How do I purge a keg?

[makisupapolice14]

Ha, tbh I was once 'that guy' too. We all have to start somewhere, right?



As for oxygen-free transferring, you can first purge your keg (many of us fill it completely with sanitizer and use CO2 to push it out, effectively leaving very minimal residual O2 in the keg). Then you can connect your tubing from your racking cane to a quick-disconnect, and have the beer flow into the keg via the 'out' post (diptube). You'll have to either pop up the PRV and keep it open so that the air in the keg can escape as the beer fills it, or you can connect a gas QD to the gas post and let the air out that way.



Here's a pic to illustrate:





Purging the keg afterwards is still recommended.



If you really don't want the beer to touch O2, you can also get one of the carboy caps with 2 ports and use one for your racking cane, and the other to push CO2 into the carboy (and thus use the CO2 to push the beer out via the racking cane). I don't go this far, as I feel that the few minutes that the beer may have in contact with any O2 drawn into the carboy will be purged anyway. It's such a short period of time and I don't find the beer has a chance to absorb any O2 (though I'm sure it happens on a very small scale).

Newb kegger question but with this method once you have the prv released do u just rack/pump the autosiphon as usual and let "gravity" do the work with the beer floating through the liquid out dip tube while pulling the prv to release co2? In other words I don't need to apply any additional co2 or have the gas hooked up correct? Thanks!

 

[LKABrewer]

Correct

 

[makisupapolice14]

Thanks so much!

 

[ParanoidAndroid]

So, when we purge at 30 psi 13 times, is that empty, then fill, then do 13 more?....or is it fill, then purge 13 times?

 

[UndeadFred]

Every time you purge you are "watering down" the air/Oxygen in the headspace of the keg with more and more CO2.

On a ball lock, that is typically the PRV with the ring pull on it to purge. On a pin (or pin converted to ball lock), you disconnect the gas in, and use a coin or screw driver to press in the poppet, accomplishing the same thing.

13 times is probably excessive, but no matter how many times you will never get zero O2. There are people who will recommend filling the keg up with sanitizer and pumping that into another keg with CO2 to purge for that reason.. but as soon as you siphon in you are going to have O2 in it again. You have to be able to pump out of the fermenter using CO2 to avoid Oxygen entirely.

Probably the only way to have no O2 in the Keg is to transfer mid fermentation and use a Spunding valve (a pressure relief valve) or to ferment in a keg that way and transfer to a second one using CO2. (You use a shortened dip tube in the first if you do that to leave trub in the first keg).

Having said all of that, most of us purge three to six times after siphoning our beer into the keg. It's what I define as "adequate for most uses"... 13 times likely is going to be a waste of CO2 for what little you will gain over 3-6 times...

One other way to reduce O2 a little is to "keg condition" or prime in the keg.. the yeast in carbonating the beer will remove O2 in the headspace as well.. but likely not 100% again.

 

[TorMag]

There are way too many big words in this thread. I just drink my kegged beer fast enough that there oxy thing don't happen.

 

[doug293cz]

So, when we purge at 30 psi 13 times, is that empty, then fill, then do 13 more?....or is it fill, then purge 13 times?

The calculations are based on what's in the headspace after venting. So, pressurize 13 times, vent 13 times (or use whatever number you are comfortable with), and then pressurize one last time for carbonating.

Brew on