Preventing O2 ingress when cold-crashing for lagering - ideas?

[Spivey24]

I use a couple of those cold crash guardians. They work well enough, but it is not possible to make sure all oxygen is out of the device as there is always some space left in the bag and hoses. I figure after a few flushes though it is good enough.

Off topic question though. I usually cold crash to 33F for a few days. I get some suck back as the temperature drops and the balloon deflates some. But after a couple of days at 33F I will get a lot more suck back. I can’t quite figure out what’s going on. I have checked the device many times and it free flows back out of the bag with no issue. And the temp is monitored by the Tilts so I am reasonably sure of the temperature of the beer.

 

[Indian_villager]

Any interest in a shitty CO2 generator? As in 2L soda bottle with water, sugar, bakers yeast, use some carbonation caps and bs to attach to your lid. Include a tee between your CO2 generator and your fermenter and have the third leg of that tee go into a small container of star san, this way you don't risk over pressurizing your fermenter.

 

[tracer bullet]

I use a couple of those cold crash guardians. They work well enough, but it is not possible to make sure all oxygen is out of the device as there is always some space left in the bag and hoses. I figure after a few flushes though it is good enough.

I don't own one and don't know for sure, but aren't they hooked up at the beginning of fermentation? Like when you pitch your yeast and get the rest all set up? At that point in time O2 is fine, the yeast will use anything that is in the headspace as it dissolves into the wort. The device is just a slight extension of the headspace. I think anyhow - sound right?

 

[MaxStout]

Seems that they are concerned about some suck-back due to evaporation through the barrels. For the ones that use wood of course. So there may be some commonality there.

I didn't quite get what the device does, something about filling it with wine? I'm only familiar with the typical homebrew 3-piece airlocks, or the single piece with the sideways S shape in them. I looked somewhat carefully at it but the glass makes it hard to know what's going on. A little Google searching just got frustrating.

Unless I'm missing something, I don't see any advantage of this vs a standard airlock. If there is sufficient negative pressure within the FV, it looks like outside air will still be drawn through the airlock. My concern in this thread is O2 ingress, not just liquid suckback.

In any case, it doesn't appear to address my concerns. I have decided to use a CO2 capturing device, like the Cold Crash Guardian.

 

[MaxStout]

Any interest in a shitty CO2 generator? As in 2L soda bottle with water, sugar, bakers yeast, use some carbonation caps and bs to attach to your lid. Include a tee between your CO2 generator and your fermenter and have the third leg of that tee go into a small container of star san, this way you don't risk over pressurizing your fermenter.

If I were collecting CO2 from beer fermentation I don't see how generating more from sugar/bakers yeast would be necessary.

However, my issue today is I hadn't collected fermentation CO2 and now I need some to accommodate the cold crash.

Filling a Cold Crash Guardian from a CO2 tank would be a more elegant and less messy solution.

 

[mac_1103]

I use a couple of those cold crash guardians. They work well enough, but it is not possible to make sure all oxygen is out of the device as there is always some space left in the bag and hoses. I figure after a few flushes though it is good enough.

I don't own one and don't know for sure, but aren't they hooked up at the beginning of fermentation?

Yes, they're designed to capture fermentation gas and they will be fully flushed of O2 if you use them that way. They even come with a check valve. Filling something from a CO2 tank is only happening in this case because OP's other CO2 capture device failed.

 

[jerrylotto]

I agree this would do the trick. But if your able to pressurise the bucket (even if the pressure would be very low) you wouldn't need to transfer to a new bucket/keg in my opinion. Then you can just cold crash in the original and still avoid stuck-back. Or am I missing something?

Carbon dioxide dissolves in beer, and the amount that dissolves increases as temperature drops. So if you're going to cold crash you're going to have to be under pressure or you are going to pull a vacuum.

 

[MaxStout]

Yes, they're designed to capture fermentation gas and they will be fully flushed of O2 if you use them that way. They even come with a check valve. Filling something from a CO2 tank is only happening in this case because OP's other CO2 capture device failed.

I plan to purge the bag a couple times with CO2 from a tank, then fill again and connect. It looks like one of those collapsible water jugs people use for camping, with a hose and check valve attached. Rather clever, I think.

But I will use it with a blowoff jar next time.

 

[MaxStout]

Info is scarce, but it seems that the colmatore style airlock is basically like a regular 3 piece (in functionality), except it has a reservoir below the "airlock" section.

I think that's the crux. Since, AFAIK, vintners have no need to cold crash and tend to store fermenting wine at a fairly constant temp (wine people correct me if I'm wrong), there only needs to be enough barrier to hold back air ingress caused by minor temp changes. Just by looking at the pic I can see that the reservoir in the colmatore airlock does just that. It provides enough hydraulic pressure to withstand a relatively minor pressure differential. Therefore, it would be adequate to prevent O2 ingress only in cases of minor temp changes.

OTOH, those of who lager are dropping temps by 25 to 30F or so. The contraction of the CO2 in the headspace, combined with the increased solubility of gas in beer as temp decreases, requires more than just an airlock. The pressure differential can require several liters of CO2 from an external source.

I'm not trying to pick a fight. Just saying the colmatore airlock is the wrong tool for the job here.

 

[General Sterling Price]

I think that's the crux. Since, AFAIK, vintners have no need to cold crash and tend to store fermenting wine at a fairly constant temp (wine people correct me if I'm wrong), there only needs to be enough barrier to hold back air ingress caused by minor temp changes. Just by looking at the pic I can see that the reservoir in the colmatore airlock does just that. It provides enough hydraulic pressure to withstand a relatively minor pressure differential. Therefore, it would be adequate to prevent O2 ingress only in cases of minor temp changes.

OTOH, those of who lager are dropping temps by 25 to 30F or so. The contraction of the CO2 in the headspace, combined with the increased solubility of gas in beer as temp decreases, requires more than just an airlock. The pressure differential can require several liters of CO2 from an external source.

I'm not trying to pick a fight. Just saying the colmatore airlock is the wrong tool for the job here.

>I'm not trying to pick a fight.

No worries, buddy...I didn't get that impression. The forums are for sharing knowledge, and friendly debate.

>The contraction of the CO2 in the headspace, combined with the increased solubility of gas in beer as temp decreases, requires more than just an airlock.

Can you give me a ballpark figure at to how many CC's (or liters) of volume shrinkage a guy can expect from a 23 liter carboy FULLY topped up to the lip (ie: zero headspace) before a cold crash? Say from 68F to 35ish?

>Therefore, it would be adequate to prevent O2 ingress only in cases of minor temp changes.

This is kind of what I was hoping for in a sense...viewing the cold crash as a series of minor temp changes, and topped up throughout with perhaps a finished (CO2 laden) beer? Of course this depends on just how much space I'd have to make up.

*note - Sorry about the goofy "quotes"...I can't seem to figure out the quote function, OR "quit" a reply once I've brought up a reply box.

 

[tracer bullet]

Some % of wine could be lost through the wood barrels, right? Angel's share and all that in whisky terms. I wonder how much? They could have legit backfill issues.

I can't quit figure out how that glass thing works for wine. Google skills are failing me. It seemed like a standard 3-piece airlock for beer but seems there's more to it.

One could argue that a giant 3-piece airlock might do it, one where the little piece that pops up and down was big enough to hold a ton of CO2 (a liter perhaps) and not the couple of cc's they normally do.

 

[tracer bullet]

I think I figured out a little more. Look at the earlier picture. Note the wine in it... There is no headspace in the barrel. It's filled to the top, and into this airlock contraption's stem. Without the airlock it'd actually be overflowing.

Still it seems as this wine was drawn into the barrel, air would be drawn in through the top, that wine sitting up there would oxidize, and then get into the barrel. Maybe they count on it sitting up there above and not mixing in?

Hmm. I could be wrong, Maybe that helps the mystery a bit. Since we are already off topic anyhow, haha.

 

[tracer bullet]

Can you give me a ballpark figure at to how many CC's (or liters) of volume shrinkage a guy can expect from a 23 liter carboy FULLY topped up to the lip (ie: zero headspace) before a cold crash? Say from 68F to 35ish?

https://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html
Just over a half liter, apparently.

 

[Dland]

I cold crash after racked into kegs and spunded (carbonated by residual fermentation), or force carb after crash. Back when I bottled, I cold crashed after they were primed and carbonated.

Yes, there will be a little yeast sediment at bottom of keg or bottle, but not much more than what one would get racking and not wasting too much beer.

The whole thing with balloons and stuff kind of baffles me.

 

[General Sterling Price]

Some % of wine could be lost through the wood barrels, right? Angel's share and all that in whisky terms. I wonder how much? They could have legit backfill issues.

I can't quit figure out how that glass thing works for wine. Google skills are failing me. It seemed like a standard 3-piece airlock for beer but seems there's more to it.

One could argue that a giant 3-piece airlock might do it, one where the little piece that pops up and down was big enough to hold a ton of CO2 (a liter perhaps) and not the couple of cc's they normally do.

>Some % of wine could be lost through the wood barrels, right? Angel's share and all that in whisky terms. I wonder how much? They could have legit backfill issues.

Probably quite a bit, also (according to this article) the volumes they deal with are subject to tidal activity....

https://www-poderesanpierino-it.tra...tr_sl=it&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc
>I can't quit figure out how that glass thing works for wine. Google skills are failing me.

It's not you....I had a hell of a time finding out what I have already...lol.

>One could argue that a giant 3-piece airlock might do it

That exactly what I was hoping/wondering about, they're quite large (this one has a 4 liter reservoir)....

https://www.colmatoriperbotti.com/
....of course trying to get one to fit a standard carboy might be difficult.

 

[General Sterling Price]

https://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html
Just over a half liter, apparently.

Oh wow......I was expecting a lot more!

 

[MaxStout]

>I'm not trying to pick a fight.

No worries, buddy...I didn't get that impression. The forums are for sharing knowledge, and friendly debate.

>The contraction of the CO2 in the headspace, combined with the increased solubility of gas in beer as temp decreases, requires more than just an airlock.

Can you give me a ballpark figure at to how many CC's (or liters) of volume shrinkage a guy can expect from a 23 liter carboy FULLY topped up to the lip (ie: zero headspace) before a cold crash? Say from 68F to 35ish?

>Therefore, it would be adequate to prevent O2 ingress only in cases of minor temp changes.

This is kind of what I was hoping for in a sense...viewing the cold crash as a series of minor temp changes, and topped up throughout with perhaps a finished (CO2 laden) beer? Of course this depends on just how much space I'd have to make up.

*note - Sorry about the goofy "quotes"...I can't seem to figure out the quote function, OR "quit" a reply once I've brought up a reply box.

It can be a lot. I'd say the biggest factors are headspace (CO2 contraction inside the FV), and amount of dissolved CO2 already in the beer (how much more will dissolve when dropping temp, etc). Contraction of the beer itself contributes some to the effect. I typically rack around 6 gallons into a 7 gal FV, so I don't leave much headspace. In the past I had less than 1/2 gallon suckback.

Wish I had a better answer, but there are so many variables it's difficult to predict.

Someone around here has a suckback calculator, but I can't find it. There's some discussion of volumes here.

I'd say plan for more than you think you need. I ordered the CO2 collector thingy from Brew Hardware. I'll find out how well it works in coming weeks.

 

[mashdar]

https://www.brewhardware.com/product_p/ccguardianv3.htmedit: oops, looked and didn't see this yet, but I missed bobo's post above.

 

[mac_1103]

edit: oops, looked and didn't see this yet, but I missed bobo's post above.

That's OK, he missed wepeeler's above his.

 

[doug293cz]

Off topic question though. I usually cold crash to 33F for a few days. I get some suck back as the temperature drops and the balloon deflates some. But after a couple of days at 33F I will get a lot more suck back. I can’t quite figure out what’s going on. I have checked the device many times and it free flows back out of the bag with no issue. And the temp is monitored by the Tilts so I am reasonably sure of the temperature of the beer.

The first bit of deflation is due to gas volume contraction due to the temperature drop. The continued deflation is from additional CO2 being absorbed into the beer, since at a constant CO2 partial pressure, the beer will hold more CO2 at a lower temperature.

Brew on

 

[General Sterling Price]

The first bit of deflation is due to gas volume contraction due to the temperature drop. The continued deflation is from additional CO2 being absorbed into the beer, since at a constant CO2 partial pressure, the beer will hold more CO2 at a lower temperature.

Brew on

If the main "force", or "reason" behind the first contraction is the drop in temperature...then what is the "force" behind the second contraction? What's compelling the liquid to draw in CO2, oxygen, or any other gasses if temp is no longer an issue? Does this "force" still exist if there's no available gasses? Thanks, this is interesting.

 

[mashdar]

If the main "force", or "reason" behind the first contraction is the drop in temperature...then what is the "force" behind the second contraction? What's compelling the liquid to draw in CO2, oxygen, or any other gasses if temp is no longer an issue? Does this "force" still exist if there's no available gasses? Thanks, this is interesting.

It's a bit of a tautology, but the lower temperature increases solubility of CO2 in water, decreasing vapor pressure for a given state, and decreasing the overall equilibrium point.

(edit: Think of the vapor pressure as how hard the gas is "pushing" to leave solution. Vapor prssure will match gas pressure at equilibrium.)

 

[MaxStout]

If the main "force", or "reason" behind the first contraction is the drop in temperature...then what is the "force" behind the second contraction? What's compelling the liquid to draw in CO2, oxygen, or any other gasses if temp is no longer an issue? Does this "force" still exist if there's no available gasses? Thanks, this is interesting.

It's simply diffusion of the gas into the liquid. It's gradual, as the pressure is lower.

Similar situation if you boil water, which drives off any dissolved O2. Let the water cool and atmospheric O2 will diffuse back in, something well-known to low-oxygen (LODO) brewers.

The surface area exposed will be a factor as to how quickly a gas will dissolve. The top surface of the beer in a fermenter is a fairly large area. A couple months of lagering and the dissolved CO2 level can become quite high--drawn from your CO2 reservoir.

Pressure is a big factor. That's why you can force-carbonate beer in a matter of hours if it's cold.

 

[VikeMan]

It seems as though the water portion has enough to seal the air out,

Unfortunately, water is permeable to oxygen. The O2 in the atmosphere seeks equilibrium with the O2 in the water, which in turn seeks equilibrium with O2 in the fermenter headspace.

 

[Red over White]

Any interest in a shitty CO2 generator? As in 2L soda bottle with water, sugar, bakers yeast, use some carbonation caps and bs to attach to your lid. Include a tee between your CO2 generator and your fermenter and have the third leg of that tee go into a small container of star san, this way you don't risk over pressurizing your fermenter.

This idea is a great work around.

 

[General Sterling Price]

It's simply diffusion of the gas into the liquid. It's gradual, as the pressure is lower.

Similar situation if you boil water, which drives off any dissolved O2. Let the water cool and atmospheric O2 will diffuse back in, something well-known to low-oxygen (LODO) brewers.

The surface area exposed will be a factor as to how quickly a gas will dissolve. The top surface of the beer in a fermenter is a fairly large area. A couple months of lagering and the dissolved CO2 level can become quite high--drawn from your CO2 reservoir.

Pressure is a big factor. That's why you can force-carbonate beer in a matter of hours if it's cold.

So....am I'm understanding this correctly, the effect is purely passive, in the sense that "no surface area or available gas = no suck back effect"? Like, there's nothing inherent in the liquid "drawing" matter into itself, but simply the gas molecules randomly being absorbed due to their activity (motion) of being a gas?

 

[tracer bullet]

"no surface area or available gas = no suck back effect

You're talking 2 different things.

If beer has no surface available to any CO2 or O2, true it wont' absorb those things.

Suck-back as discussed earlier is the beer cooling and literally shrinking, and creating a vacuum and / or headspace that wants to get filled up from the ambient air being at a higher pressure.

 

[General Sterling Price]

You're talking 2 different things.

If beer has no surface available to any CO2 or O2, true it wont' absorb those things.

Suck-back as discussed earlier is the beer cooling and literally shrinking, and creating a vacuum and / or headspace that wants to get filled up from the ambient air being at a higher pressure.

Thanks Tracer. I was referring to the "second" suck back effect that doug293cz mentioned......after the temperature drop.

​

 

[doug293cz]

Thanks Tracer. I was referring to the "second" suck back effect that doug293cz mentioned......after the temperature drop.

​

When the headspace CO2 pressure is in equilibrium with the carbonation level in the beer, CO2 is still being absorbed by the beer, and CO2 is still escaping from the beer into the headspace. Nothing changes because the rate of absorption is exactly equal to the rate of escape. When the temperature drops, the rates of absorption and escape both drop because the CO2 molecules are moving more slowly at lower temperatures (temperature is a measure of the kinetic energy of the molecules, and kinetic energy is equal to mass times the square of the velocity.) But, as the temperature drops, the rate of absorption drops faster than the rate of escape, and the rate of escape is proportional to the concentration of CO2 dissolved in the beer. So, for the headspace pressure to be in equilibrium with the carbonation level at the lower temperature, the concentration of CO2 in the beer has to increase to get the rate of escape to again be equal to the rate of absorption.

Brew on

 

[Brewer dad]

Unfortunately, water is permeable to oxygen. The O2 in the atmosphere seeks equilibrium with the O2 in the water, which in turn seeks equilibrium with O2 in the fermenter headspace.

Not quite OP but still I think relevant to discussion in re water permeability to oxygen. I do the FV connected to keg full of starsan to purge thing. I saw blowoff coming so took that line off keg and dropped it into bucket with water. From point above are you saying it could begin to absorb O2 through this eventually since it’s water?

At moment still bubbling a bit from residual pressure in FV but thinking more long term were it to sit a while.

 

[VikeMan]

Not quite OP but still I think relevant to discussion in re water permeability to oxygen. I do the FV connected to keg full of starsan to purge thing. I saw blowoff coming so took that line off keg and dropped it into bucket with water. From point above are you saying it could begin to absorb O2 through this eventually since it’s water?

I wouldn't really worry about it until the outflow of CO2 slows significantly. But yes, there will come a point where that flow isn't sufficient to prevent O2 that's leaving the water from diffusing up the blowoff hose. And then there's the permeability of the hose itself. I look at blowoff hoses as a sometimes necessary evil, but when I use them I switch over to a spunding valve as soon as practical.

 

[tracer bullet]

Agreed w/ the above. Yeah there are a ton of sources of O2. But the good news is that they are at a lot of different levels and so you can kind of rank them by importance. And take care of the lesser stuff over time.

Once upon a time I'd drain a fermenter sitting on a countertop into a keg below, I'd at least use a tube to be sure it reached inside, but after that it was splash city. And of course hop flavors never lasted and other flavors developed. Nowadays I also do the closed transfer to a purged keg, but still use silicone lines because it's only for a period of like 5 minutes. I also have a PET fermenter with stainless blow-off tubing, haha. I don't care to invest in SS fermenters and PET isn't too awful, but my silicone lines I used to use (and have a long length in place for a few weeks) almost certainly were.

Do what you can, when you can. Closed transfer is one of the biggest things, after that it's worth it to continue pursuing removing O2 ingress but certainly not as important. And don't forget your serving lines, and CO2 lines as well.

 

[AlcheMania]

Winemakers are subject to the same challenges of oxidation as brewers.
They use airlocks the same way we do....except (as I've now discovered) that they also use them to mitigate the potential for oxidation VIA suck back.

Info is scarce, but it seems that the colmatore style airlock is basically like a regular 3 piece (in functionality), except it has a reservoir below the "airlock" section, it's larger (around the size of a 2 liter pop bottle), reservoir can be filled VIA the large tube in the airlock portion, and the center piece (lock) can be readily removed for filling.

I finish at bout 12 psi before slow crash over 3 days and the 3rd day i connect to pressure. (I ferm in kegs) beer stays under co2 pressure thruought.

 

[MaxStout]

I should jump back in here to report how the Cold-Crash Guardian from Brew Hardware worked out for my recent lager.

I had 5.25 gallons of Baltic Porter in a 7 gallon Brew Bucket, so almost 2 gallons headspace. I was using the larger, 2.5 gallon Guardian. I attached the Guardian to the FV, with the output tube submerged into a small blowoff jar of StarSan. During active fermentation the bag swelled up and excess CO2 bubbled into the blowoff jar. Then I cold-crashed, dropping from upper 50s to mid 30s. The check valve worked perfectly--the blowoff StarSan didn't draw even an inch up the tubing. The bag contracted to about 1/4 of its original volume. Glad I opted for the big bag, as the 1 gallon bag wouldn't have been sufficient.

The Guardian worked great. I should buy a second one.

 

[JohnDBrewer]

I wouldn't really worry about it until the outflow of CO2 slows significantly. But yes, there will come a point where that flow isn't sufficient to prevent O2 that's leaving the water from diffusing up the blowoff hose. And then there's the permeability of the hose itself. I look at blowoff hoses as a sometimes necessary evil, but when I use them I switch over to a spunding valve as soon as practical.

Would using another liquid help with this? I've always used vodka, is alcohol better or worse, do you think?

 

[jerrylotto]

The rate of oxygen diffusion through water is less than 0.1 cm3/hr and that's assuming full and unrestricted exposure. I'm not going to obsess about that.

 

[VikeMan]

Would using another liquid help with this? I've always used vodka, is alcohol better or worse, do you think?

IIRC, oxygen is more soluble in ethanol than in water. If so, ethanol might pick up O2 from the air faster, but OTOH it would need to reach a higher level of O2 before gasing off into the blowoff tube. I suspect it would be pretty much a wash after some amount of time. But it's not something I've done any calculations on. And I'm thinking about it from a solubility perspective.

I bet @doug293cz would have some insight here.

 

[Ballaratguy]

IIRC, oxygen is more soluble in ethanol than in water. If so, ethanol might pick up O2 from the air faster, but OTOH it would need to reach a higher level of O2 before gasing off into the blowoff tube. I suspect it would be pretty much a wash after some amount of time. But it's not something I've done any calculations on. And I'm thinking about it from a solubility perspective.

I bet @doug293cz would have some insight here.

It’s pretty simple. Don’t let oxygen get to your fermented beer
I have typed up how to pressure ferment fill kegs from that and how to not get any oxygen in suck back from cold crash
If you can make beer maybe with a bit of thought you can work out how to do that because I’m not going to tell you
I worked out how to do it you should be able to work it out too

 

[VikeMan]

It’s pretty simple. Don’t let oxygen get to your fermented beer
I have typed up how to pressure ferment fill kegs from that and how to not get any oxygen in suck back from cold crash
If you can make beer maybe with a bit of thought you can work out how to do that because I’m not going to tell you
I worked out how to do it you should be able to work it out too

I don't know why you addressed that to me. I was simply responding to a question about O2 through water vs O2 through vodka. FWIW, I do know a bit about how to minimize O2 ingress. But assuming I didn't, why would you essentially say "I know all about O2 control, but I'm not going to share." I mean, why participate on the forum at all if that's the attitude?

 

[mashdar]

The rate of oxygen diffusion through water is less than 0.1 cm3/hr and that's assuming full and unrestricted exposure. I'm not going to obsess about that.

Surely the units should be in cm/hr/pa, and with asymptotic behavior? I don't think there is one value available.

edit: also, 0.1cm3/hr is 250ppb per day into 19L, so let's hope it's not that high : )