CO2 purging barrels/cornys. How do you do it?

[Bolsover Brewer]

I am just about to do my first closed transfer and stumbled upon this old thread!

I want to do Method 2, where I purge the StarSan out of the keg, but is it really not an issue that you will be leaving some of the sanitiser behind in the keg?
I know it is 'no-rinse' but my kegs once empty will always have a decent amount of liquid left at the bottom that didn't make it out.

For myself what I would do to purge a keg is sanitise first, the Star San will dry leaving an acid film on the keg. Connect the keg to the gas out post of the fermenter so the gas produced by the fermenting wort will purge the keg with the blow off attached to the keg.
Not ideal as gasses mix at low pressure, but the sheer volume of CO2 would reduce any O2 in the keg far more effectively than pushing out StarSan which has carried O2 into the keg with the bubbles. To really purge the keg would involve a series of purges at high pressure to stop the gasses mixing and force the CO2 from the keg.

 

[Davegase]

For myself what I would do to purge a keg is sanitise first, the Star San will dry leaving an acid film on the keg. Connect the keg to the gas out post of the fermenter so the gas produced by the fermenting wort will purge the keg with the blow off attached to the keg.
Not ideal as gasses mix at low pressure, but the sheer volume of CO2 would reduce any O2 in the keg far more effectively than pushing out StarSan which has carried O2 into the keg with the bubbles. To really purge the keg would involve a series of purges at high pressure to stop the gasses mixing and force the CO2 from the keg.

Where are the bubbles coming from ? if CO2 to leaves the fermenter and enters the keg in via the gas in post at the top, and the starsan leaves the keg via the liquid outpost from the dip tube which is at the bottom of the keg ? Or am I missing something?
I've been using this method for some time, but with the addition of a second empty keg in a daisy chain setup to receive the starsan via the liquid dip tube on the empty keg and a spunding valve on the empty keg gas post to create the desired pressure.

 

[Bolsover Brewer]

Where are the bubbles coming from ? if CO2 to leaves the fermenter and enters the keg in via the gas in post at the top, and the starsan leaves the keg via the liquid outpost from the dip tube which is at the bottom of the keg ? Or am I missing something?
I've been using this method for some time, but with the addition of a second empty keg in a daisy chain setup to receive the starsan via the liquid dip tube on the empty keg and a spunding valve on the empty keg gas post to create the desired pressure.

The bubbles are the foaming agent in the sanitiser. It would be preferable to use a none foaming sanitiser. As I mentioned previously the CO2 from the ferment would do as good a job as any in reducing O2 in a keg to an acceptable level, its free and simple.

 

[Davegase]

The bubbles are the foaming agent in the sanitiser. It would be preferable to use a none foaming sanitiser. As I mentioned previously the CO2 from the ferment would do as good a job as any in reducing O2 in a keg to an acceptable level, its free and simple.

The keg is completely filled with a starsan till all the foam is forced out of the of the keg so it's completely filled with liquid.

 

[Bolsover Brewer]

The keg is completely filled with a starsan till all the foam is forced out of the of the keg so it's completely filled with liquid.

And you are saying there is no O2 taken up by the liquid?

 

[Davegase]

And you are saying there is no O2 taken up by the liquid?

Obviously not, water does contain O2 !
But pushing the solution out with CO2 is obviously easier than purging air out with CO2 . Air and C02 will mix much more freely than sanitiser solution and CO2 !

 

[Bolsover Brewer]

Obviously not, water does contain O2 !
But pushing the solution out with CO2 is obviously easier than purging air out with CO2 . Air and C02 will mix much more freely than sanitiser solution and CO2 !

I am not asking you to change what you are doing. Just pointing out that a far more simple and effective method would be to use the CO2 produced by fermentation of the wort through an empty sanitised vessel. It is more difficult to compress liquid than gas, the O2 in the liquid will be forced out by the CO2 pressure on the liquid mixing with the CO2. A couple of kg of CO2 purging through a keg over a 3 day period would be as effective if not more so. And it costs nothing.

 

[Davegase]

I am not asking you to change what you are doing. Just pointing out that a far more simple and effective method would be to use the CO2 produced by fermentation of the wort through an empty sanitised vessel. It is more difficult to compress liquid than gas, the O2 in the liquid will be forced out by the CO2 pressure on the liquid mixing with the CO2. A couple of kg of CO2 purging through a keg over a 3 day period would be as effective if not more so. And it costs nothing.

I already use the fermentation gas to push the sanitizer out, when the sanitizers out the fermentation gas continues to go through the keg.
I don't know the exact figures, but I would have thought there was more oxygen in 19 l of air than there was in 19 l of water.
I don't apply pressure with the spunding valve until after the sanitizer has pushed out.

 

[Bolsover Brewer]

I already use the fermentation gas to push the sanitizer out, when the sanitizers out the fermentation gas continues to go through the keg.
I don't know the exact figures, but I would have thought there was more oxygen in 19 l of air than there was in 19 l of water.
I don't apply pressure with the spunding valve until after the sanitizer has pushed out.

Well if you are pushing sanitiser out with the gas from the ferment then your ferment is under pressure! The volume of air in a keg is far far less than the volume of CO2 coming from a fermenting vessel.
Because there is no pressure the gasses will mix and vent together, I would say, and put money on, that by the end of the ferment there will be minimal O2 in the keg.

 

[RoomWithABrew]

I think you are forgetting about gas laws. Basically a liquid is just a really dense gas or vice versa.

The links in this post explain the science / the physics.

If the keg to be prepared for receiving the beer is filled with starsan to full there is no foam. Yes there will be a small amount of dissolved oxygen in the starsan solution but in equilibrium with air.
Purge with ferment gas ideally after the first half of fermentation to ensure that you are not purging with ferment gas that has residual oxygen from the start of ferment. Yes the liquid is difficult to push out, however if it is directed to an open second keg you can set up a siphon so it's easy. Be careful with this as it can collapse your pet fermenter if you are using one of those and you could empty wort / beer out through your fermenter gas port.
Once the keg is empty of starsan then put your spunding valve on the gas post of the keg and continue to purge to reduce any retained oxygen further.
Start with this thread
https://www.homebrewtalk.com/threads/purging-keg-with-ferm-co2-anvil-bucket.699284/#post-9246833
and then if you have a clear head read post 3 of this thread although a lot of info in the other posts

https://www.homebrewtalk.com/threads/keg-purging-with-active-fermentation.628658/#post-8004741
You could of course sanitise with Starsan, then empty keg, fill keg with sodium metabisulphite solution ( which will react with any dissolved oxygen ) and then purge that with ferment gas. When you are ready to use keg just invert keg and pull PRV to get the last dregs of Sod met Water solution out and fill her up. Some people add ascorbic acid at the transfer stage as this also binds free oxygen. Both of these "additions " tend to divide people and I'm on the fence about it.
But this recent thread discusses Ascorbic acid ( vitamin C )

https://www.homebrewtalk.com/threads/vitamin-c-the-game-changer.698328/

 

[Bolsover Brewer]

I think you are forgetting about gas laws. Basically a liquid is just a really dense gas or vice versa.

The links in this post explain the science / the physics.

If the keg to be prepared for receiving the beer is filled with starsan to full there is no foam. Yes there will be a small amount of dissolved oxygen in the starsan solution but in equilibrium with air.
Purge with ferment gas ideally after the first half of fermentation to ensure that you are not purging with ferment gas that has residual oxygen from the start of ferment. Yes the liquid is difficult to push out, however if it is directed to an open second keg you can set up a siphon so it's easy. Be careful with this as it can collapse your pet fermenter if you are using one of those and you could empty wort / beer out through your fermenter gas port.
Once the keg is empty of starsan then put your spunding valve on the gas post of the keg and continue to purge to reduce any retained oxygen further.
Start with this thread
https://www.homebrewtalk.com/threads/purging-keg-with-ferm-co2-anvil-bucket.699284/#post-9246833
and then if you have a clear head read post 3 of this thread although a lot of info in the other posts

https://www.homebrewtalk.com/threads/keg-purging-with-active-fermentation.628658/#post-8004741
You could of course sanitise with Starsan, then empty keg, fill keg with sodium metabisulphite solution ( which will react with any dissolved oxygen ) and then purge that with ferment gas. When you are ready to use keg just invert keg and pull PRV to get the last dregs of Sod met Water solution out and fill her up. Some people add ascorbic acid at the transfer stage as this also binds free oxygen. Both of these "additions " tend to divide people and I'm on the fence about it.
But this recent thread discusses Ascorbic acid ( vitamin C )

https://www.homebrewtalk.com/threads/vitamin-c-the-game-changer.698328/

And the simple way is, as I have been saying, clean and sanitise the keg, let it dry. Hook the keg up to the fermenter and the venting CO2 will get as good if not better than any other method.
At the moment I have a plastic bucket with a tap I fill my kegs up through the tap using a hose. Prime with a sugar solution and in all the years have never had an oxidised beer.

 

[RoomWithABrew]

@Bolsover Brewer
Some beers are meant to be oxidised anyway.
But if you want your dissolved oxygen in the parts per billion range you have to start with as little oxygen as possible and then reduce it more. Which is explained in the maths by doug293cz. I'm not suggesting you change your own practice which works for you and many others, just directing those reading the thread towards another option which might give them better short and long term results. Certainly will pay off if you want a super hoppy beer to drink consistently from beginning to end.
I don't make many beers like that but do purge starsan out with ferment gas and pressurise the keg up to my vols needed then use that pressure to drive the closed transfer as well. It keeps my beer happy and saves CO2, which we all need to do.

 

[foxy]

Making beer isn't as complicated as some home brewers make it out to be. I have said a few times oxidation in the home brewing world isn't the bogey man to the home brewer as it is to the commercial brewers.
I would say those who have been brewing for a while and those without a closed vessel system can fill either kegs or bottles from the fermenter and never come within a bulls roar of oxidised beer.
I have had an oxidised beer once and it took 2 to 3 years to oxidise. Our beers aren't travelling great distances, getting shook up, being kept at temperatures above 20 C.
I have put this guide up a few times now regarding kegging maybe it should be pinned.
https://www.themodernbrewhouse.com/...rging-transferring-stabilizing-finished-beer/

 

[Buffers brewery]

Making beer isn't as complicated as some home brewers make it out to be. I have said a few times oxidation in the home brewing world isn't the bogey man to the home brewer as it is to the commercial brewers.
I would say those who have been brewing for a while and those without a closed vessel system can fill either kegs or bottles from the fermenter and never come within a bulls roar of oxidised beer.
I have had an oxidised beer once and it took 2 to 3 years to oxidise. Our beers aren't travelling great distances, getting shook up, being kept at temperatures above 20 C.
I have put this guide up a few times now regarding kegging maybe it should be pinned.
https://www.themodernbrewhouse.com/...rging-transferring-stabilizing-finished-beer/

That’s an interesting article @foxy . I think the quest for absolutes in ridding our brews of oxygen is a folly. Reducing is a sensible approach with whatever method, simple or complicated (my preferred option ) is the way to go. I can see merits in all the methods mentioned, each having their own trade-off.

 

[Eskdale]

In the brewery we daisy chain the kegs, fill the first with PAA and de oxygenated water pushed through with nitrogen. Two reasons PAA is environmental friendly and readily breaks down, nitrogen is also environmentally friendly, and cheaper than co2.
I don't keg but use a secondary, I flush with co2 from the ferment if dry hopping with the dry hops already in the secondary, cold condition and collect the yeast from the primary fermenter.

Emma

 

[RoomWithABrew]

Nitrogen is a lot more expensive than CO2 for us. But I use the ferment gas to purge and carbonate the beer and run the transfers. So I use very little, trying to compensate for having the environmental " disaster " of a leak when I set the keg fridge up and lost a whole 5kg cylinder.
It's penance or OCD!

 

[RichardS]

I was thinking about the water v starsan question. I'm not sure that I want to dump 19 litres of starsan away just to get an O2 free keg. But then method 1 uses a lot of CO2.
How about filling the keg with water, and then displacing it with CO2 gas.
To sanitise, pressurise a plastic coke bottle filled with a litre of starsan and transfer to the keg. Shake the keg around, and then connect to the gas and pour out the starsan

 

[Paul7189]

I clean three or four kegs and fill one to the brim with starsan. I then connect the gas to the liquid of the next keg and purge the first keg with CO2, displacing the starsan into the next keg. Then that will be purged into the next keg and so on. One full keg of starsan to sanitise 4 kegs. You could use your fermentation to provide the CO2 but the resistance on a few kegs might be a bit much. After they’re all purged I pressurise them to 15psi with my cylinder to ensure they remain sealed. I check the relief valve before use each time.
Once this is finished I tag each keg as clean, sanitised and purged with CO2 with a sticker. Then for transfer I use a closed transfer feeding the co2 back into the fermenter.