trying to achieve a cheap CO2 storage system
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From the picture it looks like the OP is using the kind of material hops and food are vacuum sealed in. We know those hop and food packs stay hard over long times (years), which may prove gases (such as O2) don't pass the membrane.
Mylar is another option, even Helium can't get through, or very slowly. That may be another material to try. Not sure how easy it is to seal, though. The thick, silver hop bags I've gotten from Hops Direct were multilayer mylar. guessing 4-8 times as thick as a mylar party balloon.
Searching with the phrase "gas permeability food storage bags" produced various hits. Here's one.
This other one might be better. It might be sensible to just choose a bag that holds food intended for a long shelf life.
Cheers!
fwiw, I did about 20 minutes worth of investigation wrt metallized mylar bags and a couple other materials and every one of the sellers also sells oxygen scavenging packets that are recommended to be inserted in the bags before filling with whatever wants to be O2-free.
I did not find PET or EVA bags. I was hoping they're out there but no joy...
Cheers!
I did not find PET or EVA bags. I was hoping they're out there but no joy...
Cheers!
I have a $25 little vacuum pump that can hit 28 PSI that I use for pressure fermentation starting/head pressure. It has two barbs, one in and one out. I know this is under 3 bar, but what if you could increase your storage volume? Something like a 10 gallon keg at 3 bar would hold quite a lot of CO2.
To paraphrase Fox Mulder, the bags are out there.. Maybe Ale could just re-use a bag that, e. g., cashews came in...
Maybe the need for the O2 scavenging could be avoided by venting/discarding one 5 gal. batch worth of gas, which @doug293cz indicates would effectively purge a (much larger) 5 gal. corny.
Speaking of which, I confess affection for the two-keg design mentioned above, but Ale clearly wants to try the bag thing.
And it's clearly possible to fall into an absolutist mode re our beloved and hated O2. A well-chosen bag could work very well.
DuncB
Well-Known Member
Especially if made of thick metal!
I've done some research here and there, mostly on some manufacturer's homepage.
It's very difficult to have a technical datasheet for a single product... so It could be quite difficult to know diffusion/resistance data of the bag you're choosing, at O2.
What I have learned is that an aluminum coating reduces the O2 permeability significantly against plastic bags without alu, but how much is not exactly clear to me: best value I've seen is 3cc (cm3) of O2 in 24 hours diffused through a m2 of surface (which is a very huge diffusion!!!). A year ago my homebrew shop "upgraded" their malt and hop packages from clear to "silver" ones.... this empirically supports the idea that I need this type of bag to preserve from O2.
The only sensible upgrade I can think of at this time is to ask the shop to sell me some silver bags.
I also need them to replace the bags I put inside my Corny kegs, I must admit, with very little knowledge of the consequences.... When kegs are quite empty I have had the impression to get lower carbonated beer (due to CO2 exitin the bag?) and a loss of flavor and possibly oxidation (due to O2 gettin in?). I also noticed that the Corny was clean inside but had a bad vinegar smell (again due to anything goin' out of bag because of its permeability?... outside the bag the "ambient" isn't sanitized, because there's no need to do it).
Damn!!! the whole project is slowing down thanks to the increase in knowledge!
Thank you and bye,
Ale
It's very difficult to have a technical datasheet for a single product... so It could be quite difficult to know diffusion/resistance data of the bag you're choosing, at O2.
What I have learned is that an aluminum coating reduces the O2 permeability significantly against plastic bags without alu, but how much is not exactly clear to me: best value I've seen is 3cc (cm3) of O2 in 24 hours diffused through a m2 of surface (which is a very huge diffusion!!!). A year ago my homebrew shop "upgraded" their malt and hop packages from clear to "silver" ones.... this empirically supports the idea that I need this type of bag to preserve from O2.
The only sensible upgrade I can think of at this time is to ask the shop to sell me some silver bags.
I also need them to replace the bags I put inside my Corny kegs, I must admit, with very little knowledge of the consequences.... When kegs are quite empty I have had the impression to get lower carbonated beer (due to CO2 exitin the bag?) and a loss of flavor and possibly oxidation (due to O2 gettin in?). I also noticed that the Corny was clean inside but had a bad vinegar smell (again due to anything goin' out of bag because of its permeability?... outside the bag the "ambient" isn't sanitized, because there's no need to do it).
Damn!!! the whole project is slowing down thanks to the increase in knowledge!
Thank you and bye,
Ale
You're not leaving us, are you?
Discussions like these are the best to gather input and ideas from a group with an interest in the matter, aka, brainstorming.
Not sure if moisture was addressed, but I can think of reasons why you wouldn't want "beer vapor" ending up in your (final) CO2 holding keg.
When you say "store for further usage", what is your goal for the CO2? Just carbonate and serve? Is so, how many kegs do you need to carbonate/serve from?
Basically, how much CO2 are you looking to capture and store?
Basically, how much CO2 are you looking to capture and store?
Yeah, those look like the multi-layer mylar* bags I was referring to in #42, as used by Hops Direct, here in the US.
* At least I hope all the plastic used in the bags is indeed mylar.
Bassman2003: please forget what I've said before, because I've had new inputs so I'll have to revise my project....
Before making a prediction on how many liters I'll need or on the purpose (carbonation or transfer?), I need to better understand the risk of diffusion of O2 in the system.
This i s crucial. When I face this I will go further implementing the system.
Ty and bye,
Ale
No I think I won't, even if I have a big linguistic limitation and therefore posting costs me a bit: I have to get a mental image of what I want to say in English, then I have to try to write it and finally (if I'm not particularly pissed off and so I don't care) I want to feed it to google translate to see if there are many differences compared to what I would write.You're not leaving us, are you?
Discussions like these are the best to gather input and ideas from a group with an interest in the matter, aka, brainstorming....
A good pain in the ass.
But while it's worth it...
Tx and bye,
Ale
Just trying to find out your end goal. Why are you attempting the project? - Cheap CO2 or pure CO2?
Bassman2003: this is a bit of a difficult question for me!
I think what drives me is the passion for DIY, which I inherited from my father. And perhaps even earlier by my grandfather, who made his own wine (all year round), cultivating the vines; he also raised hens, rabbits, chinchillas, for food and to monetize.
It's been forty years and things have changed a lot
and I don't want to be pathetic! I'd like to be as self-sufficient as possible and produce what I need by myself... that's why I grow hops and try to recycle the yeasts between one brew and another, sometime with evident under-pitching, other times with great results. I'm not interested in winning a homebrew contest, but in producing a decent beer for family use: "homemade"... like grandfather's wine which they say (I was too young), was decent.
So could my goal be "self-produced CO2 with some trade-offs"?
Bye
Ale.
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DuncB
Well-Known Member
I feel another pressure ferment safe vessel corny or fermzilla, feed a CO2 engine with sugar wash and nutrient, you can closed top this up and use this to run your keg setup. Easily run it at 15 to 20 psi, inline reg to your kegs. With beer carbonated by spunding this should easily keep you going.Bassman2003: this is a bit of a difficult question for me!
I think what drives me is the passion for DIY, which I inherited from my father. And perhaps even earlier by my grandfather, who made his own wine (all year round), cultivating the vines; he also raised hens, rabbits, chinchillas, for food and to monetize.
It's been forty years and things have changed a lot
I'd like to be as self-sufficient as possible and produce what I need by myself... that's why I grow hops and try to recycle the yeasts between one brew and another, sometime with evident under-pitching, other times with great results. I'm not interested in winning a homebrew contest, but in producing a decent beer for family use: "homemade"... like grandfather's wine which they say (I was too young), was decent.
So could my goal be "self-produced CO2 with some trade-offs"?
Bye
Ale.
Vapours / odours could be removed by inline carbon filter or activated charcoal in the fermenter.
25 litres at 20 psi with the regulator should push a lot of pints. @doug293cz I think did the maths on this perhaps in thread already mentioned above or elsewhere.
Thanks. It is a nice goal. It is difficult to replace a CO2 tank as it holds so much CO2 due to the very high pressure. You could try to naturally carbonate and use a 2nd keg to capture the CO2 at the same pressure. But the problem will be (as you know) that the CO2 pressure will go down as you serve the beer. This is why your were thinking of a bag and a pump. But I think that will be difficult to get working properly. Not just oxygen ingress but knowing when and how long to turn on the pump etc... will be tricky. Run the pump too long and it might start sucking out of the fermenter. At 6-7 bar that will do some serious damage in the wrong situation.
Not sure how to make this work without large holding containers and/or an expensive pump setup.
Not sure how to make this work without large holding containers and/or an expensive pump setup.
No good unless you don't mind the fermenter running under pressure. In order to be worth triggering the pump that first keg would need to be under at least a few PSI and then it would have to stop before it reached atmospheric otherwise the lid would be drawn down and leak air in. The pump would need to be hooked to a pair of accurate pressure switches and then all your fermenters would be under some level of pressure.
this is what I was thinking to try before getting stuck with the O2 problem above....
A potentiometer who can detect bag height and activate/de-activate compressor.
I was quite ready to start experimenting with some simple esp-32 code... but I got stuck with the O2 and bag question...
damn!
A potentiometer who can detect bag height and activate/de-activate compressor.
I was quite ready to start experimenting with some simple esp-32 code... but I got stuck with the O2 and bag question...
damn!
I'll bite, this is interesting! How about submerging your bag in a container filled with some sort of fluid? Choose the right bag material and fluid to solve for O2 permeability (any good ideas here?). As the bag inflates, it will displace the fluid, and you can use a float switch or level sensor to turn on your compressor.
DuncB
Well-Known Member
Many bags are permeable to small molecules.
See this experiment
https://www.etsu.edu/uschool/faculty/tadlockd/documents/bio_sample_lab_report_avg.pdf
What liquid would you suggest that wasn't permeable to gases?
See this experiment
https://www.etsu.edu/uschool/faculty/tadlockd/documents/bio_sample_lab_report_avg.pdf
What liquid would you suggest that wasn't permeable to gases?
Definitely was a question, as I am no materials engineer. Was thinking of an oil of some sort… certainly a can of worms!
DuncB
Well-Known Member
worms will like oxygen, they certainly won't do well in a plastic bag.
But the can you are onto something with that.
But the can you are onto something with that.
beren
Well-Known Member
The military uses heavy duty layered foil and plastic for its MRE meals. They last years but they are really thick and would not stand being inflated over and over like a set of lungs.
lol! If I was crouched in a hole somewhere in a combat zone I don't think I'd be over-analyzing the character of my MRE.
Otoh, as I sit in my overstuffed recliner sipping my latest neipa, I can afford to be hyper-critical about quality
iow, "quality" is not a fixed metric....
Cheers!
Otoh, as I sit in my overstuffed recliner sipping my latest neipa, I can afford to be hyper-critical about quality
iow, "quality" is not a fixed metric....
Cheers!
You might almost say it was... qualitative.
Please Lizard explain why... the only drawback I imagine if moisture goes into the storage keg... is the possibility to encourage bacterial/yeast growth...
Tx,
Ale
p.s.: what about replacing bag with this one?
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Exactly that, to eliminate the possibility of "things" growing in there. I doubt the moisture carryover from fermentation, transported outside the fermenter by its gases, to be sterile.
Although the atmosphere inside the bag, pump, tubing, and kegs is mostly CO2, not a conducive environment for growth of anything, over time something may be developing. A musty smell on opening, or any deposits inside the keg may point to that. So keep an eye (and nose) on those, just in case.
Nah... too much oxygen intrusion.
The "vacuum bag" you're planning to use is much better.
But I'm clueless how to trigger the pump's on/off cycles in an elegant way. It needs some sort of sensor/trigger when pumping should start and stop. Some clever Arduino application perhaps. Maybe something optical, triggered by the height (rise/collapse) of the bag?
That was my thought as well. I presumed a rectangular bag, placed in a cradle formed to keep the bag's perimeter dimension relatively static (so movement would be primarily vertical) and that would hold an IR emitter and receiver on opposite sides in an adjustable plane relative to the top of the bag.
All that is needed is a viable bag...
Cheers!
Have the bag under a platform that has guides at the corners so the platform rides evenly up and down. Have the platform trigger switches at the min and max height.
beren
Well-Known Member
Rube Goldberg enters the chat
“If it is stupid and works, then it isn't stupid.”
Reading some articles about brewery scale co2 capture like: CO2 Recovery System Saves Brewers Money, Puts Bubbles into Beer | NASA Spinoff
They do mention scrubbing, drying, and/or using desiccants to get any contaminants and moisture out of the final product which seems like a good idea regardless of if you are compressing and storing, or just using co2 from fermentation to purge a vessel. Any thoughts on DIY solutions here?
They do mention scrubbing, drying, and/or using desiccants to get any contaminants and moisture out of the final product which seems like a good idea regardless of if you are compressing and storing, or just using co2 from fermentation to purge a vessel. Any thoughts on DIY solutions here?
Hacksawbob
New Member
In the article, “CO2 capture starts when O2 reaches 0.6%,” that’s 6 parts per thousand. O2 in the final product is 6 parts per billion, and the bulk CO2 they use measures 20 parts her billion. In terms of removing O2, looks like there’s still a long way to go from capture to packaging. From the other articles, liquefaction of the final product helps with this greatly. How to start a cryo plant in the garage?
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0.6% is 6 parts per thousand.
Check, math before coffee.
beren
Well-Known Member
The first step is getting it to work to spec. Cost effective is another good bar to meet.
beren
Well-Known Member
I’d hazard an estimate that most organisms on earth don’t need O2 to grow. Mostly the large ones need it. Lots of single cell organisms thrive without O2. Yeasts and bacteria esp.
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