[beersk]

PET bottles under CO2 pressure then into the freezer.
I store one pound of hops in each bottle at a time.
They will keep for many years this way.

That's a great idea!

Even better - I use this cap on the PET bottles for CO2 pressurization!
Use your standard ball lock gas fitting from your CO2 tank to fill.
 

So, how does the oxygen that is in there get purged?

[blatz]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

[jeffy]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

[morticaixavier]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

I have always assumed that the idea is to fill the container with co2, wait a bit for things to settle down in there and then purge through a top opening which should get most of the o2 out as it will have migrated to the top portion of the container. still some o2 but a lot less

[blatz]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

right, but what I do is hit it with CO2 and depress the poppit to let the gas out 2-3 times to hopefully purge the oxygen. 

[hopfenundmalz]

Here is a way to get all (all for practical purposes) of the O2 out. A pet bottle used for soda should hold a high pressure, you might start with 20 PSI, 30 would be better and this link says it would be OK, but I would use precautions.
http://waterrocket.uh-lab.de/lr010101_bursttest.htm

There is about 21% O2 in the air in the container, or about 1 part in 5. Fill the containter to 30 PSI, and you have added 2 atmospheres, so you now have 1 part in 15. Vent the CO2, fill again. Repeat 2 or 3 times more and the amount is a very small part. If someone want to do that math, I will leave it to the motivated brewer.

[Joe Sr.]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

I have always assumed that the idea is to fill the container with co2, wait a bit for things to settle down in there and then purge through a top opening which should get most of the o2 out as it will have migrated to the top portion of the container. still some o2 but a lot less

My understanding of how it works is that the gas does not form layers in that way but rather mixes uniformly in the container (over time, of course, not immediately).

Regardless, purging it a couple times should do a pretty good job.

[morticaixavier]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

I have always assumed that the idea is to fill the container with co2, wait a bit for things to settle down in there and then purge through a top opening which should get most of the o2 out as it will have migrated to the top portion of the container. still some o2 but a lot less

My understanding of how it works is that the gas does not form layers in that way but rather mixes uniformly in the container (over time, of course, not immediately).

Regardless, purging it a couple times should do a pretty good job.

It mixes initially but in absence of air currents or over movement it will form layers. however it takes very little to cause the gases to mix again. but what hopfen says makes a lot more sense to me. you are really just diluting the o2 until you are at levels where it just doesn't matter anymore.

[Jimmy K]

It mixes initially but in absence of air currents or over movement it will form layers.

I don't remember that from chemistry class. Gasses mix unformly regardless of weight. Stratification is only temporary and acheived with gentle handling. (But chemistry was a long time ago)

[erockrph]

It mixes initially but in absence of air currents or over movement it will form layers.

I don't remember that from chemistry class. Gasses mix unformly regardless of weight. Stratification is only temporary and acheived with gentle handling. (But chemistry was a long time ago)

Stratification can occur, but (in the absence of thermal gradients) for the difference of partial pressures in a gas mixture to be significant enough to result in an appreciable gradient you would need a huge container (not gonna do the math, but likely several kilometers in diameter).

Gas mixtures do not act like mixtures of liquid. The heavier molecules do not push the lighter ones out of the way and sink below them. Gas mixtures can be thought of separate mixtures of each component that do not interact. Both the O2 and the CO2 will expand to fill the container equally as if the other was not there.

[jjflash]

I do it much more simply:

I remove the ball lock gas fitting from the gas hose on my CO2 tank, stuff it down the PET bottle and fill with CO2. Then dump in one pound of hop pellets. Cap with the carbonator cap and fill to 15psi CO2.  After I open the bottle to use some of the hops I again stuff the hose in the bottle, gas it, then cap and give it 15psi. Been doing this way for years and works great.   

[ajk]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

I have always assumed that the idea is to fill the container with co2, wait a bit for things to settle down in there and then purge through a top opening which should get most of the o2 out as it will have migrated to the top portion of the container. still some o2 but a lot less

That's not how gases work.  Otherwise, basements would be deadly. :-)

[blatz]

so then what are we doing when we purge kegs prior to filling, and then purge the headspace after sealing?  Is this not worth it?

[Joe Sr.]

so then what are we doing when we purge kegs prior to filling, and then purge the headspace after sealing?  Is this not worth it?

See Jeff's post above:

Here is a way to get all (all for practical purposes) of the O2 out. A pet bottle used for soda should hold a high pressure, you might start with 20 PSI, 30 would be better and this link says it would be OK, but I would use precautions.
http://waterrocket.uh-lab.de/lr010101_bursttest.htm

There is about 21% O2 in the air in the container, or about 1 part in 5. Fill the containter to 30 PSI, and you have added 2 atmospheres, so you now have 1 part in 15. Vent the CO2, fill again. Repeat 2 or 3 times more and the amount is a very small part. If someone want to do that math, I will leave it to the motivated brewer.

You are essentially diluting the mixture to the point that (hopefully) the oxygen is minimized. Better to do so than not.

The only way to eliminate the oxygen entirely would be to transfer under pressure to a keg prefilled with co2.  Even then, you probably have some minimal amount of oxygen in the keg.

[hopfenundmalz]

So, how does the oxygen that is in there get purged?

like any standard pin lock - depressing the poppit in the middle.

He said "oxygen."  When you have liquid in the PET bottle you can squeeze all the air out before capping it with the carbonator, then add CO2, but with hops, I don't think you can do that, so there will be some O2 in there, but very little.

I have always assumed that the idea is to fill the container with co2, wait a bit for things to settle down in there and then purge through a top opening which should get most of the o2 out as it will have migrated to the top portion of the container. still some o2 but a lot less

That's not how gases work.  Otherwise, basements would be deadly. :-)

Breweries with basement fermentation areas need to have CO2 alarms, as the CO2 source will pool. I worked in a place with sources in the form vehicles, and the confined spaces had to be tested before entry (think the pits for hydraulic hoists) as the heavier gases would pool. The mixing of gases from diffusion is not instantaneous.
http://en.wikipedia.org/wiki/Lake_Nyos