Air-Free Transfers - Worth it?

[Brewddah]

I'm thinking about doing an air-free carboy-to-keg transfer for an IPA. I want those delicious hop oils to stick around as long as possible. Is it worth the effort?

I think I have all the right equipment - dual port carboy cap, racking cane, and 5/16" swivel nut to connect to the ball lock fitting, which attaches to the beer out port. Connect the CO2 line to the small port on the cap, open the relief valve on the keg, and beer should start filling, correct? I'm thinking I should set the regulator to 5 or so?

Am I forgetting anything?

 

[Homercidal]

You will want to pre-fill the keg with co2 and then release the pressure just before you fill. Push the carboy cap with CO2. It doesn't take much, as you are really just starting a siphon. Give it just enough gas to keep the siphon flowing nicely.

There isn't much to it.

 

[JonM]

I do that on every transfer.

Two tips: watch the fermenter. If not enough gas is going in, the sides will start to suck in. Too much gas and that carbon cap will pop off with a hell of a bang. Control the flow with the little valve between the reg and the hose.

 

[iijakii]

Yeah, second on the low gas. Mine's probably on 2 or 3 when I do it. Just enough to get it to flow. Any more and my carboy cap leaks a lot of the gas out.

 

[HausBrauerei_Harvey]

I got all excited about this about a year ago and did it for a few brews (stouts and belgians), I'm not sure if I did something wrong but I found my transfers were much slower than just using a racking cane with big tubing, as your limited by the flow you can get through the liquid tube. I could fill a keg with my racking cane in a few minutes, but found it was taking me 10-20 minutes/keg with the air-free method.

I went back to standard transfers and still haven't had any problems with oxidation, but I always purge a bit of CO2 into the keg before transferring, and purge the head space a good 5-10 times post filling, while of course being very careful not to splash/agitate the beer when racking into the keg.

 

[iijakii]

I got all excited about this about a year ago and did it for a few brews (stouts and belgians), I'm not sure if I did something wrong but I found my transfers were much slower than just using a racking cane with big tubing, as your limited by the flow you can get through the liquid tube. I could fill a keg with my racking cane in a few minutes, but found it was taking me 10-20 minutes/keg with the air-free method.

I went back to standard transfers and still haven't had any problems with oxidation, but I always purge a bit of CO2 into the keg before transferring, and purge the head space a good 5-10 times post filling, while of course being very careful not to splash/agitate the beer when racking into the keg.

You can always just run the hose through the lid instead of going through the dip tube.

 

[AnOldUR]

You can always just run the hose through the lid instead of going through the dip tube.

Yeah. That's what I do. Just throw a StarSan soaked paper towel over the top to minimize O2 getting into the opening. As it fills the CO2 from purging is being forced up and out, further reducing the risk of O2 making its way to your beer.

 

[Brewddah]

I do that on every transfer.

Two tips: watch the fermenter. If not enough gas is going in, the sides will start to suck in. Too much gas and that carbon cap will pop off with a hell of a bang. Control the flow with the little valve between the reg and the hose.

Now I'm a little concerned - I only have glass carboys. I don't want an explosion or an implosion...

 

[BlueHouseBrew]

This is similar to the method I use when transferring from a carboy. Only differences are that I start/maintain the flow with very low pressure (needle just off the stop / just enough to get the flow started), I attach a gas disconnect to the gas post, rather than hold the PRV open, and I purge the receiving keg with CO2 by filling it completely with StarSan and pushing that out with CO2, so there is absolutely no O2 in the keg.

I also only have glass carboys. It is crucial to use low pressure, low enough that the carboy cap will stay on. The pressure I use is at or below what you could generate by blowing into the carboy through the gas line.

Edit: I should note that it is important to start the flow of gas by adjusting the regulator pressure slowly from zero to the point where the flow of liquid starts. It could be dangerous to set a low pressure on the regulator and try to control the flow with a valve, because that would not stop the pressure in the carboy from rising, should the outflow be restricted.

 

[AnOldUR]

Once the flow starts I back off the pressure and then, with my ear at the regulator, turn it back up until I hear the slightest hiss of gas leaving the tank. It's not even enough to raise the needle on my regulator. Just enough to displace the beer leaving the carboy (glass in my case).

The carboy cap popping of is like a safety feature to keep from building up too much pressure. I've seen some people put a hose clamp around it. Not a good idea IMO.

 

[gnef]

I say give it a try and figure out if it works for you and your priorities.

Many years ago, I went all in to closed transfers using co2. I even drilled new holes in some of my bucket lids for a second gromet and schrader valves. I used them for a while, but came to realize that I was wasting so much CO2, and like others mentioned, going through the dip tube has some challenges: it is significantly slower, and you also need to be much more careful with trub, as you can easily block the poppet opening.

It was cool for a bit, but then I realized it was too much of a hassle for me and what I thought was important. We all have different priorities, so this may be a must for you, and you won't know until you try.

There are a lot of things that I've tried, only to realize later that it didn't suit me, but it very well may suit others. The only way to know is to give things a try and see how it works for you.

 

[schematix]

Here's a better trick for purging a keg.... fill it COMPLETELY full of water, then push the water out with CO2. Run it out at 5psi and you'll use a lot less CO2 than purging/venting/repeat. Also if you do this there is no need to purge the keg after you rack.

I also rack under CO2 pressure through the dip tube. Pop the safety release as soon as flow starts and cut it off as soon as flow stops. Minimal CO2 introduction this way.

I noticed an immediate difference the first time i did it this way.

 

[HausBrauerei_Harvey]

You can always just run the hose through the lid instead of going through the dip tube.

Somehow, this never occurred to me. This sounds like a nice compromise between the two methods, with a reduction of potential for oxidation, but we'll see if feel like going to the effort next time I have to rack, i've had great luck so far with my standard transfer method.

 

[orangehero]

Here's a better trick for purging a keg.... fill it COMPLETELY full of water, then push the water out with CO2. Run it out at 5psi and you'll use a lot less CO2 than purging/venting/repeat. Also if you do this there is no need to purge the keg after you rack.

I also rack under CO2 pressure through the dip tube. Pop the safety release as soon as flow starts and cut it off as soon as flow stops. Minimal CO2 introduction this way.

I use the same method, except I keep a carboy full of star-san for purging and sanitizing kegs. Siphon star-san into keg. Then push star-san back into carboy or daisy chain another keg if doing multiples.

It's the only way to get the O2 as low as possible.

Personally I only use CO2 to start the siphon, I just let air displace the beer in the carboy. I don't think there is any significant oxygen absorption in the time it takes to transfer, just make sure to stop before the racking cane starts sucking air.

Somehow, this never occurred to me. This sounds like a nice compromise between the two methods, with a reduction of potential for oxidation, but we'll see if feel like going to the effort next time I have to rack, i've had great luck so far with my standard transfer method.

Just siphoning into an open keg is not any kind of compromise, it defeats the whole purpose of using CO2 to move the beer.

 

[JonM]

Here's a better trick for purging a keg.... fill it COMPLETELY full of water, then push the water out with CO2.

I recently did this with a robust porter I'm aging for many months. Bonus if you fill the vessel with starsan and displace it with CO2. Then you get a sanitized and oxygen free vessel. Run the beer through the same racking cane you used to remove the starsan. Overkill? Maybe. (Probably.) But I don't worry about that batch one bit.

 

[schematix]

I'm running a sorta-experiment right now with (not) sanitizing kegs.

Once a keg blows i continue to keep it pressurized and refrigerated. When I need the keg, I give it 2-3 hot water shakes/rinses and then a cold rinse. Then i fill it with cold water and purge as stated above. Since i'm putting fermented beer into it and keeping it cold i'd expect my odds of an issue to be on the low side. Fingers crossed, but so far no problems.

 

[day_trippr]

So, this is for science?

Cheers!

 

[schematix]

So, this is for science?

Cheers!

No it's for laziness!

 

[Homercidal]

Somehow, this never occurred to me. This sounds like a nice compromise between the two methods, with a reduction of potential for oxidation, but we'll see if feel like going to the effort next time I have to rack, i've had great luck so far with my standard transfer method.

Frankly, this is what I would do. Having a CO2-filled keg is not going to promote oxygenation like one filled with air, so there is some benefit, while avoiding the slow transfer rate and potential blockage of going through the Post. If you can transfer really clear beer with minimal trub being picked up, this might not be a concern.

Just siphoning into an open keg is not any kind of compromise, it defeats the whole purpose of using CO2 to move the beer.

If the keg is filled with CO2, it's better than pushing with air into a keg filled with air. There is *some* compromise. Whether there is a noticeable difference in beer flavor in the end, I don't know. I think that gentle handling is more important than whether you don't have any air contacting the surface of the beer in the carboy or keg for a short time. It takes time for the oxygen to be taken up by the beer, so if this is only for a few minutes before CO2 is used to flush the headspace, it's probably not a big deal.