Purging headspace when bottling

[McKnuckle]

Linked below is a pretty revealing scientific article which discusses the erroneous perception that CO2 sinks. Worth at least a partial read for those so inclined. Bottom line is that CO2 does not sink, but the variables related to gas mixing and stratification are complex - moreso than anyone typically addresses here on the forum. Very interesting.

THE LEGEND OF CARBON DIOXIDE HEAVINESS
https://caves.org/pub/journal/PDF/v71/cave-71-01-100.pdf

 

[Vale71]

It is basic buoyancy and denser items, fluids or solids, sink in comparatively less dense fluids, and, yes, if they're fluid they'll likely, with few exceptions, eventually mix, which is something I've been saying all along, but TEMPORARILY they don't and if you don't WANT to understand, that only affects you, not reality.

Okay, I'll bite. You say they TEMPORARILY don't mix. For how long? What is the event or condition that makes them suddenly start mixing? Is it a fixed amount of time? Can you control that behaviour at all?

 

[bu_gee]

Okay, I'll bite. You say they TEMPORARILY don't mix. For how long? What is the event or condition that makes them suddenly start mixing? Is it a fixed amount of time? Can you control that behaviour at all?

Now that is a complicated subject. Diffusion rates are dependent on a number of factors including density, kinetic energy, molecular "compatibility" (analog to oil and water), etc.

Look, the CO2 once poured from that guy's bottle is probably too diffuse to do what it did to the candle in just a few seconds or another 4 inches and probably undetectably diffused into the room within a minute. This I just a sense of how I've seen it behave, not actual math, well, because I don't hate myself that much.

 

[Taket_al_Tauro]

I'm unsure how reputable a source Wikipedia is, but how would one explain the Lake Nyos dysaster?

If it is false that CO2 at least TEMPORARILY sinks because it is heavier, then did this happen just because of the sheer amount of CO2 released all of a sudden by the eruption?
So in this case, the CO2 diffused rather than sinked onto nearby villages and its concentration increased to a level high enough to kill that many people and animals?

From Wikipedia:
"

On 21 August 1986, a limnic eruption at Lake Nyos in northwestern Cameroon killed 1,746 people and 3,500 livestock.

The eruption triggered the sudden release of about 100,000–300,000 tons (1.6 million tons, according to some sources) of carbon dioxide (CO
2).[1][2] The gas cloud initially rose at nearly 100 kilometres per hour (62 mph) and then, being heavier than air, descended onto nearby villages, displacing all the air and suffocating people and livestock within 25 kilometres (16 mi) of the lake.[3][4]

"

 

[Beermeister32]

I believe natural gas also exhibits the same behavior. When a stove is valve is left on there is a temporary stratification of the air favoring the natural gas more towards the floor. Temporarily of course!

 

[Vale71]

I'm unsure how reputable a source Wikipedia is, but how would one explain the Lake Nyos dysaster?

If it is false that CO2 at least TEMPORARILY sinks because it is heavier, then did this happen just because of the sheer amount of CO2 released all of a sudden by the eruption?
So in this case, the CO2 diffused rather than sinked onto nearby villages and its concentration increased to a level high enough to kill that many people and animals?

From Wikipedia:
"

On 21 August 1986, a limnic eruption at Lake Nyos in northwestern Cameroon killed 1,746 people and 3,500 livestock.

The eruption triggered the sudden release of about 100,000–300,000 tons (1.6 million tons, according to some sources) of carbon dioxide (CO
2).[1][2] The gas cloud initially rose at nearly 100 kilometres per hour (62 mph) and then, being heavier than air, descended onto nearby villages, displacing all the air and suffocating people and livestock within 25 kilometres (16 mi) of the lake.[3][4]

"

That description of the phenomenon is rife with inaccuracies. Yes, if a huge amount of CO2 is released it will diffuse in all directions, including into the valleys. There it will not displace "all the air" neither does it need to do so as CO2 concentrations as low as 10% can already be deadly due to CO2's inherent toxicity. Valleys are usually hit the heaviest because they are more protected from air currents than an open plain, so it can take quite a long time for CO2 to dissipate mostly through gas diffusion. Since CO2's toxicity is the combined effect of exposure level and exposure duration valleys unfortunately are were you'll find most of the fatalities. There is no need to postulate the existence of "CO2 rivers" to explain this tragic phenomenon.

 

[bu_gee]

I'm unsure how reputable a source Wikipedia is, but how would one explain the Lake Nyos dysaster?

If it is false that CO2 at least TEMPORARILY sinks because it is heavier, then did this happen just because of the sheer amount of CO2 released all of a sudden by the eruption?
So in this case, the CO2 diffused rather than sinked onto nearby villages and its concentration increased to a level high enough to kill that many people and animals?

From Wikipedia:
"

On 21 August 1986, a limnic eruption at Lake Nyos in northwestern Cameroon killed 1,746 people and 3,500 livestock.

The eruption triggered the sudden release of about 100,000–300,000 tons (1.6 million tons, according to some sources) of carbon dioxide (CO
2).[1][2] The gas cloud initially rose at nearly 100 kilometres per hour (62 mph) and then, being heavier than air, descended onto nearby villages, displacing all the air and suffocating people and livestock within 25 kilometres (16 mi) of the lake.[3][4]

"

This goes back to it being a very complicated intersection of fluid dynamics and biology, which is pretty much what this entire thread is.

Volcanic eruptions also add into the mix particles which drag gases down along with them. If we can't control a small amount of CO2 in a bottle, I think a volcano is going to be well out of our grasp.

Edit: I should have said "describe" instead of "control."

 

[InspectorJon]

I'm pretty sure natural gas is lighter than air and rises. Propane is heavier and sinks. I think I lost track of what we are debating here. Didn't it have something to do with head space in beer bottles? I see the OP has left the room.

 

[bu_gee]

Okay, I'll bite. You say they TEMPORARILY don't mix. For how long? What is the event or condition that makes them suddenly start mixing? Is it a fixed amount of time? Can you control that behaviour at all?

Now I see the problem, you think by "temporary" I meant that it doesn't mix for a while and then suddenly it all mixes. That is not what I intended to imply and I apologize for my poor choice of words which I will admit were imprecise due to convenience.

What I meant by this is that the diffusion rates are slow enough that localized pockets of gases can have effects that approximate gases not being mixed for a short duration of time while the diffusion processes do their work.

Now, with that being said, what are the most precise 1-3 words to describe this?

 

[Vale71]

Now I see the problem, you think I meant that it doesn't mix for a while and then suddenly it all mixes. That is not what I intended to imply and I apologize for my poor choice of words which I will admit were imprecise due to convenience.

What I meant by this is that the diffusion rates are slow enough that localized pockets of gases can have effects that approximate gases not being mixed for a short duration of time while the diffusion processes do their work.

Now, with that being said, what are the most precise 1-3 words to describe this?

The whole point of the discussion is that you cannot really displace air through CO2 unless it's a closed container and you perform a complicated series of evacuation cycles. CO2 released in an open container, be it released by the beer itself through outgassing or via a short burst from a gas cylinder will immediately start mixing with the extant atmosphere. No actual displacement takes place, there will just be a continuous gradient in the composition of the gas mix. What this means in the specific case at hand (bottling beer with as little O2 as possible) is that all you will achieve is a (possibly significant) reduction of the amount of O2 but any belief that CO2 will completely replace the air in the headspace is unfounded.

 

[InspectorJon]

I'm kind of afraid to ask this question as it may start a whole new round of...discussion. Does the rate of dilution/mixing with the air in the room have any relationship to the size of the opening at the top of the container? If I quickly open my fermentor with a small opening in the top to drop in some hops and seal it back up how much air is going to mix with the Co2 in the container?

 

[Beermeister32]

Another interesting experiment you can do which visually shows this is throwing a chunk of dry ice into a 5 gallon bucket with some warm water inside, and set it on the floor. The gas visually pours out the top of the bucket and down the sides and settles to the floor below. Then it would diffuse into the room air.

Which might suggest temporary gas "clouding" would be beneficial to some operations, acknowledging it is temporary until it blends with the surrounding air.

 

[bu_gee]

Another interesting experiment you can do which visually shows this is throwing a chunk of dry ice into a 5 gallon bucket with some warm water inside, and set it on the floor. The gas visually pours out the top of the bucket and down the sides and settles to the floor below. Then it would diffuse into the room air.

Which might suggest temporary gas "clouding" would be beneficial to some operations, acknowledging it is temporary until it blends with the surrounding air.

If I'm not mistaken, in that experiment the clouds are actually water vapor clouds, just like in the sky. While vapor is technically not a gas, in this case the droplets are so small that they effectively behave like heavy gas "particles.". There is probably a better word for that, but I can't come up with it at the moment.

Eventually the droplets will get bigger and settle or evaporate into the air.

 

[Taket_al_Tauro]

If I quickly open my fermentor with a small opening in the top to drop in some hops and seal it back up how much air is going to mix with the Co2 in the container?

The opening, yes the opening! It is our last resort when all blankets fail. Glad I changed from buckets to Speidels some time ago. But I'm not ready to go the "stainless + crazy O2 free dry hopping contraption " route yet.

 

[bu_gee]

I'm kind of afraid to ask this question as it may start a whole new round of...discussion. Does the rate of dilution/mixing with the air in the room have any relationship to the size of the opening at the top of the container? If I quickly open my fermentor with a small opening in the top to drop in some hops and seal it back up how much air is going to mix with the Co2 in the container?

A lot, but natural diffusion wouldn't be your biggest problem here. Falling objects can drag a significant amount of air along with them. But that also depends on your definition of significant. For most brewing purposes and for most people, I would venture that this is an acceptable amount of O2.

Edit: NATURAL diffusion.

 

[InspectorJon]

A lot.

Darn, I wish he had said "a little". These words are so imprecise. So how much is "a lot" and how do we decide when "a lot" is "too much"? Will putting "some" co2 into the beer below the head space of a bottle and creating co2 bubbles we cap on top of help a little or a lot?

 

[Vale71]

If I'm not mistaken, in that experiment the clouds are actually water vapor clouds, just like in the sky. While vapor is technically not a gas, in this case the droplets are so small that they effectively behave like heavy gas "particles.". There is probably a better word for that, but I can't come up with it at the moment.

Eventually the droplets will get bigger and settle or evaporate into the air.

Vapor technically is a gas (it's the gas phase of H2O) and it's invisible. It's a good thing because it's all around us mixed into the atmosphere.

What you see coming out of this type of fog machine is condensed vapor which is nothing but plain old water. Being a liquid the droplets will drop (nomen omen) to the floor, albeit very slowly because of aerodinamic drag and possibly partly evaporating again on the way down. Convection is also involved as dry ice will create a convective cell due do it constantly absorbing heat from the atmosphere in order to sublimate to CO2 gas. The droplets evaporating also will power the convective cell as they too need heat to become vapor again and this will keep cooling the air further.

 

[Cloud Surfer]

I pressure transfer out of my stainless conical fermenter into a keg that’s been CO2 purged and pre-filled with the priming sugar.

I then use a bottling gun. The gun has a liquid line and a CO2 line. I put the gun in the bottle and pull the CO2 trigger to fill the bottle with CO2 then pull the liquid trigger and fill the bottle to overflowing. I cap immediately. This is about as oxygen free as I can get it on a home brew scale.

When I used to use the bottling bucket I was always worried about oxidation and infection in an open system, and felt like I had to work as fast as I could to get beer into bottle. The whole bottling process is so calm now.

 

[day_trippr]

fwiw, molecular motion alone diffuses gases...

 

[Vale71]

I pressure transfer out of my stainless conical fermenter into a keg that’s been CO2 purged and pre-filled with the priming sugar.

I then use a bottling gun. The gun has a liquid line and a CO2 line. I put the gun in the bottle and pull the CO2 trigger to fill the bottle with CO2 then pull the liquid trigger and fill the bottle to overflowing. I cap immediately. This is about as oxygen free as I can get it on a home brew scale.

When I used to use the bottling bucket I was always worried about oxidation and infection in an open system, and felt like I had to work as fast as I could to get beer into bottle. The whole bottling process is so calm now.

Counterpressure filling with actual evacuation and purging is possible at the homebrew level too, so what you're doing is only the next best thing. Your belief that you're actually filling the bottle with CO2 is incorrect which is the whole point of the lengthy discussion we've been having. Not only is the CO2 mixing with air, but as you calmly fill your bottles atmospheric oxygen is also calmly diffusing back into the bottle (which is still a completely open system) and into the beer.

 

[Vale71]

fwiw, molecular motion alone diffuses gases...

Damn you, emergent behaviour!!

 

[connell89]

You are all hurting my head and making homebrewing why to complicated. Purge the bottles with CO2, fill with beer and cap. Drink before oxidation sets in. But I think somewhere in the first 10 posts, your question was answered. No, don't leave the caps on loose or try it and see what happens.

 

[doug293cz]

Thread locked for cooling down period, and clean up.

doug293cz
HBT Moderator

 

[doug293cz]

Thread is reopened. Stay on topic, and don't get personal.

doug293cz

 

[Snuffy]

The best solution would be to create a sealed environment totally filled with carbon dioxide, enter it via a vacuum portal in an astronaut suit and then bottle away with no worries.

 

[Birrofilo]

The best solution would be to create a sealed environment totally filled with carbon dioxide, enter it via a vacuum portal in an astronaut suit and then bottle away with no worries.

In hospitals they have oxygen tents. A CO2 tent could be devised.
Instead of an astronaut suit, a diver setup could be used. You need no wetsuit and fins, only the respirator.
The thing is more feasible than at first thought.
Actually I wouldn't be surprised if anybody did anything like that
Problem I see is the cost of the CO2.

 

[Miraculix]

I pressure transfer out of my stainless conical fermenter into a keg that’s been CO2 purged and pre-filled with the priming sugar.

I then use a bottling gun. The gun has a liquid line and a CO2 line. I put the gun in the bottle and pull the CO2 trigger to fill the bottle with CO2 then pull the liquid trigger and fill the bottle to overflowing. I cap immediately. This is about as oxygen free as I can get it on a home brew scale.

When I used to use the bottling bucket I was always worried about oxidation and infection in an open system, and felt like I had to work as fast as I could to get beer into bottle. The whole bottling process is so calm now.

If you can, don't purge the bottles, but create foam with your co2 once the bottles are filled and immediately cap directly on the co2 foam. This is the only way how you get almost no O2 trapped in the bottle. Vale71 already explained why purging does not work, capping on co2 foam ensures minimum oxygen in the bottle.

 

[Birrofilo]

Is it possible to purge the headspace with the CO2 from the beer? My idea is to fill the bottles and leave the caps on loosely for a period of time (a few hours?) and returning later to cap? The infection risk is obviously present but I think it's small.

Purging is certainly possible as you will see in the thread and pictures in the threads which was quoted in text #11 of this thread, which I consider a very interesting reading for all brewers.

Regarding going away for a few hours, I don't think it would work because the bottle is opened and the diffusion will prevail. Just purge the neck of the bottle and cap immediately.

This text, from the blog of Columbia University, explains how in a confined environment the CO2 gas molecules tend to stratify over the wine, while in an open bottle diffusion will make your gases escape outside of the bottle neck

https://blogs.ei.columbia.edu/2020/09/23/carbon-dioxide-distribution-atmosphere/
Stratification of heavy gases (gases with a high molecular weights) is a well-known concept and is the object of regulation on labour safety and other safety compulsory measures, regarding CO2, propane, butane and other heavy gases. People die because of stratification of gases!

Those who want more information can search for norms and guidelines about work into silos for grain stockage, or norms about underground parking places and LPG vehicles.

 

[BrewnWKopperKat]

back to the original question.

Any thoughts? If anyone has some any other ideas I'm all ears

FWIW, these two topics offer approaches that result in bottles that are good for 40+ days.

https://www.homebrewtalk.com/thread...le-conditioned-ipa.653784/page-6#post-8877059

https://www.homebrewtalk.com/thread...n-and-alternatives.686774/page-2#post-9054118

eta: I will not be suprised to see "rebuttal" posts (with regard to the processes in those topcis) in 45 to 90 days. Better beer can be made when processes are "put to the test".

 

[Snuffy]

In hospitals they have oxygen tents. A CO2 tent could be devised.
Instead of an astronaut suit, a diver setup could be used. You need no wetsuit and fins, only the respirator.
The thing is more feasible than at first thought.
Actually I wouldn't be surprised if anybody did anything like that
Problem I see is the cost of the CO2.

Or one of those hazardous materials rigs with the plastic arm gloves. That would minimize the volume and require less CO2 and no breathing apparatus.https://i.pinimg.com/originals/82/ba/60/82ba606cc57683cad31c8e72cfaca929.jpg