[Pinski]

Will be racking and kegging this afternoon and have heard talk about adding a CO2 "cover" to carboys and cornies prior to transfer in effort to isolate the beer from oxygen.  I have a 5# tank and regulator with a flare disconnect available to provide the CO2.  Do I simply remove the disconnect at the flare and dispense some CO2 into the corny/carboy prior to stating the siphon?  If anyone could offer more precise instruction I would feel much more confident in my process. ie; what is the appropriate PSI to dispense from the tank and for how long should i do this for an effective oxygen barrier.  Thanks and happy saturday to all.

[corkybstewart]

I brew 10 gallon batches so I always have 2 kegs.  I mix up a gallon of StarSan solution in the first keg, shake it every few minutes while I get other stuff ready.  Then I use my CO2 to push the Starsan from the beer-out tube into the beer out post of the second keg.  This leaves the first keg full of CO2 and sanitizes the beer-out tubes of both kegs.  You'll need to make a jumper hose with 2 beer out connectors.  While the first keg is filling I'll push the Starsan into a 3rd keg and store it for future use, if I'll be needing it soon.  I just open the keg lid enough to get the hose in so there's minimal mixing with air again.  The beer will push the CO2 and the Starsan foam out.

[hopfenundmalz]

For carboys you can put the CO2 hose in and give it a shot for 20-30 seconds befoer you rack.  Then give it a shot when you are done.

You can also use carboy caps to transfer under CO2 the whole time.  Some random guys take on doing this.   
http://www.maltosefalcons.com/tech/racking-co2

You can also rack into CO2 filled kegs through the liquid out post.  Let the CO2 out through the gas in, and have the end of the gas in hose in a pail of water to keep O2 out of that path.  You can figure out when it is full with a scale.

[tom]

Gases mix/diffuse, so they don't block each other. The only way to make sure that there is no oxygen is to push out some liquid with carbon dioxide. I fill my corny with StarSan and then push it into another keg.This leaves the corny clean, sanitized and full of CO2.

[Pinski]

Thanks for the great suggestions guys.  We're much more comfortable working with CO2 and cornies after this weekend.

[calpyro]

Will be racking and kegging this afternoon and have heard talk about adding a CO2 "cover" to carboys and cornies prior to transfer in effort to isolate the beer from oxygen.  I have a 5# tank and regulator with a flare disconnect available to provide the CO2.  Do I simply remove the disconnect at the flare and dispense some CO2 into the corny/carboy prior to stating the siphon?  If anyone could offer more precise instruction I would feel much more confident in my process. ie; what is the appropriate PSI to dispense from the tank and for how long should i do this for an effective oxygen barrier.  Thanks and happy saturday to all.

CO2 has a vapor denisity of 1.53 (air is 1.0) meaning that CO2 is heavier than air. As long as the vessel that the beer is transfered into has CO2 in it, the CO2 will have a blanket over the beer. The air which is lighter will be displaced upwards.
If you use a two hole carboy cap, one will fit a racking tube and the other can be used for CO2 in. One PSI will push the beer.

[tom]

That is a common misconception. But gases diffuse to fill their space, that's what they do. That is a basic definition of what a gas is. Air is a mixture of gases, including carbon dioxide. If CO2 didn't diffuse, then my basement would be full of CO2 from the 12 years of fermentations, serving, purging, etc.

[kgs]

Then could CO2 be used to protect beer during the bottling process, by purging a (covered) bottling bucket with CO2 and then snaking the siphon hose through the airlock hole?

[Will's Swill]

That is a common misconception. But gases diffuse to fill their space, that's what they do. That is a basic definition of what a gas is. Air is a mixture of gases, including carbon dioxide. If CO2 didn't diffuse, then my basement would be full of CO2 from the 12 years of fermentations, serving, purging, etc.

OK, you said it first, I don't want to be the nay-sayer here.  But I've been wondering about this while CO2 blanket thing.  It seems to me that if I lay on the floor in my basement, well, I should croak.  Wait, let me try it...

Nope, didn't croak.  So is the whole CO2 blanket thing an urban legend?  Maybe you need convection currents to mix gases and you don't really get those in a closed container so a CO2 layering effect is possible?  I've read here about burned nostrils from CO2 after sticking your head in a keezer, but I'm having doubts.  I should not doubt...

[tschmidlin]

It will diffuse on it's own, but it's not instantaneous.  Air currents will help mix it, but those burned nostrils have been experienced first hand by me when fermenting in an enclosed space.  So yes, it is possible to create a temporary CO2 blanket if you account for both diffusion and air currents.  But it probably doesn't work as well as some people think.

If you are really worried about O2, fill a keg with starsan and push it out with CO2.  You will have a keg full of mostly CO2 (there will be traces of O2 from what is dissolved in the starsan).  Then gently push the beer into the keg through the beer out fitting while venting the keg to let the pressure out.

[hopfenundmalz]

The CO2 blanket is one thing that helps, but is probably not 100%.  Do I do it for carboys? Yes.  For kegs I use the fill and flush with CO2 method.  As Tom says it takes time for difusion and the convection currents to mix the gas.

There have been natural events where villages have been wiped out in Africa, where lakes have a CO2 build up  and when it burps, the cloud of CO2 suffocates the people.  I used to work in a place with many hydraulic in floor car hoists and other confined spaces.  Those had to be tested before entry was allowed, as CO2 and other gases would pool there if there was a source.  

Edit: I case you were not around when this happened.  Better explaination.
http://mhalb.pagesperso-orange.fr/nyos/nyos.htm

[WDE97]

There have been natural events where villages have been wiped out in Africa, where lakes have a CO2 build up  and when it burps, the cloud of CO2 suffocates the people.  I used to work in a place with many hydraulic in floor car hoists and other confined spaces.  Those had to be tested before entry was allowed, as CO2 and other gases would pool there if there was a source.  

Edit: I case you were not around when this happened.  Better explaination.
http://mhalb.pagesperso-orange.fr/nyos/nyos.htm

National Geographic Channel has had a great show on recently about this. I think it is on their Nature Untamed series, episode is called Death Fog. 

Thanks to everyone for the info. I am just starting to keg and was also wondering the best way to purge my kegs of O2.

[narcout]

Here's a page with step by step instructions and pictures for closed transfers.  I've been using this method for a couple of years, and it works really well.

http://www.thebeerjournals.com/Racking.html

[Pinski]

Thanks alot Narcout!  That's a great infomative piece you've put together there.  I have two batches to keg this afternoon and a keezer collar to stain and finish off.  I better get busy.

[narcout]

That's a great infomative piece you've put together there. 

Just to clarify, that's not my website - it is Dean Palmer's.