How to keep 2-liters of soda from going flat?

[Kelemvor]

Howdy,

I've read that you can get some sort of pump cap for 2-liter bottles of soda that you can pump more air into the bottle to increase the pressue and make the CO2 come out of the soda more slowly. Does anyone know if these things actually work and where you can buy them?

We've started drinking from 2-liter bottles at home as they are so much less expensive than cans but sometimes when we near the bottom it gets flat pretty quickly.

Thanks,

 

[Coquito]

Close it tighter. Tight enough so that it takes a really good grip to get it loose.

 

[Cattlegod]

they should work in theory. or you can just drink them faster, or buy smaller bottles.

 

[waggy]

or drink it one setting.

 

[TheGizmo]

yea closing it tighter will help but no matter what by the bottom if you open it like 10 times will be pretty flat. a cap that can put c02 in soda would be cool.

 

[gnumantsc]

Stop drinking soda it ain't good for ya!

 

[Enfer Singe]

Text

 

[Goosemaster]

Originally posted by: waggy
or drink it one setting.

I like multiple settings, lie the beach, parties, peep shows etc

 

[DaTT]

Buy 2 liters of rye and a 4 liter glass, enjoy!

 

[mugs]

Don't refrigerate it

 

[sao123]

the CO2 cap is worthless.

Get a soda fountain... always carbonated... always fresh.

 

[Whoozyerdaddy]

Originally posted by: DaTT
Buy 2 liters of Crown and a 4 liter glass, enjoy!

Fixed

 

[Jaihahih]

put seltzer water in it when you drink. Or carbonized water. Flatness is gone.

 

[Ronstang]

In order to keep soda from going flat the pressure inside the bottle needs to be higher that the partial pressure of the dissolved CO2. Each time you take soda out of the bottle the volume of air increases and when you close the cap the CO2 will establish equillibrium based on it's partial pressure at that given temperature. Each time it does this more CO2 is released from the soda and it becomes progressively flatter at each opening. One of those screw on pump things should allow you to pump the bottle to a pressure just higher than the partial pressure of the CO2 and thus keep it in solution with the soda. It is worth a try, I have never personally done it but it should work in theory but that isn't any guarantee.

 

[DaTT]

Originally posted by: Whoozyerdaddy

Originally posted by: DaTT
Buy 2 liters of Crown and a 4 liter glass, enjoy!

Fixed

A worthy fix my friend, and error on my part that shall never be made again.

 

[bonkers325]

encase it in frozen carbonite

 

[Midlander]

Originally posted by: Ronstang
In order to keep soda from going flat the pressure inside the bottle needs to be higher that the partial pressure of the dissolved CO2. Each time you take soda out of the bottle the volume of air increases and when you close the cap the CO2 will establish equillibrium based on it's partial pressure at that given temperature. Each time it does this more CO2 is released from the soda and it becomes progressively flatter at each opening. One of those screw on pump things should allow you to pump the bottle to a pressure just higher than the partial pressure of the CO2 and thus keep it in solution with the soda. It is worth a try, I have never personally done it but it should work in theory but that isn't any guarantee.

I thought you were heading the correct direction. Pumping air (mainly O2 and N2) into the bottle will help, but the CO2 will still reach its partial pressure in the headspace over the soda.

The only way to really solve this would be to pump CO2 into the headspace every time the bottle is resealed. I don't think it's practical. I suggest drinking what you want and expect to throw some of it away. It will still be cheaper than most alternatives.

 

[scorpmatt]

um, I always find that it's easy to keep a 2 liter bottle of soda from going flat by not putting it places where things can make it go flat. truck tires, heavy equipment, that kind of stuff.

 

[Ronstang]

Originally posted by: Midlander

Originally posted by: Ronstang
In order to keep soda from going flat the pressure inside the bottle needs to be higher that the partial pressure of the dissolved CO2. Each time you take soda out of the bottle the volume of air increases and when you close the cap the CO2 will establish equillibrium based on it's partial pressure at that given temperature. Each time it does this more CO2 is released from the soda and it becomes progressively flatter at each opening. One of those screw on pump things should allow you to pump the bottle to a pressure just higher than the partial pressure of the CO2 and thus keep it in solution with the soda. It is worth a try, I have never personally done it but it should work in theory but that isn't any guarantee.

I thought you were heading the correct direction. Pumping air (mainly O2 and N2) into the bottle will help, but the CO2 will still reach its partial pressure in the headspace over the soda.

The only way to really solve this would be to pump CO2 into the headspace every time the bottle is resealed. I don't think it's practical. I suggest drinking what you want and expect to throw some of it away. It will still be cheaper than most alternatives.

You are right about the C02, I just didn't finish my thought process.

 

[Midlander]

Originally posted by: Ronstang

Originally posted by: Midlander

Originally posted by: Ronstang
In order to keep soda from going flat the pressure inside the bottle needs to be higher that the partial pressure of the dissolved CO2. Each time you take soda out of the bottle the volume of air increases and when you close the cap the CO2 will establish equillibrium based on it's partial pressure at that given temperature. Each time it does this more CO2 is released from the soda and it becomes progressively flatter at each opening. One of those screw on pump things should allow you to pump the bottle to a pressure just higher than the partial pressure of the CO2 and thus keep it in solution with the soda. It is worth a try, I have never personally done it but it should work in theory but that isn't any guarantee.

I thought you were heading the correct direction. Pumping air (mainly O2 and N2) into the bottle will help, but the CO2 will still reach its partial pressure in the headspace over the soda.

The only way to really solve this would be to pump CO2 into the headspace every time the bottle is resealed. I don't think it's practical. I suggest drinking what you want and expect to throw some of it away. It will still be cheaper than most alternatives.

You are right about the C02, I just didn't finish my thought process.

:thumbsup:

 

[Kelemvor]

Originally posted by: sao123
the CO2 cap is worthless.

Get a soda fountain... always carbonated... always fresh.

We actually might do that. Guy at work has one setup for Sprecher Rootbeer. I might do the same thing with some soda and of course beer.

 

[white]

use this cap. you'll also need a CO2 tank with the proper fittings.

carbonator

 

[GagHalfrunt]

Originally posted by: Coquito
Close it tighter. Tight enough so that it takes a really good grip to get it loose.

100% worthless, the gas does not escape through the seal. It's all a matter of pressures. For a new bottle a little gas escapes into the neck of the bottle and that equalizes the pressure between the void and the liquid, so no more gas escapes. When you open the bottle that built-up gas escapes (hence the hssssssssss sound when you unscrew the cap). When you reseal the cap there's no more pressure there, so more of the carbonation escapes the liquid into the void which is now larger than it was before since you poured out some liquid. When enough gas has fillled the void the pressure then is equalized again and no more gas escapes the liquid. The pump-caps accomplish the same thing, they equalize the pressure between the void and the liquid so that it's not the carbonation filling the void. The pump caps are a pain in the ass though. Luckily there's an easier way.

The void is the issue. As it grows more and more gas escapes into it every time you open the bottle. If you get rid of the void between the top of the liquid and the cap, the gas has nowhere to escape to and the liquid stays carbonated. And how do you get rid of the void? Simple. Squeeze the bottle. That's it. After you pour off a serving squeeze the bottle so that the remaining soda fills the space. That leaves nowhere for the gas to escape to, the pressure stays equal and the soda stays carbonated.

 

[Kelemvor]

Originally posted by: GagHalfrunt

Originally posted by: Coquito
Close it tighter. Tight enough so that it takes a really good grip to get it loose.

100% worthless, the gas does not escape through the seal. It's all a matter of pressures. For a new bottle a little gas escapes into the neck of the bottle and that equalizes the pressure between the void and the liquid, so no more gas escapes. When you open the bottle that built-up gas escapes (hence the hssssssssss sound when you unscrew the cap). When you reseal the cap there's no more pressure there, so more of the carbonation escapes the liquid into the void which is now larger than it was before since you poured out some liquid. When enough gas has fillled the void the pressure then is equalized again and no more gas escapes the liquid. The pump-caps accomplish the same thing, they equalize the pressure between the void and the liquid so that it's not the carbonation filling the void. The pump caps are a pain in the ass though. Luckily there's an easier way.

The void is the issue. As it grows more and more gas escapes into it every time you open the bottle. If you get rid of the void between the top of the liquid and the cap, the gas has nowhere to escape to and the liquid stays carbonated. And how do you get rid of the void? Simple. Squeeze the bottle. That's it. After you pour off a serving squeeze the bottle so that the remaining soda fills the space. That leaves nowhere for the gas to escape to, the pressure stays equal and the soda stays carbonated.

I've seen a lot of places on both sides of that argument and never saw a difinitive answer on if it really helps or not...

 

[FoBoT]

drink it faster or stop drinking it