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

[Davegase]

I always do option 1 - the purge and vent. I have floating dip tubes in all my cornys and I find they are less effective in extracting the last of the liquid from the bottom of the keg than the fixed dip tube. I'm concerned that if I used the sanitised water displacement method then I would be left with too much sanitised water in the bottom than I would want. It would defeat the object if I then had to open the keg and tip the remaining water out.

I haven't yet suffered an oxidised beer using the purge and vent method, or at least not one that was obviously oxidised.

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[Hazelwood Brewery]

For pretty much everything method 1.

I have just started trying something different for highly hopped ales and it might be an option 5…or a variant of several others . After primary fermentation replace the bubble trap with a Mylar balloon partially filled with CO2 to allow the fermenter to “breath” CO2. At the time of kegging, I have a Mylar balloon full of CO2 doing nothing so I pour the CO2 from the Mylar balloon into the keg before siphoning the beer in. Being heavier than air it will fall to the bottom of the keg displacing the air. This won’t remove 100% of the oxygen in the space above the beer but I think it’s probably quite close. When the keg is full I then purge and vent (method 1) as usual. I’ve no idea whether this makes any difference yet as I’ve just started doing it.

 

[Tess Tickle's Brewery]

I have a question please. If I wanted to use method 1 only, how long would I need to pull the PRV for? I know they say pull it three times plus, but for how long?

The reason I ask is at some point I want to pressure transfer onto some fruit puree so making my usual method 3 very awkward. Also can't use method 3 if my fermentation is shut away in a fridge.

Perhaps a tiny bit of metabisulfite in the fruit puree 24 hours before transfer?

 

[BlackRegent]

@LisaMC

I pull the PRV until I can hear it depressurise. It normally evacuates before the cylinder can fill it back up again. Maybe 2-3 seconds at most.

 

[Tess Tickle's Brewery]

OK thank you. What would happen if I pulled it for longer (on an empty keg)? Am I just wasting gas?

 

[Buffers brewery]

For pretty much everything method 1.

I have just started trying something different for highly hopped ales and it might be an option 5…or a variant of several others . After primary fermentation replace the bubble trap with a Mylar balloon partially filled with CO2 to allow the fermenter to “breath” CO2. At the time of kegging, I have a Mylar balloon full of CO2 doing nothing so I pour the CO2 from the Mylar balloon into the keg before siphoning the beer in. Being heavier than air it will fall to the bottom of the keg displacing the air. This won’t remove 100% of the oxygen in the space above the beer but I think it’s probably quite close. When the keg is full I then purge and vent (method 1) as usual. I’ve no idea whether this makes any difference yet as I’ve just started doing it.

Sounds like the beginnings of a method 5. Just a suggestion, how about running the CO2 from your balloon through a long(ish) tube to the bottom of the keg so it fills from the bottom, minimising mixing with the air that’s already in the keg? Are you squeezing the balloon or just letting it vent naturally?

 

[Hazelwood Brewery]

how about running the CO2 from your balloon through a long(ish) tube to the bottom of the keg

Should be easy, I could use the syphon tube prior to syphoning.

Are you squeezing the balloon or just letting it vent naturally?

Gentle squeeze - enough to push the CO2 out, not enough (I hope) to create too much turbulence in the keg.

 

[The-Engineer-That-Brews]

A quick observation about method #1 vs. method #2:

Pressurising an empty 20L keg at 20 PSI means adding 12L of pure CO2 to the gas already in it (from Boyle's Law).​

​

Therefore after one pressurise/vent cycle the keg would contain 60% CO2 and 40% air,​

after two cycles, 84% CO2 and 16% air,​

after three cycles, 93% CO2 and 6.4% air.​

​

This procedure would use 36L CO2, and the gas in the keg would still be 6.4% air (1.3% oxygen).​

In contrast, method #2 uses 19L of CO2 and results in the gas in the keg being 100% CO2.

 

[The-Engineer-That-Brews]

[...] tube to the bottom of the keg so it fills from the bottom, minimising mixing with the air that’s already in the keg

I'm pretty sure that air and CO2 would actually mix rather quickly, due to the high velocity of the gas molecules (over 500 metres/sec at room temp)

 

[RoomWithABrew]

@LisaMC

I pull the PRV until I can hear it depressurise. It normally evacuates before the cylinder can fill it back up again. Maybe 2-3 seconds at most.

Not a corny user but if your gas post is very short ( might need surgery ) then invert the keg after the starsan is purged and it's pressured with ferment CO2.
Pull the FRV briefly and you'll vent the last of the starsan.

Other option is to clean your kegs and sanitise with starsan and drain. Then fill with Water and Sod Met, purge this and any remaining liquid with Sod met in will continue to sanitise and scavenge any oxygen plus any oxygen when you closed transfer.

 

[Hazelwood Brewery]

A quick observation about method #1 vs. method #2:

Pressurising an empty 20L keg at 20 PSI means adding 12L of pure CO2 to the gas already in it (from Boyle's Law).​

​

Therefore after one pressurise/vent cycle the keg would contain 60% CO2 and 40% air,​

after two cycles, 84% CO2 and 16% air,​

after three cycles, 93% CO2 and 6.4% air.​

​

This procedure would use 36L CO2, and the gas in the keg would still be 6.4% air (1.3% oxygen).​

In contrast, method #2 uses 19L of CO2 and results in the gas in the keg being 100% CO2.

One of us has misunderstood method 1. I don’t purge using method 1 until AFTER filling the keg. I then purge the tiny head space.

 

[RoomWithABrew]

One of us has misunderstood method 1. I don’t purge using method 1 until AFTER filling the keg. I then purge the tiny head space.

How do you purge the dissolved oxygen from the liquid that will come out to get equilibrium once you have purged the tiny head space?

 

[Hazelwood Brewery]

How do you purge the dissolved oxygen from the liquid that will come out to get equilibrium once you have purged the tiny head space?

I don’t. Oxygen in the air comes into contact with the surface of my beer as I fill the keg and some will get dissolved. I accept that.

As I noted earlier for more hoppy beers I try to blanket the beer as it goes into the keg to reduce any contact of air with the surface of my beer.

In my latest few brews I’ve also added high alpha-acid hops to the mash to complex metal ions. This reduces the number of pro-oxidative ions in the finished beer and makes it less of an oxygen sponge.

In general though I don’t have a problem because I don’t brew many highly hopped beers and I drink my beers fairly quickly.

 

[Tess Tickle's Brewery]

This is all very confusing.

My husband states I am taking the oxygen thing too seriously and from what I can gather he's probably right!

 

[Hazelwood Brewery]

This is all very confusing.

My husband states I am taking the oxygen thing too seriously and from what I can gather he's probably right!

I think you need to take it more seriously as you increase the hops and the longer you want your beer to last.

For regular bitters, stouts, mild, pale ales that you expect to drink within a couple of months, you don’t need to take special measures - but don’t invite oxygen either with lots of exposure and splashing.

If you’re making an insanely hopped NEIPA you do need to be paranoid about any contact with oxygen. Even the oxygen caught between the leaves of leaf hops (while dry hopping) can turn one of these beers bad in days.

 

[Tess Tickle's Brewery]

Oh my goodness! I'll carry on being paranoid then

My nerves are shot from worrying about it lol

 

[Tess Tickle's Brewery]

A quick observation about method #1 vs. method #2:

Pressurising an empty 20L keg at 20 PSI means adding 12L of pure CO2 to the gas already in it (from Boyle's Law).​

​

Therefore after one pressurise/vent cycle the keg would contain 60% CO2 and 40% air,​

after two cycles, 84% CO2 and 16% air,​

after three cycles, 93% CO2 and 6.4% air.​

​

This procedure would use 36L CO2, and the gas in the keg would still be 6.4% air (1.3% oxygen).​

In contrast, method #2 uses 19L of CO2 and results in the gas in the keg being 100% CO2.

If you do method 2, can you get all the sanitiser out? That's one of the reasons I haven't tried this yet.

 

[The-Engineer-That-Brews]

One of us has misunderstood method 1. I don’t purge using method 1 until AFTER filling the keg. I then purge the tiny head space.

From the OP:

Method 1
Pressurise the container (barrel or corny) with CO2 from a regulated gas cylinder. Vent and repeat 3 or more times.

... nothing about filling it with water first?

 

[The-Engineer-That-Brews]

If you do method 2, can you get all the sanitiser out? That's one of the reasons I haven't tried this yet.

I just use plain water Lisa... having already sanitised and rinsed out the keg beforehand :-)

 

[Hazelwood Brewery]

From the OP:

... nothing about filling it with water first?

Not water, BEER!