Flushing Kegs With Co2

[lonte]

Curious how best to flush a keg with CO2 prior to filling? Seeing that (to my eye anyway) CO2 and air are both invisible how do you know that you've fully flushed it? One theory I have heard is that since CO2 is heavier than air then if you fill from the bottom it'll sit low and push the air up and out. Nice theory, but I'd put money on the reality that the turbulence of the CO2 coming in under any sort of pressure in fact stirs up the keg contents and forms a CO2/air mixture rather than a perfect layering of gases.

The other method I have heard is to fill the keg with water (sanitiser even better?) and fill CO2 through the gas in, emptying the liquid out of the beer out. Once it 'blows' you've pretty much emptied the water and the only thing going in was CO2 so it's flushed. That theory sounds good enough to me.

So, does anyone bother with the liquid fill method, or are there other simple approaches to this?

Cheers, L.

edit: crappy grammer

 

[Bribie G]

My filling tube loops a bit at the bottom so when I fill a keg from the bottom it swirls rather than splashes. It only takes a minute or so to fill, then I extract the tube and flush the small headspace. Thus there is probably less concentration of O2 in the headspace than in a conventional bottle filled with a bottling cane. Wouldn't worry too much.

 

[clarkey7]

Lonte,

The first theory you decribed is what I pin my hopes on. I beleive this is fine when you consider you've pushed almost all the gases out by the time the keg is full of beer too.

Then you purge the smaller headspace at the end to be sure.

PB

 

[MHB]

I'm of the flushing/burping with CO2 being a complete WOFTAM school of thought.

Beer in a fermenter is saturated with CO2, as the keg is filled there is enough turbulence created to cause a fair amount of the CO2 to gas off.

To test this theory, I once went and brought a box of BBQ matches, you know the ones about 150mm long, fit a hose to the tap of the fermenter one that goes right to the bottom of the keg being filled, when the keg is about half full, light a match, let the head burn out, then see just how far into the keg it will go before the CO2 extinguishes the flame short answer is not very far.

As a reasonably slow fill of the keg wont stirrup the CO2 too much, I think it very effectively displaces most of the O2 out of the keg (it's the O2 part of the air we are worried about).

Further as we are kegging beer with live yeast in it, the yeast will snap any stray O2 in pretty short order.

I do however think it's a good idea to give a filled keg a squirt of CO2, (just at serving pressure) to make sure all the poppet's and hatch O-ring have seated properly as they are all designed to close by internal pressure. The next day I like to tickle the PRV, just to confirm that the keg is holding a bit of pressure, fairly important if you are keg conditioning your beer as I like to do with most of mine.

MHB

 

[clean brewer]

I:

• Reassemble keg with dip tube, posts, seals etc etc after sitting in sanitiser.
• Pour in 1ltr Sanitiser and attach lid, give a real good shake around.
• Attach gas and dial just enough pressure just to push the sanitiser up the dip tube and out the Bronco Tap into my Jug of Sanitiser.
• Release excess pressure and take hatch(lid) off and place in sanitiser.
• Fill keg, put lid back on and Burp.
• Done

The keg before filling is full of CO2, as Ive only released excess pressure and filled straight away..

:icon_cheers: CB

 

[buttersd70]

I agree fully with Mark, although naive little me had to use google-fu for the woftam comment :lol: .

 

[Maxt]

I am from the school of thought, that if you sanitise your kegs, why not just wait until you are ready to transfer, then push the liquid out under pressure, then fill your keg. Takes all of 5 minutes That way you know there's no (or very very little) O2. It's not my experience that over time beer won't show effects if transfered by just pouring it in.
I think that poorly handled beer is a huge crime. You put all that effort into making the thing, to let yourself down at the last stage is crazy.
In competitions many good beers end up being scored down because of the oxidisation that smacks you over the palate!
My ten cents.

 

[Fourstar]

I agree fully with Mark, although naive little me had to use google-fu for the woftam comment :lol: .

Google-fu. Nice one butters!

I am from the school of thought, that if you sanitise your kegs, why not just wait until you are ready to transfer, then push the liquid out under pressure, then fill your keg. Takes all of 5 minutes That way you know there's no (or very very little) O2. It's not my experience that over time beer won't show effects if transfered by just pouring it in. I think that poorly handled beer is a huge crime. You put all that effort into making the thing, to let yourself down at the last stage is crazy. In competitions many good beers end up being scored down because of the oxidisation that smacks you over the palate!

I Agree with you completly there Maxt, i used to follow this method but somone knowledgeable on here (I think it was butters' arch nemises) said it was NQR to store acid based sanitisers or iodophor in SS. i Can't remember which. Either way i just clean my kegs now and the day of kegging i sanitise for 1/2 hour or so with star san.

As for the CO2 side of things. I'm quite the beer handling nazi and am quite afraid of oxidation. i usually pump in 2-3 bursts of CO2 @ 10 psi and vent before beginning to fill. Now that im going to be filtering majority of my beers i also have to deal with purging the filter with C02 as well. Oh JOY!