Shorten the Pin lock gas dip tube to vent more O2 while purging CO2?

[diS]

All my kegs are pin lock, so there is no pressure release valve.
Since sometimes I leave keg on longer aging (without carbonating) I want to ensure that there is minimum oxygen left in it.

Before racking I purge the keg with CO2 for few seconds (lid off) and then rack the beer under CO2 blanket.
What I am concerned is oxygen that stays compressed under the lid, dip tube is about 1"1/4 long and it penetrates in keg long enough to leave space above it. I don't think that simple purging CO2 will vent out all O2, as it probably would on lid with pressure release valve.

I am thinking to cut gas dip tube so it barely peeks inside of keg, to reduce space between it and lid.

Do you see any disadvantage about this.. am I predicting something?

 

[stpug]

I'm interested in an answer to the shorter diptube question. I've wondered the same at times.

One alternative would be, after having finished transferring to your keg, purge the headspace with co2 and put the lid on. Then seal the lid and vent headspace pressure a couple times, with a final sealing of the lid. I feel like this would supply sufficient blanketing of co2.

Another alternative, which I've only read about is, to transfer to a fully sealed/purged keg through the liquid valve. The idea is you have a fully sealed and sanitized keg that's purged with co2. You transfer from BK through a liquid disconnect down internal diptube while providing gas venting so the siphon continues. When the transfer is done you disconnect siphon tube and gas venter, hook up to co2 gas disconnect, and hit with co2 to seal the lid. Since you never opened the keg, and the pressure was always going out, you've never exposed the keg or your beer to o2 or at least that's my understanding. Again, I've only read about this intriguing method. I DO wonder about things like pressure issues in carboy/fermenter vs keg, and small diameter disconnect hole size (1/4 - 3/16"), and how they might affect this method.

 

[beaksnbeer]

Not necessary Co2 is heavier and will push most of the oxygen to the tube the little bit that is left is inconsequential. One of the reasons ballocks are more popular you can vent easy and the vent is at the top of keg.

 

[shelly_belly]

I have several that are only 1/4" long. They work just fine.

 

[beaksnbeer]

I have several that are only 1/4" long. They work just fine.

Sounds to easy to get beer into the gas QD's and poppets IMHO

 

[diS]

I'm interested in an answer to the shorter diptube question. I've wondered the same at times.

One alternative would be, after having finished transferring to your keg, purge the headspace with co2 and put the lid on. Then seal the lid and vent headspace pressure a couple times, with a final sealing of the lid. I feel like this would supply sufficient blanketing of co2.

Another alternative, which I've only read about is, to transfer to a fully sealed/purged keg through the liquid valve. The idea is you have a fully sealed and sanitized keg that's purged with co2. You transfer from BK through a liquid disconnect down internal diptube while providing gas venting so the siphon continues. When the transfer is done you disconnect siphon tube and gas venter, hook up to co2 gas disconnect, and hit with co2 to seal the lid. Since you never opened the keg, and the pressure was always going out, you've never exposed the keg or your beer to o2 or at least that's my understanding. Again, I've only read about this intriguing method. I DO wonder about things like pressure issues in carboy/fermenter vs keg, and small diameter disconnect hole size (1/4 - 3/16"), and how they might affect this method.

I thought about 1st option too and it seems reasonable, but IMO cutting dip tube would have better effect since you are venting oxygen in upper part of keg (above 1 1/4" dip tube).

I think I'll go that way since I don't see any advantage if it is longer than needed.

If anyone have better suggestion please advice me before I take pipe cutter or angle grinder in my hand..

 

[zachattack]

The whole "CO2 blanket" concept sounds nice, but it's not entirely valid.

CO2 is indeed heavier than air, but gases will mix with other gases very readily due to Brownian motion (see Kinetic Theory of Gases). So your "protective blanket" of CO2 will happily mix with the air that remains in the top of the headspace.

I do agree with others that the amount of oxygen left is very small. In a closed ball lock with a PRV, the general practice is to pressurize then purge, and you usually do it a couple times. Each time you're diluting the air that's in there, then venting it. After a few cycles, the amount of air left in the keg will be almost nothing.

 

[raouliii]

MHO

AIR has about 78% Nitrogen, 21% Oxygen and 0.03% CO2 plus some other stuff. AIR and CO2 will reach a diffused equilibrium over time. The diffusion is very fast when turbulence is involved. Consequently, stratification of the AIR and CO2 inside the keg doesn't really happen because of the turbulence involved with injecting a flow of CO2. And equilibrium is eventually reached in the closed system, therefore, there wouldn't be a CO2 "blanket", just a CO2/AIR ratio.

I believe we inject CO2 and purge our kegs with the intention and result of increasing the ratio of CO2 to AIR, thereby reducing the amount of O2 and oxidation our brew is subjected to. I do think that one can increase the CO2/AIR ratio to a fairly high value by pushing in CO2 from the liquid tube while venting the lid or gas post. While diffusion would be occurring very fast, the sheer volume of CO2 entering the keg would overcome the diffusion rate and the CO2/AIR ratio would spike. The keg would need to remain sealed from that point on, in order to maintain that ratio. Opening the lid would result in the start of diffusion of outside AIR back into the keg with the eventual equilibrium of just AIR.

I gently fill my AIR filled kegs to just below the gas tube, pressure and purge at 30psi about 3 or 4 times and call it good.