Discouraging First Keg Experience

[Brüverine]

Sorry for veering the thread off into cold O2 mitigation discussions, it doesn't appear that was the likely culprit.

Making good beer should be attainable with some fixes. It looks like you are taking good steps to address the problem.

It's when you are chasing the best beer that all the other stuff down the rabbit hole comes into play (and for some people that's part of the fun)

I'm honestly just super stoked at how many people showed up to help. This is all extremely useful knowledge. Plus, I would imagine that reducing oxidation to such a degree as mentioned here will greatly prolong the life and quality of a beer (assuming I don't smash it first).

 

[bracconiere]

The weight change on your CO2 cylinder is the same for every purge cycle. The weight change of the keg itself gets smaller with each successive purge cycle. It is the keg that needs to be monitored for purge effectiveness, not the CO2 cylinder.

Brew on

well i'm sure a mg scale that's accurate to 60lbs is out of my price range! but now i have to google O2 meters and, think of a way to vent over one to see it drop! or co2?

I'm honestly just super stoked at how many people showed up to help.

i'm just having fun trying to be part of the group! i noticed doug already posted the chart!

 

[tracer bullet]

When you add CO2 and then pull the PRV, you are not evacuating all of the gas. You'd need vacuum to do that. Think of it more like you've got a bucket partially filled with some water and strong dye to represent the O2 in it. Adding the CO2 is like adding more water to the dye; higher CO2 pressure would be equivalent to adding more water. Pulling the PRV to get back to atmospheric pressure is like then dumping out the solution back to your starting volume - you're still going to have plenty of dye in there, just less concentrated. Then you are repeating until the dye is not noticeable.

Just for the record, I'm purging the headspace above the star san solution, which is filled as high as I can possibly get it. I fill the keg in a utility sink and it's overflowing when I put the lid in place. The headspace which I'm purging is incredibly small, so small I could probably not even bother to purge it yet I still do. I bet it's an ounce or so of "air" I couldn't quite get out, maybe less, when it's sealed up and I attach CO2.

I was really wondering why Golddiggie seemed to fill with star san, purge it out, and then with their CO2 filled keg did additional purges. Seems like a waste of CO2, but maybe I misunderstood.

Slightly different subject, when it comes to using fermentation CO2 tp purge a keg, one thing I always wondered was if that CO2 not only purges the keg, but the connection of it to the fermenter might also mean that via partial pressure and such that the O2 molecules might also be taken up by the yeast themselves doing their thing. So instead of just continued dilution doing it, maybe they are actually actively taken in? No idea, but always thought that might be part of it.

 

[Golddiggie]

@tracer bullet I don't fill my kegs with Starsan (even though I'm using 2.5 and 3 gallon kegs). I add a couple quarts of Starsan and use that to sanitize inside. I pressure transfer the beer from conical (already fully carbonated) into keg on packaging day. The rest of each batch typically goes to can (Tapcooler counter pressure filler where the cans are CO2 purged before being filled).

IME, using CO2 to push the Starsan out, then filling via pressure transfer gives the beer a good amount of CO2 in the headspace above the beer as it enters the keg (via the liquid post). Since CO2 is heavier than oxygen/air, it's purging while I'm filling. I don't put the keg gas post back to the fermenter, it goes into a bucket of Starsan to act as an airlock. This is a method I've seen breweries use to fill their kegs. Granted, filling 1/2 bbl kegs is a larger scale, but the process/method is the same.

 

[Vale71]

(actually I'm kind of curious about where we would max out purging gains if our gas is 99.9% pure CO2, with 0.1% air [which is about 20% O2, so 0.02% or 200PPM]...)

The residual impurity is not air. Most of it is made up by inert gases (argon, N2) which by their very nature are hard to get rid of on account they tend not to react with anything and then some combustion by-products. Residual O2 levels as has already been mentioned are usually quite low provided you get food-grade CO2 from a reputable source.

 

[Vale71]

Slightly different subject, when it comes to using fermentation CO2 tp purge a keg, one thing I always wondered was if that CO2 not only purges the keg, but the connection of it to the fermenter might also mean that via partial pressure and such that the O2 molecules might also be taken up by the yeast themselves doing their thing. So instead of just continued dilution doing it, maybe they are actually actively taken in? No idea, but always thought that might be part of it.

Diffusion from the headspace into the liquid is way too slow to play any role in the timeframe a beer usually fully ferments (a few days). 99.999% of the headspace O2 is simply driven off by the huge amount of CO2 being produced by fermentation.

 

[Vale71]

Since CO2 is heavier than oxygen/air, it's purging while I'm filling.

Relative density is completely irrelevant, gases mixed rather quickly and don't form layers. This has been discussed way too often on HBT. The only way to prevent O2 from getting to the beer is effectively purging the keg before filling it.

 

[tracer bullet]

Diffusion from the headspace into the liquid is way too slow to play any role in the timeframe a beer usually fully ferments (a few days). 99.999% of the headspace O2 is simply driven off by the huge amount of CO2 being produced by fermentation.

I've been poking around for how to calculate it but nothing yet. There must be at least some amount of it happening in just a few days, else we wouldn't talk quite so much about purging kegs to prevent oxidizing the beer after it's finished. fermenting wort has some actual surface and other motion as well.

Anyhow, agreed that whatever amount is that is taken in by the yeast, it's probably very small.

 

[doug293cz]

Relative density is completely irrelevant, gases mixed rather quickly and don't form layers. This has been discussed way too often on HBT. The only way to prevent O2 from getting to the beer is effectively purging the keg before filling it.

And then doing a closed transfer.

If you open the keg after purging it, enough O2 will get in to give you oxidation problems (at least for very hoppy beers.)

Brew on

 

[shoengine]

If you do a pressure transfer to a corney with the PRV open you are essentially performing a very long purge. I typically pressurize my keg and purge five times, then transfer under positive CO2 from the fermentor to the keg with the PRV open until the keg starts spitting out foam. Pumping action should do a fairly good job of pushing out anything in the headspace, and since the keg is almost always warmer than the fermentor in my case CO2 will be continually diffusing into the headspace during the transfer. What are the PPx of O2 left in the headspace? No idea. I haven't had bad results though.

FWIW, closed transfer is a misnomer. Unless the keg is looped back to the fermentor, it is still open on one side. The assumption is that with pressure being applied to one side, there is no hope of oxygen ingress on the open end.

 

[TheMadKing]

FWIW, closed transfer is a misnomer. Unless the keg is looped back to the fermentor, it is still open on one side. The assumption is that with pressure being applied to one side, there is no hope of oxygen ingress on the open end.

I did exactly this for a year before getting a better system, and returned the keg CO2 back to the fermenter.

The transfer is still closed even using a spunding valve on the gas post because the transfer is of beer, not CO2, and the beer never contacts the environment, therefore it is closed off from the environment.

 

[shoengine]

I did exactly this for a year before getting a better system, and returned the keg CO2 back to the fermenter.

The transfer is still closed even using a spunding valve on the gas post because the transfer is of beer, not CO2, and the beer never contacts the environment, therefore it is closed off from the environment.

It's fine, we can have different definitions for the term closed transfer.

 

[Spikybits]

adding some jet fuel... you can ferment and serve in the same keg, eliminating any O2 exposure

bend your dip tube 1" off the bottom, fill only to 4g and use a spunding valve - you will pour with yeast for a few pints but then after that all glory.

not to mention you're fermenting in a stainless steel vessel and fermentation will consume all the o2/purge the headspace

 

[doug293cz]

adding some jet fuel... you can ferment and serve in the same keg, eliminating any O2 exposure

bend your dip tube 1" off the bottom, fill only to 4g and use a spunding valve - you will pour with yeast for a few pints but then after that all glory.

not to mention you're fermenting in a stainless steel vessel and fermentation will consume all the o2/purge the headspace

You could also use a floating dip tube, in which case you do not need to shorten anything, nor will you pull yeast when you start serving.

Brew on

 

[Spikybits]

You could also use a floating dip tube, in which case you do not need to shorten anything, nor will you pull yeast when you start serving.

Brew on

Ya had to 1up me didn't ya

 

[doug293cz]

Ya had to 1up me didn't ya

I often forget useful options when I post, and others often fill in the missing information. Kinda the way things should work around here. There are lots of ways to do things, and the more people know about the different options, and their pros & cons, the better they will be able to make decisions that are the best for them.

Brew on

 

[marc1]

Just for the record, I'm purging the headspace above the star san solution, which is filled as high as I can possibly get it. I fill the keg in a utility sink and it's overflowing when I put the lid in place. The headspace which I'm purging is incredibly small, so small I could probably not even bother to purge it yet I still do. I bet it's an ounce or so of "air" I couldn't quite get out, maybe less, when it's sealed up and I attach CO2.

I was really wondering why Golddiggie seemed to fill with star san, purge it out, and then with their CO2 filled keg did additional purges. Seems like a waste of CO2, but maybe I misunderstood.

Slightly different subject, when it comes to using fermentation CO2 tp purge a keg, one thing I always wondered was if that CO2 not only purges the keg, but the connection of it to the fermenter might also mean that via partial pressure and such that the O2 molecules might also be taken up by the yeast themselves doing their thing. So instead of just continued dilution doing it, maybe they are actually actively taken in? No idea, but always thought that might be part of it.

I came across the post where @doug293cz measured the headspace around the PRV, so now you can calculate the O2 contribution from it and decide if it's worth it to you to worry about or not:

https://www.homebrewtalk.com/thread...secondary-co2-and-airlock.568745/post-7330461

 

[TLaffey]

I came across the post where @doug293cz measured the headspace around the PRV, so now you can calculate the O2 contribution from it and decide if it's worth it to you to worry about or not:

https://www.homebrewtalk.com/thread...secondary-co2-and-airlock.568745/post-7330461

Yeah, I decided to worry about this little bubble and my solution was to add some metabisulfite to the Starsan solution. That helps eliminate the chloramine in the water used to mix the Starsan as well as the remaining oxygen. Is anyone else doing this? Or is there a reason I should stop doing it? (I'm not concerned about the very small amount of metabisulfite carried into the beer.)

 

[TheMadKing]

I came across the post where @doug293cz measured the headspace around the PRV, so now you can calculate the O2 contribution from it and decide if it's worth it to you to worry about or not:

https://www.homebrewtalk.com/thread...secondary-co2-and-airlock.568745/post-7330461

I had not read that one before thanks for posting, that's some great info. And thanks Doug for all your work in providing the info to us!

 

[tracer bullet]

I came across the post where @doug293cz measured the headspace around the PRV, so now you can calculate the O2 contribution from it and decide if it's worth it to you to worry about or not:

https://www.homebrewtalk.com/thread...secondary-co2-and-airlock.568745/post-7330461

Nice, thanks. And thanks to Doug as well.

When I drop the lid into a full keg, much of that headspace under the PRV is also filled with liquid since I go in at an angle, so I suspect I end up with less than stated (which I'd get if I were to fill the keg in the manner described). But in the end it looks like I'll continue to purge even that amount, whatever it is.

Someone needs to make lids that don't have a PRV spot that goes "into" the keg... I wonder if that's a strength thing.