Closed Transfer Question (Pressure Transfer with CO2)

[eric19312]

My fermenter sits too low to gravity transfer and in interest of saving my back and also reducing cold side oxygenation I've been using CO2 to push beer from fermentor to kegs. I've been using the star san purging method for the kegs and have it down pretty well. Any idea how much oxygen am I picking up using CO2 to push beer out of my fermentor? It takes me about 45 minutes to move 15 gallons into kegs.

But in addition I am then force carbing with bottled CO2. I hope my vendor is selling the beverage quality pure CO2 but tbh not sure. He is a dive shop next door to a welding shop. I'll ask him next time I need a fill to make sure he is using FDA certified beverage grade gas.

So would spunding take care of both problems? Would the yeast activity in the keg consume at least some of that O2 I introduce using a pressure transfer?

 

[mongoose33]

You're introducing a little oxygen to the process if you push beer out with CO2, and since CO2 isn't pure (some say 99.5% pure), the extra .5 percent, if it's air, contains 21 percent oxygen. So 21 percent of .5 percent is just about .1 percent, or 1 part in 1000.

Same with force carbing. You're forcing gas that is not perfectly pure into solution. Some of that gas is O2.

Yes, spunding would take care of this. However, how are you going to serve it? How are you going to push that beer out of the keg into the taps and into the glass? So you'll still have O2 entering the keg.

I've been trying to adopt as many LODO principles as I can, and I've had some success with it. However, the difference has mostly been a matter of degree. Some of the recommendations are, IMO, faintly ridiculous, e.g., pitching yeast before oxygenating, when the difference (2 minutes) in the larger scheme of things is well less than 1 part in 1000. Nobody I know can discern that difference.

Some of this has to do with shelf life. If you drink your beer in a timely fashion then some of the concerns are moot.

Anyway, IMO the trick is to keep moving toward having less and less O2 in the process (except when oxygenating wort). People produce terrific beer who haven't even considered that CO2 isn't perfectly pure. How the heck is that possible, unless some of the concerns aren't really....all that important in the grand scheme of things?

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That said, the only way I can give the ideas of LODO brewing a fair hearing is to try to implement as many as I can, and see if the result is worth it. Still working on it. I don't expect to have a preliminary conclusion before May.

 

[Morrey]

Eric, like Mongoose33 surmises, it is highly unlikely that even the most strict of LODO purists will ever achieve 100% O2 free brewing processes. Focusing on the cold side relating to your thoughts, it seems as if you have taken every step possible to be O2 free.

I have a friend who moved from the home brew ranks to become a professional brewer. He shared he feels it is critical to transfer from fermenter to brite tank with CO2 and not use a pump as many breweries do. He checks his transfers with a DO meter and said his dissolved oxygen is among the lowest he has read about.

 

[MSK_Chess]

Pure natural Co2 is better than industrial food grade Co2 but sometimes we need to make compromises. Spunding is awesome in my opinion, but tricky to just catch it right. As we gain experience though these things will surely become simply a matter of fact.

 

[beersk]

Eric, like Mongoose33 surmises, it is highly unlikely that even the most strict of LODO purists will ever achieve 100% O2 free brewing processes. Focusing on the cold side relating to your thoughts, it seems as if you have taken every step possible to be O2 free.

I have a friend who moved from the home brew ranks to become a professional brewer. He shared he feels it is critical to transfer from fermenter to brite tank with CO2 and not use a pump as many breweries do. He checks his transfers with a DO meter and said his dissolved oxygen is among the lowest he has read about.

On this topic though, I'm quite sure that breweries get a higher grade of co2 than we have available to us as homebrewers. So he doesn't have much to worry about there...

 

[mongoose33]

I toured Third Space Brewing in Milwaukee last summer; we were taken around by the Brewmaster himself who had only recently hired his second employee. He was the first one, of course.

We walked past his lab--about a 10x10 room--and I saw a Milwaukee MW-102 pH meter there, and a dissolved-oxygen meter. I asked him about that, he said it had cost him $12,000. I asked if I could borrow it, he laughed and said "sure, if you give me a $12,000 deposit."

Anyway, he was canning beer in addition to kegging, and had a system designed to do everything he could to limit O2 in the can. That $12,000 DO meter was to help him ensure that what was going into those cans had as little O2 as he could manage. You could tell how much he was concerned with O2 on the cold side, and in fact was why he'd chosen cans instead of bottles to sell his beer.

I don't have any doubt O2 matters, but what matters more to me is how much and how long it takes to make its presence known and detectable. Since the brewmaster didn't know how long his beer would sit before a consumer decided to drink it, he felt he had to ensure absolute oxygen-free packaging, or as close as he could get it.

For us, I don't think it matters quite as much.

 

[Big Monk]

My fermenter sits too low to gravity transfer and in interest of saving my back and also reducing cold side oxygenation I've been using CO2 to push beer from fermentor to kegs. I've been using the star san purging method for the kegs and have it down pretty well. Any idea how much oxygen am I picking up using CO2 to push beer out of my fermentor? It takes me about 45 minutes to move 15 gallons into kegs.

But in addition I am then force carbing with bottled CO2. I hope my vendor is selling the beverage quality pure CO2 but tbh not sure. He is a dive shop next door to a welding shop. I'll ask him next time I need a fill to make sure he is using FDA certified beverage grade gas.

So would spunding take care of both problems? Would the yeast activity in the keg consume at least some of that O2 I introduce using a pressure transfer?

Using CO2 to push beer is small potatoes compared to force carbing. If you can eliminate force carbing you’ll be in great shape.

 

[Big Monk]

For us, I don't think it matters quite as much.

How much it matters is down to each brewer and thier sensory analysis of thier beers.

For some it will be of great importance if they start to see a flavor decline related to oxygen exposure.

 

[mongoose33]

How much it matters is down to each brewer and thier sensory analysis of thier beers.

For some it will be of great importance if they start to see a flavor decline related to oxygen exposure.

My point in part was that if we don't have to guarantee long shelf life and we actually consume our beers with alacrity, then it isn't as important.

 

[Big Monk]

My point in part was that if we don't have to guarantee long shelf life and we actually consume our beers with alacrity, then it isn't as important.

That’s certainly one way of looking at it.

For those who don’t consume larger amounts of beer in short periods of time (like myself), “shelf life” is very important.

Different strokes for different folks. Best practice is to produce the most “shelf stable” beer you can. If you’ve come far enough into brewing to be even entertaining LOB, you might as well produce the best, most flavor stable beer you can.

On the other hand, flavor is subjective, and people should let thier taste buds be thier guide. We make recommendations based on OUR experience and the experience of others who have followed those recommendations. Our taste buds say everything matters to some degree but that doesn’t mean it does for everyone else.

If you were making what you thought was good beer before LOB and implementing some of the methods improved your beer, then keep pushing until you get to the point where you are satisfied. Subjectivity can be a powerful indicator as to what matters to you. Trust your sensory analysis and adjust your effort based on that.

 

[eric19312]

Thanks for the feedback all. I'm probably going to try spunding just as an excuse to buy one of those tilt hydrometers in near future. Might do a side by side with one keg force carbed and other spunded and see if I can tell the difference after a few weeks.

I'm also a LODO skeptic but willing to consider the possibilities. Like others I am content to focus on CSA for now and see how the evidence re HSA works out. When I started homebrewing HSA was a thing and then for a number of years it just wasn't a thing in fact was labeled by many to be either a myth or just not a factor at the homebrew level. Now there is movement to make it a thing again. Given that progression my instinct is it might be a thing but it is not a huge obvious thing. CSA however has never been not a thing in my brewing experience.

What I really like about the LODO science is the concept of the additive nature of oxygen ingress into the final product. It's not all or nothing. You pick up some O2 in your very best closed transfer. Perhaps more from force carbing, then again more from serving with CO2. Finally even more just leaving your kegs hooked up to gas "set it and forget it" style...If I can reduce or eliminate some of that ingress along the way from fermentor to glass perhaps it will be noticeable improvement in the time frame that matters to my brewing.

 

[MSK_Chess]

I was a LODO skeptic until I read Kunze, now I am completely paranoid about oxygen getting anywhere near my beer. Nah seriously its just good science thats all and should be good fun!

 

[SanPancho]

To the OP. Heres an easy one- connect your fermenter blow off to your keg1 out tube with jumper from keg1 in to keg 2 out, keg2 in jumpered to keg3 out with a spunding valve set super low on the gas in of keg3. Back pressure on fermenter wil be minimal and your kegs will be as o2 free as humanly Possible.

Then transfer with co2 into kegs individually. Effective and easy.

If you are worried about timing for spunding at end of primary then you can leave a bit of priming sugar in each keg before you seal them up and connect for purging. Once you transfer beer into each keg it should carb itself up and eat any o2 hopefully. Id make sure kegs are dry before you add the sugar.

 

[eric19312]

To the OP. Heres an easy one- connect your fermenter blow off to your keg1 out tube with jumper from keg1 in to keg 2 out, keg2 in jumpered to keg3 out with a spunding valve set super low on the gas in of keg3. Back pressure on fermenter wil be minimal and your kegs will be as o2 free as humanly Possible.

Then transfer with co2 into kegs individually. Effective and easy.

If you are worried about timing for spunding at end of primary then you can leave a bit of priming sugar in each keg before you seal them up and connect for purging. Once you transfer beer into each keg it should carb itself up and eat any o2 hopefully. Id make sure kegs are dry before you add the sugar.

I’m curious about this whole practice of using fermentation gas to purge kegs.

First ... if it takes 15 purges of 25psi pure CO2 to purge a keg how can you expect low pressure fermentation gas to do it? Won’t it be constant dilution?

Second ... what about the non CO2 gasses from fermentation? Higher alcohols, off flavors and such...don’t you want to get rid of this stuff? Don’t pros that capture CO2 from fermentation scrub the gas before returning it to their beer?

 

[SanPancho]

The sheer volume of co2 produced generally clears it all out. 4 gravity ooints is typically enough to carb a beer. 40p is alot more.

 

[doug293cz]

I’m curious about this whole practice of using fermentation gas to purge kegs.

First ... if it takes 15 purges of 25psi pure CO2 to purge a keg how can you expect low pressure fermentation gas to do it? Won’t it be constant dilution?

Yes, it's constant dilution, but that is equivalent to an infinite number of infinitely small purges, and it comes down to how much CO2 was produced divided by the volume being purged. I presented a detailed analysis of this here. The tl:dr version is that this type of purging can get you to single digit ppb O2 levels (assuming no O2 ingress to the system - a rather large caveat.)

Second ... what about the non CO2 gasses from fermentation? Higher alcohols, off flavors and such...don’t you want to get rid of this stuff? Don’t pros that capture CO2 from fermentation scrub the gas before returning it to their beer?

Would depend on just how much of these contaminant gases are produced, whether they are produced early or late in the fermentation (i.e. how much will they get diluted during the purge), and how much gets reabsorbed by the beer during the keg filling process (most of the contaminant vapors will be pushed out during filling.) Sounds like an intractable analysis at the homebrewer level, although a well equipped analytical chem lab should be able to measure a lot of this. Personally, I don't think it would be much of an issue.

Brew on

 

[FunkedOut]

Or fill the keg with star san and use the fermentation gas instead of a CO2 bottle to push the star san out.
Most of that gas will be pushed out of the keg when you push the beer in later.

 

[doug293cz]

Or fill the keg with star san and use the fermentation gas instead of a CO2 bottle to push the star san out.
Most of that gas will be pushed out of the keg when you push the beer in later.

If you have a well sealed fermenter, that can withstand a few PSI of pressure, this will work.

However, if you want to keg hop, you might want to put the hops in a dry keg(s), that then gets purged by the fermentation gas. Haven't tried this yet, but it's on my todo list.

Brew on

 

[Big Monk]

Or fill the keg with star san and use the fermentation gas instead of a CO2 bottle to push the star san out.
Most of that gas will be pushed out of the keg when you push the beer in later.

But you have to contend with the sanitizer left behind. Usually you invert a purged keg to get rid of the remaining sanitizer solution. If you can still do that, then that would work. The whole point of the fermentation purge though was to simplify the process completely. It’s meant to be a set and forget method and the analysis the doug provided gives a very good theoretical grounding in why it’s successful.

 

[mongoose33]

The sheer volume of co2 produced generally clears it all out. 4 gravity ooints is typically enough to carb a beer. 40p is alot more.

Let me extend this a bit. Using SanPancho's example numbers, say a beer starts at 1.055 gravity, finishes at 1.015 gravity.

That's a drop of 40 points. If 4 points is enough to carb at, say, 2.5 volumes, then 40 points would be producing 10x that, or 25 volumes.

So if you feed all that fermentation gas into the keg, you have effectively 21 purges. (25-4).

It's as if you're cutting in half the amount of non-CO2 gas in the keg 21 times. And if you start with a keg that has been purged using the Star-San method, you don't start with air in the keg, you start with 99.5% pure CO2 (or whatever purity yours is), so at the end....as close to pure CO2 as you're going to get.

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This is my understanding of this. If anyone sees a flaw in it, correct away, or to extend, please do.

 

[mongoose33]

But you have to contend with the sanitizer left behind. Usually you invert a purged keg to get rid of the remaining sanitizer solution. If you can still do that, then that would work. The whole point of the fermentation purge though was to simplify the process completely. It’s meant to be a set and forget method and the analysis the doug provided gives a very good theoretical grounding in why it’s successful.

Not if you do it the right way. When I push the Star-San out of my kegs, they end up being pressurized to around 15 psi (depending on what pressure I choose at the time). I'll attach my racking tube/disconnect to the liquid-out side, and immediately I'm releasing pressure through that. Holding it over the sink, I'll rock the keg back and forth a bit so whatever sanitizer is left is blown out, being sucked up into the liquid dip tube. Whatever residual sanitizer is left--and it might be a tenth-ounce I suppose--I expect to be evaporated over the course of 20+ volumes of ferm gases purging the keg after that.

I think that's about as close as one can get to perfect.

 

[eric19312]

Ok I didn’t realize the ferm gasses was in addition to the bottled CO2 purge. You are doing all this and spunding?

 

[mongoose33]

Ok I didn’t realize the ferm gasses was in addition to the bottled CO2 purge. You are doing all this and spunding?

(Please don't assume I know a lot about this. I've been toying with this LODO stuff since early fall 2017. An expert I am not.)

Anyway, I actually am doing what you describe above. I think it would be described as best practice, as they say, and the only way I can give this LODO stuff an honest trial is to try to do all of it the best I can.

So what I've been doing is purge a star-san-filled keg by forcing that star-san out into another keg, leaving behind a CO2-purged keg with a tiny bit of star-san in the bottom. RPIScotty would probably note, and correctly so, that the residual star-san is liquid that has O2 in solution. Not a lot, but some. So I blow out the residual star san by attaching a liquid-out QD to which is connected a tube. The pressure comes rushing out and as I tilt the keg back and forth, I catch all that residual liquid star-san in the bottom. You can hear it, and see it come out the tube. Into the sink that goes. Or a bucket.

Then I'll attach the tubing to the fermenter to catch the fermentation gases and route them through this newly-purged keg.

Couldn't I just use fermentation gases to purge the keg of Star-San. In my case, no. I don't have a sealed system that would allow that. Further, I'm not clearing that last bit of Star-San from the bottom if I did it that way, though I suspect much would evaporate away. Doing it this way allows me to blow any residual star-san out of there.

An alternative that I haven't explored is simply to dump the Star-san from the keg into a bucket. That would fill the keg with air, of course, which is then purged away with fermentation gases. I'm just being a little anal about it. I always purge the star-san from one keg to another, so I always have a star-sanned keg ready to go the next time I need one. I have a couple spares.

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And then, I'm spunding. This happens after I've transferred the beer from the fermenter to the now-O2-evacuated keg. But that process is not perfect so some air (and O2) is likely to have entered somewhere. The finishing of fermentation with spunding in the keg will allow the still-fermenting yeast to consume that O2 and as they do this, they're naturally carbonating the beer rather than my force-carbing it with CO2 that is not perfectly pure.

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Overkill? That's for others to decide. It's more involved, that's for sure, though as I've done this it's become easier. Much like how it was with all of us when we started brewing. Lots of moving parts and processes, but then it all settled down.

But it is all more involved. Just pre-boiling the strike water, then chilling it down to strike temp, not overshooting, that makes things more involved. I've shortened up some of that by boiling some of the water on my stove, the rest in my kettle fired by propane, but still.

 

[FunkedOut]

But you have to contend with the sanitizer left behind. Usually you invert a purged keg to get rid of the remaining sanitizer solution. If you can still do that, then that would work. The whole point of the fermentation purge though was to simplify the process completely. It’s meant to be a set and forget method and the analysis the doug provided gives a very good theoretical grounding in why it’s successful.

@mongoose33 hit it.
I’ll attach a spunding valve to the serving keg and it ends up at 15psi.
My serving keg dip tubes leave less than 1oz at the bottom.
If your dip tubes are shorter, then you can invert and pull the ring.

 

[SanPancho]

Take your gas dip tube and cut it short so it doesnt protrude below keg surface. Now you can blow out star san thru gas in post with no residual if you lift it upside down.

 

[Big Monk]

@mongoose33 hit it.
I’ll attach a spunding valve to the serving keg and it ends up at 15psi.
My serving keg dip tubes leave less than 1oz at the bottom.
If your dip tubes are shorter, then you can invert and pull the ring.

Yup. That’s it.

We just did a series of blog posts and part 2 detailed the purging process.

 

[Dog House Brew]

Take your gas dip tube and cut it short so it doesnt protrude below keg surface. Now you can blow out star san thru gas in post with no residual if you lift it upside down.

What are you using to get a smooth cut? My tubing cutter is going to leave it too long.

 

[SanPancho]

Tube cutter is a bit tough. Now i use a dremel.

 

[Dog House Brew]

Tube cutter is a bit tough. Now i use a dremel.

What I figured, I was worried about any rough edge. I guess I’ll get a good thin wheel and polish them the best I can. Thanks

 

[day_trippr]

I clamp the dip tube between soft pine and use the Dremel fiber cutoff wheel.

I then use a cone grinder bit to smooth the inside and outside edges...

Cheers!