# Oops! Forgot To Purge Keg Before Beer Went In!



## Aus_Rider_22 (24/2/10)

I could be worrying over nothing here! I just sat down and started sipping away after filling a keg up with a basic Coopers Lager/Cluster recipe and just realised I didn't pump Co2 into the keg to purge the air. Do I have much to worry about? I curled the racking line along the bottom of the keg so the beer shouldn't have splashed at all when it was transferred. I purged it at the end 3 times. Should this be sufficient?


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## marksfish (24/2/10)

it should be o.k as long as it is kept cold.


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## jyo (24/2/10)

Aus_Rider_22 said:


> I could be worrying over nothing here! I just sat down and started sipping away after filling a keg up with a basic Coopers Lager/Cluster recipe and just realised I didn't pump Co2 into the keg to purge the air. Do I have much to worry about? I curled the racking line along the bottom of the keg so the beer shouldn't have splashed at all when it was transferred. I purged it at the end 3 times. Should this be sufficient?



As long as you didn't splash while transfering, which sounds like you didn't, then you should be right mate.


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## Aus_Rider_22 (24/2/10)

jyo said:


> As long as you didn't splash while transfering, which sounds like you didn't, then you should be right mate.



Yeh hopefully that part is fine.  



marksfish said:


> it should be o.k as long as it is kept cold.



I am conditioning it in the keg so it will be kept at 25-30. Bit early to drink it.

How come you say it would have to be kept cold?


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## marksfish (24/2/10)

the main reason to keep your beer cold is the lower temp the effects of possable oxidisation will take longer to show.


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## Pete2501 (24/2/10)

Aus_Rider_22 said:


> I could be worrying over nothing here! I just sat down and started sipping away after filling a keg up with a basic Coopers Lager/Cluster recipe and just realised I didn't pump Co2 into the keg to purge the air. Do I have much to worry about? I curled the racking line along the bottom of the keg so the beer shouldn't have splashed at all when it was transferred. I purged it at the end 3 times. Should this be sufficient?



Transfer beer while cold - Check 
Avoid splashing - Check
Purge with CO2 - Check

Relax, stress less and have a home brew - Pending. 

As my beer is cold when I transfer to a keg I don't worry so much about purging before transfer. Stop stressing so much dude.


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## Greg Lawrence (24/2/10)

I think you should be OK as long as the keg was sterile.
I have never purged a keg with C02 before filling and havent had a problem so far after close to 80 kegs.
Most of the time they only get quick rinse between fills and a good clean every 3 or so fills.
I have even filled a few kegs witout cleaning them out 1st (by mistake) without a problem, but there were full of C02 from serving the last beer.

Thats just my experience, Im sure someone will shoot me down in flames and tell me Im an idiot.
Maybe my methods will change after my 1st infection.


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## chappo1970 (24/2/10)

Oh crap your beers prpably buggered. Better send to Chappo Manor for immediate evaluation! Stat! Don't waste time getting into the post ASAP!

RHAHB!


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## Aus_Rider_22 (24/2/10)

haha sorry fellas. I was just worried. I see alot of threads and think some people overstress but this time it was me!  

I always rinse the keg out after she runs dry and leave it upside down. Gave it a good wash out this arvo, took out poles and dip tubes and StarSanned it all. Was a bit of froth on the internals but I've read that's not a bad thing. 



Gregor said:


> I have never purged a keg with C02 before filling and havent had a problem so far after close to 80 kegs.



That's awesome to hear! I haven't had an infection yet (knocks on wood!) It's probably inevitable that I will one day but hopefully not in this keg. I am currently polishing of the last of LCBA clone and this month is going to painful to wait! Shame on me for not being better prepared and having enough beer ready!


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## peas_and_corn (25/2/10)

I've never purged with CO2. It just strikes me as being a waste of CO2.


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## MarkBastard (25/2/10)

peas_and_corn said:


> I've never purged with CO2. It just strikes me as being a waste of CO2.



I've only started doing it recently since using Starsan. I use co2 to push the Starsan out so it's in there anyway. Not a bad way to do it.


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## Thirsty Boy (25/2/10)

Your beer will have more dissolved oxygen than it would if you had purged the keg - therefore it will go stale faster than it would if you had purged the keg.

Will that be before you have drunk it all??? depends on how long you take to drink it.

Oxygen in your finished beer is about rate of decline - lots of oxygen and it will probably be knackered in a few weeks, very good practice & low oxygen and you might get 6 or 8 months out of it before it really starts to show its age (talking light lagers here)

Its not about "oh I have ruined it", its about _how long_ till it starts to head south.


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## Fourstar (25/2/10)

Thirsty Boy said:


> Your beer will have more dissolved oxygen than it would if you had purged the keg - therefore it will go stale faster than it would if you had purged the keg.
> Will that be before you have drunk it all??? depends on how long you take to drink it.
> Oxygen in your finished beer is about rate of decline - lots of oxygen and it will probably be knackered in a few weeks, very good practice & low oxygen and you might get 6 or 8 months out of it before it really starts to show its age (talking light lagers here)
> Its not about "oh I have ruined it", its about _how long_ till it starts to head south.



Well said Thirsty.

The way i transfer to the keg with minimal O2 uptake is:

- Purge the keg entirely via the beer out ppost and bleed the PRV and gas in post.
- I then connect a beer disconnect which has also been purged with CO2 to the beer out post.
-This has a length with a length of line to a JG fitting with some silicone hose attached and plugs onto the fermenter tap (fermenter connector from craftbrewer for filter).
- Open PRV and then open tap.

Problem solved.


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## Greg Lawrence (25/2/10)

Thirsty Boy said:


> Your beer will have more dissolved oxygen than it would if you had purged the keg - therefore it will go stale faster than it would if you had purged the keg.




Surely purging the keg with co2 once filled (before force carbing) would overcome this problem.
I dont think the beer would absorb too much oxygen when filling the keg as it is not under any pressure.

Gregor


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## mxd (25/2/10)

if you are going to "naturally" carbonate in a keg should you purge the Keg with CO2?

I had one keg, I filled with CO2 then burped and naturally carbonated and when I put it in the freezer (3 weeks later) it was seemed as though it had not carbonated.

The one I did a couple of weeks ago I didn't purge or burp and when I put it in the fridge the carbonation level seemed great.

So I am now more confused about to do.

Fortunately my risk mitigation is to finish kegs in 3 weeks


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## Cortez The Killer (25/2/10)

peas_and_corn said:


> I've never purged with CO2. It just strikes me as being a waste of CO2.


Agree


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## Tony M (25/2/10)

I'm far too stingy to purge a keg with CO2 but I make sure the fill hose goes right to the bottom of the keg. That way, there is no splashing or turbulence after the first litre or so and that is the biggest culprit when it comes to oxygen uptake.


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## Fourstar (25/2/10)

peas_and_corn said:


> I've never purged with CO2. It just strikes me as being a waste of CO2.





Cortez The Killer said:


> Agree



Considering i got 40 odd batches, force carb, serving and purging from a large size mykegonlegs i dont think i lost all that much c02 down the drain. 5 bucks worth? if that?!


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## Greg Lawrence (25/2/10)

This is getting to be like a fold or scrunch debate. Both methods work, neither side can be convinced that the other way is better.
Im a folder by the way.

Edit: I dont purge before filling and am not too concerned with wasting C02. Its one of the cheapest parts of brewing.


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## SpillsMostOfIt (25/2/10)

Consider that with the method Thirsty Boy describes you get a completely sanitised system that is guaranteed to be purged of any atmospheric oxygen. If you're filtering, that gets sanitised into the bargain. It does cost you money, but so does almost everything you do as part of brewing. I guess it is up to the individual brewer to decide if it is a reasonable expense for them.

Kegged beer is for drinking at my house, so I don't bother. But I do so with the filtering unit if I am using it and on special occasions - such as if I am going to take it to a party or something. But, it also goes into the fridge almost as soon as it has been filled, so although it has probably absorbed some oxygen, the effects will be slowed - hopefully enough that it isn't noticed until after the last glass is drained.

If I am naturally carbonating in any sized vessel, I would have thought that doing so with yeast in their anaerobic state is best and therefore reducing available atmospheric oxygen remains a good idea.

Clearly what is needed is to make the brewery completely air-tight but for a small PRV in the roof/ceiling so the CO2 produced by fermentation expels all other gas in the brewery. The brewer then simply needs to don a small aqualung to safely conduct any packaging tasks. :lol:


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## Greg Lawrence (25/2/10)

I usually fill 2 bottles per brew and keg the rest of it.
Maybe I should be purging the bottles of oxygen before filling to get a better result.
Do any of you purgers do this?


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## Aus_Rider_22 (25/2/10)

Gregor said:


> I usually fill 2 bottles per brew and keg the rest of it.
> Maybe I should be purging the bottles of oxygen before filling to get a better result.
> Do any of you purgers do this?



ha! That's actually an interesting point I hadn't thought of! :huh:


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## Thirsty Boy (25/2/10)

Gregor said:


> Surely purging the keg with co2 once filled (before force carbing) would overcome this problem.
> I dont think the beer would absorb too much oxygen when filling the keg as it is not under any pressure.
> 
> Gregor



Better than not doing it - but not as good as purging



mxd said:


> if you are going to "naturally" carbonate in a keg should you purge the Keg with CO2?
> 
> I had one keg, I filled with CO2 then burped and naturally carbonated and when I put it in the freezer (3 weeks later) it was seemed as though it had not carbonated.
> 
> ...



Whether it carbonates or not has nothing to do with purging or not purging



Tony M said:


> I'm far too stingy to purge a keg with CO2 but I make sure the fill hose goes right to the bottom of the keg. That way, there is no splashing or turbulence after the first litre or so and that is the biggest culprit when it comes to oxygen uptake.



Once again, better than not watching out for it, but not as good as purging. You can splash all you like if there is no oxygen in there, so your technique stops being a critical control point.

Oxygen post fermentation is bad - it is the worst - barring an outright infection - thing that you can do to your beer if shelf-life is a concern. Like I said, you don't "ruin" your beer by not worrying, or worrying less - but naturally carbonated or not - less oxygen exposure is better for your _shelf life_.

Whether the cost/effort of purging is worth it too you... that might be debatable and I'm not saying anyone is doing it "wrong" - but there really isn't any sensible argument around the fact that reducing packaging oxygen (and purging your keg is one way to do it) is better than not reducing packaging oxygen.

Its all about where you personally decide to draw the line


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## Brewman_ (25/2/10)

Sounds like a discussion between the "best practice" and "fit for purpose". Take your pick.

Just one extra point, CO2 is heavier than O2, so CO2 will naturally fall below O2 and N2 in air. So even if you do not purge your keg with CO2, then the liquid rising in your keg will gently move the air out containing the O2, while at the same time any CO2 that is precipitating from the beer will generally form a layer over the rising liquid, and so mitigate to an extent any O2 dissolving into your beer.

Hey there are risks. There are risks in every step of brewing, but are they acceptable, that's the question.

Fear_n_loath


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## jyo (25/2/10)

I have been kegging for a few years now, and #1 rule I was told by many was to purge the keg. Because CO2 is heavier than air, you don't need to chuck much in there, so wastage should not be an issue; it sits at the bottom of the keg, and the blanket of gas rises with the level of the beer whilst filling. 
I just do it, 'cause I'm a pedantic prick.

Edit, Fear n Loath just covered some of this.


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## Thirsty Boy (26/2/10)

jyo said:


> I have been kegging for a few years now, and #1 rule I was told by many was to purge the keg. Because CO2 is heavier than air, you don't need to chuck much in there, so wastage should not be an issue; it sits at the bottom of the keg, and the blanket of gas rises with the level of the beer whilst filling.
> I just do it, 'cause I'm a pedantic prick.
> 
> Edit, Fear n Loath just covered some of this.




I think that the blanket of C02 thing is hooey - the level of mixing from brownian motion, let alone the turbulence of gassing, filling, moving the keg etc is enough to completely disrupt it. C02 blankets are folklore rather than fact. Better than nothing I suppose, but hardly worth it IMO.

I'd rather see someone not worrying, than wasting time effort and money on something that is going to be fundamentally ineffective.

Pressurize and release will reduce the O2 in the keg - pressurize to 1 atmospheres (15psi) and vent... half the 02 and halve again each time you repeat. Best practice though is to displace a liquid which will completely remove any non C02 gases.

Once again, its about how much trouble you want to go to - displacing a liquid fits really well with my filter and sanitation process, so its no effort for me. So its what I think is "right" - whats right for you will be different.


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## Brewman_ (26/2/10)

[half the 02 and halve again each time you repeat. 

Well that sounds the the way to go.

How many times would you reccomend that you repeat? What is a "safe" level of O2?

Fear_n_Loath


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## Thirsty Boy (27/2/10)

fear_n_loath said:


> [half the 02 and halve again each time you repeat.
> 
> Well that sounds the the way to go.
> 
> ...



Back to the "how much gas do you want to waste" thing - if you pressurize and vent, you lose (at 1 atmosphere) 1/2 the O2 .. but also a kegs full of CO2 - and again every time you do it... so its 1/2 - 1/4 - 1/8 - 1/16th... and 80L of C02

The safe level of 02.. is the least you can manage. Less is always better. So for mine, three pressurize/vent cycles minimum and then transfer carefully to minimise picking up the any of whats left (12% ish of the amount you started with) or save yourself the time and don't bother.

However - If you displace a full keg of water or sanitiser you get rid of 100% of the O2 and use maybe 20-22L of C02 - and thats what I would recommend.

A trick if you dont want to have to deal with a full kegs worth of sanitiser, is to use a high foaming no-rinse like starsan - then you can half fill the keg, push gas into the liquid side till it froths - the froth will be 100% full of CO2 and as it rises will push out the oxygen, when foam comes out the pressure relief, then the keg is fully purged. Same thing but you only have to have a container big enough to hold 9 or 10L of sanitiser instead of the full 20ish needed to completely fill a keg.


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## SpillsMostOfIt (27/2/10)

fear_n_loath said:


> Just one extra point, CO2 is heavier than O2, so CO2 will naturally fall below O2 and N2 in air. So even if you do not purge your keg with CO2, then the liquid rising in your keg will gently move the air out containing the O2, while at the same time any CO2 that is precipitating from the beer will generally form a layer over the rising liquid, and so mitigate to an extent any O2 dissolving into your beer.



I believe this to be a common home-brewing myth. If it were completely true, we would all die of suffocation on still days and SCUBA gear would be a more common part of a dry caver's equipment.


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## jyo (27/2/10)

SpillsMostOfIt said:


> I believe this to be a common home-brewing myth. If it were completely true, we would all die of suffocation on still days and SCUBA gear would be a more common part of a dry caver's equipment.



You are never going to achieve the concentrations of CO2 in the natural environment that you will in a keg. As CO2 only comprises 0.038% of all atmoshephere gases, the possible levels that form a layer of C02 in a cave would be tiny. 

C02 is much heavier than air- fill up a balloon from your bottle, and blow one up with normal air and drop them at the same time. What i am getting at is that the concentrations we pump into a keg to form the layer is MUCH higher than that in the atmoshpere, therefore, you are looking at a nice buffer of about 10-15 cm's of gas, which is pleasing to my pedantic mind.
I'm not trying to be a smart arse, SpillsMostOfIt, merely justifying my overuse of gas. :icon_cheers: 

Cheers, john.


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## SpillsMostOfIt (27/2/10)

jyo said:


> You are never going to achieve the concentrations of CO2 in the natural environment that you will in a keg. As CO2 only comprises 0.038% of all atmoshephere gases, the possible levels that form a layer of C02 in a cave would be tiny.
> 
> C02 is much heavier than air- fill up a balloon from your bottle, and blow one up with normal air and drop them at the same time. What i am getting at is that the concentrations we pump into a keg to form the layer is MUCH higher than that in the atmoshpere, therefore, you are looking at a nice buffer of about 10-15 cm's of gas, which is pleasing to my pedantic mind.
> I'm not trying to be a smart arse, SpillsMostOfIt, merely justifying my overuse of gas. :icon_cheers:
> ...



If the atmosphere is between 11 and 100 kilometres thick (depending on how you define it) and CO2 did drop to the bottom of any container it found itself in, would we not find the lower 4 metres of so of the air we breath significantly more than 0.038% CO2?

I *am* trying to be a smart arse  , but I also do not subscribe to the blanket theory. I *do* subscribe to doing whatever works for you though.


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## jyo (27/2/10)

SpillsMostOfIt said:


> If the atmosphere is between 11 and 100 kilometres thick (depending on how you define it) and CO2 did drop to the bottom of any container it found itself in, would we not find the lower 4 metres of so of the air we breath significantly more than 0.038% CO2?
> 
> I *am* trying to be a smart arse  , but I also do not subscribe to the blanket theory. I *do* subscribe to doing whatever works for you though.



I see your point, but we also have trees and algae that pump out O2 at ground/ sea level.

Agree, whatever works. If brewers have no issues with not purging, then brew away happily.


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## SpillsMostOfIt (27/2/10)

jyo said:


> I see your point, but we also have trees and algae that pump out O2 at ground/ sea level.



... and wind and thermal gradients and birds and stuff  as we do high-pressure gas bottles that push the CO2 into kegs and stir things up. My real point is that there is enough going on in the gas soup inside your keg that you are unlikely to get any stratification of gas in there unless you leave it for quite a while at a *very* low and *very* constant temperature to settle out - and at that point you've either lost interest in waiting and your beer went off in the fermenter or you burnt your fingers trying to move the keg.

I recall reading somewhere - probably on the interwebs, so it is likely rubbish - that in professional packaging circles, 5% airspace in a beverage bottle is considered okay. At the risk of veering towards the original subject (oh no!!) I wonder *how much* oxygen is required to ruin beer at what rate...


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