How big of a temperature swing will induce oxygen into S airlocks?

[Matteo57]

So I have some long term aging/souring beers going, and most have S Style Airlocks on them. Most of them are kept fairly stable temperatures, but I know that the S style will allow oxygen into the beer if the temperature swings are pretty high up and down. I'm sure people have measured this sort of thing somewhere but I couldn't find it. Anyone have that info handy at all? I have a few that aren't kept steady and am interested in this sort of thing for winter.
Thanks!

 

[davejanssen]

This is going to depend a lot on your specific conditions like how much headspace there is and how full the airlock is so I'm not sure that there is a set number out there that one could give. I also don't know how much you ought to worry about it. I wouldn't be too concerned about it. If you were really worried about O2 pickup, the S type airlocks make a worse seal with the bung because of the way they are molded. Better bottle did a study about different closures on carboys and they demonstrated that. I imagine if the beer is in a carboy for a year or so that worse seal would allow in a comparable amount of O2 to some air being sucked in on cold nights, if not more.

If you really wanted to prevent that you could get a solid bung for the winter time once you know the beers are not active. Or one of those one way breathable silicone stoppers (but silicone is also quite O2 permeable).

 

[dantheman13]

I've resolved the issue for myself by using Better Bottles with their $50 Dry Tap airlocks. Expensive, but I've had too many oxidation issues in the past due to dry air locks, vacuum suckage, rubber bungs popping off from pressure, etc. So far I think the investment is worth it.

 

[Matteo57]

This is going to depend a lot on your specific conditions like how much headspace there is and how full the airlock is so I'm not sure that there is a set number out there that one could give. I also don't know how much you ought to worry about it. I wouldn't be too concerned about it. If you were really worried about O2 pickup, the S type airlocks make a worse seal with the bung because of the way they are molded. Better bottle did a study about different closures on carboys and they demonstrated that. I imagine if the beer is in a carboy for a year or so that worse seal would allow in a comparable amount of O2 to some air being sucked in on cold nights, if not more.

If you really wanted to prevent that you could get a solid bung for the winter time once you know the beers are not active. Or one of those one way breathable silicone stoppers (but silicone is also quite O2 permeable).

The issue with the solid bungs is that with a sour, it takes a long time for all activity to really cease. So I'm not sure that's really the way to go on a sour.
I know what you are talking about with the S style airlocks, some seem worse than others also. Some I have to almost push all the way down so the "ball" part at the bottom really sticks right into the top of the rubber stopper. Almost feel like a bit of glue around it would be best for a long term project on those... Superglue!

 

[Matteo57]

I've resolved the issue for myself by using Better Bottles with their $50 Dry Tap airlocks. Expensive, but I've had too many oxidation issues in the past due to dry air locks, vacuum suckage, rubber bungs popping off from pressure, etc. So far I think the investment is worth it.

what's the difference on that one compaired to something like a silicone stopper like this?
http://morebeer.com/products/silico...fMLTj8DzdVgpwcGKfTIH0zZJO-21f1duFwaAsVw8P8HAQ

 

[davejanssen]

The issue with the solid bungs is that with a sour, it takes a long time for all activity to really cease. So I'm not sure that's really the way to go on a sour.
I know what you are talking about with the S style airlocks, some seem worse than others also. Some I have to almost push all the way down so the "ball" part at the bottom really sticks right into the top of the rubber stopper. Almost feel like a bit of glue around it would be best for a long term project on those... Superglue!

Yeah, I know with sours that there is still activity for a while, but the active CO2 evolution is pretty minor after a few months. Many producers who are fermenting in barrels solid bung their barrels pretty early on. And I know a barrel will breath more than a carboy but I'm not sure pressure will really build up that much. If you are worried about air suck back in winter and pressure in summer then you could solid bung in winter (when the temp drop would overwhelm any CO2 evolution) and switch to an airlock as it starts to warm in spring/summer, with CO2 purging whenever you switch out.

The silicone stoppers you mention will breath a fair bit because of the O2 permeability of silicone. I would stick with the airlock and make sure it doesn't run dry but deal with any minor air suck back.

 

[davejanssen]

Here is that better bottle study about different closure types that I mentioned:

http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf

 

[dantheman13]

what's the difference on that one compaired to something like a silicone stopper like this?
http://morebeer.com/products/silico...fMLTj8DzdVgpwcGKfTIH0zZJO-21f1duFwaAsVw8P8HAQ

Silicone is very permeable to oxygen. It's one of the reasons they use that material for contact lenses. There have been a couple of studies that show this:

http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf

(Out of "Wild Brews" by Jeff Sparrows): https://www.homebrewtalk.com/attach...pellicle-photo-collection-image-521505612.jpg

 

[Matteo57]

Silicone is very permeable to oxygen. It's one of the reasons they use that material for contact lenses. There have been a couple of studies that show this:

http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf

(Out of "Wild Brews" by Jeff Sparrows): https://www.homebrewtalk.com/attach...pellicle-photo-collection-image-521505612.jpg

Cool, thanks for the articles! I'll check them out!

 

[TNGabe]

If the s-style airlock isn't overly full, it won't suck back in. Problem solved. You will have to have to check more often to make sure it hasn't gone dry. I prefer to use 3 piece, but have a ton of s-style and use those as well.

$50 airlock looks like a waste of money to me.

 

[dantheman13]

If the s-style airlock isn't overly full, it won't suck back in. Problem solved. You will have to have to check more often to make sure it hasn't gone dry. I prefer to use 3 piece, but have a ton of s-style and use those as well.

$50 airlock looks like a waste of money to me.

It still sucks back air. I don't think that the air would be sanitized as it bubbles through the airlock water/vodka. Is the cap on the airlock fine enough to filter any dust?

 

[davejanssen]

It still sucks back air. I don't think that the air would be sanitized as it bubbles through the airlock water/vodka. Is the cap on the airlock fine enough to filter any dust?

I don't think you need to worry about the sanitary characteristics of the air bubbling in. You're right, the cap is not a sanitary filter. But most of the dust would likely be scrubbed out/stick to one of the many wet surfaces in the process of getting through the holes, passing along a damp tube, bubbling through liquid, changing direction and passing through another damp tube and then changing direction again and passing through a damp tube before making it into your beer. At this point the beer has ethanol, a low pH, no simple sugars, and much higher cell counts of other stuff so anything that makes it through all of that is going into a pretty hostile environment.

 

[dantheman13]

I don't think you need to worry about the sanitary characteristics of the air bubbling in. You're right, the cap is not a sanitary filter. But most of the dust would likely be scrubbed out/stick to one of the many wet surfaces in the process of getting through the holes, passing along a damp tube, bubbling through liquid, changing direction and passing through another damp tube and then changing direction again and passing through a damp tube before making it into your beer. At this point the beer has ethanol, a low pH, no simple sugars, and much higher cell counts of other stuff so anything that makes it through all of that is going into a pretty hostile environment.

Yeah, I think you are right. It seems like a lot of people are able to age their sours with water airlocks without getting Acetobacter infections, so it must be relatively low risk. The air suck back and high levels of ethyl acetate are my main concern. Commercial breweries usually temperature control their barrel rooms (not always), which alleviates this concern for them, but I don't have that luxury! For me, the $50 investment is worth it, even though I don't really know if I am getting less air suck back (they also let in some air according to the BB study).

 

[TNGabe]

It still sucks back air. I don't think that the air would be sanitized as it bubbles through the airlock water/vodka. Is the cap on the airlock fine enough to filter any dust?

Whoops. I thought OP was worried about the airlock liquid sucking back into the beer.

You really don't need to worry about any sort of contamination via the airlock due to temp change. Or oxidization. Unless you are using inert gas or a parastaltic pump to move your beer and counterpressure filling bottles that have been flushed with CO2, you'll be introducing a lot more oxygen elsewhere in your process.

 

[TAK]

I know Jamil suggests embracing O2 permeability (and really O2 suck-back would be covered too) to emulate the permeability of a barrel when glass is being used instead. However, the major factor is the amount of headspace in the carboy. He recommends filling the carboy all the way up to the narrow neck. When the headspace is very small, like single digit cubic inches, then the amount of O2 that will be in the headspace and the surface area of exposed beer, just a few square inches, is an acceptable amount that is close to the same pick-up you could expect from a large barrel. On the other hand, if you have the typical amount of headspace, or probably even a quart of headspace, then that's a different ball game and prevention/mitigation needs to be considered.

 

[bd2xu]

$50 for an airlock??? I use better bottles, these airlocks cost more than their fermenters? Wow.



Primary: Maibock, Helles (first partigyle batch)
Secondary: Mojave Red, Irish Stout
On tap: Orange Belgian IPA, Turbo IIPA
Bottled: Dwarven Gold Ale, La Fin Du Mond clone, Hefeweizen

 

[dantheman13]

I know Jamil suggests embracing O2 permeability (and really O2 suck-back would be covered too) to emulate the permeability of a barrel when glass is being used instead. However, the major factor is the amount of headspace in the carboy. He recommends filling the carboy all the way up to the narrow neck. When the headspace is very small, like single digit cubic inches, then the amount of O2 that will be in the headspace and the surface area of exposed beer, just a few square inches, is an acceptable amount that is close to the same pick-up you could expect from a large barrel. On the other hand, if you have the typical amount of headspace, or probably even a quart of headspace, then that's a different ball game and prevention/mitigation needs to be considered.

Yeah, I've never really adopted his opinion on this one. While it is a viable way of doing it, it certainly isn't "the best" way. I think a lot of what he based this on is from Raj Apte's studies (Raj was trying to identify the exact level of micro-oxygenation in barrels, and reproduce it in carboys). That said, Michael Tonsmeire and many others have had great success by not filling all the way to the neck and using simple airlocks. Those orange carboy caps just seem way too leaky to me.

We know that Brettanomyces metabolizes oxygen, and the level of micro-oxygenation that barrels provide usually (not always) produces good results. We know that too much oxygen exposure creates acetic acid and ethyl acetate. But what about really low levels of O2? I've asked this question on several forums and haven't gotten a good answer. We know that Brett can produce more funky flavors when under pressure in a keg or a bottle... so does the "perfect" amount of oxygen exposure really exist? Hell, is any oxygen really needed? I am skeptical that there is a necessary level of micro-oxygenation. My approach is to limit the micro-oxygenation as much as possible so as to avoid acetic acid. Besides, as someone else pointed out, any kind of sampling introduces a lot more oxygen into the fermenter than the type of airlock used (that doesn't excuse using a leaky airlock system though).

In other words, I am much more concerned about keeping oxygen out than letting in the right amount.

 

[TAK]

I totally get it. You're right, he does suggest those leaky orange carboy caps. I am very near my first souring adventure, and I don't think I'll be using those. I plan on filling to the neck to reduce headspace and surface area, but using a stopper and liquid airlock.

 

[dantheman13]

I totally get it. You're right, he does suggest those leaky orange carboy caps. I am very near my first souring adventure, and I don't think I'll be using those. I plan on filling to the neck to reduce headspace and surface area, but using a stopper and liquid airlock.

I would use a rubber stopper too, but I had one pop off once. I was lucky enough to be standing in the same room when it happened or I may not have noticed for a long time! Unfortunately sours can keep producing CO2 for an unknown time.

 

[Matteo57]

I would use a rubber stopper too, but I had one pop off once. I was lucky enough to be standing in the same room when it happened or I may not have noticed for a long time! Unfortunately sours can keep producing CO2 for an unknown time.

Exactly! I would use a rubber stopper but I don't want to have it pop off when I'm not looking and not notice it for awhile!

 

[Matteo57]

Whoops. I thought OP was worried about the airlock liquid sucking back into the beer.

You really don't need to worry about any sort of contamination via the airlock due to temp change. Or oxidization. Unless you are using inert gas or a parastaltic pump to move your beer and counterpressure filling bottles that have been flushed with CO2, you'll be introducing a lot more oxygen elsewhere in your process.

No, I forget where I read it, I just read that if you have constant fluctuations in temperature change that an S airlock could get air, and thus oxygen suck back, and I wanted to know how big of a temperature swing would be needed to create the suck back. which I don't think anyone has yet answered but I doubt it's really a set number, probably a lot of factors in play.

Thanks all for y'alls info

 

[kh54s10]

No, I forget where I read it, I just read that if you have constant fluctuations in temperature change that an S airlock could get air, and thus oxygen suck back, and I wanted to know how big of a temperature swing would be needed to create the suck back. which I don't think anyone has yet answered but I doubt it's really a set number, probably a lot of factors in play.

Thanks all for y'alls info

In thinking more about this I doubt you can get a true "number". It would depend on the activity of the beer, how much co2 is being produced. The amount of liquid in the airlock would have a small effect on how much pressure can build up in the carboy. So it may have enough pressure that it would take a lot to flow backward, or if all activity is done and the internal pressure is low it might not take much to reverse the flow.

 

[davejanssen]

No, I forget where I read it, I just read that if you have constant fluctuations in temperature change that an S airlock could get air, and thus oxygen suck back, and I wanted to know how big of a temperature swing would be needed to create the suck back. which I don't think anyone has yet answered but I doubt it's really a set number, probably a lot of factors in play.

Thanks all for y'alls info

You're right, there is no set number. Water doesn't contract and expand very much with temperature compared to air so if you want to minimize the airlock suck back fill your carboys all the way to the top.

 

[dantheman13]

I get suck back in my fermenter room, which has a swing of about 5-8 degrees F.

 

[Singletrack]

OP, I calculate that a temperature change of about 2 F will cause a bubble of air to get through the air lock. I assumed the distance from the water surface in the airlock to the U-trap is 1-1/2". Close?

This 2 degree temperature change is not the ambient (room) temp change, and it is not the beer temp change, it is the change in temperature of the headspace air. The changes in headspace temp would be expected to lag any room temperature changes due to the thermal mass of the beer/carboy.

The amount of carboy head space has almost no impact on the temperature required to cause a bubble. However, if you have a very small head space, you will have a very small volume of air moving through the airlock when the temp swings 2 degrees. If you have a large head space, you will have a larger volume of air bubbling through.