oxidation question

[doug293cz]

Glad this thread is helping. I just wanted to clarify a few things:

1) I would leave the burp approach in the dust. There are better ways!
2) When you fill with Starsan or other sanitizer you need to push it out under pressure. (bottled CO2) Using fermentation gas will not work and is a different approach. See #3
3) Daisy chaining empty kegs to your fermenation gas output uses empty kegs. Many people use two kegs, one hooked up to the fermentation blowoff and the 2nd hooked up to the 1st keg. The airlock goes on the last keg and the 1st keg is the one used for adding your beer to. But there are many permutations. In the end, it is pure CO2 that is free if your fermentation chamber allows for it.

1) Yes, the burping is only needed if you open the keg to the atmosphere after a good purge - to add dry hops for example, or a non-closed transfer to the keg.
2) It only takes ~2 psi to push sanitizer out of a keg (but add another 0.5 psi for each additional foot the outlet is above the keg.) So, if your fermenter can be even slightly pressurized, you can use fermentation CO2 to push sanitizer out. BUT, if you hook the keg to the fermenter at the beginning of the fermentation, there is no need to have it filled with liquid.

Brew on

 

[doug293cz]

If you are "burping" the keg a few times after filling it, the O2 in the keg headspace is minimal. Like a fraction of a percent. I would store the keg cold.

free air is only 21% oxygen. Before you pressurize the keg it's at 14.7 PSI sea level () gauge PSI). When you blast the keg with CO2 to say maybe 60 PSI and then bleed the PRV, you have just expelled 80% of that air and 80% of it's O2. Leaving about 4% O2. Burp it again and another 80% of the oxygen is expelled down to under 1% in the head space. Only takes a few times to get to 0.0?% oxygen left.

A little priming sugar will clean up any oxygen that remains. After a few days for the yeast to do it's thing, cold crash and store cold. I think that might fix your oxidation issues.

Yes, the O2 concentration drops a lot with each purge cycle. The problem is that the O2 target is about 100 ppb (0.1 ppm), and it takes a lot of purges to get there (higher pressure requires fewer purges.) Also, the O2 never gets to 0 theoretically, and practically you can't go lower than the O2 content of the CO2 you are using to purge. I published the following chart and table about residual O2 content vs. purge cycles a long time ago, and it's been reposted many times on HBT.

Brew on

 

[odie]

yep...CO2 is 2 parts oxygen anyway...

just toss a little priming sugar into the keg, purge a few times, let the yeast tackle any errant O2 and call it good.

I seriously doubt oxygen can ever be eliminated...only minimized...

 

[VikeMan]

yep...CO2 is 2 parts oxygen anyway...

The "O2 content of the CO2" @doug293cz referred to is not the "O2" part of the CO2 molecules. He's talking about the free oxygen molecules (O2) that exist as a contaminant (along with other gas contaminants, BTW) in CO2 supplies. It would take a lot of energy to split O2 off from CO2, thus making it available to oxidate the beer. This doesn't happen. If it were easy, we could solve global warming just like that.

 

[Bassman2003]

1) Yes, the burping is only needed if you open the keg to the atmosphere after a good purge - to add dry hops for example, or a non-closed transfer to the keg.
2) It only takes ~2 psi to push sanitizer out of a keg (but add another 0.5 psi for each additional foot the outlet is above the keg.) So, if your fermenter can be even slightly pressurized, you can use fermentation CO2 to push sanitizer out. BUT, if you hook the keg to the fermenter at the beginning of the fermentation, there is no need to have it filled with liquid.

Brew on

Yes, correct. It is tough to write posts so well that all scenarios are covered.

1) What I meant was burping is not the best way to approach getting O2 out of kegs and is kind of "old" homebrew thinking imho.
2) What I meant to stress was that "normal" fermentation gas output is not enough to push sanitizer out of a keg. So one can not just hook your blowoff to a keg and push the sanitizer out. Which to your point, you would not need liquid in there in the first place if you hooked your blowoff tube to the keg!

 

[VikeMan]

2) What I meant to stress was that "normal" fermentation gas output is not enough to push sanitizer out of a keg. So one can not just hook your blowoff to a keg and push the sanitizer out. Which to your point, you would not need liquid in there in the first place if you hooked your blowoff tube to the keg!

Normal fermentation gas output can push the sanitizer out of a keg, assuming the fermenter isn't leaky. But as noted, you don't need the sanitizer (except to sanitize).

 

[Bilsch]

Better to sanitize and flip/drain your kegs as starsan isn't supposed to be a beer flavor.

 

[odie]

Isn't Starsan "neutral"? Isn't that why we use it? granted, I have not tied a shot of it...

 

[Bilsch]

granted, I have not tied a shot of it...

Go ahead.. I dare ya!

 

[VikeMan]

Go ahead.. I dare ya!

I betcha it's "tart."

 

[odie]

Is that a double dog dare?

 

[Bassman2003]

Normal fermentation gas output can push the sanitizer out of a keg, assuming the fermenter isn't leaky. But as noted, you don't need the sanitizer (except to sanitize).

I have never used my fermenter to push sanitizer out of a keg but I do use a CO2 tank. Seems like it would be tough to get the last bits out but others are doing it. Something I would like to look into with my setup.

 

[Bilsch]

I betcha it's "tart."

Yea for sure phosphoric is going to be tart but I'll bet the dodecylbenzenesulfonic acid ester component is delicious.

 

[Bassman2003]

I am amazed at that word. Had to have been discovered by a German at least...

 

[Bilsch]

I am amazed at that word. Had to have been discovered by a German at least...

Yes, for degreasing the engine in his Benz.

 

[Gozie Boy]

Purge (burp) more. I always felt 3-5 times is not enough. I burp it 15-20 times lol. It's worth the $ (gas) to me.

If your keg is filled as much as possible with StarSans, then it's not really that much gas.

 

[doug293cz]

If your keg is filled as much as possible with StarSans, then it's not really that much gas.

If your keg is really as full as possible with liquid, you can't burp it.

Brew on