Flush kegs woth CO2 before filling?

On my new keg instructions it says that some people flush their kegs with CO2 before filling them each time.

1. Does that mean store them under a little pressure, give them a burst before filling them or is it for closed transfers only or ????

2. Should I do this? Should I store under pressure?

3. While I got your attention, do I really need the PBW or can I just use OxyClean to get the same effect at a much lower price?

No, you don't need to do that. However, after filling the kegs with beer, I give them a little CO2, purge a little, give a little more, and purge little. That way there's a layer of CO2 on top of the beer to protect it from oxidation.

I don't use PBW. Use oxiclean to clean it as best as you can, rinse it all out, then starsan to sanitize.

Most just purge the keg after they fill it. Hit it with 5-10 psi and release the pressure valve a couple of times.

I don't store them under pressure although mine normally get cleaned and refilled the same day.

Yes you can use Oxyclean instead. Target has it cheap.

Yup, no need to purge. Just make sure you get the unscented oxyclean.

Most folks purge a keg with CO2 a couple of times before filling it with beer. No need to store an empty keg under CO2.

I purge before and put the fill hose all the way to the bottom of the keg.

Yes, some purge w/ CO2 before filling, I would guess most do as I do and don't bother. From what I understand, oxidation occurs over a long period of time at higher temperatures, I do purge after filling, but really can't be bothered purging prior to filling.

I fill through the bev out port so only the beer surface is hitting air. I then put the CO2 on it and purge the head space a bit.

wilserbrewer said:

From what I understand, oxidation occurs over a long period of time at higher temperatures.

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Oxidation occurs at a faster rate at higher temperatures (room temperature and up). For example, that's why hot coffee goes stale quickly.

If you introduce oxygen at refrigeration temperatures, it will eventually oxidize the beer but the process may take weeks. If you warm it up to room temperature, the process will take hours.

Kayos said:

On my new keg instructions it says that some people flush their kegs with CO2 before filling them each time.

1. Does that mean store them under a little pressure, give them a burst before filling them or is it for closed transfers only or ????

2. Should I do this? Should I store under pressure?

3. While I got your attention, do I really need the PBW or can I just use OxyClean to get the same effect at a much lower price?

Click to expand...

1) If I give the kegs a few pounds of pressure to test the seal prior to filling than they receive some co2 purge. I've never purposely purged a keg prior to
filling.

2) I only store full kegs under pressure. You could store empty kegs with a couple psi so they are ready to fill if you wanted to.

3) The generic Oxyclean works well. Some people have a hard time rinsing it compared to PBW, but I think they usually have hard water. I have soft water and the Oxyclean rinses easily.

Hmm. I always fill the keg with some co2 and then bleed it down, fill through the line in dip tube and leave the PRV cracked open so the co2 has somewhere to go. Maybe it's overkill but I like it.

I give it a squirt of CO2 through the "out" tube just to get a small layer of gas on the bottom of the keg.

I think people put too much emphasis on the "CO2 blanket"... remember, there is CO2 in air. Air mixes. You can't just say that a layer of CO2 is completely separate from "air." They end up mixing. Therefore, it's not really worth it to me to store kegs under pressure - just a little bit in the bottom of the keg will cut down on the oxygen contact during transfer.

Pure co2 is heavier than "air" so if you fill the keg with some pressurized co2, and release the pressure, you would be left with say 12 times the co2 than just air if you had the regulator set at 13 psi. Think of it as a cloud, or how dry ice "smoke" lingers and collects (it's cold co2). If you are dealing with 5lb or less sized tanks, this could be expensive. If you have 20lb tanks, the cost is negligible.

I always purge kegs when filling. I also purge secondary carboys the same way. I trickle the CO2 in continuously while racking which is probably overkill, but I do it anyway.

After I clean a keg, I put in a gal or less of Starsan, seal it up give a good sloshing then charge with 10 lb of CO2 to push the Starsan out through the beverage out plumbing. There is usually a lb or so of pressure left when the Starsan is evacuated and I leave it like that until I fill so I guess I am purging my kegs

bendavanza said:

Pure co2 is heavier than "air" so if you fill the keg with some pressurized co2, and release the pressure, you would be left with say 12 times the co2 than just air if you had the regulator set at 13 psi. Think of it as a cloud, or how dry ice "smoke" lingers and collects (it's cold co2). If you are dealing with 5lb or less sized tanks, this could be expensive. If you have 20lb tanks, the cost is negligible.

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The dry ice is a great thing to bring up because it's so visible. I think my point still stands about the CO2 blanket. Eventually it will be dispersed in the air. If you fill a glass with dry ice, let it completely sublimate into gas, let it sit for awhile, and then come back later, I'd be willing to bet the gas inside the glass has pretty much the same composition as air.

Sure, kegs are a closed system, but I bet it's impossible to purge the headspace of a keg so that it's filled with 100% CO2. Purging a keg is great short term protection when transferring, but after it sits for awhile, the gases will eventually mix evenly. That's why the purging/venting thing is recommended three times.

I make my own PBW from unscented Oxiclean and phosphate free TSP... When they are emptied of the good stuff.. I fill them with hot tap water, then push a little CO2 in them to force hot water out the dip tube.. Then I fill them with hot PBW solution and let them sit for 30-60 mins with the top on..

Then I use a little CO2 (again with the party tap) to force a couple gallons through the dip tube (usually into a second corny I'm cleaning)..

Then I do it all again with a Hot water rinse... Finally I then put a gallon or two of star san solution in them, shake them violently and again use a bit of pressure to force the star san through the dip tube... I'll then pour the remaining sanitizer out and force the liquid in the dip tube out... I'll then pout it under pressure and allow some gas to slowly escape through the pressure release on top..

Then they are stored...

When ready to use, I do the star san thing again, and fill... Then I put them under pressure and slowly let some gas out of the pressure release until I am satisfied that it's mostly gas in the corny...

I then feel safe to let the kegs sit at room temp some more for aging... until ready for use..

Sometimes, if I'm cleaning up a bunch of stuff from a brew/ferment, I take the dip tube, dip tube valve and gas valve apart and soak them in the deep sink full of PBW with all the rest of the stuff...

Probably way overkill the way I do things.. But the thought of going through all the work, expense, and wait of brewing up and fermenting of 10G or more of beer, only to have it ruined by bacteria, scares the crap out of me... I would be highly disappointed were that to ever happen...

If you do two or three cornys at a time this way, it's really not that bad... eventually, I'll put together the fittings and hoses so that I can do them all simultaneously.. fill the first and have it automatically all pushed through the second, third, and fourth corny with one blast of gas..