Houston, TX
608 Posts


So Olan, my purge calculation was for post filling the Keg, assuming you didn't do any type of CO2 purge prior to racking to the keg. 

I personally don't CO2 purge my kegs beforehand. I would only start doing this if I was going to be doing a completely closed transfer (meaning I pushed beer into a purged keg with CO2). Closed transfers can be done on carboys if you use those orange carboy caps. I haven't bothered with this as of yet and I have not seen any issues with oxidation in my beers.

What I would recommend doing is to clean and sanitize your keg by whatever method you choose. Transfer from carboy to keg as gently as possible (similar to bottling). Then close the keg up, set your regulator to 30 psig and let it sit for ~3-5 minutes. Then bleed the pressure down (using either the relief valve, or by pressing the poppet down with a scredriver (make sure you do this on the gas side). Repeat the process of purging 4 or 5 more times to ensure there is very little O2 remaining in the keg (I'll double check my numbers, but I think 4 purge cycles should get you down to ~0.18 wt % O2).

Then carbonate by whatever means suits your fancy (low and slow, shaking, etc.)

Hope this helps.




Posted 34 days ago.

flapjackcarl
Houston, TX
608 Posts


Stupid double post :(



Posted 34 days ago.

homebrewdad
Charter Member
Birmingham, AL
2480 Posts


Carl, that clarifies your process a ton for me. I could see how that would really reduce the amount of oxygen that the beer comes into contact with, too.

Understand, I'm not really having oxidation issues even now with bottling (at least, not as far as I can detect); my motivation is to do as much as I can to preserve hop aroma life, which I understand oxygen exposure has a role in.




Posted 34 days ago.

Necropaw
Charter Member
Central WI
608 Posts


Purging the remaining headspace after the beer is in is something ive done before. Im not sure my processes are perfect (both the charge/release, as well as just leaving the lid off and running the gas for a few seconds), but thats minimal gas 'wasting', so it doesnt really bug me.




Posted 34 days ago.

flapjackcarl
Houston, TX
608 Posts


Yea, I think that oxidation concerns are fairly mild on our scale, especially if you use some best practices on transfers (no splashing, etc). I find the purge after you fill it to give some good peace of mind given how easy it is and how little CO2 it uses. Especially since that is the atmosphere your beer is going to sit in for as long as the keg lasts.






Posted 34 days ago.

homebrewdad
Charter Member
Birmingham, AL
2480 Posts


This sounds like the sort of thing that would really appeal to me. Thanks for the suggestion.




Posted 34 days ago.

testingapril
Charter Member
Atlanta, GA
595 Posts


Olan, hop aroma/flavor loss is due to oxidation. I've said it before and I'll say it again. Oxidation doesn't just mean cardboard/stale. There are hundreds, thousands, maybe millions of different oxidation reactions that can happen in beer. Some can even be desirable, especially in certain styles. Most of them are undesirable though, but the effects are not always obvious.

If you do the star San fill and push out with co2, I see no reason you can't rack with an autosiphon into the liquid post with the purge valve open. That would virtually eliminate any o2 in the keg when racking. I think the turbulence on the surface of the beer in the receiving vessel is probably where most oxygen pickup occurs during racking. Residual O2 is probably a bigger overall concern, so pressurizing and purging the headspace several times sounds like a great solution.





Posted 34 days ago.

Necropaw
Charter Member
Central WI
608 Posts


Isnt CO2 heavier than air?

Assuming youre being relatively careful, getting some CO2 in the keg to start with and then racking under it seems like a pretty efficient way to keep O2 off the beer.


As far as racking beer gently goes, i do use an autosiphon, and i start with the keg lifted 18 or so inches off the ground so my siphon tube is on the bottom of it.

Once the keg is about halfway full i drop it down to floor level so it can finish filling the keg (otherwise the top of the keg would be above the bottom of the liquid in the fermenter). You can pretty much do it whenever you have enough beer in the keg so that the tube wont get above the liquid level when you lower the keg.

This will of course depend on the setup you have (height of where you rack from, floor level, legnth of siphon tubing, etc).

Assuming all of your equipment is working properly, i kinda think that oxygenation while racking is probably worried about too much.




Posted 34 days ago.

flapjackcarl
Houston, TX
608 Posts


April,

I definitely agree with what you're saying, and I think purging the keg prior to filling is a solid insurance policy. In terms of where oxidation is most likely to occur though, I don't know if I fully agree about it being in the keg. The turbulence in the liquid should be minimal once you establish a liquid level in the keg (although still greater than in the carboy). But the surface area in the keg is significantly smaller than what you have in the carboy. If I had to guess on which side has more oxygen pickup, I'd guess that it would be very close between the two. Because of that, I've tended to focus more on purging post transfer instead of prior to it. So basically, I agree with you. But I would say that purging after transfer is an absolute must do given that you know any residual O2 will eventually end up in your beer over time. I think that closed transfers further eliminate any amount of oxidation you have if you really want to minimize any O2 pickup. Just my take though. I'd be curious to see measurements with a DO meter taken, but I doubt many of us homebrewers have one of those sitting around




Posted 34 days ago.

flapjackcarl
Houston, TX
608 Posts


Hey Necro, that whole CO2 blanket thing you see people talking about is a complete and utter misnomer. Diffusion of gasses is governed by concentration gradients. If you're curious, you can read about Fick's law of diffusion. The gist of it is: closed systems like to reach equilibrium. Concentration gradients (i.e. pure CO2 above air), provide a motive force for the gasses to mix and create an equilibrium mixture.



Posted 34 days ago.

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