Author Topic: Using collapsable bags to displace o2 during racking/packaging  (Read 2615 times)

Offline ynotbrusum

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #15 on: June 13, 2021, 01:41:28 pm »
I routinely stack up my clean kegs and use the fermenter CO2 to push sanitizer out of the first filled keg to a bucket and then pour into the next keg filling it and repeat.  You can also daisy chain them to go with multiple kegs for one fermentation, dropping them out as they become empty.  Easy use of CO2 and not wasting it - you could put the airbag in the first spot in line and give it a try.
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Offline RC

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #16 on: June 13, 2021, 06:12:09 pm »
This is a great idea, and I love the idea of capturing and re-using the CO2 from fermentation.

That said, I do wonder how much O2 is ingressing during an open transfer from fermenter to keg, which is what I do. I use a siphon starter, and the hose is attached to the beer-out connector on closed, purged keg, which is filled until beer spills out of the opened PRV. There's always at least 1/2 gallon of beer left behind in the fermenter (a 7-gal Fermonster), usually it's ~3/4 gal.

Oxygen is not very soluble in liquid. In the 15-ish minutes it takes to fill my keg, I doubt enough oxygen has dissolved in the beer to the point where it has seeped below the top ~1 inch of beer in the fermenter. IOW, I doubt that the beer that actually gets into the keg has any oxygen in it due to the open transfer.

My doubts can be easily dispelled by data on oxygen ingress from open transfer, if anyone has any. Otherwise we're all just speculating, and I'll choose doing nothing (i.e. the KISS principle) over doing something if I can get away with it, which so far I have been able to.

Offline majorvices

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #17 on: June 14, 2021, 07:16:29 am »
I agree, it may be overkill. Without any actual testing it is impossible to know if there is any effect of the final DO levels. And this method might be impossible to do with an auto-siphon.

I have been bottle conditioning most of my homebrews for the last couple of months and I am not purging the bottles before filling and I have to admit they are turning out pretty great (for me). And the ones I put in kegs with autosiphon turned out pretty great (for me) as well. So who knows? I may try to test it with a DO meter here in the next couple of months just for grins. It makes me feel better and, since I am lazy, it allows me to harvest the yeast at a later date since I don't feel there is any risk of added infection with my "kitchen air". Two great danes and a crazy cat -- not the cleanest home ever. ;)

« Last Edit: June 14, 2021, 07:28:33 am by majorvices »

Offline neuse

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #18 on: June 14, 2021, 10:02:38 am »
I think a big factor is how long the bottles or keg sit before drinking them. I don't purge my bottles with CO2, but for the last couple of years I've been planning brew days so that I can start drinking a batch when it is carb'd up, rather than brewing ahead. It seems to help a lot in terms of hop aroma. That might be why experiences differ for different brewers. I like a low tech solution.

Offline majorvices

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #19 on: June 14, 2021, 10:15:04 am »
With hop aroma fresher is always better. And oxidation is a big enemy if you are trying to retain those aromas. I have mostly been brewing German lagers and English style ales at home. Regardless, I think this would work extremely well for hoppy beers. And ... uhm, this is an extremely low tech solutions.  It's a collapsable plastic bag. ;)

Offline RC

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #20 on: June 14, 2021, 06:30:14 pm »
I agree, it may be overkill. Without any actual testing it is impossible to know if there is any effect of the final DO levels. And this method might be impossible to do with an auto-siphon.
I may try to test it with a DO meter here in the next couple of months just for grins. It makes me feel better and, since I am lazy, it allows me to harvest the yeast at a later date since I don't feel there is any risk of added infection with my "kitchen air". Two great danes and a crazy cat -- not the cleanest home ever. ;)

Outside air, specifically "garage air", is permanently in my fermenters until I fill them with wort. Unless you're in a clean room at NASA, IMHO worrying about outside air is probably not all that useful. But your point is taken, especially vis-a-vis harvesting at a later time. Probably a good idea to keep great dane slobber out of your harvests :-[.

One thing I wonder: if you test DO or TPO and get a very low reading, how do you know it's due to having very low ingress vs. having lots of ingress but all the O2 reacted with stuff already? Where I worked, we had temporary access to a very fancy, very expensive industrial-brewing DO meter, and it read below the machine's resolution of 13 ppb for the three batches we were able to test. Great! But this low is virtually impossible to achieve at any scale. Was this due to us being amazing brewers (answer: absolutely, definitely NOT), or was there a lot of ingress but all the O2 already reacted with stuff, which gave us that low reading?

Offline majorvices

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #21 on: June 14, 2021, 07:20:58 pm »
Were you using any oxygen scavenging ingredients like metabisulphite in the BT? We used "Beer Protect" (from Erbslöh) for a while and it brought our DO levels to ridiculously low levels. Also if it wasn't calibrated correctly (using a Beverly) then the levels were never correct.

Also my wife worked for Nasa for a few years. And I know some people who work for Nasa and Boeing. So clean room ... maybe!
« Last Edit: June 14, 2021, 07:29:05 pm by majorvices »

Offline RC

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #22 on: June 14, 2021, 07:34:52 pm »
Didn't use any scavenging ingredients. It was several years ago, but the brand name of Beverly sounds correct. We had the rep there at the time, that's how we "borrowed" it...the darn thing better have been calibrated correctly, since the rep was right there watching me!

Very cool that your better half worked at NASA, btw...

Offline majorvices

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #23 on: June 14, 2021, 07:47:08 pm »
There are 2 ways to calibrate it. It will give you decent results PPM calibrating with just Co2, like off a tank. But if you want PPB you have to use the calibration gas. Took me a while to figure that out because we had stupid low levels that were unrealistic. Also wasn't cheap, I believe it was about $600 for the calibration gases.
« Last Edit: June 14, 2021, 07:49:30 pm by majorvices »

Offline RC

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #24 on: June 14, 2021, 08:44:25 pm »
There are 2 ways to calibrate it. It will give you decent results PPM calibrating with just Co2, like off a tank. But if you want PPB you have to use the calibration gas. Took me a while to figure that out because we had stupid low levels that were unrealistic. Also wasn't cheap, I believe it was about $600 for the calibration gases.

Never heard of calibration gas. But yeah I thought our levels were too low to be realistic...

Anyway, my overarching point is that I think we homebrewers can get away with a lot more than we think we can, whether it comes to pitch rate, or DO, or mash temp, or cleaning/sanitizing, or...(fill in the blank)...

Of course, not having the pressure to sell our beer is a huge plus.

Offline Visor

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #25 on: June 16, 2021, 04:14:14 pm »
I think a big factor is how long the bottles or keg sit before drinking them. I don't purge my bottles with CO2, but for the last couple of years I've been planning brew days so that I can start drinking a batch when it is carb'd up, rather than brewing ahead. It seems to help a lot in terms of hop aroma. That might be why experiences differ for different brewers. I like a low tech solution.

   I've never messed with the hassle of purging bottles, I figure the beer pushes the air out as it fills and what little mixing that does take place with the tiny surface area in a bottle during the 5 or 10 seconds it takes to fill can't be adding any consequential amount of DO, and bottle conditioning should clean most of that up. I'll admit that my sense of taste isn't world class, but I don't have many batches that start tasting stale prematurely, and most of the ones that do seem to be Lagers like Marzens. I have a goodly number of beers on hand that are well over a year old that still taste great, many keep getting better with age. Most of those though had O.G.s well in excess of 60.
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Offline majorvices

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #26 on: June 16, 2021, 06:05:30 pm »
I think a big factor is how long the bottles or keg sit before drinking them. I don't purge my bottles with CO2, but for the last couple of years I've been planning brew days so that I can start drinking a batch when it is carb'd up, rather than brewing ahead. It seems to help a lot in terms of hop aroma. That might be why experiences differ for different brewers. I like a low tech solution.

   I've never messed with the hassle of purging bottles, I figure the beer pushes the air out as it fills and what little mixing that does take place with the tiny surface area in a bottle during the 5 or 10 seconds it takes to fill can't be adding any consequential amount of DO, and bottle conditioning should clean most of that up. I'll admit that my sense of taste isn't world class, but I don't have many batches that start tasting stale prematurely, and most of the ones that do seem to be Lagers like Marzens. I have a goodly number of beers on hand that are well over a year old that still taste great, many keep getting better with age. Most of those though had O.G.s well in excess of 60.

Oh, I agree it is probably overkill. I also probably won't do it since I haven't noticed any issues on the bottle conditioned beers I have been brewing. But I have thought about it. That said "pushing the air out" is introducing some oxidation, and it's difficult to say how much oxygen the yeast actually does clean up without testing. I think that Homebrewers have a huge advantage over commercial beers since we can keep the cold with minimal jostling. Plus, if the beers start to go south we can notice immediately and drink them up.

Offline Bilsch

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #27 on: June 18, 2021, 09:23:20 pm »
Oxygen is not very soluble in liquid. In the 15-ish minutes it takes to fill my keg, I doubt enough oxygen has dissolved in the beer to the point where it has seeped below the top ~1 inch of beer in the fermenter. IOW, I doubt that the beer that actually gets into the keg has any oxygen in it due to the open transfer.

Actually oxygen is quite soluble in water/beer but does have a saturation limit of about 8ppm depending on the temperature. Just because the saturation point is a low number does not mean that the oxygen dissolves in slowly. The speed is relative to the concentration gradient. If there is little or no DO in your beer then the force to push it in there will be greater. And as the O2 that went into solution reacts with the antioxidants in said beer, that makes room for more to come in. It's a vicious circle.

Concentration gradient is also germane to the polymer CO2 bag idea being discussed in this thread. Since all plastics are oxygen permeable to a certain extent, some much more than others, this idea wont protect your beer from oxidation or staling. Unless your using a good (read expensive) barrier polymer for storing the CO2 (and the fittings and lines to connect them) then the clock is ticking on it's O2 concentration. Every minute the difference in oxygen concentration on the outside of the bag is pushing/forcing O2 molecules in the bag through the plastic and that process wont stop until the inside and the outside reach equilibrium.

In other words it's probably a waste of time trying to store a low oxygen gas in a plastic bag and expect it to be low oxygen for long.

Offline RC

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #28 on: June 19, 2021, 12:13:48 am »
Actually oxygen is quite soluble in water/beer...

This is not correct. Oxygen is not very soluble at all. It's ~40 times less soluble than CO2 and only about twice as soluble as N2--itself being, for the most part, insoluble. Like N2, O2 is a non-polar solute trying to be dissolved in a polar solvent. That said, O2 makes a difference for better and for worse in very small amounts. Maybe this is why everyone thinks it's so soluble. But it's not.

The speed is relative to the concentration gradient. If there is little or no DO in your beer then the force to push it in there will be greater.

Also incorrect. If there is little or no DO in the beer, it won't take anything to add oxygen. The rate of dissolution will be rapid at first but will slow down tremendously as you approach equilibrium with the atmospheric concentration. It will slow down so much that it will be almost impossible to reach atmospheric concentration (but you'll get close). This is the same reason why chilling the wort happens so rapidly at first but slows down as you approach your groundwater temp. The first ~130 degrees of chilling happen in a few minutes but the final 20 degrees takes forever. So it is with O2 dissolution. The 2nd law of thermodynamics is a real b**ch.
Oxygen is not very soluble in liquid. In the 15-ish minutes it takes to fill my keg, I doubt enough oxygen has dissolved in the beer to the point where it has seeped below the top ~1 inch of beer in the fermenter. IOW, I doubt that the beer that actually gets into the keg has any oxygen in it due to the open transfer.

Concentration gradient is also germane to the polymer CO2 bag idea being discussed in this thread. Since all plastics are oxygen permeable to a certain extent, some much more than others, this idea wont protect your beer from oxidation or staling.
Reality kicks theory's butt on this one.

Oxygen is not very soluble in liquid. In the 15-ish minutes it takes to fill my keg, I doubt enough oxygen has dissolved in the beer to the point where it has seeped below the top ~1 inch of beer in the fermenter. IOW, I doubt that the beer that actually gets into the keg has any oxygen in it due to the open transfer.

In other words it's probably a waste of time trying to store a low oxygen gas in a plastic bag and expect it to be low oxygen for long.

Storing a low oxygen gas in a plastic bag is not at all what the OP was describing.

Offline majorvices

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Re: Using collapsable bags to displace o2 during racking/packaging
« Reply #29 on: June 19, 2021, 05:46:31 am »
Oxygen is not very soluble in liquid. In the 15-ish minutes it takes to fill my keg, I doubt enough oxygen has dissolved in the beer to the point where it has seeped below the top ~1 inch of beer in the fermenter. IOW, I doubt that the beer that actually gets into the keg has any oxygen in it due to the open transfer.

Actually oxygen is quite soluble in water/beer but does have a saturation limit of about 8ppm depending on the temperature. Just because the saturation point is a low number does not mean that the oxygen dissolves in slowly. The speed is relative to the concentration gradient. If there is little or no DO in your beer then the force to push it in there will be greater. And as the O2 that went into solution reacts with the antioxidants in said beer, that makes room for more to come in. It's a vicious circle.

Concentration gradient is also germane to the polymer CO2 bag idea being discussed in this thread. Since all plastics are oxygen permeable to a certain extent, some much more than others, this idea wont protect your beer from oxidation or staling. Unless your using a good (read expensive) barrier polymer for storing the CO2 (and the fittings and lines to connect them) then the clock is ticking on it's O2 concentration. Every minute the difference in oxygen concentration on the outside of the bag is pushing/forcing O2 molecules in the bag through the plastic and that process wont stop until the inside and the outside reach equilibrium.

In other words it's probably a waste of time trying to store a low oxygen gas in a plastic bag and expect it to be low oxygen for long.

Hey Blisch -- tell you what. I'll fill that bag with Co2 and let you inhale it. Then you tell me how much Co2 you think is in it. ;) It definitely displaces the fermenter with Co2 when used as I suggedsted.

Yeah, eventually that collapsable bag will exchange o2. Though these are extremely sturdy bags. They aren't exchanging o2 over the 1-2 hours I'm using them.

I'm guessing you either didn't entirely read the purpose I proposed or you are fixated my suggesting they could be a way to capture Co2 for bottle conditioners or secodnary users without acess to Co2. I still think they could be used for this as well. I think they will exchange very little gas in that period.
« Last Edit: June 19, 2021, 07:17:47 am by majorvices »