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Pumping air into partially full beer bottles to preserve carbonation

  1. Jan 21, 2009 #1
    I was thinking of buying a cheap device to pump air into large bottles of beer that I didn't finish drinking to keep up the carbonation for another day or so, but the following Amazon reviews of a similar more expensive device got me wondering if it's a waste of time and money.


    The second reviewer, Erik L. Russell, M.D., (click on "See all 14 customer reviews..." and proceed to Page 2) brings up the law of partial pressure to debunk the usefulness of this device. Since the air being pumped into the bottle consists of only approximately 0.04% carbon dioxide (Dr. Erik claims 2%), is he correct that this device won't be effective? Or will the pressure of any gasses pushing down on the liquid prevent carbon dioxide from escaping?
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  3. Jan 21, 2009 #2


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    Yes it will, however it will also force oxygen into the beer turning it stale.
  4. Jan 21, 2009 #3
    I realize oxygen is generally not great for beer (oxidation actually gives desired tastes in beers that age well), but I'd rather have a beer that hasn't gone flat than one that doesn't have a day's worth of oxidation (different story with red wine containing lots of tannins, and you'd use a vacuum pump for red wine anyway).

    So why doesn't the principle of partial pressure render these types of products ineffective as Dr. Erik claimed?
  5. Jan 21, 2009 #4


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    I'm guessing the pressure inside a CO2 bubble is so high that you would have to pressurise the air above the bottle to a ridiculous amount to keep it in solution.
  6. Jan 21, 2009 #5
    Now it seems you're saying these devices don't work. :confused:
  7. Jan 21, 2009 #6


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    I don't know the particular product claims - but i would be surprised if the couple of extra PSI you could put in a bottle with a wine-pump type gadget makes a significant difference to the amount of CO2 in solution as opposed to just putting the cork back in and keeping it cool.
  8. Jan 21, 2009 #7
    "The champagne function pumps air into the bottle, preventing the dissipation of the bubbles and preserves your champagne for days."

    Okay, I'm going to send for similar device, perform an experiment and I'll post the results here. :)
  9. Jan 21, 2009 #8


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    The pressure in a champagne bottle is about 3-4 atm so this gadget is going to need a hefty mechanism to hold it to the bottle and a fairly chunky pump to produce that.
  10. Jan 21, 2009 #9
    You're assuming that the pressure that's present in an unopened bottle of champagne is necessary to prevent an appreciable loss of carbonation; a less amount of pressure may suffice. For instance, the amount of pressure present in the head space of a soda bottle is much less, but it's enough to keep the soda from going flat.
  11. Jan 22, 2009 #10


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    You could try my approach—don't quit drinking until the bottle is empty. :rolleyes:
    On the other hand, beer stays acceptable until the next day when open. If it's going to be longer than that, just cork the bloody thing. In absence of a cork, a chunk of plastic such as Saran Wrap, held on with a rubber band, works fine for a couple of days.
  12. Jan 22, 2009 #11
    There are little devices, screw on with a small pump, called fizz keepers you can buy that enable you to pump air into the bottle to increase the pressure, they also act as bottle tops as well. These stop most of the CO2 from leaking into the bottle, and they double the life of fizz in my experience, I think they are about £2 each. Simple and much cheaper than paying out on gas, nozzle and so on. They definitely work, but they do take some effort once the bottle is fairly empty.
    Last edited: Jan 22, 2009
  13. Jan 22, 2009 #12


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    Alternatively, just buy smaller bottles!
  14. Jan 22, 2009 #13
    Apart from keeping the fluid under pressure, you also need to ensure that the gas on the beer should be the right one and no bacteria inside (I'm not sure of this point though).

    One idea that came to my mind is...why not pressurize the fluid itself?
  15. Jan 22, 2009 #14
    The beer has to be carbonated from an originally non-carbonated state anyway. Couldn't you just find a way to just re-carbonate it period?
  16. Jan 22, 2009 #15
    That's similar to the cheaper device I mentioned getting in the OP, but that's basically what the more expensive device in the Amazon link does.

    That's the question posed in the OP- Will ordinary air pressure pressing down on the beer in the bottle help keep the beer carbonated?

    Bacteria is fine. The fermentation process is done and beer that's recapped and stored in the fridge for a few days doesn't suffer off-tastes from contamination, just from loss of carbonation and to some degree oxidation.


    Possibly. But getting it just right would be difficult and I'm not interested in a complicated system. Also, I'm interested in the answer to the OP from a physics standpoint.
  17. Jan 22, 2009 #16


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    The carbonation is produced by the yeast - only in 'fizzy beer-like drink' is CO2 added.
  18. Jan 23, 2009 #17


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    I agree with mgb, but don't see any mention of partial pressure here. All gases in a mixture act independently of each other and since air contains very little carbon dioxide, using pressurized air will have virtually no effect on how fast CO2 escapes from a beer. You'd need thousands of psi of air pressure to get the partial pressure of CO2 high enough to matter.
  19. Jan 23, 2009 #18
    Of course they do actually work in practice though: and no I don't mean I assume they work, if you have an almost empty bottle it goes flat very quickly, but with those it lasts a few days, which is a problem for theory.
  20. Jan 23, 2009 #19
    Over the long run the partial pressure problem will mean that your beer will go flat. But if you notice when you open a beer or a soda you get bubbles of CO2 all throughout the bottle. The pressure drop is enough so that CO2 comes out of solution in the middle of the bottle, basically anywhere it can find a nucleation site. By raising the pressure of the air in the bottle you limit the CO2 loss to the surface of the beer. If you have it in a cold refrigerator that is not disturbed you will definitely extend the life of the carbonation.
  21. Jan 23, 2009 #20


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    Would the partial pressure affect bubbles forming out of solution?
    Isn't that just total pressure, otherwise the gas in solution at the bottom of the bottle has to 'know' what mixture of gasses are present in the air above the liquid.
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